1 TRACE METAL CONCENTRATIONS AND THE PHYSIOLOGICAL ROLE OF ZINC IN THE WEST INDIAN MANATEE ( T richechus manatus ) By NOEL YOKO TAKEUCHI A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL F ULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2012
2 2012 Noel Yoko Takeuchi
3 To my parents, for without them, I would not be where I am today. As first generation Japanese immigrants, they contin
4 ACKNOWLEDGMENTS I want to first, and foremost, thank my amazing advisor, Dr. David Barber, for his dedication to his students, his great insight to science, life and family, and for being encouraging whe n times were tough. I want to also give a huge thank you to my committee members: Drs. Roger Reep, Robert Bonde, Robert Cousins and Michael Walsh. This could not hav e been accomplished without their support, advice and expertise. The greatest part of sci ence is working together to answer a common question. As a result, I have a number of collaborators and organizations to thank for being a part of this project. The magnificent U nited S tates G eological S urvey ( Sirenia Project ) Florida Fish and Wildlife C ommission (Dr. Charles Deutsch), Nicole Auil Gomez and Dr. James Powell (Sea to Shore Alliance), Dr. Ramiro Isaza, Carla Bernal, Natalie Hall (UF) and Dr. Ellen Wiedner (Ringling Brothers) for elephant samples, the Marine Mammal Pathobio logy Laboratory (Dr Martine de Wit and staff), Mote Marine Laboratory and Aquarium ( Joseph and Joyce Kleen (Crystal River National Wildlife Refuge) for plant surveys, Dr. Jim Wellehan and Heather Maness for their help with phylogenetic analysis, Drs. David Silverman and Chi ng kuang Tu for their patience and expertise in carbonic anhydrase kinetics (UF Biochemistry), Joseph Aufmuth Anthony Lau and Dr. Dan Slo ne (USGS) for their help with GIS, Melanie Pate (UF) Terry Merano (UF), Sharon Norton and Carolyn Diaz (UF ICBR) for their assistance in protein analysis Dr. Raymond Bergeron and Elizabeth Nelson (UF Pharmacy) for t he i r years of patience and assistance with the ICP MS c) Thank you to the University of
5 their assistance and support. I would also like to acknowledg e the Physiological Sciences department in the College of Veterinary Medicine, both faculty and students, for their support. I also want to thank everyone at the CEHT, especially those in the Barber Lab (Nicholas Doperalski, April Feswick, Erica Anderson, Ley Cody Smith), for sharing their knowledge with me and for all their support throughout the years. inspire me through their passion, and collaborative attitude in the field of marine mammal science. I want to thank my friends across the country for listening to my struggles in graduate school, coming to visit, all the late night phone conversations and the continuous laughter. Thank you to Kai, Sheri and Pingel for puttin g up with me and willing to share common grounds and Jayson for his patience, support and love. Lastly, thank you to my family for all their support and understanding throughout my years in graduate school. My family has guided me and helped shape the pe rson who I am today They believed in me when I didn even believe in myself and were always there for me through thick and thin. College of Veterinary Medicine Team Building G Animal Health Program, the for Marine Research, and the Graduate Student Council Travel Grants. I also want to thank the National Science Foundation (NSF) and t he Australian Academy of Sciences for providing me a great opportunity to begin a career as an international researcher in Australia through the NSF East Asia and Pacific Summer Institute Program in 2009.
6 This research was approved by the University of F Care and Use Committee (IACUC) under study #201105936 and #201101961 and the United States Fish and Wildlife Service (FWS ) Federal Research #MA791721 4. Additional permission was obtained from Homosassa Springs Wildlife State Park and Mote Marine Laboratory. A saltwater fishing license (State of Florida Recreational License #395975378) from FWC allowed for a maximum of five gallons of saltwater seagrass and a permit from the Department of Agriculture was approved for fre shwater plants (Florida Department of Agriculture and Consumer Services, Certificate of Nursery Registration #48006548). Samples we re taken opportunistically from animals and in conjunction with health assessments and were not taken solely for the purpose of this project.
7 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ .......... 12 LIST OF FIGURE S ................................ ................................ ................................ ........ 1 4 LIST OF ABBREVIATIONS ................................ ................................ ........................... 16 ABSTRACT ................................ ................................ ................................ ................... 17 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 21 Overview of Metals in Marine Mammals in Relation to Sirenians ........................... 22 Past Studies of Metal Accumulation in Dugongs ................................ .............. 24 Past Study of Metal Accumulation in Manatees ................................ ............... 25 Factors Affecting Metal Accumulation ................................ .............................. 26 Sampling Methods in Marine Mammals ................................ ........................... 27 Metals in Whole Blood of Marine Mammals ................................ ..................... 28 Metal Toxicity and the Importance of Baseli ne Levels ................................ ............ 29 Metal Detoxification Mechanisms in Marine Mammals ................................ ........... 32 Mercury and Selenium ................................ ................................ ..................... 32 Metallothioneins ................................ ................................ ............................... 33 The Physiological Role of Zinc ................................ ................................ ................ 35 Zinc and Metallothionein Gene Expression ................................ ...................... 36 Carbonic Anhydrase ................................ ................................ ......................... 37 Manatee Physiology ................................ ................................ ............................... 39 Gastrointestinal Tract ................................ ................................ ....................... 39 Hindgut Fermentation ................................ ................................ ....................... 41 Metabolism ................................ ................................ ................................ ....... 42 Diet and the Environment ................................ ................................ ....................... 42 Vegetation Preference and Possible Role in Metal Exposure .......................... 43 Metals in Sediment ................................ ................................ ........................... 44 Manatee Evolution ................................ ................................ ................................ .. 45 Fossil Evidence ................................ ................................ ................................ 45 Phylogeny Classification ................................ ................................ ................... 46 Project Objectives ................................ ................................ ................................ ... 48 Chapter 2 Objective ................................ ................................ .......................... 49 Chapter 3 Objective ................................ ................................ .......................... 50 Chapter 4 Objective ................................ ................................ .......................... 50 Chapter 5 Objective ................................ ................................ .......................... 51 Chapter 6 Objective ................................ ................................ .......................... 51 Chapter 7 Objective ................................ ................................ .......................... 52
8 Significance of the Project ................................ ................................ ...................... 52 2 BASELINE TRACE METAL LEVELS IN BLOOD O F WILD AND CAPTIVE WEST INDIAN MANATEES ( Trichechus manatus ) IN FLORIDA AND BELIZE ..... 67 Background ................................ ................................ ................................ ............. 67 Materials and Methods ................................ ................................ ............................ 69 Wild Manatees ................................ ................................ ................................ .. 69 Captive Manatees ................................ ................................ ............................ 70 Blood Collection ................................ ................................ ............................... 70 Sample Analysis ................................ ................................ ............................... 71 Statistics ................................ ................................ ................................ ........... 72 Fractionation and Reference Range Calcula tions ................................ ............ 73 Results ................................ ................................ ................................ .................... 74 Whole Blood ................................ ................................ ................................ ..... 74 Plasma ................................ ................................ ................................ ............. 76 Erythrocytes ................................ ................................ ................................ ..... 76 Blood Fractionations and Reference Interval ................................ .................... 77 Whole Blood Comparis ons to Other Marine Mammals and Components ........ 77 Discussion ................................ ................................ ................................ .............. 78 Copper ................................ ................................ ................................ .............. 79 Zinc ................................ ................................ ................................ .................. 81 Arsenic ................................ ................................ ................................ ............. 83 Selenium ................................ ................................ ................................ .......... 85 Summary ................................ ................................ ................................ ................ 86 3 TRACE METAL DISTRIBUTION IN TISSUES OF WILD FLORIDA MANATEES ( Trichechus manatus latirostris ) FROM PAST TO PRESENT .............................. 104 Background ................................ ................................ ................................ ........... 104 Materials and Methods ................................ ................................ .......................... 106 Carcass Samples ................................ ................................ ........................... 106 Live Manatee Samples ................................ ................................ ................... 107 Sample Analysis ................................ ................................ ............................. 108 Reference Conversion Factor ................................ ................................ ......... 109 Statistical Ana lysis ................................ ................................ .......................... 110 Results ................................ ................................ ................................ .................. 111 Liver ................................ ................................ ................................ ............... 111 Kidney ................................ ................................ ................................ ............ 111 Skin ................................ ................................ ................................ ................ 112 Feces ................................ ................................ ................................ .............. 113 Urine ................................ ................................ ................................ ............... 114 Other Tissues ................................ ................................ ................................ 114 Conversion Factor ................................ ................................ .......................... 114 Thirty Year Comparison of Metals in Manatees ................................ .............. 115 Discussion ................................ ................................ ................................ ............ 115 Copper ................................ ................................ ................................ ............ 115
9 Zinc ................................ ................................ ................................ ................ 117 Selenium ................................ ................................ ................................ ........ 119 Arsenic ................................ ................................ ................................ ........... 119 COD and District Locations ................................ ................................ ............ 120 From Past to Present ................................ ................................ ..................... 122 Summary and Significance ................................ ................................ ................... 123 4 COPPER, ZINC, SELENIUM AND ARSENIC DISTRIBUTION IN VEGETATION AT KINGS BAY, CR YSTAL RIVER, FLORIDA WITH RELATION TO THE FLORIDA MANATEE ( Trichechus manatus latirostris ) ................................ ......... 136 Background ................................ ................................ ................................ ........... 136 Materials and Meth ods ................................ ................................ .......................... 139 Vegetation Samples ................................ ................................ ....................... 139 Water ................................ ................................ ................................ .............. 140 Sediment ................................ ................................ ................................ ........ 140 Sample Analysis ................................ ................................ ............................. 141 GIS ................................ ................................ ................................ ................. 142 Thirty Year Comparison of Metals in Vegetation ................................ ............ 143 Statistical Analysis ................................ ................................ .......................... 143 Results ................................ ................................ ................................ .................. 143 Vegetation ................................ ................................ ................................ ...... 144 Copper ................................ ................................ ................................ ............ 144 Zinc ................................ ................................ ................................ ................ 145 Arsenic ................................ ................................ ................................ ........... 145 Selenium ................................ ................................ ................................ ........ 146 Roots ................................ ................................ ................................ .............. 146 Water ................................ ................................ ................................ .............. 146 Sedime nt ................................ ................................ ................................ ........ 147 GIS ................................ ................................ ................................ ................. 147 Discussion ................................ ................................ ................................ ............ 148 Metals and Vegetation ................................ ................................ .................... 148 Copper ................................ ................................ ................................ ..... 148 Zinc ................................ ................................ ................................ .......... 1 49 Arsenic ................................ ................................ ................................ ..... 149 Selenium ................................ ................................ ................................ .. 150 Opportunistic Herbivory ................................ ................................ .................. 151 Roots, Water, and Sediment ................................ ................................ .......... 152 Possible Anthropogenic Influences ................................ ................................ 152 Conservation Impact ................................ ................................ ............................. 154 5 PURIFICATION AND CATALYTIC PROPERT IES OF TWO ISOZYMES OF CARBONIC ANHYDRASE IN THE FLORIDA MANATEE ( Trichechus manatus latirostris ) ................................ ................................ ................................ .............. 163 Background ................................ ................................ ................................ ........... 163 Materials a nd Methods ................................ ................................ .......................... 165
10 Blood Samples ................................ ................................ ............................... 165 Preliminary Quantification of CA Isozymes in Hemolysate ............................. 166 Inhibition of Ethoxzolamide ................................ ................................ ............. 167 CA Purification ................................ ................................ ................................ 167 Carbonic Anhydrase Kinetics 18 O Exchange Meth od ................................ .. 168 Carbonic Anhydrase Purity Assessment ................................ ........................ 169 Database Analysis ................................ ................................ .......................... 171 Results ................................ ................................ ................................ .................. 171 Preliminary Quantification ................................ ................................ ............... 171 Catalytic Activity ................................ ................................ ............................. 172 Manatee Carbonic Anhydrase I and II Identification ................................ ....... 172 Discussion ................................ ................................ ................................ ............ 173 Significance and Future Studies ................................ ................................ ........... 175 6 IDENTIFICATION AND INDUCTION OF METALLOTHIONEIN IN THE WEST INDIAN MANATEE ( Trichechus manatus ): POTENTIAL BIOMARKER FOR METAL CONTAMINATION ................................ ................................ ................... 186 Background ................................ ................................ ................................ ........... 186 Materials and Methods ................................ ................................ .......................... 190 Manatee Leukocytes ................................ ................................ ...................... 190 Cell Culture ................................ ................................ ................................ ..... 191 Manatee Skin ................................ ................................ ................................ 192 RNA Purification and cDNA ................................ ................................ ............ 193 MT 1: Cloning and Sequence Determination ................................ .................. 194 ................................ ................................ .......................... 195 TmMT 4: Cloning and Sequencing ................................ ................................ 195 Housekeeping Gene ................................ ................................ ....................... 196 Real time PCR of MT Expression ................................ ................................ ... 197 Statistical Analysis ................................ ................................ .......................... 198 Results ................................ ................................ ................................ .................. 198 TmMT 1 ................................ ................................ ................................ .......... 198 TmMT 4 ................................ ................................ ................................ .......... 200 Discussion ................................ ................................ ................................ ............ 200 TmMT 1 and TmMT 4 ................................ ................................ ..................... 200 Induction of MT 1 by CdCl 2 ................................ ................................ ............. 201 Induction of MT 1 by ZnCl 2 ................................ ................................ ............. 202 TmMT 4 as a Biomarker ................................ ................................ ................. 203 Zinc and Wound Healing ................................ ................................ ................ 204 Future Studies ................................ ................................ ................................ ...... 205 7 TRACE METAL CONTROL IN PAENUNGULATA WITH PHYLOGENY OF METALLOTHIONEIN CDNA IN FLORIDA MANATEE ( Trichechus manatus latirost ris ) AND ASIAN ELEPHANT ( Elephas maximus ) ................................ ....... 218 Background ................................ ................................ ................................ ........... 218 Materials and Methods ................................ ................................ .......................... 221
11 Trace Metal Samples ................................ ................................ ..................... 221 Sample Analysis ................................ ................................ ............................. 221 EmMT Cloning and Sequencing ................................ ................................ ..... 222 ................................ ................................ .............................. 224 Phylogenetic Analysis ................................ ................................ .................... 225 Statistics ................................ ................................ ................................ ......... 226 Results ................................ ................................ ................................ .................. 226 Blood and Liver Comparisons ................................ ................................ ........ 226 EmMT Sequence ................................ ................................ ............................ 227 Phylogenetic Analysis ................................ ................................ .................... 227 Discussion ................................ ................................ ................................ ............ 228 Zinc in Blood ................................ ................................ ................................ ... 228 Metallothionein ................................ ................................ ............................... 228 8 CONCLUSION ................................ ................................ ................................ ...... 237 Chapter 1 ................................ ................................ ................................ .............. 237 Chapter 2 ................................ ................................ ................................ .............. 237 Chapter 3 ................................ ................................ ................................ .............. 238 Chapter 4 ................................ ................................ ................................ .............. 238 Chapter 5 ................................ ................................ ................................ .............. 239 Chapter 6 ................................ ................................ ................................ .............. 240 Chapter 7 ................................ ................................ ................................ .............. 240 Significance ................................ ................................ ................................ .......... 240 LIST OF REFERENCES ................................ ................................ ............................. 242 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 272
12 LIST OF TABLES Table page 1 1 Metal concentrations in kidney and liver ................................ ............................. 54 1 2 Whole blood metal concentrati ons in various marine mammal species ............. 63 2 1 Metal concentrations in whole blood of wild, captive and rehabilitating (rehab) West Indian manatees based on location. ................................ ............. 88 2 2 Pearson correlation of metal concentrations ................................ ..................... 91 2 3 Metal concentrati ons in wild, captive, and rehabilitating West Indian manatees in Florida and Belize ................................ ................................ .......... 92 2 4 Metal concentrations in plasma. ................................ ................................ ........ 93 2 5 Metal concentrations in erythrocytes. ................................ ................................ 94 2 6 M etal concentrations in whole blood from various mammalian species. ........... 97 2 7 Copper, zinc, selenium, and arsenic concentratin of various aquatic animals submitted to the laboratory. ................................ ................................ .............. 100 2 8 Reference Range. ................................ ................................ ........................... 103 3 1 Manatee carcasses. ................................ ................................ ........................ 124 3 2 T issues from wild and necropsied manatees from 2008 2011. ..................... 125 3 3 The reference conversion factors ................................ ................................ .... 129 3 4 The conversion factor from dry weight to wet weight. ................................ ...... 130 3 5 Thirty year comparison of kidney and liver metal concentratins in the Florida manatee. ................................ ................................ ................................ .......... 131 3 6 Liver and kidney comparisons between various marine mammal species ...... 1 32 4 1 Metals in roots and shoots. ................................ ................................ .............. 158 5 1 Carbonic anhydrase activity comparison ................................ ......................... 178 6 1 Oligonucleotide primers used for cloning and real time PCR. ......................... 210 6 2 Correlation of TmMT 4 transcript. ................................ ................................ .... 217 7 1 Blood comparisons of captive Asian elep hant and wild Florida manatee. ..... 231
13 7 2 Liver comparisons in Paenungulata. ................................ ................................ 232 7 3 Phylogenetic analysis of MT 1 and 2 nucleotide sequences. .......................... 234
14 LIST OF FIGURES Figure page 1 1 Schema tic diagram of the role of zinc on transcription of MT. ............................ 66 2 1 Zinc meanstandard deviation in whole blood of various mammalian species .. 99 2 2 Blood compartments ................................ ................................ ........................ 101 2 3 Reference interval box plots. ................................ ................................ ........... 102 3 1 Metal concentration in tissues of the Florida manatee. ................................ .... 128 4 1 Plant survey stations with map of Florida. ................................ ..................... 155 4 2 Average trace metal concentrations in total vegetation.. ................................ 156 4 3 Average trace metal concentrations per vegetation species. .......................... 157 4 4A Geographic Information System o f average copper concentration ................. 159 4 4B Geographic Information System of average zinc concentration in. .................. 160 4 4C Geographic Information System o f average arsenic concentration ................ 161 5 1 Inhibition by iodide of CA in manate e hemolysate ................................ ........... 176 5 2 Purification of CA from hemolysate of the Florida manatee. ............................ 177 5 3 Isoelectrical focusing w ith 2D gel electrophoresis for manatee CA ................. 179 5 4 Multiple species comparison in CA II. ................................ .............................. 180 5 5 The pH profile for the catalysis of the hydration of CO 2 determined by 18 O exchange method.. ................................ ................................ ........................... 181 5 6 Purified isozyme I Spectrum ................................ ................................ ............ 182 5 7 Protein Identificaton.. ................................ ................................ ....................... 183 5 8 Purified isozyme II Spectrum. ................................ ................................ .......... 184 5 9 Protein Ident ificaton ................................ ................................ ......................... 185 6 1 Schematic diagram of CdCl 2 and ZnCl 2 exposures. ................................ ........ 208 6 2 AlamarBlue data. ................................ ................................ .......................... 209
15 6 3 Alignment of TmMT 1 ................................ ................................ ...................... 211 6 4 Alignment of TmMT 4. ................................ ................................ ..................... 212 6 5 Alignment of housekeeping gene ................................ ................................ .... 213 6 6 Time response curve ................................ ................................ ....................... 214 6 7 Dose response curve ................................ ................................ ...................... 215 6 8 Metallothionein 4 expression in wild manatees ................................ ................ 216 7 1 MT alignment in the Asian elephant and Florida manatee ............................... 233 7 2 Bayesian tree of MT 1 and 2. ................................ ................................ ........... 236
16 LIST OF ABBREVIATION S CA carbonic a nhydrase bp base pair dw dry weight GIS Geographic Information System ICP MS Inductively Coupled Plasma Mass Spectrometry IEF i soelectrofocusing MT m etallothionein MRE metal response element ppb parts per billion ppm parts per million SAV submerged aquatic vegetation SL s traight length Wt w eight ww wet weight
17 Abstract of Dissertation Presented to the Graduate School of the Uni versity of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy TRACE METAL CONCENTRATIONS AND THE PHYSIOLOGICAL ROLE OF ZINC IN THE WEST INDIAN MANATEE ( TRICHECHUS MANATUS ) By Noel Yoko Takeuchi May 2 012 Chair: David S. Barber Major: Veterinary Medical Sciences Due to the potential impact of contaminants in marine mammals, many studies have examined metal levels in cetaceans and pinnipeds However only two studies have been reported for the endange red West Indian manatee ( Trichechus manatus ). Thus, the objectives of this study are: 1 ) Determine baseline levels of metals in the Florida manatee in wild and captive West Indian manatees 2 ) Evaluate metal loads in various tissues of the Florida manatee 3 ) Asses trace metals found in the surrounding environment of Kings Bay, Crystal River, Florida, 4 ) Examine carbonic anhydrase in the Florida manatee, 5 ) Evaluate MT as a biomarker for monitoring metal exposure and induction of MT expression in manatees, and 6) Compare metal concentrations and MT expression in other Paenungulata species With collaboration from United States Geolo gical Survey Sirenia Project, Florida Fish and Wildlife Conservation Commiss ion, and Sea To Shore Alliance, blood samples fro m 151 wild West Indian manatees were collected during health assessments in Florida and Belize from 2008 2011 In addition, capt ive and rehabilitating manatee samples were obtained Blood was analyzed via ICP MS for various metals and a clinical referenc e range for metal levels in whole blood, plasma and red blood cells was
18 obtained Based on this data, reference ranges for up to 22 elements in manatee blood were determined. Zinc (11.24.5 ppm) was of main interest, as levels were higher in manatees th an in other related species, such as the Elephas maximus and other marine mammals M etal distribution in manatee carcasses was examined and acc umulation of Zn was primarily present in the liver with a range of ( 32.39 288.55 ppm, w w ) To evaluate potent ial sources of metal exposure, the surrounding environment and vegetation samples from Kings Bay, Crystal River were evaluated for Zn, Cu, As, and Se. Our study determined that plant material is likely to be a significant source of metal exposure. Diet may be contributing to Zn accumulation in manatees with levels of Zn higher in favorable vegetation species, such as Vallisneria americana and Najas guadalupensis Moreover, metal levels were higher in the northern areas of Kings Bay with possibly anthrop ogenic influences Due to the fact that zinc levels were high without apparent adverse effect, w e explored possible physiological factors underlying the high zinc levels. Carbonic anhydrase is a zinc metalloenzyme which catalyzes the hydration/dehydrati on of CO 2 and functions in respiration, acid base balance, and fluid formation Two isozymes of carbonic anhydrase from manatee s were confirmed by isoelectrofocusing with 2D SDS PAGE and LC MS/MS and confirmation of CA I and CA I I was unique compared to ot her marine mammal species which only have one isozyme Catalysis of CO 2 hydration by manatee erythrocyte CA I was measured by 18 O exchange method and showed a maximum k cat /K m of 3 x10 7 M 1 s 1 that was influenced by two ionizations with a pKa of 7 0.1 and 5 0.5 possibly due to an additional attachment of an amino acid to
19 the active site Manatee CA I I catalyzed with a maximum k cat /K m of 6 x10 7 M 1 s 1 and showe d a single ionization of pKa 6 0.1. These kinetic constants for CO 2 hydration are s imilar to those of other mammalian species In addition to CA, m etallothionein (MT) was evaluated in the Florida manatee. Metallothionein is a metal binding protein involved in divalent metal homeostasis that has not been examined in manatees and elephants We successf ully cloned and sequenced MT 1 (381 bp) from isolated peripheral blood mononuclear cells of the Florida manatee that was 83% identical to rhesus macque ( Macaca mulatta ) MT 1 E and 84% identical to chimpanzee ( Pan troglodytes ) MT 1 x. MT expression was induce d in cultured manatee leukocytes exposed to 2x 10 9 M CdCl 2 and 2x 10 5 M ZnCl 2 demonstrating a 7 fold and 13 fold increase following 24 hr exposure, respectively. Maximal induction of MT expression occurred at lower doses of CdCl 2 of 2x10 11 M than 2x10 8 M and higher doses of ZnCl 2 of 2x10 4 M compared to 2x10 6 M. Moreover, a partial sequence for MT 4 (182 bp) was obtained and evaluated as a potential biomarker for metal exposure However, MT 4 expression in manatee skin did not correlate with metal lev els in blood or skin. This is the first study to evaluate carbonic anhydrase kinetics and metallothionein expression in O rder Sirenia. Manatees belong to clade Paenungulata, with elephants as the closest relative next to the dugong. Asian e lephant MT ( 376 bp) was cloned and sequenced with phylogenetic analysis resulting in a maximum likelihood of 74% to manatee MT 1 Sirenians are unique amongst the marine mammals, as the only herbivorous species and are sentinel species to the health of our waterways The results of this study will aid
20 environmental agencies and management officials to monitor trace metal accumulation in the aquatic environment for manatee health and conservation
21 CHAPTER 1 INTRODUCTION With an ever increasing human population, an thropogenic contaminants in the aquatic environment are a topic of interest to many researchers. M etals from anthropogenic influences (industrial effluents, sewage outfalls, and agricultural runoff) and natural sources (atmospheric changes, erosion of roc ks, and volcanic activity) frequently find their way into the aquatic environment, espe cially near shore estu aries. 1999; Sahu et al., 2007). Sirenians are unique among marine mammals in that they are fully aquatic, obligate her bivores, confined to food sources in shallow, near shore estuaries, rivers, bays and freshwater habitats (Reynolds et al., 1999). Because these areas are commonly impacted by anthropogenic influences and contaminants, including metals, sirenians may be us ed as a biomonitoring tool to track the health of our aquatic environment (Bonde et al., 2004; Bossart, 2006). This dissertation will examine the levels of metals in manatees from various locations to determine a ba seline reference range any geographic va riation in metal levels, and how these metal levels vary in the manatee diet. Levels of zinc observed in manat ees were unusually high, thus, possible roles for metallothionein and carbonic anhydrase in contributing to the physiological need of elevated zi nc levels observed in manatee blood will also be examined. There are now four living species of the Order Sirenia, which include two families (Reynolds et al., 1999): Family Dugongidae and Family Trichechidae. The Family Dugongidae consists of the dugong, Dugong dugon Whereas, the Family Trichechidae include s the Amazonian manatee ( Trichechus inunguis ), the West African manatee ( Trichechus senegalensis ), a nd the West Indian manatee which is comprised of the
22 Florida manatee ( Trichechus manatus latirostri s ) and the Antillean manatee ( Trichechus manatus manatus ). This study will focus on metal concentration and physiological mechanisms of the West Indian manatee, especially that of the Florida manatee. The Florida manatee is the only sirenian in the wate rs of the United States The population is in distress despite protection since June 6, 1893 and is currently protected under the Endangered Species Act of 1973, the Florida Manatee Sanctuary Act of 1978, and the Marine Mammal Protection Act of 1972 (Rizz ardi, 1997) Despite the legal protection, the current estimated population li es at 3,3 00 4,000 (Reep and Bonde, 2006) to approximately 5,000 (FWS, 2011 ) with many uncertainties about the very little genetic diversity (Garci a Rodriguez et al., 1998; Vianna et al., 2006) low reproductive rate ( Odell et al., 1995; Rathburn et al., 1995; Reynolds and Odell, 1991 ), and decr ease areas of warm water refugia (Laist and Reynolds, 2005). Therefore the manatee population should be m onitored for any threats in their surrounding environment. In addition, manatees are commonly hunted and consumed in many parts of the world, such as West A frica, and Central and South America Thus, assessing and understanding the levels of metals in th e West Indian manatee will not only help the population of manatees, but human populations as well. Overview of Metals in Marine Mammals in Relation to Sirenians Many studies have been performed on metal burdens in marine mammals, especially that of ceta ceans and pinnipeds. Cetaceans are useful sentinel species for contaminant loads in the environment due to their longevity, position on top of the food chain, ad aptations for diving to great depths, and large fat reserves (Aguilar and Borrel l, 2001 ). Moreover, the amphibious lifestyle and smaller size of pinnipeds makes them more obtainable f or scientific studies. However, m anatees
23 are primary consumers that are in direct association with the aquatic environment, making them prim e subjects for monitoring metal loads. There are many factors involved in the distribution and accumulation of metals in marine mammals Varying effects of ecological stressors as well as phy siological stress of an animal and their health can affect me tal levels in an animal ( Bennet t et al., 2001; Caurant et al., 199 5 ; Das et al., 2003 ; Law, 1996 ) H arper et al. ( 2007 ) found that hepatic Hg levels were significantly higher in California sea lions ( Zalophus califnornianus ) diagnosed with domoic acid tox icity. Moreover Das et al. (2004) examined Zn, Cd, Cu, Fe, Se, and Hg concentrations in 132 harbor porpoises ( Phocoena phocoena ) and found Zn concentrations in various tissues increased in those individuals that were emaciated or diagnosed with bronchopn eumonia In addition, metal levels accumulate differently depending on species, as shown in Table 1 1. Arsenic levels were 3x higher in dugong liver than in other marine mammal species, such as the Californ ia sea lion (Harper et al., 2007 ), while Fe leve ls exceeded 35,000ppm in the liver of the dugong (Haynes et al., 2005). Hepatic Cu levels in dugongs were 10x other marine mammal species, with levels generally greater in the liver than the kidney for most marine mammal species. Moreover, Se levels were l ower in dugongs when compared to other marine mammal species, while Zn levels were 25 100x g reater in sirenians. With respect to non essential metals, sirenians were similar to other marine mammal species. Mercury and cadmium levels were usually lower in mystecetes than odontocete s, as seen in the bowhead whale ( Balaena mysticetus ; Byrne et al., 1985; Krone et al., 1999; Rosa et al., 2008), with levels higher in the kidney
24 than the liver. As a result, sirenians seem to be unique in metal accumulation of essential elements when compared to other marine mammal species. Past Studies of Metal Accumulation in Dugong s Many studies h ave been performed with respect to determining trace metal concentrations in cetaceans and pinnipeds but only a f ew studies have been performed o n sirenians. Contaminant levels were first investigated in the dugong of all the sirenians. Metals, including As, Cd, Cu, Hg, and Zn, are the most common metals to be released into the aquatic environment due to agriculture, with continual release of metals into the marine environment via storm water and wastewater discharges from industrialization (Haynes and Johnson, 2000). Studies of metals in sirenians first began roughly 30 years ago when Miyazaki et al. (1979) first evaluated metals (THg, MeHg, Se, Fe, Mn, Zn, Cu, Pb, Ni, Co, Cd, As) in the muscle of two dugongs. They found higher levels of each element, except for arsenic, in older dugongs from Indonesia suggesting that age is a factor in metal accumulation. The most extensive study of metals in dugongs was by Denton et al. (1980). They reported levels of metals (Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, Ag, and Zn) in various tissues in 43 dugong carcasses from northern Queensland in 1974 1978. Concentrations of Cd, Fe, Zn, Cu, Cd, Co, and Ag were highest in the liver and kidney. The concentrations of Fe (778 82,363 g/g, dw), Zn (219 4,183 g/g, dw), Cu (9.1 608 g/g, dw), Co (0.5 72 g/g, dw), and Ag (0.2 38.8 g/g, dw) in the liver and Cd (0.2 309 g/g, dw) in the kidney were higher than those found in other marine mammals (Table 1 1). Denton et al. (1980) concluded that the unusual metal accumulation may be due to the dietary fluctuations of elements in the seagrass. These unusual metal levels were also noted by Marsh (1989) from three
25 dugongs stranded after a cyclone in 1984 as well as Haynes et al. (2000 ) who examined three dugongs from the Great Barrier Reef. Past Study of Metal Accumulation in Manatees Human activities and population have increased throughout the years, with coast al development for housing, agriculture, and commercial purposes negatively affecting manatee habitats. In addition to urban growth, environmental changes caused by channel dredging, industrial and municipal discharge, and increased nutrient loading are of concern for the manatee as well (Burns et al., 1997; Smith, 1993). Metals in examined tissue samples (liver, kidney, blubber, and muscle) from roughly 54 manatee carcasse s from October 1977 to January 1981. Due to their herbivorous diet and low position on the food chain, lead, iron, selenium, cadmium, and mercury were not of significant concern to researchers. However, they found Cu concentrations in the liver to be of concern with levels in a range of 4.4 1,200 ppm (dw) with the highest concentrations in individuals from the northwest coast and Crystal River population. As studies have shown that hepatic Cu concentrations of greater than 500 ppm wer e linked to the death of sheep and lethal Cu poisoning is seen in liver concentrations of 1,250 ppm in cattle. These high hepatic Cu levels in manatees were associated with areas of high Cu based herbicide use, suggesting that management contro l the Cu based herbicides in areas where manatees are present. As a result, this study helped deter the use of copper based herbicides for aquatic plant control in Crystal River, Florida; a valuable ecosystem where the largest aggregation of manatees is p resent during winter (Hartman, 1974). Despite the significance of this study m etal levels in Florida manatees have not been addressed
26 since the 1980s until this project. Due to collaboration with Dr. Tom incorporated his data into Chapte rs 3 and 4 in order to monitor the health of the Florida manatee within the past thirty years. Factors Affecting Metal Accumulation A ccording to Das et al. (2003 ), the key factors influencing metal accumulation in marine mammals are geographic location, di et, age, sex, tissue and metabolic rate. For instance, mercury is naturally higher in the Mediterranean Sea (Andre et al. 1991) and cadmium levels tend to be higher in the Arctic (Johansen et al. 1980). Noda et al. (1995) found Mn and Hg in tissues of the northern fur seal ( Callorhinus ursinus ) to be significantly higher in Sanriku, Japan than the Pribilof Islands, Alaska, as Seixas et al. (2008) found the highest hepatic Hg levels were present in F ranciscana dolphin ( Pontoporia blainvillei ) from the sout hern end of Brazil. Moreover, Meador et al. (1999) examined brain, kidney, and liver of 44 stranded bottlenose dolphins ( Tursiops truncatu s ) and found MeHg and THg in the liver and kidney were higher in Florida dolphins, whereas Pb, Cu and Zn liver an d kidney values were higher in Texas dolphins. The effect of age dep ends on the metal of interest It has been found that cadmium and mercury concentrations generally increase with age, where as zinc and copper levels are highest in young marine mammals, as summarized in Das et al. ( 2003 ). Lavery et al. (2008) found that in common dolphins ( Delphinus delphis ) and bottlenose dolphins from South Australia, liver Cd, Hg, Se, and Pb concentrations increased with age, as Cu decreased with age. Age dependant factors were also seen in California sea lions, with hepatic Cd and Hg increasing with age, as well as renal Zn levels (Harper et al. 2007). This was also seen in phocids, where hepatic Cd and renal
27 Cd, inorganic Hg, and Zn increased with an increase in le ngth in fifteen harbor seals in Japan (Tohyama et al., 1986) There are patterns in metal accumulation ba sed on the tissue of interest where mercury accumulates pre dominately in the liver and cadmium primarily in the kidney Factors, such as pregnancy, parturition, and lactation can also influence metal concentrations, as studies have shown transplacental transfer of metals ( Ronald et al., 1984; Honda et al. 1987 ; Yang et al. 2004 ) and transfer through milk during nursing as well (Canella and Kitchene r 1992). Therefore, a number of factors may contribute to the accumulation of metals in marine mammals. Sampling Methods in Marine Mammals Metal concentrations in marine mammals have been commonly evaluated by organs accessed from subsistence hunting, wh aling, and strandings. In addition to organ samples, metals in marine mammals have ut ilized bone (Lavery et al., 2009 ), baleen (Hobson et al., 2004), and teeth (Ando et al., 2005; Kinghorn et al., 2008) as a useful indicator of long term accumulation comp ared to soft tissue. In addition, molts have provided researchers with an effective and non invasive tool for metal sampling in pinnipeds (Andrade et al., 2007; Gray et al., 2008). This alternative sampling technique was demonstrated in dugongs as well. Edmonds et al. (1997) used X ray fluorescence (XRF) imaging for metal analysis o f an adult female dugong tusk and found Zn concentrations increased as the animal aged, but Zn levels were lower than those found in human teeth. This study found five to eig ht year periods of variation in tusk Zn concentrations, which may indicate varying exposure levels or a possible adaptive change to metal exposure by the dugongs during the 55 years of life. Due to the large size and aquatic lifestyle of marine mammals, v arious sample techniques have been utilized to determine metal burdens.
28 M etals in W hole B lood of Marine M ammals Whole blood is the preferred method of measuring metal levels of live, wild animals. A number of studies have validated the use of blood in mar ine mammal species as a tool to investigate metal levels and its impact on the health of the animals. This is of great importance for our study in manatees, as we utilized whole blood to determine a baseline refere nce range for metals (Chapter 2 ), examine d the enzymatic functions of carbonic anhydrase in red b lood cells (Chapter 5 ), and characterized an important protein, metallothio nein, in lymphocytes (Chapter 6 ). Blood has been utilized in a number of marine mammal species in order to determine metal concentrations as shown in Table 1 2. Metal levels in whole blood of the Florid a manatee (Stavros et al., 2008a ) were within the range of other marine mammal species, except for Zn and Se. Zinc values were 2 4x that of other marine mammal species Rela tively h igh Zn ( Phocoenoides dalli ; Fujise et al., 1988; 3.91 9.89) and Weddell seal ( Leptonychotes weddellii ; Yamamoto et al., 1987; 4.02 17.2) ; however highest values were found in a single fetus or neo nate, respectively, with Zn levels usually highest in younger animals. Selenium concentrations in the Florid a manatee (Stavros et al., 2008a ) were lowest of all marine mammal species and were more than half the values of other species. The difference in elevated Zn and low Se levels compared to other marine mammal species was also reflective in liver values in Table 1 1 The only known publication that reports metal levels in whole blood of wild sirenians was a recent study by Stavros et al. (2008 a ). T hey examined eight manatees in Crystal River, Florida and found high zinc (11.3 0 1.18 ppm, ww ) and arsenic ( 0.340.04 ppm, w w ) levels in whole blood and alu minum (4.914.98 ppm, ww ) in the
29 skin. However, due to the small sample size and restricted geograp hical distribution of Stavros (2008 a ), it is important to expand this data set with additional manatees from multiple sites to develop a robust data set that can be used to derive accurate reference ranges for trace metals, as seen in Chapter 2. Metal Toxi city and the Importance of B aseline L evels Metal toxicity can occur at l evel s below or above normal baseline values There have been very few reports of metal toxicosis in marine mammals as it is difficult to make associations but it is a possibility. Ma rine mammals are commonly found in zoos and aquaria with the potential of accidental toxicosis by staff and visitors. This project was based upon discussions with Dr. Michael Walsh who observed metal toxicosis in captive bottlenose dolphins due to ingest ion of pennies. He discovered that visitors were tossing pennies into the enclosures in order to make a wish. With a combination to be the probable cause of death in some of the dolphins Regarding sirenians, the only study to report toxicity in a sirenian was by Oke (1967) who ob served copper sulfate toxicity i n a captive dugong at Cai rns Oceanarium, thus, illustrating that sirenians are s usceptible to metal toxico sis with no further details in signs of sirenian Cu toxicity I t has been found that Cu toxicity may be species depende nt, as sheep are more sensitive to copper than cattle, horses, swine, turkeys and dogs (Moeller, 2004). Ruminants are also particularly more susceptible to Cu toxicity due to the interaction of molybdenum and sulfate than monogastric animals. Deficiencies of molybdenum in feed can result in elevated Cu absorption by the GI tract and an increase in Cu storage in the cells of the kidney (M oeller, 2004; Thompson, 2007 a ). Animals within 24 hours of excess Cu present signs of toxicity with salivation,
30 gastroenteritis, abdominal pain, dehydration, shock, and death. Postmortem signs of toxicity are gastroenteritis, blue green coloration of the GI tract, and lesions on the kidney and liver (Thompson, 2007 a ). In addition to Cu toxicity, Pb toxicosis has been reported in marine mammals. The first documented Pb poisoning in a cetacean was found by Shlosberg et al. (1997). A male bottlenose dolphin housed in an aquarium in Tel Aviv, Israel, exhibited bilateral mydriasis on June 6, 1995 after two years in captivity. The animal began deteriorating, lost weight, refused to train, and eventually died on July 22, 1995. Upon necropsy, 55 air gun pellets (40% lead with traces of copper and zinc) were found in the stomach. In addition, there was a friable, swollen and yellow liver, icteric and edematous fat deposits and a soft brain. The liver contained metal levels (ppm, ww) of: 3.6 Pb, 4.2 Cu and 31 Zn, as the kidney cortex had Pb values of 2.3 ppm Cu was 7.3 ppm and Zn at 35 ppm The 25g of lead pellets, thought to be from children aquarium visitors, were concluded to be the source of chronic lead toxicosis and death of the animal. Lead toxicosi s was also found to be the cause of death in an adult harbor seal (Zabka et al. 2006). On June 25, 2004, the 5 year old, multiparous re strand ed harbor seal was admitted into the Marine Mammal Center in Sausalito, California with signs of disorientation intermittent seizures and weakness, but was able to move from one location to another with no abnormalities in the blood examination. Seizures became more frequent despite treatment and the animal was found dead four days later Blood Pb levels were found to be 0.66 ppm (ww) with postpartum liver levels at 84 ppm ( ww ). According to Gwaltney Brant (2004), lead concentrations in blood less than 0.06 ppm can be toxic, 0.1 0.35 ppm is categorized as subclinical exposure, and above 0.35 ppm
31 is termed acu te lead toxicosis. In addition, a level greater than 10 ppm in the liver is considered toxic (Thompson, 2007 b ), therefore, the harbor seal, indeed, suffered from Pb poisoning. A lead sinker was the source of toxicosis in the harbor seal, as the sinker wa s 90 98% lead. Metal levels can be a helpful tool in helping monitor the health of our oceans, as well as maintaining the health of our captive marine mammal populations. Thus, these studies exemplify the importance of reporting case studies in order to h elp understand the potential sources and metal burdens which can lead to metal toxicosis in marine mammals. In addition to acute toxicity and death it is possible that metals can be chronic affecting reproduction and the immune system. Metal levels may h ave an impact on reproduction in mammals, with transplacenta l and transmammary transfer of total Hg (THg) in northern elephant seals (Habran et al., 2011), transplacental transfer of Hg in harbor seals (Brookens et al., 2007) and transplacental transfer o f Hg in harp seals ( Pagophilus groenlandicus ; Wagemann at al., 1988). This detrimental effect of methylmercury ( MeHg ) on reproduction was seen in victims of Minimata Disease in Japan, where liver values of 22 70.5 ppm and renal values of 21.2 140 ppm were present (Harada, 1995). Cadmium can also affect the embryo resulting in craniofacial, neurological, cardiovascular and vertebrate abnormalities in humans (Review by Thompson and Bannigan, 2008). Thus, metals can be detrimental in an endangered species w ith a low reproduc tive rate, such as the manatee. Metals may also be of contaminants in marine mammals may be associated with immunosuppression (Das et al. 2003 ; Kakuschke et al. 2005; Kakuschke et al. 2006; Kakuschke et al. 2008;
32 Kakuschke and Prange 2007), thus, possibly causing reproductive failure and mass mortalities (Kubota et al. 2005). As with other stressors, such as cold stress and red tide events (Walsh et a l. 2005), the immune system may be suppressed in manatees possessing high metal accumulation, which then may affect the overall population of this species. Therefore, understanding the physiological mechanisms and control of metals and its potential as a toxicant is imperative to the survival of this endangered population. In order to determine if metal toxicity is of concern, it is critical to be able to compare the levels in an animal with normal values. In the clinical setting, the most practical and common method of evaluation is from a whole blood sample. There is besides that provided by Stavros et al. (2008 a ) This causes the practitioner to use values from other spec ies for comparison which may lead to inappropriate decisions regarding treatment or case management. Metal Detoxification Mechanisms in Marine Mammals H igh metal levels have been r eported in many marine mammals with cases of metal intoxication limited This has led to the investigation of the mechanisms that marine mammals use to detoxify metals, including formation of Hg:Se complexes and metallothionein. Mercury and S elenium Studies have shown that marine ma mmals accumulate MeHg from their diet. The MeHg is then transformed to inorganic mercury in the liver, which is less toxic than MeHg (Itano et al. 1984; Law 1996; Thompson 1990; Yang et al. 2002). Caurant et al. (1996) found that pilot whales are not affected by toxic levels of Hg, but rather have a
33 high tolerance to Hg by demethylation of MeHg by Se resulting in a Hg Se complex This mechanism has been identified in a variety of other species, including the harbor porpoise (Bennett et al ., 2001 ; E ndo et al. 2008) and dolphins off the coast o f Brazil (Kunito et al., 2004) Researchers also suggested Ag as a detoxification method by forming Ag2Se in the liver of Franciscana dolphins (Kunito et al., 2004) Manatees are at a lower trophic level than other marine mammals which is likely to affec t their intake of methylmercury However it appears at this time that Hg is not of a concern in sirenians (Table 1 1). Metallothioneins The detoxification mechanism of metallothionein (MT) will be emphasized, as MT will be examined in the West Indian ma natee (Chapter 6 ). Mammalian MT was first discovered in an equine kidney by Margoshes and Vallee (1957). MT is a heat stable protein with a low molar mass (6,000 7,000 Da), high cysteine content (~20 cysteines), no aromatic amino acids or histidines, and 60 68 amino acids (Cousins 1983; Das et al. 2002; Decataldo et al. 2004; Hamer 1986; Kgi et al. 1984; Kgi and Schffer 1988, Palmiter 1998; Stillman 1995). In m ammals, there are four isoforms of MT: MT 1 4. MT 1 and MT 2 are expressed in all o rgans, MT3 is predominately found in the brain and MT 4 2005). In addition, MT is highly conserved throughout mammals (~56% of the 61 amino acid residues) with 20 cysteine and most of the lysine and argi ni ne residues conserved (K gi and Kojima, 1987 ). Although there is still much debate to the function of metallothioneins, it has been suggested that metallothioneins bind to physiological or xenobiotic metals providing homeostasis, transport and detoxificat ion mechanisms (Palmiter 1998; and Hasler 2000 ).
34 MT is an important detoxifying mechanism for non essential metals and free radicals ( Heuchel et al. 1994). Hamer (1986) suggested MT prevents long term toxicity of Cd by binding to metals with dif ferent affinities in the order of Cd>Cu>Zn The high affinity for the highly toxic Cd and the long half life of Cd containing protein make MT a good detoxifying protein. Metallothioneins bind to non essential metals, such as Cd 2+ Ag + Hg2 + and Pb 2+ red ucing t he bioavailability and preventing toxicity. In addition to detoxification purposes, MT has also been suggested to be a transport and storage protein for essential metals, such as Cu and Zn Researchers have hypothesized that the primary function o f MT is to maintain low intracellular levels of free Cu ions while still allowing sufficient free ions to enable function of copper containing enzymes (Hamer 1986). Moreover, MT may be a key intracellular protein for controlling Zn uptake, distribution, storage and release and under normal physiological conditions, Zn is favored to bind to MT 2005) It has been suggested that metallothionein in marine mammals is also used as a detoxificati on mechanism and for homeostasic control of metals, tho ugh there have been no studies conducted on sirenians. In a review by Das et al. (2000), marine mammals are prime subjects for MT studies, as many are exposed to high levels of Cd and Hg. Metallothionein concentrations in marine mammals were higher in th e kidney (1.2 1.6x) than li ver based on data from 10 pinni p e ds and odontocetes. There was a strong relationship between Cd and MT, suggesting that MT is a method of detoxification of Cd obtained from the diet. It has also been found that 9 98% of cytosoli c Cd in marin e mammals is in the bound to MT form (Das et al., 2003). In addition to detoxification, MT has also been found to be a mechanism of homeostatic
35 control in marine mammals. Das et al. (2006) examined 14 liver and kidneys of harbor porpoises st randed along the Belgian coasts and found that MT was utilized as a means of Zn and Cu homeostasis by binding to 50% of hepatic Zn and 34% to hepatic Cu With an increase in hepatic Zn concentrations, there was an increase to Zn bound to MT and not high mo lecular weight proteins. Moreover, induction of MT 1 and MT 2 was exhibited in grey seal peripheral blood leukocytes exposed to Cd Cl 2 and Zn Cl 2 with maximal induction of Zn at 3 hours, remaining throughout the 24 hour exposure (Pillet et al., 2002). MT mRNA expression will be evaluated in manatee peripheral blood mononuclear cells in Chapter 6. The Physiological Role of Zinc As indicated above, manatees appear to have an elevated zinc level in whole blood when compared to other marine mammal species. Th is will be discussed in further d etail in Chapter 2 therefore the importance and physiological use of Zn will be introduced at this time. Zinc was first found to be required for proper growth and development in the 1930s. Zinc is an essential element f ound in many metalloenzymes and is vital for proper growth, skeletal development, wound healing, and reproduction (Osweiler, 1996). Zinc is an important element involved in a number of catalytic, structural and regulatory functions (Cousins 2006), such as gene transcription and zinc dependent regulatory proteins (Vallee, 1995; Beyersmann and Haase, 2001 ), as well as for a variety of biological functions, involving protein, nucleic acid, carbohydrate, and lipid metabolism (Vallee and Falchuk, 1993; Vallee 1995). There are many unknowns in regards to zinc in tissues a nd intracellular binding, but it is suggested that most zinc is bound to a protein and under homeostatic control via a number of transport proteins (Jackson 1989; Rink and Haase 2007 ). Th e tight
36 homeostatic control of zinc in mammalian cells is controlled by Zip proteins which transport Zn into the c ytosol from extracellular space /intracellular organs, while ZnTs transport Zn out of the cytosol. Most ZnT proteins are loca ted in the Golgi endosomes, or endoplasmic reticulum as many proteins are predominately found along the plasma membranes ( Cousins et al., 2006). Along with Zn transporters, Zn can be bound to proteins, such as metallothionein, as another means of homeostatic control (R ink and Haase 2006). Zinc is of importance in this study, as it is central ion for metallothionein (Chapter 6 ) and is critical to the function of carbonic anhydrase (Chapter 5 ). Zinc and Metallothionein Gene Expression As shown in Figure 1 1, Zn homeosta sis is retained by Zn dependant transcriptional regulation of MT At the promoter site of the MT gene, lays a 12 bp sequence of the metal response elements (MRE) which controls MT transcription (review by Giedroc et al., 2001). MRE is activated by metal response element transcription factor 1 (MTF1) for the regulation of MT and ZnT1 (Langmade et al., 2000) MTF1 is known to be a cytoplasmic Zn sensor and is vital for maintaining basal MT levels, as well as metal induced MT (Heuchel et al., 1994). MTF1 a cquires Zn from the intracellular pool which then moves to the nucleus to activate MRE s, thus signaling transcription of MT and other genes Apo MT can then bind to Zn from the cellular Zn pool or can interact with other Zn proteins or MTs, regulating Z n homeostasis in the cell. MT Zn then interacts with Zn binding sites of other proteins to influence gene expression, cell proliferation and differentiation and decreases the chances of apoptosis. MT can also respond to oxidative stress (ROS, NO, etc.) r esulting in the release of Zn, and the degradation of
37 apo MT (s ummarized by Davis and Cousins, 2000; Giedroc et al. 2001; Cousins et al. 2006). Zinc is also important in regards to MT structure. MT is made up of two domains, where three Zn atoms bind to 9 cysteines in the domain and four Zn atoms bound to 11 cysteines in the domain. The tetrahedral configuration of Zn to four cysteines and the structure of MT suggest that conformational change of the protein is needed in order to release Zn (Maret 2000). Although MT has a higher binding affinity for Cd 2+ or Cu ions, Zn is far more abundant with favorable binding to Zn (Jacob et al. 1998). As a result, Zn is important for the structure and transcription of MT, while MT has been suggested as a mean s of homeostatic control of Zn providing a feedback loop that is tightly regulated. Carbonic Anhydrase Carbonic anhydrase (CA) is the most abundant Zn metalloenzyme in erythrocytes. Zinc in erythrocytes is found predominantly in the cytosol bound to carb onic anhydrase (Gardiner et al. 1984; Ohno et al. 1985). Carbonic anhydrase is an important Zn metallo enzyme that is found in almost every living organism involved in the hydration /dehydration of carbon dioxide (CO 2 +H 2 O HCO 3 +H + ), thus, will be an im portant enzyme to eval uate in the Florida manatee. CA is involved in a number of physiological processes including respiration, acid base balance (i.e. acidification of urine), cell growth, bone resorption and calcification, and a number of other pathways Carbonic anhydrase comprises three families with genetically unrelated isoforms ( and which can be found in a number of organisms. However, v ertebrates only contain CA, while plants, other eukaryotes and invertebrates can have CA and
38 CA and CA can only be found in archaebacteria, eubacteria and plants (Chegwidden and Carter 2000). There are 14 isoforms, with 11 (CA I VII,CA IX, and CA XII XIV) of the 14 active (unactive = CA RP VIII, X, and XI or CA related proteins) isoforms (Hew ett Emmett, 2000; Hewett Emmett and Tashian, 1996; Sly and Hu 1996; Tashian, 1992; Tashian et al., 2000). The CAs are monomeric zinc metalloenzymes with a molecular weight of 29kDa with a Zn ion bound by three histidines. Within mammals, CA I, II, I II, and VII are cytosolic, CA IV is an anchor protein CA V is mitochondrial and CA VI is found in saliva (Sly and Hu 1995). Carbonic anhydrase in mammals is found in erythrocytes, kidney, gastric mucosa, pancreas, central nervous system, retina and lens of the eye, salivary glands and testis but is found most abundantly in the erythrocytes (Larimer and Schmidt Nielsen 1960). This study will focus on CA I and CA I I (Chapter 5 ) in the Florida manatee. CA I and II are found to be expressed concurrently w ith CA II having high er activity and CA I having higher abundance The isozymes differ with species, as well as the kinematics of CA. The isoelectric pH varies by isozyme and species with no correlation to activity of erythrocytes (Carter 1972). Accord ing to Furth (1968), the isoelectric pH in a horse is 6 for CA I and 10 for CA I I, while humans is 5.7 for CA I and 7.4 for CA II (Rickli et al. 1964). In Larimer and Schmidt Nielsen (1960), fifteen mammals were exam ined in order to determine CA and found that smaller animals generally had higher CA activity than larger animals possibly due to : 1) their high metabolic rate causing higher CO 2 production, or that 2) Small species have more acid sensitive hemoglobin
39 from the rapid hydration of CO 2 allowing f ast er O 2 delivered to tissues from the capillaries. Manatee Physiology In regards to metal accumulation, physiology plays an important role in metal absorption thus, will be introduced at this time Manatees are generalist herbivores with specialized a natomy designed for their strict diet of freshwater and/or saltwater plants. Specializations occur throughout the gastrointestinal tract and, with hindgut fermentation and a low metabolic rate this animal is well adapted to its ecological niche. The Fl orida manatee is the mos t studied species of manatees and will be described in detail here. Gastrointestinal Tract Marshall et al. (1998) explored how the facial anatomy of the Florida manatee assists in feeding. The muzzle of the manatee is covered with short sinus hairs and approximately 220 modified vibrissae creating a vibrissae muscular complex (Reep et al., 1998) which Marshall and collegues (1998) hypothesized was most likely used to identify aquatic vegetation through input from this vibrissae mus cular complex. It was also observe d that manatees typically close their eyes during feeding, perhaps to protect their eyes from injury or to become more sensitive to touch Once vegetation enters the oral cavity, it must be masticated and swallowed. Acco rding to Domning and Magor (1977), there are no functional incisors and teeth are constantly replaced with newer teeth developing in the rear, migrating to the tip of each jaw, with old teeth falling out in the front. This unique mechanism of unrestricted horizontal tooth replacement (polyphydont) of the six to eight erupted molars per row is stimulated when calves begin to chew vegetation and moves at a rate of 1 mm/month.
40 In addition to teeth, the lips and tongue may also assist in feeding. Levin and Pfeiffer (2002) described the tongue of the manatee as slim, muscular and fixed caudally in the oral cavity. As a result, manatees are not able to push their tongue forward, but the tongue can assi st in mastication or manipulation of vegetation. Once foo d is masticated and swallowed, it enters the narrow, muscular esophagus as it passes into the stomach. The stomach is large and is positioned slightly left of the midsagittal plane, with the stomach and its contents making up 0.7 3.9% of the total body we ight (Reynolds and Rommel, 1996). Sirenians have a specialized diverticulum structure attached to the stomach, called the cardiac gland, where the gastric glands enzyme s and acid secreting cells (parietal, chief, and mucous neck cells) are located (Murray et al., 1977). Columnar and goblet cells in the mucosa of the cardiac gland, as well as the columnar cells and gastric pits in the pyloric region of the stomach, contribute to the lubrication needed in or der for digestion to occur. This viscous mucous i n the stomach minimizes absorption of nutrients in the stomach before passing into the duodenum in these hindgut fermenters (Reynolds and Rommel, 1996). Passage rates seem to be relatively rapid through the small intestines with digesta entering the cecu m before the loops of the large intestines. The small intestines are approximately 20m in length and with contents equal to about 1.4 5.6% of the total body weight. The small intestine is comprised of the duodenum, jejunum, and ileum. When compared to o ther mammals, the small intestine of the manatee is made up of short villi, fewer Paneth, absorptive, and argentaffin cells, and is predominately comprised of goblet cells (Reynolds and Rommel, 1996). The small intestine is the major site of Zn absorption with regulation in the brush border membrane, with potentially minor roles for
41 the stomach, cecum and c olon (summarized in L nnerdal, 1989). Trace metal analysis of various organs of the manatee will be evaluated in Chapter 3. Hindgut Fermentation Manatees are non ruminant, hindgut fermenters with the majority of digestion occurring in the cecum and proxim al colon of the large intestine (Burn, 1986; Murray et al., 1977; Reynolds and Rommel, 1996). Hindgut fermentation is time consuming, decreases the rate of food passage through the GI tract, and occurs after gastric digestion and absorption in the small intestines. Manatees are highly proficient cellulose digesters at 83 91% with c ellulos e breakdown predominately occurring in the large intestine (>83%), es pecially in the cecum (33%) and proximal colon (37%; Burn, 1986). The cecal horns of manatees are thick a nd muscular, 15 20 cm in length, with the cecum as the site for volatile fatty acid production and absorption and where cellulose is broken down by ba cteria (Burn, 1986; Reynolds and Rommel, 1996; Snipes, 1984). Digestion of fiber, protein, and lipids also occurs in the cecum and proximal colon as well. Less mucous is produced in the large intestine compared to the small intestine or stomach, as an ab undant number of absorptive cells, and less goblet cells, are found. Manatees may have a slow passage rate due to the large length (>40 m) of the entire GI tract and the number of perpendicular ridges found in the mucosa of the large intestine which can delay rate of passage and digestion of the high fiber content of feed. The colon can exceed 20 m in length (6 7 body lengths) and is at least 15 cm in diameter. The large size of the gast rointestinal tract of manatees may play an additional role in Zn ab sorption.
42 Metabolism Manatees have a very low metabolic rate which may be due to their size and habitating tropical and subtropical waters where they are consuming low quality food (Irvine, 1983). The large size of the gastrointestinal tract and low meta bolic rate results in a slow GI transit time of 146 hours, or 5.4 7 days (Lomolino and Ewel, 1984; Larkin et al., 2007). Due to this low metabolic rate, the Florida manatees prefer inhabit ating waters >20 22 0 C W hen temperatures drop, they are forced to refuges at the 14 power plant discharge s and several natural warm water springs throughout Florida during winter months (Laist and Reynolds, 2005) as t hey are physiologically unable to tolerate cold temperatures (Irvine, 1983). Location has been found to affect metal accumulation in marine mammals, as currents, pH, temperature, salinity, and sediment composition can influence metal input into the environment. Diet and the Environment It has been shown that diet is the primary means of metal accumulation in marine mammals. Therefore, it is extremely important to not only understand the anatomy of the manatee, but the diet as well. Sirenians have a unique diet, in that they are the only herbivorous marine mammal. They consume a broad assortment of veget ation, with over 60 different plant species, in freshwater, brackish and marine environments (Best, 1981; Hartman, 1979; Reep and Bonde, 2006). Manatees also feed on a variety of vegetation from submerged plants, overhanging plants, bank growth, algae, l ive oak leaves ( Quercus virginiana 1986). Manatees spend approximately 6 8 hours/day foraging (Bertram and Bertram, 1964; Hartman, 1979), consuming roughly 7 11% of their body weight (Bengston, 1983; Bes t, 1981; Etheridge et al., 1985; Reynolds, 1981). As a result, large quantities of
43 diverse vegetation are consumed, where the vegetation may contain a number of contaminants (Bela ) including metals Vegetatio n Preference and Possible Role in Metal Exposure There may be many factors influencing vegetation choice in wild manatees. Food preference may depend on palatability of plant species and plant parts, abundance of vegetation and depth (Allsopp, 1966 ; Hart man, 1979). The most preferred type of aquatic vegetation was submerged aquatic vegetation (SAV), with floating vegetation preferred next and rooted/emergen t vegetation last (Allsopp, 1966 ; Bengtson, 1981; Hartman, 1979). Although water hyacinth was con sumed when submerged plants were not present, water lettuce ( Pistia stratiotes ), water lilies ( Nymphaea mexicana ) and water ferns ( Azolla caroliniana ) were ignored by manatees. Thus, floating vegetation was not a pr eferred aquatic plant by some manatees, p ossibly due to the evolutionary adapta tion of the rostral deflection ( Domning, 1982; Hartman, 1979). Out of the SAV, manatees seemed to prefe r certain species over others probably due to palatability. In the 1960s in Crystal River, w hen choosing between Ceratophyllum demersum and Myriophyllum spicatum Ceratophyllum was preferred by manatees, while Ruppia maritima and Myriophyllum were preferred over Potamogeton pectinatus Najas guadalupensis was consumed incidentally and Potamogeton illinoiensis P. pu sillus and Zannichellia palustris were only found in trace amounts and were never seen to be eaten by manatees (Hartman, 1979). Feeding may also be dependent on plant abundance and water depth as well. For instance, although Vallisneria americana and C eratophyllum were preferred species, the majority of the plant consumed in Crystal River was the most abundant Hydrilla verticillata Moreover, although Hydrilla are capable of growth to 10 m, manatees were
44 never found to dive more than 4 meters for Hydri lla and only fed at one to three meters on Ceratophyllum and Myriophyllum in Crystal River (Hartman, 1979). Seagrasses found in saltwater are an important dietary source for manatees and dugongs (Burns et al., 1997; Dawes et al., 1985 ) and can absorb meta ls from the surrounding environment Studies by Lewis et al. (2007) found high levels of copper and arsenic in the surface water of the Gulf of Mexico at 13.9 61.1 g/L and 36.3 75.6 g/L, respectively. Of the 10 metals evaluated, 16 89% was detected in r oots and rhizomes, while 26 89% of the metals were found in blades of the seagrass. Mercury, cadmium, nickel, lead and silver was found in more than 50% of turtle grass ( Thalassia testudinum ) and shoal grass ( Halodule wrightii ), with the limit of detection of 0.004 0.4 g /g ( dw ). This suggests that seagrasses may be an important source of metals w hen manatees are in saltwater. Given the wide variety of plants that are consumed by manatees and the importance of diet as a route of exposure to metals, this study examined the metal content of various freshwater plant species in Crystal River to determine a difference in metal accumulation by plant species or location that may affect manatee metal exposure (Chapter 4). Metals in Sediment Metals entering the aquatic environme nt may also deposit in sediment and be incidentally ingested by manatees during feeding. Loc ation of sediments, especially proximity to anthropogenic influences, affects the concentrations and profiles of metals in sediment. A number of studies have been performed throughout Florida on environmental metals, including the Florida Bay sediment (Caccia et al., 2003; Cantillo et al., 1997), the Indian River Lagoon (Trocine and Trefry, 1996), Florida soil (Chen et
45 al., 1999) and other manatee habitats in Mexic o (Garcia Rios and Gold Bouchot, 2003). Caccia et al. (2003) found higher concentration of metals in the north central and western parts of the Florida bay, with Mn and Fe concentrations decreasing from the Everglades to the Florida Keys, showing great di stribution and variability of metals within an estuarine system. Trocine and Trefry (1996) found a wide range of copper (0.6 206 ppm) in sediment in the Indian River Lagoon (IRL) with distribution of metals related to distance from marinas and harbors whe re anti fouling, copper based paints and pesticides are frequently present. This study will also examine surface sediment to determine possible exposure to manatees in Chapter 4. Manatee Evolution Fossil E vidence In order to understand the current biology and physiology of manatees, one must understand how manatees evolved into their particular niche. Although the evolution of manatees is based primarily on a theory proposed by Domning (1982) and available fossil records, it provides some insight into how the sirenians came to be today. Sirenians may have originally come from the Old World, similar to other species in superorder Afrotheria, and migrated to the New World. Based on fossil records, the earliest known sirenian Pezosiren portelli was present in the Caribbean about 50 million years ago. This four legged amphibious creature had a long rostrum and dense bones, similar to modern day sirenians. They may have consumed aquatic vegetation with their incisors, canines, premolars, and molars and did not have the horizontal replacing of molars which is a characteristic of the manatee today (Reep and Bonde, 2006). It has been thought that dentition and feeding habitats may have driven the evolution of manatee species.
46 With the extinction of the proras tomids and protosirenid s 30 million years ago, dugong species thrived in the Caribbean, while trichechids were found in freshwater and estuarine environments. A biogeographical change in South America resulted in a change in food resources, and, as a resu lt, supernumerary molars were present due to the abrasive vegetation consumed from the increase in true grasses caused by erosion and runoff during the Andean tectonic event. The Amazon was then confined and trichechids were restricted to the floating veg etation in the Amazonian waters, giving rise to T. inunguis T. inunguis evolved a number of characteristics unique in the Amazonian manatee, such as smaller and more complex molars, thickened supraoccipital, loss of nails, reduced number of dorsal verteb rate and increased diploid chromosome number. The West Indian manatee on the Eastern Coast of South America gave rise to the Antillean ( T. manatus manatus ) and Florida ( T. manatus latirostris ) manatee. T. manatus has a rostrum with twice the downturn of T inunguis loss of bicipital groove on the humerus, and wider ribs. This rostral deflection suggests T. manatus evolved to consume a wider range of vegetation, such as seagrasses on the sea floor, while T. inunguis had less of a rostrum deflection and at e mostly floating plants (Domning, 1982; Reep and Bonde, 2006). However, it has also been suggested that the Florida manatee subspecies migrated to Florida from the Caribbean sometime within the last 12,000 years (Garcia Rodriguez et al., 1998). Finally, the third species of manatee, T. senegalensis came to reach Africa due to the wave dispersal via ocean currents roughly 1.5 million years ago (Domning, 1982). Phylogeny Classification Simpson (1945) classified manatees and dugongs as class Mammali a, infraclass Eutheri a, superorder Paenungulata and O rder Sirenia, but later studies have
47 determined manatees to belong to superorder Afrotheria and clade Paenungulata. Placental mammals (Eutheria) were thought to have evolved from Africa as a result of p late tectonics (Springer et al., 1997). Divergence of placental mammals occurred during the Cretaceous period, approximately 97 112 mya, based on molecular results (Springer et al., 2003). There has been much debate on the phylogeny of superorder Afrothe ria. For instance, aardvarks, elephants and hyraxes were once thought to be associated with ungulates, the golden mole and tenrecs with Insectivora, and elephant 2001). Mo reover, van Dijk et al. (2001) analyzed protein sequences and found that the African insectivore, the otter shrew ( Micropotamogale lamottei ), should also be included in Afrotheria as well. Currently, superorder Afrotheria is comprised of six orders: Probo scidea (elephants), Sirenia (manatees and dugongs), Hyracoidea (hyraxes), Tubulidentata (aardvark), Macroscelidea (elephant shrew), and Afrosori cida (golden mole and tenrecs; Stanhopek 1998). The five placental orders and golden moles most likely origina ted from Africa, whereas sirenians from the ocean between Gondwana and Laurasia, called the Tethys Sea (de Jong et al., 1981; Springe r et al., 1997; Stanhope et al., 1998), supporting the spread of the African animals to the Southern Hemisphere due to the break in Go ndwanaland (Springer et al., 1997). Similar to Afrotheria, phylogenetic reconstruction within clade Paenungulata has also occurred. Simpson (1945) first grouped orders Proboscidea, Sirenia, and Hydracoidea into Paenungulata based solely on fos sil records with a possibility of Hydracoidea closer to order Perissodactyla. However, with the advancement of molecular techniques, researchers began incorporating molecular characteristics with
48 fossil records and anatomical relationships. Protein seque nces corroborated the work of Simpson (1945) and revealed that Paenungulata had no closer relationship to ungulates than other placental mammals (Goodman et al., 1985; Kleinschmidt et al., 1986; Miyamoto and Goodman, 1986). This evidence confirmed the gro uping of Proboscidea, Sirenia, and Hydracoidea in Paenungulata (Kleinschmidt et al., 1986). In addition, Goodman et al. (1985) showed that Paenungulata and Edentata were the oldest separated eutherians with divergence of Paenungulata from other non Paenug ulata approximately 80 mya, according to chromosomal evolution (Pardini et al., 2007). Kellogg et al. (2007) also showed evidence that manatees belong to clade Paenungulata within superorder Afrotheria using chromosomal painting. Moreover, Kuntner et al. (2011) examined sequences encoding mitochondrial cytochrome b, 12s, 16s, and NADH2, nuclear a 2B receptor (ADRA2B), androgen receptor (AR), growth hormone receptor (GHR), von Willebrand factor (vWF), and interphotoreceptor retinoid binding protein (IRBP) a nd suggested that hyraxes, manatees and elephants comprised Paenungulata. In this study, we will be examining the phylogenetic analysis of manatee s and elephants in regards to metallothionein (Chapter 7 ). Project Objectives This project will result in a n umber of applicable implications to help us monitor the health of th e West Indian manatee, as well a s to further understand the biology of this unique aquatic mammal. In terms of clinical purposes, this project will aid in establishing baseline values of trace metals in the West Indian manatee. By obtaining samples from wild and captive animals at various sites in Florida and Belize, we will be able to construct a reference range for whole blood, plasma and erythrocytes in West Indian manatees to be used for clinical and research purposes. In addition to live
49 animals, we will examine body burdens and metal distributions in Florida manatees. Moreover, we have surveyed the surrounding environment of Crystal River, Florida, to understand the possible sources of metal accumulation. We have also evaluated carbonic anhydrase and characterized metallothionein in order to begin to understand metal homeostasis and physiological control of metals in the Florida manatee. Thus, the long term goal of this project is to gain a better unde rstanding of metal levels and control in manatees. To this end, we established a metal reference range, examined body burdens in various tissues, the effects of the surrounding environment on metal accumulation and the physiological control in homeostasis of trace metals in the Florida manatee. Chapter 2 O bjective The objective to Chapter 2 was to determine baseline levels of metals in the Florida manatee via wild and captive blood samples. The current metal baseline concentration is based on eight individuals in Crystal River, Florida (Stavros et al. 2008 a ). We have increased the sample size in wild manatees by examining four different locations throughout Florida and Belize, in collaboration with the USGS Sirenia Project, Flori da Fish and Wildlife Commission, and Sea To Shore Alliance. This established metal reference range can be used to compare the levels in the West Indian manatee to other species, such as the West African manatee, the Amazonian manatee, and the dugong. In addition to wild data, we also obtained captive samples from Homosassa Springs Wildlife State Park and Mote Marine Laboratory and tested the hypothesis that trace metal levels in wild manatees will be higher than captive manatees due to environmental impac ts contributing to metal accumulation. Our overall goal of
50 this chapter was to establish a clinical reference range of trace metals in blood of wild and captive manatees at various locations in Florida and Belize. Chapter 3 O bjective The objective of Cha pter 3 was to examine body burdens of metals in the Florida manatee. Carcass samples were provided by Martine deWit, DVM and staff from the Fish and Wildlife Research Institute, Marine Mammal Pathobiology Laboratory in St. Petersburg, Florida. We obtaine d various tissues from a number of different age groups and sexes to determine distribution of trace metals and have hypothesized that trace metal levels will be higher in urban areas than rural areas and cold stress manatees will have higher levels of tra ce metals due to possible immunosuppression. In addition, we compared our results to past studies by Dr. Thomas of USGS in order to determine if a change in metal levels in manatees has occurred in a 30 year time difference in Florida. Chapter 4 O b jective The objective to Chapter 4 was to determine if metal concentrations in the manatee were correlated to environmental metal concentrations. Diet, water and sediment exposures may be possible sources of metal accumulation in the Florida manatee Th erefore, we examined the surrounding environment of Kings Bay, Crystal River, Florida, using vegetation to evaluate the sources of metal accumulation in the Florida manatee. Crystal River, Florida, is home to the largest winter aggregation of manatees at a natural refuge, a popular ecotourism destination, and has historically been a concern for contaminants in the past, thus, making Kings Bay a prime location for study. Although there are many sources of metal intake, we predicted that diet is the
51 primary source of metal accumulation in the Florida manatee. Our overall goal was to assess the diet as a predominant form of metal intake in the Florida manatee Chapter 5 O bjective The objective of Chapter 5 was to evaluate carbonic anhydrase activity in the F lorida manatee. Carbonic anhydrase is the most abundant zinc metalloenzyme found in erythrocytes. Due to the high level of Zn found in the manatees and Zn levels highest in erythrocytes, we hypothesized that manatees had increased carbonic anhydrase activ ity than other animal species, thus, accounting for their high Zn levels. Chapter 6 O bjective The objective of Chapter 6 was to evaluate metallothionein as a biomarker of exposure in the Florida manatee. Causal effects of contaminants on the physiology of marine mammals are difficult to determine due to restrictive regulations and large size. However, it is possible to begin to elucidate the response of sirenians to metal exposure. A major mammalian metal regulator is the family of stable, low molecula r wei ght proteins, metallothioneins. M etallothionein s regulate toxicity and homeostasis of metals, such as zinc and cadmium, and have been characterized in a number of aquatic species. However, MTs have not been explored in sirenians as a means of mainta ining metal homeostasis and detoxification of metals. We cloned and sequenced MT 1 and 4 from peripheral blood leukocytes and skin, respectively, and conducted in vitro studies of MT 1 expression. We tested the hypothesis that metallothionein is utilized as means of homeostatic control in the Florida manatee. Many studies have examined levels in marine mammals, but with advancement of molecular techniques, we can now begin to understand mechanisms involved in metal induction of MT in the Florida manatee.
52 Chapter 7 O bjective The objective of Chapter 7 was to determine metallothionein sequences and phylogenetic relationship in species of Paenungulata. A result of this objective was to compare baseline reference values of metal concentrations for species in Paenungulata, in this case the Asian elephant and the Florida manatee, which has been a significant gap in knowledge. We predicted the elevated level of zinc was a physiological adaptation in manatees and the zinc concentrations would not be similar in t he elephant. In addition, we cloned and sequenced elephant MT in order to comp are our results to manatee MT with the hypothesis that metallothionein c DNA would be highly conserved within Paenungulata. Understanding the exposure and response of a species t o contaminants is extremely important in order to establish appropriate guidelines to protect the health of that animal, especially for endangered species in Paenungulata. Significance of the Project The West Indian manatee is a strict herbivore and primar y consumer, thus, can be regarded as a sentinel species in regards to the amount of trace metals found in the environment. According to Bonde et al. (2004), manatees are in direct association with sediments and aquatic vegetation s which may possess contam inant loads from various sources. Sources, such as pesticide and fertilizer run off from agricultural and urban use, recreational boating, paint, boat sewage, and municipal waste, all are possible contributors to trace metal accumulation. Due to the wide range of manatee habitat throughout the state of Florida, trace metal levels in manatees may vary depending on location, age, and sex. However, baseline values of metals have not been determined in the Florida manatee for more than eight animals (Stavros et al., 2008 a ) As a number
53 of manatees are admitted into rehabilitation centers and are present in captive facilities, veterinarians and biologists would benefit greatly from a reference range of metal concentrations for diagnostic purposes and assessin g overall health in manatees. There is a clear need to understand what levels of metals are normal to maintain health and to understand the physiology that contributes to the differences seen in manatees compared to other marine mammal species In summar y, the proposed research will advance our understanding of trace metal regulation in Florida manatees and will benefit clinicians treating captive and injured manatees by establishing a metal reference range. In addition, it will provide the foundation fo r further basic research on the mechanisms by which manatees accumulate and regulate metal levels. As Belanger and Wittnich (2008) states, conservation of species is most successful when prevention, rather than reaction, occurs. Contaminants, including t hat of trace metals, need to be monitored and managed regularly to assist the recovery of the endangered manatee population. This research will help management officials and agencies monitor metal accumulation of trace metals in the aquatic environment. I n addition, manatees are commonly hunted and consumed in many parts of the world, such as West Africa, Central and South America Assessing the levels of metals in the Florida manatee will provide baseline levels found throughout the state of Florida whic h can then be extended to other countries to protect, not only the population of manatees, but human populations as well.
54 Table 1 1 Metal concentrations in kidney and liver of various marine mammal spec ies in increasing order (ppm, w w). Element n Tissue Mean Range Species Location Reference As 80 Kidney 0.7 0.5 2 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 80 Liver 0.8 0.5 14 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 38 Liver 3 0.5 7.7 Dugong ( Dugo ng dugon ) Australia Haynes et al. (2005) Cd 38 Liver <0.005 32.5 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) 31 Liver <0.1 0.2 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 16 Kidney <0.1 0.4 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 43 Liver <0.1 15.5 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 43 Kidney 0.03 59.4 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 19 Liver 0.7 0.1 1.3 Steller sea lion ( Eumetopias jubata ) Hokkaido, Japan Hamanaka et al. (1982) 3 Liver 0.95 1.6 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) 2 Liver 1.1 1 1.3 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 9 Liver 1.8 0.6 4.6 N. Fur seal ( Callorhinus ursinus ) Wash ington, USA Anas (1974) 2 Liver 2.6 2.1 3.1 Ribbon seal ( Histriophoca fasciata ) Okhotsk Sea Hamanaka et al. (1977) 21 Kidney 4.2 0.8 10 Steller sea lion ( Eumetopias jubata ) Hokkaido, Japan Hamanaka et al. (1982) 9 Kidney 5.8 0.2 15.6 N. Fur seal ( Cal lorhinus ursinus ) Washington, USA Anas (1974) 57 Liver 6.3 <0.1 11.1 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 80 Liver 6.3 0.2 142 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 2 Kidney 6.4 2.9 9.9 Wedd ell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 38 Kidney 6.8 nd 50 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) *Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
55 Table 1 1 Continued Element n Tissue Mean Range Species Location Reference Cd 2 Liver 7 4.3 9.7 Dugong ( Dugong dugon ) Australia Marsh, 1989 29 Liver 7.3 2.7 14.9 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980 ) 4 Liver 7.8 4.4 14.1 Ringed seal (Phoca hispida) W. Greenland Sonne et al. (2009) 1 Liver 10.3 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 5 Liver 11.5 7.8 18.2 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 1 Kidney 15 Dugong ( Dugong dugon ) Australia Marsh, 1989 54 Kidney 24.8 <0.1 69.6 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 80 Kidney 25 0.2 231 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 5 Kidney 28.5 12.7 36.2 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 5 Liver 29.2 17 39 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) 4 Kidney 29.7 21.9 44.2 Ringed seal (Phoca hispida) W. Greenland Sonne et al. (200 9) 1 Kidney 30.2 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 37 Liver 32 1.3 130.8 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 29 Kidney 37.4 9 146.2 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 54 Kidney 63.5 1 205.4 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 5 Kidney 84.6 49 129 Hooded seal ( Cystophora cristata ) Barents Sea Sonne et al. (2009) Cu 43 Kidney 0.5 3.2 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 54 Kid ney 2.3 1.8 3.5 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 16 Kidney 2.3 4 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 43 Liver 2.4 160 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 30 Kidney 3.1 1.5 6.1 Str iped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) *Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
56 Table 1 1 Continued Element n Tissue Mean Range Species Location Reference Cu 5 Kidn ey 3.4 2.7 3.8 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 58 Liver 2.6 17 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 37 Liver 5.3 2 20.3 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 1 Kidney 5.4 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 57 Liver 8.1 3.6 15.2 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 2 Kidney 8.1 5.1 11 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 80 Kidney 9.5 3 19.8 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 1 Liver 9.7 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 5 Liver 10.5 6.5 16.5 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) 29 Kidney 10.6 5 21.8 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 29 Liver 11.6 4.5 22.3 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 5 Kidney 12.8 10.3 15.6 Hooded seal ( Cystophora cristata ) Barents Sea Sonn e et al. (2009) 5 Liver 15.5 6.6 20.7 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 2 Liver 16.8 5.8 28.2 Dugong ( Dugong dugon ) Australia Marsh, 1989 2 Liver 20.4 15 25.8 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamam oto et al. (1987) 3 Liver 20.3 44.2 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) 54 Liver 33.7 0.9 230.8 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 80 Liver 41.4 7.6 138 CA Sea Lion ( Zalophus califor nianus ) California Harper et al. (2007) 38 Liver 101 9.5 303 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) *Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
57 Table 1 1 Continued Element n Ti ssue Mean Range Species Location Reference Fe 80 Kidney 121.9 48 455 CA Sea Lion ( Zalophus californianus ) California Harper et al. (2007) 1 Kidney 136 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 30 Kidney 143 Striped dolphin ( Sten ella coeruleoalba ) Japan Honda et al. (1983) 57 Liver 215 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 2 Kidney 389 159 618 Weddel seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 35 Liver 369 88.5 157.7 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 43 Kidney 42.7 588.3 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 1 Liver 425 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 80 Liver 508.5 44.4 144 0 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 2 Liver 665 389 940 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 38 Liver 35776 1660 172300 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) 2 Liv er 6810 18257 Dugong ( Dugong dugon ) Australia Marsh, 1989 43 Liver 204 21674.5 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 3 Liver 621 5210 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) Pb 9 Liver 0.5 0.2 0.8 N. Fur seal ( Callorh inus ursinus ) Washington, USA Anas (1974) 54 Kidney 0.02 <0.01 0.1 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 1 Liver 0.02 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 37 Liver 0.03 0.01 0.1 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 1 Kidney 0.03 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
58 Table 1 1 Continued Element n Tissue Mean Range Species Location Reference Pb 29 Liver <0.01 0.03 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 29 Kidney <0.01 0.5 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 43 Liver <0.03 <0.07 Dugong ( Dugon g dugon ) Australia Denton et al. (1980) 43 Kidney <0.03 <0.08 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 20 Kidney 1.4 0.9 1.9 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 19 Liver 0.5 0.4 0.9 Flori da manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 38 Liver <0.08 3.08 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) 30 Kidney 0.2 0. 01 0.7 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 57 Live r 0.2 0.03 0.6 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 3 Liver 0.04 0.1 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) 31 Liver 0.1 0.6 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 16 Kidney 0.1 0. 6 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 80 Kidney 0.7 0.5 5 CA Sea Lion ( Zalophus californianus ) California Harper et al. (2007) 9 Kidney 1 0.8 1.8 N. Fur seal ( Callorhinus ursinus ) Washington, USA Anas (1974) 80 Liver 3.2 0.5 179 CA Sea Lion ( Zalophus californianus ) California Harper et al. (2007) Hg 1 Liver <0.01 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 2 Kidney <0.01 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 3 Liver 0.02 0.03 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) 19 Liver nd 0.04 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
59 Table 1 1 Continued Element n Tissue Mean Range Species Location Reference Hg 29 Kidney 0.1 0.4 N. Fur seal ( Callorhinus ursinus ) Washington, USA Anas (1974) 6 Kidney 0.2 0.09 0.3 Minke whale ( Balaenoptera acutorostrata ) West Greenland Johan sen et al. (1980) 6 Liver 0.2 0.07 0.4 Minke whale ( Balaenoptera acutorostrata ) West Greenland Johansen et al. (1980) 5 Kidney 0.2 0.1 0.4 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 38 Liver 0.3 0.05 1.1 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) 4 Kidney 0.5 0.4 0.5 Ringed seal ( Phoca hispida ) W. Greenland Sonne et al. (2009) 4 Liver 0.6 0.4 0.9 Ringed seal ( Phoca hispida ) W. Greenland Sonne et al. (2009) 2 Kidney 0.7 0.4 1 Weddell seal ( Leptonychotes weddel lii ) Antarctica Yamamoto et al. (1987) 54 Kidney 1.7 0.4 5.7 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 80 Kidney 1.7 0.5 10 CA Sea Lion ( Zalophus californianus ) California Harper et al. (2007) 5 Kidney 1.9 1 2.8 Hooded seal ( Cystophor a cristata ) Barents Sea Sonne et al. (2009) 1 Kidney 3.3 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 2 Liver 5.8 3.1 8.5 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 37 Liver 6.1 0.6 13.1 Narwhal ( Monodo n monoceros ) Canada Wagemann et al. (1983) 20 Kidney 8.7 0.9 17.6 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 16 Kidney 1.6 12.5 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 31 Liver 1.6 160 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 29 Liver 3 19 N. Fur seal ( Callorhinus ursinus ) Washington, USA Anas (1974) Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
60 Table 1 1 Continued Eleme nt n Tissue Mean Range Species Location Reference Hg 1 Liver 15 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 10 Liver 16.7 2.8 44.4 Hooded seal ( Cystophora cristata ) West Greenland Johansen et al. (1980) 5 Liver 23.1 3.2 73.6 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) 80 Liver 51.4 0.5 442 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 45 Liver 205 1.7 485 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) Se 19 Liver 0 .08 nd 0.2 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 3 Liver 0.3 0.6 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) 38 Liver <0.02 3.6 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) 2 Kidney <0.1 0.1 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 2 Liver 0.1 <0.1 0.1 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 54 Kidney 3.2 1.7 4.9 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 37 Liver 4.1 0.6 8 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 14 Kidney 5.6 Striped dolphin ( Stenella coeruleoalba ) Japan Itano et al. (1984) 4 Kidney 7.1 2.3 10 Harbor seal ( Phoca vitulina ) Wadden Sea Reijnders (1980) 1 Liver 7.7 Dall's porpoise ( P hocoenoides dalli ) Japan Yang et al. (2006) 1 Kidney 7.7 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 15 Liver 48.6 Striped dolphin ( Stenella coeruleoalba ) Japan Itano et al. (1984) 8 Liver 109 3.9 350 Harbor seal ( Phoca vitulina ) Wadden Sea Reijnders (1980) Zn 2 Kidney 23.8 19 28.5 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 17 Kidney 27 19.8 40.4 Steller sea lion ( Eumetopias jubata ) Hokkaido, Japan Hamanaka et al. (1982) 5 Kidney 27.2 22 32 Harp seal ( Pagoph ilus groenlandicus ) Barents Sea Sonne et al. (2009) Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
61 Table 1 1 Continued Element n Tissue Mean Range Species Location Reference Zn 2 Kidney 29.1 27 .4 30.7 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 30 Kidney 30.1 22.8 41.2 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 43 Kidney 14.3 53.5 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 16 Kidney 16.3 32.5 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 57 Liver 27 56 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 1 Kidney 31.5 Dugong ( Dugong dugon ) Australia Marsh, 1989 1 Liver 36.4 Dall's porpoise ( P hocoenoides dalli ) Japan Yang et al. (2006) 1 Kidney 38.2 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 37 Liver 38.8 24 63.6 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 4 Kidney 40.7 32.9 47.9 Ringed seal ( Phoca hispid a ) W. Greenland Sonne et al. (2009) 54 Kidney 41.1 3.8 85.8 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 1 Liver 43.6 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 2 Liver 44.4 41.7 47 Weddell seal ( Leptonychotes weddell ii ) Antarctica Yamamoto et al. (1987) 57 Liver 44.5 26.5 109 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 29 Liver 46 30.7 67.3 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 29 Kidney 46.2 27.9 78 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 4 Liver 46.9 34.7 59.0 Ringed seal (Phoca hispida) W. Greenland Sonne et al. (2009) 17 Liver 47 35.5 86 Steller sea lion ( Eumetopias jubata ) Hokkaido, Japan Hamanaka et al. (1982) 5 Liver 47.4 40 55 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
62 Table 1 1 Continued Element n Tissue Mean Range Species Location Reference Zn 5 Kidney 48.4 34 62 Hooded seal ( Cystophora cristata ) Barents Sea Sonne et al. (2009) 5 Liver 55.2 41 68 Hooded seal ( Cystophora cristata ) Barents Sea Sonne et al. (2009) 80 Kidney 64.3 16.5 973 CA Sea Lion ( Zalophus californianus ) California Harpe r et al. (2007) 80 Liver 96 37.3 184 CA Sea Lion ( Zalophus californianus ) California Harper et al. (2007) 2 Liver 363 507 Dugong ( Dugong dugon ) Australia Marsh, 1989 3 Liver 529 913 Dugong ( Dugong dugon ) Australia Haynes et al. (1999) 43 Liver 57.6 1100.8 Dugong ( Dugong dugon ) Australia Denton et al. (1980) 38 Liver 2658 458 5375 Dugong ( Dugong dugon ) Australia Haynes et al. (2005) Sirenian samples were converted to wet weight by 3.8 in liver and 5.2 in kidney (Denton et al., 1980).
63 T able 1 2. Whole blood metal concentrations in various marine mammal species (ppm, ww unless otherwise indicated). Element n MeanSD Range Species Location Reference As 28 0.2 0.04 0.6 Harbor Seal ( Phoca vitulina ) Wadden Sea Griesel et al. (2008) 8 0. 3 0.04 0.3 0.4 Florida manatee ( Trichechus manatus) Florida, USA Stavros et al. (2008a ) Cd 28 <0.1 3.1 Harbor Seal ( Phoca vitulina ) Wadden Sea Griesel et al. (2008) 3 <0.003 0.5 Dall's porpoise ( Phocoenoides dalli ) North Pacific Fujise et al. (1988) 3 <0.005 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 8 0.001 0.001 0.001 0.003 Florida manatee ( Trichechus manatus) Florida, USA Stavros et al. (2008a ) 6 0.004 S. elephant seal ( Mirounga leonina ) Antarctica Baraj et al. (2001) 6 0.01 0.03 Pilot whale ( Globicephala melas ) Faroe Island Nielsen et al. (2 000) 4 0.9 31.1 Sperm whale ( Physeter catodon ) Denmark Nielsen et al. (2000) Cu 1 0.8 Gray seal ( Halichoerus grypus ) Germany Kakuschke et al. (2006) 3 0.1 5.1 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 28 0.5 1.4 Harbor Seal ( Phoca vitulina ) Wadden Sea Griesel et al. (2008) 8 0.8 0.1 0.6 0.9 Florida manatee ( Trichechus manatus) Florida, USA Stavros et al. (2008a ) 3 0.7 3.4 Dall's porpoise ( Phocoenoides dalli ) North Pacific Fujise et al. (1988) 6 1.04 So uthern elephant seal ( Mirounga leonina ) Antarctica Baraj et al. (2001) Fe 3 287 915 Dall's porpoise ( Phocoenoides dalli) North Pacific Fujise et al. (1988) 8 388 44.2 323 451 Florida manatee ( Trichechus manatus) Florida, USA Stavros et al. (2008a ) 6 700 S. elephant seal ( Mirounga leonina ) Antarctica Baraj et al. (2001) 85 73386 485 1136 Harbor Seal ( Phoca vitulina) Wadden Sea Griesel et al. (2006); Griesel et al. (2008) 3 497 1119 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987)
64 Table 1 2. Continued. Element n MeanSD Range Species Location Reference Hg 7 0.01 0.02 n.d. 0.05 Florida manatee ( Trichechus manatus), THg Florida, USA Stavros et al. (2008a) 1 0.07 Dall's porpoise ( Phocoenoides dalli ) North Pacifi c Fujise et al. (1988) Pb 28 <0.02 4.5 Harbor Seal ( Phoca vitulina ) Wadden Sea Griesel et al. (2008) 3 <0.002 <0.004 Dall's porpoise ( Phocoenoides dalli ) North Pacific Fujise et al. (1988) 8 0.01 0.003 0.01 0.02 Florida manatee ( Trichechus manat us) Florida, USA Stavros et al. (2008a ) Se 8 0.2 0.1 0.1 0.4 Florida manatee ( Trichechus manatus) Florida, USA Stavros et al. (2008a ) 4 0.60.2 Sperm whale ( Physeter catodon ) Denmark Nielsen et al. (2000) 47 0.6 0.1 Bottlenose dolphin ( Tursiops t runcatus) Florida, USA Stavros et al. (2008b ) 51 0.8 0.2 Bottlenose dolphin ( Tursiops truncatus) South Carolina, USA Stavros et al. (2008b ) 46 0.8 0.2 Bottlenose dolphin ( Tursiops truncatus) Florida, USA Woshner et al. (2008) 23 0.8 0.1 Bottl enose dolphin ( Tursiops truncatus) Florida, USA Bryan et al. (2007) 85 0.9 Harbor Seal ( Phoca vitulina ) Wadden Sea Griesel et al. (2006); Griesel et al. (2008) 6 1 0.3 0.7 1.4 Pilot whale ( Globicephala melas ) Faroe Island Nielsen et al. (2000) 10 1.1 0.2 Northern elephant seal ( Mirounga angustirostris), day 5 lactation California, USA Habran et al., 2001 10 1.2 0.2 Northern elephant seal ( Mirounga angustirostris), day 22 lactation California, USA Habran et al., 2001 1 1.2 Gray seal ( Ha lichoerus grypus ) Germany Kakuschke et al. (2006)
65 Table 1 2. Continued. Element n MeanSD Range Species Location Reference Zn 85 3.40.5 2.6 6.2 Harbor Seal ( Phoca vitulina ) Wadden Sea Griesel et al. (2006); Griesel et al. (2008) 6 3.1 Southern e lephant seal ( Mirounga leonina ) Antarctica Baraj et al. (2001) 1 3.2 Gray seal ( Halichoerus grypus ) Germany Kakuschke et al. (2006) 3 3.9 9.9 Dall's porpoise ( Phocoenoides dalli ) North Pacific Fujise et al. (1988) 3 4.0 17.2 Weddel seal ( Leptonyc hotes weddellii ) Antarctica Yamamoto et al. (1987) 8 11.3 1.2 9.3 12.4 Florida manatee ( Trichechus manatus) Florida, USA Stavros et al. (2008a )
66 Figure 1 1. Schematic diagram of the role of zinc (Zn) on transcription of MT. With an influx of Zn into the cell primarily by membrane transport proteins (Zi ps), Zn induces metal response element transcription factor 1 (MTF1) which then activates metal resonse elements (MRE) found on the promoter region of metallothionein (M T) and other genes Apo MT can then bind to Zn from the cellular Zn pool and interact with other Zn proteins or MTs, regulating in Zn homeostasis in the cell. MT Zn interacts with Zn binding sites of other proteins to influence gene expression, cell prol iferation and differentiation and decreases the chances of apoptosis. MT can also respond to oxidative stress (ROS, NO, etc) resulting in the release of Zn, and the degradation of apo MT Revised diagram from Davis and Cousins (2000), Giedroc et al. (2001 ), and Cousins et al. (2006).
67 CHAPTER 2 BASELINE TRACE METAL LEVELS IN BLOOD OF WILD AND CAPTIVE WEST INDIAN MANATEES ( T richechus manatus ) IN FLORIDA AND BEL IZE Background The West Indian manatee is an endangered species exposed to a number of anthropoge nic influences that may affect population numbers. Manatees are unique among the marine mammals, as they are fully aquatic, obligate herbivores (Reynolds et al. 1999). They are in direct association with s ediments and aquatic vegetation, are sentinel sp ecies for the health of our waterways (Bonde et al. 2004), and reside in close proximity to humans. Manatees inhabit sh allow, estuarine environments, which tend to be sinks for metal contamination. Sources of common metal exposures include pesticide and fertilizer run off from agricultural and urban use, recreational b oating, paint, boat sewage, municip al waste, as well as natural sources (Law al. 1999; Sahu et al. 2007) Although known as toxic elements or heavy metals (non essential metals), (essential) metals can also be extremely important for the health and proper growth of animals. In a review by Fraga (2005), the essential metals were highlighted for their role as a n pro oxidant or antioxidant agents against free radicals. Meta l function is dependent on structure and is mostly bound to metalloproteins and other smaller molecular weight proteins which make them vital for proper function of enzymatic reactions, protein structure, normal growth and development and many other phys iological functions. However, both non essential and essential metals can be detrimental to the health of the animal if found above or below normal baseline levels.
68 Much is unknown in regards to normal baseline metal levels in blood of live, wild West Ind ian manatees in Florida and Belize. To date, there are only two previous publications which have studied metals in the Florida manatee with none on the Antillean manatee 1981 and found high copp er concentrations in the liver from areas of high herbicidal copper use. As a result of this study, copper based herbicides were eliminated in high use areas that manatees inhabit such as Crystal River, Florida. In addition to necropsy samples, Stavros et al. (2008 a ) utilized whole blood and skin samples from eight wild manatees in Crystal River, Florida an d found high levels of arsenic (0.340.04 g/g ww ) and zinc (11.3 0 1.18 g/g ww ) in the blood and aluminum (4.914.98 g/g ww ) in the skin when com pared to other marine mammal species. This study by Stavros et al. (2008 a ) is the only publication that has reported metal levels in manatee blood and provides a preliminary baseline for a small sample size in one location in Florida. As a result, the ob jective of this study is to utilize blood sample s from various sites in Florida and Belize in order to construct a baseline reference range for metals in blood of wild and captive West Indian manatees to be used for clinical, husbandry and management purpo ses. Blood depicts levels of circulating metal loads within the animal which can provide vital information in a live endangered marine mammal. This reference range will assist in monitoring the health of these endangered species in regards to metal expos ure. The West Indian manatee may be in stress as many anthropogenic influences threaten this population, including watercraft collisions and habitat loss. Thus, anthropogenic impacts in terms of contaminants, such as exposure
69 to metals, should be monito red to decrease additional pressures to th is already endangered population Materials and Methods Wild Manatees Manatee health assessments were performed in four locations throughout the state of Florida from 2007 2011: 1) King s Bay, Crystal River, Citrus County ( CCR; 28 o 53'28"N, 82 o 35'50"W) 2) Indian River, Brevard County ( CBC; 28 o 28'13"N, 80 o 45'48"W), 3) Everglades, Collier County (TEP ; 2512'00"N, 8055'08"W ), and 4) Lemon Bay, Englewood, Charlotte County (TSW ; 26 56' 41"N, 82 21' 40"W ). Health asses sments were performed by and under the authority of the USGS Sirenia Project and Florida Fish and Wildlife Commission. In addition to the United States, health assessments were conducted in Central America, Belize (BZ) in Belize City (16 0 0 Placencia Lagoon (16 0 37'56"N, 88 0 21'05"W), and Northern and Southern Lagoon (17 0 11'46"N, 88 0 19'28"W) under the authority of Sea to Shore Alliance in 2008 2011. Manatees were captured with a 122 m long net by a land set capture or boat based capture de pending on location. Morphometrics including straight line and curvilinear length, girths and weights, as well as any additional markings, were recorded during health assessments. Age categories were estimated using body length measurements. For this s 225cm=calf, 226 270=subadult, and > 270cm=adult ( revised 1985) A total of 151 wild manatees were used in this study for whole blood analysis. There were 77 samples (46 males, 31 females) from Citrus County, Florida (CCR), 20 samples (11 males, 9 females) from Brevard County, Florida (CBC), 7 samples (4
70 males, 3 females) from Collier County, Florida (TEP), 14 samples (5 males, 9 females) from Charlotte County, Florida (TSW), and 33 animals (15 males, 18 females) from Belize (BZ). Captive Manatees A total of 37 whole blood samples were obtained from 8 captive (CAP) manatees (2 males, 6 females) and 11 rehabilitating (REHAB) manatees (5 males, 6 females) with 18 of the animals in Florida and one in Belize. Samples were obtained from Homosassa Springs Wildlife State Park in Homosassa, Florida, Mote Marine Laboratory in Sarasota, Florida, and Wildtracks Manatee Rehabilitatio n Centre in Sarteneja, Belize. Blood Collection Blood was collected fr om the medial interosseous space between the radius and ulna from minimally restrained manatees by a veterinarian or highly trained biologist. Blood was collected using an 18 gauge x 38.1 mm needle into a 7 mL roy al blue top Monoject tube with K 2 EDTA an ticoagulant, specifically designed for trace element analysis. Two tubes were collected per manatee ; one for whole blood analysis and one for erythrocyte and plasma analysis. One blood tube was placed in a centrifuge at 3 000 rpm for 10 minutes in the fi eld or in the laboratory. Plasma was collected, buffy coat discarded and erythrocytes were saved. All blood samples were then put on ice while in the field and stored at 4 0 C or 80 0 C until analyzed. In addition to whole blood, erythrocyte and plasma sa mples were obtained when ever possible Recent publications have concentrated on whole blood samples, as it accurately depicts changes in circulating levels of trace metals. Past publications have also utilized serum and plasma, thus, plasma was analyzed for this study Some elements were below the level of detection (LOD), so a total of 15 elements were
71 analyzed Total p lasma sample s analyzed were : CCR=39, CBC= 10, BZ=16, CAP=8, and REHAB=4. In addition to plasma, erythrocytes were analyzed to determine the trace metal loads in each compartment of the blood. A total of 22 elements were analyzed from e rythrocyte sa mples : CCR=67, CBC=11, TEP=10, TSW=9, B Z =15, CAP=8, and REHAB=10 Sample Analysis Routine serum chemistry with a complete blood count was mea sured on blood samples and was performed in house by the Clinical Pathology Department at the College of Vet erinary Medicine at the University of Florida. Forty one whole blood samples were in 2007 a t the start of this study An aliquot of whole blood, plasma, or erythrocytes (250 1000 L) was placed in borosilicate glass tubes (18x150 mm, Fisher Scientific Company, Pittsburgh, PA) and measured for wet weight (mg). U ltrapure Optima nitric acid (Fishe r Scientific Company) was placed in each tube in a 45 well graphite digestion block at approximately 130 o C. Ultrapure 30% hydrogen peroxide (Mallinckrodt Baker, Inc., Phillipsburg, NJ) was then used to complete digestion of organic matter. Three to ten mL of Millipore deionized (DI) water was then added to dissolved samples. Each sample was filtered using a 13 mm nylon syringe filter (0.2 um, Fisher Scientific Company) and placed in a 15 mL conical tube (Corning Life Sciences, Lowell, MA) for analysis usi ng an inductively coupled plasma mass spectrometry ( Thermo Electron X Series ICP MS, Thermo Fisher Scientific, Inc., Waltham, MA) at the College of Pharmacy at the University of Florida The ICP MS provides sensitive analysis on a larger number of element s than using
72 atomic absorption spectrophotometer as used in the past (Law 1996). Although X ray fluorescence spectrometry can also be used (Griesel et al. 2006), ICP MS was accessible for our use and more commonly used for multi element analysis. For e ach sample, a maximum of 22 elements were analyzed, including: Ca, Mg, Cu, Zn, Mn, Li, Se, Sr, Mo, As, Ba, Cd, Co, Pb, Hg, Ni, Pt, Ag, Tl, U, Cr, and Fe with an internal standard of 115 In. Quality assurance for manatee samples included blank samples, repe at samples, and NOAA whale and manatee livers. The standard reference material for select elements is reported as follows ( meanSEM ) with standard laboratory results in parenthesis, for beluga whale liver II homogenate NOAA standard reference material (QC9 7LH2) : As 1.50.19 (0.390.03 ), Cd 2.110.04 (2.350.06), Cu 11.350.24 (13.160.4), Fe 62527 (66815), Se 28.82.6 (24.30.85), and Zn 201.48 (26.310.66) The pygmy sperm whale Liver III (QC03LH3 ) NOAA standard resulted in : As 0.40.04 (0.860.08), Cd 5.640.22 (5.940.38), Co 0.060.005 (0.07 0.003), Cu 2.740.15 (2.740.19), Fe 60548 (69445), Se 10.330.95 (7.871.18), and Zn 17.471.39 (21.151.65). The Triplicate runs were performed on the ICP MS on each sample and the mean was obtained in ppb. The mean was then multiplied by the volume of DI water the sample was reconstituted with to obtain total concentration in ng/mL. Concentrations of samples were then reported as ng/mg using the original weight of the sample, or ppm wet weight. Statistics Descriptive statistics for mean, standard error and range for each element w ere calculated using SigmaPlot version 11 (Systat Software Inc., Sa n Jose, CA). Samples that were below detection l imit (BDL) were included in statistical analysis by dividing the BDL by half. Non parametric statistics was used when the data was not
73 normally distributed based on the Shapiro SigmaPlot A Pearson Product Moment Correlation was performed to determine if a correlation was present for se x (male, female), age class (calf, subadult, and adult), strai ght length (cm), and weight (kg ) for each metal in wild manatees. A Kruskal Wallis o ne way analysis of variance (ANOVA) on r anks was performed to determine a significant difference (p<0.05) for ea ch metal in each age class. A one w ay ANOVA with a pairwise multiple comparisons (Holm Sidak) was performed using the average and standard error for each element based on location. In addition, a Kruskal Wallis o ne way ANOVA on r method for pairwise multiple comparison was used to find a significant difference(p<0.05) between captive and wild animals for each element. Fractionation and Reference Range Calculations In order to determine metal fractionation in each component of the b lood, 13 wild manatees from Crystal River, Florida from 2008 2009 were used for this calculation. Mean standard deviations were calculated for metal concentration of Cu, Zn, As and Se for each fraction of the blood using SigmaPlot A clinical refere nce range was determined for the West Indian manatee using MedCalc Software version 12.1.4 (Mariakerke, Belgium) A reference interval was calculated using the normal distribution, non parametric percentile method and the as described in the CLSI Guidelines C28 A3. A double sided, 95% prediction interval was used to determine the lower and upper limit of the distribution. the third quartile or below t he first quartile of the box plot. A 90% confidence interval (CI) was calculated for each element. If a sample size was >120 and was normally distributed, the 90% confidence interval was calculated using normal distribution. If a
74 sample size was >120 an d normal distribution did not pass, the 90% confidence interval using the non parametric percentile method. If sample size <120 and not normally distributed, the robust method was used. The CI could not be calculated if the sample was too small or the sa mples resulted in equal values. Results Whole B lood Trace metal concentrations of 22 elements from wild and captive manatees were determined Table 2 1 shows the mean trace metal concentrations in whole blood standard error with measured ranges from eac h location in wild captive and rehabilitating manatees Geographic location was found to have a significant impact on whole blood concentrations in a few metals. There was no significant difference in Ni (p=0.081), Pt ( p=1), Ag (p=0.97) and U (p=1) ; ho wever Ca (p=0.005) and Mg (p<0.001) were significantly higher in TEP (x=72.71 ppm and 71ppm, respectively) than CCR or TSW. Lithium (p<0.001) was statistically significant from CCR, TEP, and TSW, while Mo (p=0.02) was significantly higher in CCR than TEP and TSW. Copper (p<0.001) was significantly higher in CAP (x=1.17ppm) and REHAB (x=1.05ppm) when compared to other locations, but not significantly different from one another. Manganese (p<0.001) in BZ, CAP, and REHAB were significantly different fro m w ild Florida manatees There was a statistically significant difference in Se (p=0.003) between locations, wi th the lowest Se in CBC (x=0.09 ppm) and REHAB (x=0 .07 ppm). There was a significant difference in Sr (p=0.002), with the lowest mean in CCR (x=0.2 ppm). Zinc (p<0.001) had a significant difference in location with lowest values in BZ (x=7.75 ppm) and REHAB (x=8.89 ppm) animals. Iron (p<0.001) was statistically significant with lowest
75 values in BZ (x=285.07 ppm), while As (p<0.001) had highest valu es in BZ (x=0.43 ppm). C (p<0.001; highest in BZ), Pb (p=0.006 ) Ba (p<0.001), and Cr (p<0.001) were statistically significant ; however <0.1 ppm in all locations, while Cd (p<0.001), Hg (p<0.001 ), and Tl (p=0.005) were lower than <0.01 ppm. Moreover, th ere was a significant difference within the locations of Belize (p=0.025), with As lev els in Placencia Lagoon (x=0.69 ppm) double that of Southern Lagoon (x=0.32 p pm) and Belize City (x=0.34 ppm). For wild manatees only, t here was no significant differen ce between sexes for each metal as shown in Table 2 2 However, there was a significant difference in Cu (p<0.001), Ag (p=0.023), and Tl (p=0.02) within age class. Copper levels were highest in wild calves>sub adult>adult with a mean of 1.2>0.8>0.7 ppm, r espectively. Silver levels were highest in adults>subadults>calves with a mean of 0.006>0.002>0.0006 ppm, respectively. Thallium levels were highest in calves>subadult>adult with a mean of 0.003>0.001>0.00005 ppm, respectively. There was a significant d ifference in Cu (p<0.001), Cd (p=0.023), Pb (p=0.016), and Tl (p=0.025) within straight length measurements as straight length increased, metal concentrations decrease d In addition to sex, age class and straight length, there was a significant difference in Cu (p=0.0028), Pb (p=0.017), Ag (p=0.045 ), and Fe (p<0.001) based on weight (kgs). As weight increased in manatees, Cu and Pb concentrations tended to decrease ; while as weight increased Ag and Fe levels increased. Wild manatees were then compared to captive and rehabilitating manatees ( Table 2 3) and resulted in differences in whole blood metal concentrations There was no significant difference in Fe. However, Zn (p=0.025) and S e (p<0.001) were significantly
76 lower in REHAB animals, while Co (p<0.00 1) had highest levels in REHAB animals. Arsenic (p<0.001) and Mn (p=0.021) were statistically significant with highest levels in wild manatees, while Cu (p<0.001) and Cd (p<0.001) had highest levels in REHAB and CAP manatees. Plasma Trace metal concentra tions in plasma of 12 elements from wild captive and rehabilitating manatees were examined ( Tabl e 2 4). There was no significant difference between wild captive and rehabilitating animals in Cr (p=0.410), and Zn (p=0 076). However, wild manatees had si gnificantly lower plasma levels in Se (p=0.021). Captive manatees had significantly higher Cu (p<0.001) and Pb (p=0.046) concentrations, while As (p=0.015) and Fe (p=0.036) were statistically hig her in rehabilitating animals. Based on location in wild man atees in this study, there was no significant difference in plasma Cu (p=0.065), Zn (p=0.127), Mn (p=0.142), Sr (p=0.135), Cr (p=0.128), and Fe (p=0.608). However, there was a significant difference in Se with p=0.032 (CR>BZ>CBC: 0.1>0.07> 0.07 ppm), and A s with p<0.001 (CR>CBC>BZ: 0.02>0.01 >0 ppm). Similar to whole blood, t here was no significant difference between sexes for each trace metal in wild manatees. Erythrocytes Trace metal concentrations of 22 elements from wild captive and rehabilitating man atees were analyzed ( Tabl e 2 5). There was no significant difference in P (p=0.089) between wild captive, and rehabilitating manatees. There was a significant difference in Mo (p<0.001) and Cd (p<0.001) ; however levels in all locations were <0.01ppm. T here was a statistically significant difference in Cu concentrations (p<0.001) with h ighest levels in REHAB animals, whereas Se (p<0.001) was lowest in REHAB animals.
77 Mg (p=0.003) and Pb (p<0.001) were highest in TEP and K (p<0.001) had lowest concentrati ons in TEP. Iron concentrations were significantly different with levels highest in CBC. Zinc (p<0.001) levels were lower in BZ and REHAB animals, while Cr (p<0.001) and As levels were highest in BZ manatees. For wild manatees, there was no significant d ifference in Pb (p=0.055) concentrations based on location ; however there was a significant difference in Cu (TSW>BZ>CCR>CBC>TEP: 0.59>0.57 >0 .54> 0.49>0.34 ppm), Zn (CBC>TSW> TEP>CCR>BZ: 27.7>26>25.1> 23.5>14.9 ppm), Mn (CCR> TEP>TSW>CBC>BZ: 0.037>0.037>0 .035> 0.033>0.012 ppm), a nd As (BZ>CCR>TSW>TEP>CBC: 0.85>0.53>0.3> 0.3>0.2 ppm) with p<0.001 and Se (CCR>TSW>BZ>TEP>CBC: 0.2>0.2> 0.1>0.1>0.1 ppm) with p=0.006. Similar to whole blood and plasma, t here was no significant difference between sexes. Blood Fractionations and Reference I nterval Blood was fractionated for copper, zinc, arsenic and selenium levels (Figure 2 2). According to our results, Zn (89%), As (95%), and Se (68%) are predominately found in the eryth rocytes, while the majority of Cu (66%) is found in plasma. A reference interval was completed for up to 19 elements in the West Indian manatee After eliminating outliers (Figure 2 3) using the Tukey Method, a preliminary reference range was determined (Table 2 8). Whole Blood Comparisons t o Other Marine Mammals and Components Whole blood results were compared to other mammalian species in order to 6 shows comparisons based on meanstandard deviation. Metal levels wer e low or similar to other mammalian species except Cu, Zn, Se, and As which were of special interest.
78 We found that manatees had Zn levels up to five times that of other mammal species, as shown in Figure 2 1. Lab methodologies did vary between publicat ions, from total reflection X ray Fluorescence (TXRF; Griesel et a l 2008), graphite furnace atomic absorption spectrometry (GFAAS; Baraj et al. 2009 ), to inductively coupled plasma mass spectrometry (ICP MS; Stavros et al. 2008 a ; current study) but al l values were reported as ppm, wet weight for comparison purposes. Moreover samples from various aquatic species from Dr. Mic h a el Walsh were run for metal analysis in the Barber lab using the same methods described previously. Methods were similar and resulted in values shown in Table 2 7. There was no significant difference in Cu levels between species in Table 2 7, but there was a significant difference in Zn (p<0.001), Se (p<0.001), and As (p=0.013) levels. Discussion Studies of metal concentrations in whole blood in the endangered West Indian ma natee have been limited. M etal levels in manatees have been compared to other marine mammals in the past ; however manatees are strict herbivores that thrive in shallow fresh, brackish and salt water compa red to that of piscivorous consuming offshore marine mammals This is likely to impact their intake of a number of metals. As a result, the data was compared with other marine mammals as well as the preliminary baseline trace metal level presented by S tavros et al. (2008 a ). Due to the practical use of whol e blood analysis in many cases ( rather than plasma or erythrocytes ) the focus of this discussion will be on whole blood. Whole blood is accurate for determinating circulating metal levels and has be en used in other marine mammal species in the past Elements concentrate in various components of the blood, thus, whole blood analysis provides data on overall metal level s. Metal
79 concentrations in whole blood of manatees are affected by a number of para meters, including age class total length, weight, location, and captivity/rehabilitati on as well as differ for each metal Most elements were found at or below low levels or within comparable levels previously reported for other marine mammals ( Table 2 6 ). However, Cu, Zn, As, and Se in whole blood are of special interest. Copper Copper is an essential element and is used in almost every cell of the body with a number of vital copper dependant enzymes, such as cytochrome C oxidase and supe roxide dismut ase (Thompson 2007 a ). Based on our results, Cu levels were highest in captive and rehabilitating manatees This is of concern, as Cu is toxic at high amounts with levels >1.5 ppm in whole blood or serum considered Cu toxicosis in sheep (Osweiler, 1996 ). Values in captive manatees averaged a mean of 1.17 0.04 ppm. Although the level of Cu toxicity in whole blood is unknown in manatees, levels were significantly higher in rehabilitation and captive manatees compared to wild thus, facilities should be aw are of the repercussions of Cu toxicity an d monitor potential Cu exposure In many cases, blood Cu levels remain normal until reaching hepatoxicity due to Cu accumulation, therefore a significant rise in blood Cu levels could be used to predict an animal in jeopardy (Osweiler, 1996) In a reported case by Mazanek and Hajkova (2004), a thirty year old female Nile crocodile ( Crocodylus niloticus ) in the Brno Zoo, imported from Africa in 1973, died after symptoms of anorexia, apathy, indigestion and hemoly sis. At necropsy, 14 Cu coins were removed from the stomach with liver and kidney concentrations of 1022 ppm and 360 ppm, respectively. There was also necrotic and ulcerative gastritis and enteritis, necrosis of the liver, and degeneration of hepatocyte s. It was hypothesized that the coins could have been in the animal for 16
80 28 years, thus, resulting in organ degeneration and decreased immune system. Moreover, in the related species of the manatee, a dugong ( Dugong dugon ) was suspected of Cu poisoning due to copper sulfate algaecide at the Cairn s Oceanarium (Oke 1967). In this study, captive and rehabilitating manatees had a significantly higher level of Cu than wild manatees which warrants a need for further investigation. In wild manatees, copper concentrations were significantly higher in manatees assessed in urban areas, such as Citrus, Brevard, and Charlotte Count ies compared to the Everglades. This corroborates data from copper concentrat ions up to 1,400 pp m (dw ) in urban areas, such as Crystal River, Florida, likely due to high copper based herbicidal use. Thus, body burdens of Cu in Florida manatee carcasses will be investigated (Chapter 3 ) to compare results to and investigate possi ble environmental factors involved in the increased level of Cu in urban locations. When toxic levels of copper are accumulated, necrosis occurs in the liver, where copper is then released into the bloodstream damaging red blood cell membranes and releas ing hemoglobin. This causes the animal to become hypoxic releasing more free copper into circulation (Thompson 2007 a ). This is especially important in young animals, as calves in this study had the highest amount of copper in whole blood when compared t o adults and subadults. It has been shown that Cu is most abundant in younger animals, the result of possible transplacental transfer in other marine mammal species Yang et al. (2004) found Cu in the liver of the fetus (60.9 g/g w w ) of a single porpoise ( Phocoenoides dalli ) was higher than the mother (10.4 g/g ww ). Moreover, copper levels were highest in neonatal cetaceans and harp seals as well
81 (Fujise et al. 1988, Wagemann et al. 1988, Parsons 1999). As a result, Cu should be monitored i n the environment and in captive facilities, as Cu can affect fetal growth and development in animals Zinc Zinc is a transition metal and an essential element (Garland 2007 ) and is vital for enzymatic reactions, growth and development, endocrine, reprodu ct ion, and the immune system (Law 1996; Osweiler 1996). As was shown in Stavros et al. (2008 a ), l evels of zinc in whole blood was two to five times higher in manatees compared to other marine mammal species ( Brookens et al. 2007 ; Bryan et al. 2007; Gr iesel et al. 2006 ; Stavros et al. 2008b ). Despite this elevated level, m anatees in this study did not exhibit any clinical signs of zinc toxicity described in previous studies (Agnew et al., 1999; Dziwenka and Coppock, 2004; Garland, 2007 ; Mautino, 1997 ) The level of Zn may be species specific, as zinc levels simila r to the manatee were found in l eatherback sea turtles ( Dermocheyls coriacea ) in French Guiana with a mean and standard deviation of 11.100.28 (Guirlet et al. 2008). This elevated Zn leve l may be unique in certain sp ecies, such as the manatee and l eatherback sea turtle. H owever the underlying reasons for the species differences are unknown at this time. An interesting observation in our data was that there was no significant difference in Zn levels between wild and captive manatees. In addition, Zn levels were higher in erythroc ytes (Figure 2 2) than plasma. Due to the elevated Zn levels in wild and captive manatees, Zn fractionation in erythrocytes, and the lack of adverse reactions, we hypoth esize that there is a physiological need for elevated level s of Zn in manatees. Absorption of Zn depends on a number of factors, including interac tions of other elements (calcium copper), d ietary concentration, age, growth rate, available protei n,
82 and mineral makeup of the diet. Thus, the role of the herbivorous diet as a potential source in elevating erythrocyte Zn levels in manatees in Florida is suggested. However, when examining the herbivorous green sea turtle ( Chelonia mydas ) whole blood sa mples from Florida analyzed in our laboratory (Table 2 7), manatees were significantly higher tha n green sea turtles. A ccording to Das et al. (2003), diet is the primary source of metal exposure in marine mammals, thus, we expect metals to be e valuated in the Florida manatee (Chapter 4 ). In addition, in order to determine the physiological use of Zn in manatees, studies were performed on the induction of metallothionein (Chapter 6 ) and kinematics of carbonic anhydrase (Chapter 5 ) Although levels of whol e blood Zn in wild and captive manatees were elevated compared to other species, we found that rehabilitating manatees had significantly lower Zn concentrations which may be related to the health status of the individuals Many manatees which are admitted to rehabilitation are brought into a facility due to an illness, malnutrition, or injury. The effects of health status on decreased Zn levels were also noted in the livers of California sea lions suspected of domoic acid toxicity (Harper et al., 2007 ). Zinc is an essential element found in many metalloenzymes and is vital for proper growth, skeletal development, wound heal ing, and reproduction (Osweiler 1996). Thus, Zn may be mobilized in sick rehabilitating manatee s for purposes such as wound healing but additional studies are needed to confirm this idea and will be futher discussed in Chapter 6 Although signs of toxicity are not apparent in this study, Zn toxicosis is of interest in captive facilities nationwide. Due to the ingestion of United Sta tes pennies made after 1983, many captive animals have died of zinc toxicosis, such as a Celebes ape
83 ( Macaca nigra ; Murray et al. 1997), a striped hyena ( Hyaena hyaena ; Agnew et al. 1999), and a gray headed chachalaca ( Ortalis cinereiceps ; Droual et al. 1991). The data in this study establishes a reference range for zinc in healthy manatees and can be used to monitor captive animals for evidence of abnormal exposures. Arsenic Arsenic exposure in animals can be obtained from contami nated water, herbicide s, and agricultural runoff ( Penrose and Woolson 1974; Osweiler 19 96, Ensley 2004 ). Stavros et al. (2008 a ) found higher levels of As in whole blood of wild manatees residing in Crystal River, Florida (0.340.04 ppm) compared to other marine mammals. Ci trus County manatees examined in this study were similar in whole blood As (0.30.02 ppm) levels reported by Stavros et al. (2008 a ) but As was significantly higher in Antillean manatees in Belize (0.430.07 ppm ) and much lower in captive manatees ( 0.050. 01 ppm). Our main concern is elevated As due to anthropogenic influence. According to Lund e (1977), arsenic in the marine environment is much more detrimental than in terrestrial areas. In the marine environment, inorganic arsenic is transformed to lipop hilic and water soluble organic arsenic and is especially a concern in the lower trophic animals. Therefore, lower trophic animals, such as manatees, may be at a risk. In Kubota et al. (2001), a total of 226 liver samples from 16 species found that marin e mammals feeding on cephalalopods and crustaceans had a higher arsenic concentrati on than those feeding on fish. In addition, according to Fernandez (2002), insecticides, pesticides, herbicides, and fungicides may be a potential source of metal contamina tion in Belize. These chemicals are commonly used for banana, sugarcane, citrus, papaya and rice industries, as well as by other small farms. In addition to
84 anthropogenic influences, arsenic contamination in ground water in Central America is present, bu t poorly documented (i.e. Mexico) and not well understood (Ravenscroft and Costa Rica for contaminant analysis, but did not detect As or Zn However, Rainwater et al (2007) conducted their study o n animals found in the northern part of Belize in Gold Button Lagoon and N ew River Watershed, while this study was conducted towards the Southern end of Belize in Belize City, Placencia Lagoon and Southern Lagoon. Based on o ur results, there was a significant difference within As levels in whole blood of Antillean manatees. Arsenic levels in Placencia Lagoon were double those of Belize City and Southern Lagoon. According to Short et al. (2006), Placencia is a coastal villag e with recent increase in development and a rising tourism industry. The lagoon is affected by nutrient enrichment from groundwater, shrimp farming, and live aboard boats which can potentially contribute to the high levels of As in the area. Although leve ls may be high, arsenic speciation (via HPLC ICP MS) is highly recommended in order to determine the potential for toxic effects, if any, to manatees. Higher trophic marine mammals and sea turtles contained predominately arsenobentaine which is non toxic and has a short biological half life in marine mammals (Kubota et al. 2002; Kunito et al. 2008) The dugong on the other hand, accumulated predominately methylarsonic acid and dimethylarsinic acid as opposed to arsen obentaine (Kubota et al. 2002; 20 03) Kubota et al. (2002) suggested the difference in arsenobentaine in dugongs may be due to their seagrass diet. Thus, it has been found that marine mammals generally contain organic forms of non toxic As, and
85 despite high hepatic As accumulation, risk of toxicity remains low. As a result, speciation is of utmost importance in order to determine As toxicity in Antillean manatees. Although it has not been reported in marine mammals, excess As is of a concern in humans due to the impact on reproduction at elevated levels A rsenic has been linked to infant mortality and increased abortion rates in humans in Bangladesh (Rahman et al. 2010). It has been suggested that biomethylation of inorganic As that was once thought to be a detoxification process may be of toxic effects and as a result, dimethylarsinic acid causes genotoxic and tumorigenesis (Yamanaka et al. 2004). In marine mammals, Kubota et al. (2005) examined the potential of maternal transfer of As which indeed, do es tran sfer to the calf Although, the fetus contained half the As concentration of the mother, the effects of As is of concern in an already endangered species, such as the manatee, with a long lifespan and a slow reproductive rate. Therefore, species differen ce according to the trophic level and speciation are important when evaluating As concentrations and toxicity in marine mammals. Selenium Selenium is also an essential metal and an integral part of enzymatic functions such as the glutathione peroxidase s and thioredoxin reductase (Schomburg et al. 2004). Selenium plays a vital role in the immune system, reproductive system, normal hepatic function, neurotransmission, and in preventing carcinogenic functions (Hall 2007). Moreover, Se has been known to function as a detox ification mechanism for Hg with a 1:1 molar ratio in marine mammals with high hepatic Hg levels ( Dietz et al., 2000; Koeman et al. 1975 ). When compared to other marine mammal species, Se levels
86 seem to be quite low in the manatee (Tabl e 2 6). As with arsenic, Se uptake is dependent on diet, environment and speciation, therefore, this low Se concentration in manatees may be due to a number of possible reasons. Lewis et al. (2007) analyzed seagrasses from the West coast of Florida and the Florida Keys and found that seagrass had low levels of Se. As a result, the diet of the manatee many be involved in the lower Se concentrations in whole blood and will be examined in Chapter 4 Although Hg does not seem to be of a concern in wild West Indian manatees, Se concentrations were significantly lower in captive and rehabilitating manatees in this study. Further studies are needed in order to determine if this lower Se levels in captive and rehabilitating manatees may be of concern in a speci es with already low Se levels Husbandry concerns, such as diet and supplementation, need to be taken into account to avoid Se deficiency (or toxicity) in manatees. Selenium deficiency may be involved in a number of diseas es in humans, including Keshan d isease and Kashin Beck d isease, as well as muscle dystrophy, pancreatic fibrosis, embryonic death, and hepatic apoptosis in various animals (Fordyce 2005), ju st to name a few. Moreover, Se is known to be an antioxidant and anti inflammatory element (Raym an 2000) which can be important in malnourished or injured rehabilitating manatees. Therefore, careful monitoring of captive and rehabilitating Se levels is recommended in the manatee. Summary This is the first study to detect trace metals in live, wild manatees in a variety of locations throughout Florida and Belize. A preliminary reference range was established (Table 2 8) for use by clinicians, biologists and husbandry staff to determine trace metal concentrations in manatees. Based on recommendation s fr om the Clinical and Laboratory S tandards by Horowitz et al. (2008), a rob ust clinical reference range ha s a
87 sample size of 120. Thus, additional studies to increase the sample size should be made to determine a more solid reference range. Although or gan samples provide an insight to long term trace metal accumulation in marine mammals, samples may not be easily accessible and, most often times, are collected from stranded animals which are stressed and may have been immunocompromised. Thus, blood is a useful biomonitoring tool for current circulating levels of trace metals. However, it should be noted that elements vary in concentrations between species and blood compartments Gray et al. (2008) reported that trace metal concentrations in Weddell ( L eptonychotes weddellii ) and leopard ( Hydrurga leptonyx ) seals vary throughout the year depending on a number of parameters, including prey availability and amount consumed at the time of sampling, trophic level of the species and prey, individual health an d nutrition status, as well as anthropogenic and natural environmental exposures. Therefore, clinicians and researchers should be cautious when comparing trace metal blood concentrations between individuals, species, locations and sampling periods. In a ddition, speciation of metals is highly recommended in manatees in order to determine th e potential toxicity in this endangered species.
88 Table 2 1. M etal concentrations in whole blood of wild captive and rehabilitating (rehab) West Indian manatees ( Tric hechus manatus ) based on location. Element n CCR: Citrus County, Florida n CBC: Brevard County, Florida n TEP: Collier County, Florida n TSW: Charlotte County, Florida Ca 20 65.61.2 ----7 72.73.6 14 63.80.9 (56 74) (60 86) (58 69) Mg 20 5 4.21.8 ----7 714 13 62.12.1 (24.4 99.4 ) (50 80) (49 74) Cu 77 0.80.03 20 0.80.05 7 0.40.1 14 0.80.02 (0.3 1.4 ) (0.5 1.5 ) (0.2 0.7 ) (0.6 0.9 ) Zn 77 11.80.4 20 10.70.5 7 14.70.2 14 14.80.4 (5.7 19.7 ) (8.2 15.4 ) (13.8 15.4 ) (11.6 16.7 ) Mn 63 0.02 0.001 16 0.02 0.003 7 0.02 0.002 13 0.02 0.001 (0.004 0.04 ) (<0.050 0.06 ) (0.02 0.03 ) (0.01 0.03 ) Li 20 0.0060.001 -----7 0.01 0.001 13 0.01 0.001 (0.002 0.01 ) (0.006 0.01 ) (0.01 0.02 ) Se 77 0.2 0.011 20 0.09 0. 007 7 0.20.05 14 0.20.01 (0.06 0.6 ) (0.05 0.16 ) (0.1 0.5 ) (0.1 0.2 ) Sr 37 0.20.01 6 0.30.03 7 0.30.01 13 0.20.01 (0.1 0.4 ) (0.2 0.4 ) (0.2 0.3 ) (0.2 0.3 ) Mo 37 0.02 0.001 ----7 0.01 0.0003 13 0.010.001 (0.006 0.04 ) (0.01 0.01 ) (0.01 0.02 ) As 77 0.30.02 20 0.20.02 7 0.20.1 14 0.20.02 (0.04 1.3 ) (0.07 0.3 ) (0.05 0.7 ) (0.1 0.4 ) Ba 20 <0.00020.0003 6 0.020.005 7 0.001 0.0002 13 <0.00020.001 (<0.0002 0.004 ) (0.005 0 .04 ) (0.0003 0.002 ) (<0.0002 0.004 ) Cd 75 0.0 020.0002 20 (0.003 0.0005) 7 0.00040.0001 14 0.0010.0001 (0.0001 0.005 ) (<0.01 0.005 ) (<0.0002 0.001 ) (0.0004 0.002 ) Co 75 0.002 0.0002 20 0.0020.001 7 0.010.001 14 0.001 0.0002 (0.0004 0.007 ) (<0.01 0.01 ) (0.003 0.01 ) (0.001 0.003 ) Pb 2 0 0.030.008 14 0.020.002 7 0.030.01 14 0.010.001 (0.0003 0.001 ) (0.01 0.03 ) (0.01 0.07 ) (0.001 0.02 ) Values are given as ppm (ww) unless otherwise noted; Average standard error with ranges in parenthesis. n denotes sample size; --depicts i nsufficient data
89 Table 2 1. Continued. Hg 20 <0.0006 0.0001 20 0.010.001 7 0.0020.0005 13 0.0010.0003 (<0.0006 0.001) (0.004 0.02 ) (<0.0006 0.004 ) (<0.0006 0.003 ) Ni 20 <0.0030.0003 ----7 <0.003 14 <0.0030.001 (<0.003 0.01 ) <0.003 (<0.003 0.003) Pt 20 <0.0002 ----7 <0.0002 13 <0.0002 <0.0002 <0.0002 <0.0002 Ag 20 0.0050.001 ----7 0.0070.002 13 0.0030.001 (0.0002 0.01 ) (0.002 0.01 ) (0.002 0.01 ) Tl 20 <0.00010.0001 ----7 <0.0001 13 <0.0001 (<0.0001 0.001) <0.0001 <0.0001 U 20 <0.0001 ----7 <0.0001 13 <0.0001 <0.0001 <0.0001 <0.0001 Cr 29 0.010.001 10 0.040.002 --------(0.004 0.04 ) (0.05 <0.1 ) Fe 52 39212.9 20 417.724.1 --------(264.2 701.6 ) (3 23.8 836.3 ) Values are given as ppm (ww) unless otherwise noted; Average standard error with ranges in parenthesis. n denotes sample size; --depicts insufficient data.
90 Table 2 1. Continued. Element n BZ: Belize n CAP: Captive n Rehab Cu 33 0.7 0.04 24 1.20.04 13 1.10.2 (0.3 1.0 ) (0.7 1.7 ) (0.7 2.8 ) Zn 33 7.70.2 24 10.00.6 13 8.91.2 (5.1 11.1 ) (5.7 16.1 ) (4.6 18.5 ) Mn 33 0.01 0.0004 17 0.01 0.001 8 0.01 0.001 (0.0003 0.01 ) (0.002 0.01 ) (0.01 0.01 ) Se 33 0.20.1 24 0. 10.01 13 0.10.01 (0.02 1.3 ) (0.1 0.2 ) (0.03 0.1 ) As 33 0.40.1 24 0. 10.01 13 0.03 0.004 (0.1 1.7 ) (0.003 0.3 ) (0.01 0.05 ) Cd 33 0.0040.0003 24 0.0030.001 13 0.0030.001 (<0.01 0.01 ) (<0.01 0.01 ) (<0.01 0.01 ) Co 33 0.010.004 24 0.0040.0004 13 0.01 0.002 (<0.01 0. 1 ) (<0.01 0.005 ) (<0.01 0.01 ) Pb 33 <0.05 24 <0.05 13 <0.05 <0.05 <0.05 <0.05 Cr 33 <0.1 24 <0.1 13 <0.1 <0.1 <0.1 <0.1 Fe 33 285.17.6 24 347.614.8 13 306.218.3 (212.5 406.4 ) (192.4 467.1 ) (248.5 428.8 ) Values are given as ppm (ww) unless otherwise noted; Average standard error with ranges in parenthesis. n denotes sample size; --depicts insufficient data.
91 Table 2 2. Pearson correlation of metal concentrations based on sex, age c lass, straight length (cm), and weight (kgs) in wild West Indian manatees ( Trichechus manatus ). Ca Mg Cu Zn Cd Co Pb Hg sex r 0.1 9 0.2 0.04 0.11 0.09 0.02 0.003 0.11 p value 0.24 0.05 0.63 0.18 0.29 0.83 0.98 0.39 # samples 41 98 154 154 152 1 52 92 60 age r 0.18 0.11 0.32 0.12 0.03 0.07 0.15 0.02 p value 0.25 0 .28 0.0001 0.13 0.7 0.39 0.16 0.91 # samples 41 98 154 154 152 152 92 60 SL r 0.12 0.09 0.28 0.12 0.18 0.15 0.25 0.06 p value 0.45 0.39 0.001 0.15 0 .02 0.07 0.02 0.63 # samples 41 98 154 154 152 152 92 60 wt (kgs) r 0.36 0.04 0.29 0.09 0.01 0.14 0.33 0.13 p value 0.05 0.72 0.003 0.39 0.93 0.17 0.02 0.39 # samples 29 71 102 102 100 100 51 48 Table 2 2. Continued. Ni Pt Ag Tl U Cr Fe sex r 0.21 2.9E 08 0.0 4 0.11 2.93E 08 0.05 0.04 p value 0.17 1 0.81 0.52 1 0.65 0.72 # samples 45 40 40 40 40 76 109 age r 0.21 3.3E 08 0.36 0.37 3.29E 08 0.001 0.12 p value 0.17 1 0.02 0.02 1 0.99 0.21 # sampl es 45 40 40 40 40 76 109 SL r 0.19 1E 07 0.29 0.35 1.03E 07 0.12 0.09 p value 0.21 1 0.07 0.03 1 0.29 0.35 # samples 45 40 40 40 40 76 109 wt (kgs) r 0.26 5.1E 08 0.38 0.35 5.1E 08 0.08 0.40 p value 0.17 1 0.04 0. 07 1 0.62 0.001 # samples 29 28 28 28 28 41 70
92 Table 2 3. M etal concentrations in wild captive, and rehabilitating West Indian manatees in Florida and Belize Cu Zn Mn Se As Cd Co Pb Cr Fe p value <0.001 0.03 0.02 <0.001 <0.001 <0.001 <0.001 N/A N /A 0.08 Wild Median 0.74 10.49 0.01 0.15 0.26 0.001 0.003 0.01 0.03 353.77 # sample 154 154 135 154 154 152 152 92 76 109 Captive Median 1.17 10.05 0.01 0.1 0.06 0.003 0.004 <0.05 <0.1 347.58 # sample 24 24 17 24 24 24 24 24 24 24 Rehab Median 1.05 8.89 0.01 0.07 0.03 0.003 0.01 <0.05 <0.1 306.21 # sample 13 13 8 13 13 13 13 13 13 13 denoted significant difference R is correlation coefficient if r is positive and the p value is <0.05, the pair of variables tend to increase together If r i s negative and the p value is <0.05, one variable decreases while the other increases If p value is >0.05, there is no significant relationship between variables
93 Table 2 4. M etal concentrations in plasma of wild and non wild West Indian manatees ( Trichec hus manatus ) based on location. Element n Wild Citrus County, Florida n Wild Brevard County, Florida n Wild Belize n Captive, Florida n Rehab, Florida Cu 40 10.1 10 10.1 16 0.70.1 8 1.40.1 4 1.20.1 (0.4 1.8 ) (0.6 1.5 ) (0.2 1. 2 ) (0.9 1.8 ) (0.9 1.5 ) Zn 40 30.2 10 3.40.5 16 2.20.1 8 3.60.3 4 30.1 (1.1 6 ) (1.3 5.8 ) (1.2 3 ) (2.6 5 ) (2.9 3.2 ) Mn 25 0.0030.001 7 0.010.004 16 0.0010.0004 3 0.0020.001 ---(0.0003 0.02 ) (<0.01 0.03 ) (<0.01 0.004 ) (<0.01 0.00 3 ) Li 8 0.030.002 7 0.040.01 ----------------(0.02 0.04 ) (0.03 0.1 ) Se 40 0.10.01 10 0.10.01 16 0.10.007 8 0.10.01 4 0.10.02 (0.03 0.3 ) (0.05 0.2 ) (0.04 0.1 ) (0.07 0.2 ) (0.1 0.2 ) Sr 8 0.40.04 7 0.50.1 --------------(0.2 0.6 ) (0.3 0.9 ) Mo 8 0.030.003 7 0.030.03 ---------------(0.02 0.04 ) (0 0.2 ) As 40 0.030.01 10 0.010.002 16 0.010.002 8 0.010.002 4 0.030.01 (0.004 0.2 ) (0.01 0.03 ) (<0.01 0.03 ) (0.0002 0.01 ) (0.02 0.04 ) Ba 8 0.030.002 7 0.020.01 --------------(0.02 0.04 ) (0.01 0.08) Cd 39 0.10.05 10 <0.01 16 <0.01 8 <0.01 8 <0.01 (<0.01 2 ) Cr 31 0.010.001 3 0.00010.0001 16 0.020.01 8 0.01 0.003 8 0.0020.001 (<0.0 1 0.02 ) (< 0.01 0.0003 ) (<0.01 0.1 ) (<0.01 0.02 ) (<0.01 0.003) Fe 39 2.80.2 10 2.50.7 16 2.40.2 8 2.6 0.4 8 4.50.7 (1.2 8.8 ) (0 8 ) (1.3 3.7 ) (1.8 5.3 ) (3.1 6.3 ) Values are given as ppm (ww) unless otherwise noted; Average standard e rror with ranges in parenthesis. n denotes sample size; --depicts insufficient data.
94 Table 2 5. M etal concentrations in erythrocytes of wild and non wild West Indian manatees ( Trichechus manatus ) based on location. Element n Wild Citrus County, Flor ida n Wild Brevard County, Florida n Wild n Wild Charlotte County, Florida Collier County, Florida Ca (mEq/L) 20 12.80.3 ------8 30.76.6 9 18.32 (10 15) (17 75.9 ) (10 27) Mg 20 55.31.2 ------8 63.72.6 9 53.20.9 (mEq/L) (43 68) (51 73) (50 56) K 20 89.70.9 ------8 103.724 9 87.21.6 (82 96) (76 271.8 ) (80 92) P 20 594.47.5 ------7 585.68 9 562.814.5 (501 648) (560 623) (479 621) Cu 67 0.60.02 11 0.50.01 10 0.40.04 9 0.6 0.0 2 (0.3 1. 6 ) (0.4 0.6 ) (0.2 0.6 ) (0.5 0.7 ) Zn 67 21.70.8 11 26.80.8 10 25.40.8 9 25.80.7 (8.8 30.2) (21.5 29.7 ) (22.4 32.4 ) (22.6 28.6) Mn 51 0.040.003 8 0.050.01 7 0.040.003 9 0.04 0.0 04 (0.01 0.08 ) (0.02 0.1 ) (0.03 0.05) (0.03 0.06 ) Li ----8 0.10.01 --------(0.02 0.1 ) Se 67 0.20.02 11 0.10.01 10 0.20.05 9 0.20.01 (0.1 0.9 ) (0.1 0.2 ) (0.1 0.6 ) (0.1 0.3 ) Sr -----8 0.050.01 --------(0.01 0.1 ) Mo 34 0.010.003 8 0.10.04 7 0.0040.0002 9 0.0040.0003 (<0.01 0.1 ) (<0.01 0.3 ) (0.003 0.005 ) (0.002 0.006 ) As 67 0.50.04 11 0.30.03 10 0.40.1 9 0.30.03 (0.1 1.9 ) (0.2 0.5 ) (0.1 1.1 ) (0.3 0.5 ) Ba -----8 0.030.01 -------(0.01 0.1 ) Cd 64 0.0020.0001 11 0.0001 0.0001 7 0.0010.0001 9 0.001 (<0.001 0.01 ) (<0.01 0.001 ) (<0.001 0.001) 0.001 Values are given as ppm (ww) unless otherwise noted; Average standard error with ranges in parenthesis. n denotes sample size; --depicts insufficient data.
95 Table 2 5. Continued. Element n Wild Citrus County, Florida n Wild Brevard County, Florida n Wild n Wild Charlotte County, Florida Collier County, Florida Co 45 0.0020.0002 11 0.0010.001 ----------(0 0.01 ) (0 0.01 ) Pb 51 0.040.0 1 3 0.0040.004 8 0.10.02 9 0.030.005 (0 0.3 ) (0 0.01 ) (0.02 0.2 ) (0.01 0.1 ) Hg 64 0.020.004 ----8 0.0030.001 9 0.0020.0002 (<0.01 0 .2 ) (0.001 0.01 ) (0.001 0.002) B 20 1.6 0.2 -----7 4.30.7 9 2.50.2 (0.3 3.6 ) (1.3 7.2) (1.6 3.1 ) V 20 0.010.002 -----7 0.00030.00002 9 0.00020.00001 (0.0003 0.02 ) (0.0003 0.0004) (0.0002 0.0003) Tl 13 0.00020.00005 -----7 <0.0001 9 <0.0001 (<0.0001 0.0007) <0.0001 <0.0001 Cr 51 0.010.002 3 0.0040.004 8 0.01 0.0 09 9 0.0010.0003 (<0.01 0.04 ) (<0.01 0.01 ) (0.0004 0.1 ) (0.0003 0.003) Fe 65 8 47.453.9 11 1484.4292.8 8 787.223.4 9 841.916.3 (315.4 3508 ) (474 3134.5 ) (641.3 852) (760 916) Values are given as ppm (ww) unless otherwise noted; Avera ge standard error with ranges in parenthesis. n denotes sample size; --depicts insufficient data.
96 Table 2 5. Continued. Element n Wild Belize n Captive Rehab Florida n Florida Cu 15 0.50.03 9 0.8 0 .1 9 0.90.1 (0.3 0.7 ) (0.6 1.1 ) (0.7 1.1 ) Zn 15 14.30.7 9 23.62.7 9 16.41.2 (8.1 17.6 ) (13.4 37.3) (10.1 22.4 ) Mn 15 0.010.001 2 0.02 0.00004 ----(0.003 0.02 ) (0.02 0.02 ) Se 15 0 .20.05 9 0.10.01 9 0.10.01 (0.04 0.6 ) (0.1 0.2 ) (0.1 0.1 ) As 15 1.30.3 9 0.10.02 9 0.030.004 (0.5 4 ) (0.02 0.2 ) (0.02 0.05 ) Cd 15 <0.010.00002 9 <0.010.01 9 <0.010.002 (<0.01 0.00 03 ) (<0.01 0.1 ) (<0.01 0.02 ) Co 15 0.010.004 ----------(<0.01 0.1 ) Pb 15 0.030.01 9 0.02 0.004 9 0.0020.001 (0.01 0.1 ) (0.001 0.04 ) (0.001 0.01 ) Hg 15 <0.010.000004 --------(<0.01 0.000 1 ) Cr 15 0.10.03 9 0.070.02 ----(0.03 0.5 ) (0.01 0.2 ) Fe 15 692.424.8 9 782.532.3 9 578.336.9 (574.4 832 ) (652.1 915.5 ) (373.5 742.8 ) Values are given as ppm (ww) unless otherwise noted; Average standard error with ranges in parenthesis. n denotes sample size; --depicts insufficient data.
97 Table 2 6. Mean Standard deviation of metal concentrations in whole blood from various ma mmalian speci es (ppm, ww ). Trichechus manatus Trichechus manatus Trichechus manatus Trichechus manatus Tursiops truncatus Tursiops truncatus Crystal River, Florida, USA Crystal River, Florida, USA Everglades, Florida, USA Lemon Bay, Florida, USA Sarasota, Florida, USA Charleston, South Carolina, USA this study Stavros et al. 2008 a this study this study Bryan et al. 2007 Stavros et al. 2008 b Element n MeanSD n MeanSD n MeanSD n MeanSD n MeanSD n MeanSD Zn 77 11.83.4 8 11.31.2 7 14.70.6 1 4 14.81.6 51 3.20.3 74 2.40.4 Cu 77 0.80.2 8 0.80.1 7 0.40.8 14 0.10.1 51 0.90.1 74 0.70.2 Se 77 0 .20.1 8 0.20.1 7 0.20.1 14 0.20.02 51 0.70.2 74 0.80.2 As 77 0.30.2 8 0.30.04 7 0.20.2 14 0.20.1 51 0.10.02 74 0.10.1 Cd 75 0.002 0.0 02 8 0.0010.001 7 0.00040.0003 14 0.001 0.001 Hg 20 <0.00060.0002 7 0.010.02 7 0.002 0.001 13 0.0010.001 51 0.50.4 Ni 20 <0.0030.001 8 0.0030 7 0.002 0 14 0.0020.001 Ag 20 0.005 0.004 7 0.01 0.004 13 0.0030.003 Mn 63 0.020.01 8 0.020.01 7 0.02 0.004 13 0.02 0.004 74 0.0010.004 Pb 20 0.030.04 8 0.01 0.003 7 0.030.02 14 0.010.01 51 0.0030.002 Mo 37 0.020.01 7 0.01 0.001 13 0.01 0.002 49 0.0010.003
98 Table 2 6. Continued. Tursiop s truncatus Dermochely coriacea Phoca vitulina Mirounga leonina Halichoerus grypus Homo sapien Homo sapien USA S. America Wadden Sea Antarctica Germany Rome Sweden Stavros et al. 2008 b Guirlet et al. 2008 Griesel et al. 2008 Bar aj et al. 2001 Kakuschke et al. 2006 Alimonti et al. 2005 Baraby et al. 2001 Element n MeanSD n MeanSD n MeanSD n MeanSD n MeanSD n MeanSD n MeanSD Zn 75 2.7 0. 5 78 11.10.3 85 3.40.5 6 3.1 0.1 1 3.2 110 6.70.9 336 6.10.9 Cu 75 0.8 0. 2 78 1 .30.3 28 0.5 1. 4 6 1 0.04 1 0.8 110 0.9 0.1 331 10.1 Se 75 0.6 0.1 78 100.1 85 0.9 0 1 1.2 243 1100.2 As 75 0.1 0.02 28 0.2 0 1 0.1 Cd 78 0.1 0.03 28 0.003 0 6 0.004 0.001 1 0 343 0.0003 0 Hg 78 0.01 0.003 6 0.1 0.0 2 335 0.0 01 0 Ni 28 0.002 0 1 0.001 110 0.0010 Ag 1 0.01 Mn 71 0.0010 28 0.2 0 1 0.02 110 0.1 0.03 Pb 78 0.20.1 28 0.001 0 6 0.01 0.002 1 0 110 0.040.020 Mo 28 0.01 0 1 0 110 0.0030
99 Figure 2 1. Zinc meanstandard deviation in whole blood of various mammalian species from Table 2 6. Zinc levels in manatees are two to three times higher than other mammalian species. The legend represents the following: 1. Manatees, CCR, Florida (this study), 2. Manatees, Florida (Stavros et al. 2008 a ), 3. Manatees, TEP, Florida (this study), 4. Manatees, TSW, Florida (this study), 5. Dolphin, Florida (Bryan et al. 2007), 6. Dolphin South Carolina (Stavros et al. 2008 b ), 7. Dolphin, Flo rida (Stavros et al. 2008 b ), 8. Harbor seal, Wadden Sea ( Griesel et al. 2008), 9 Southern elephant seal, Antarctica (Baraj et al. 2001), 10 Grey seal, Germany (Kakuschke et al. 2006), 11 Humans, Rome (Alimonti et al. 2005), and 12 Humans, Sweden (B araby et al. 2001).
100 Table 2 7. Copper, zinc, selenium, and arsenic concentratin ( meansstandard deviations ) of various aquatic animals submitted to the laboratory ( p pm, ww ). Animal n Copper Zinc Selenium Arsenic Manatee 170 0.80.3 11.24.5 0.20.2 0.2 0.2 Green turtle 13 0.60.2 6.82.2 0.60.4 0.50.5 Pygmy killer whale 2 0.90.1 4.60.6 1.90.3 0.20.1 Bottlenose dolphin 1 1.2 3.4 0.6 0.2 California sea lion 1 1.10.01 4.10.3 0.7 0.001 0.20.1
101 A B C D Figure 2 2. Blood compartments separated as WB (whole blood), plasma, and RBC (red blood cells) for A ) copper, B ) zinc, C ) arsenic, and D ) seleni um. The majority of Zn, As, and Se are in red blood cells and Cu is predominately in plasma
102 A B C Figure 2 3. Reference i nter val box p lots. Box and Whisker plots were generated to determine the reference interva l for Cu, Z n, As, and Se in A) whole blood, B) Plasma and C ) erythrocytes (As could not be calculated). Outliers were eliminated using the Tukey m ethod
103 Table 2 8. Reference Range. Calculated reference interval of metal concentrations (ppm, ww) using MedCalc Sof tware (Mariakerke, Belgium) in whole blood (WB), erythrocytes (RBC) and plasma for the West Indian manatee Element n WB n RBC n Plasma Ag 40 0 0.01 --------As 144 0.01 0.5 106 0 1 ----B ----34 0 4.4 ----Ba 41 <0.01 0.04 -------Ca 38 54.8 75.4 36 1.4 26.6 ----Co 119 0 0.004 --------Cr 71 0 0.1 80 0 0.0 5 ----Cu 142 0.4 1.1 108 0.3 0.8 60 0.3 1.4 Fe 104 234 543.4 101 550.3 1022.2 62 0.4 4.4 K ----36 76.1 98.7 ----Li 33 0 0.02 --------M g 40 38.1 80.5 36 43 73 ----Mn 125 0 0.03 89 0 0.1 ----Mo ----45 0 0.01 ----P ----35 522 655.6 ----Pb 115 0 0.3 --------Se 141 0.04 0.3 101 0.01 0.3 64 0.02 0.1 Sr 61 0.1 0.3 --------Zn 143 7.3 16.9 112 9.6 36 .4 66 0.04 5.2 Values are given as ppm (ww) n denotes sample size ; --depicts insufficient data
1 04 CHAPTER 3 TRACE METAL DISTRIBUTION I N TISSUES OF WILD FLORIDA MANATEES ( T richechus manatus latirostris ) FROM PAST TO PRESE NT Background The m anatee mortali ty and carcass recovery program has been conducted in the Mammal Pathobiology Laboratory (MMPL) in St. Petersburg, Florida, has been the central location for manatee ne cropsies and an integral division for recording manatee mortality. The MMPL currently categorizes manatee cause of death in to eight categories based on gross morphology, as well as histological and microbiological evidence: 1 ) Watercraft, 2 ) Entrapment in flood gate/canal lock, 3 ) Other human related (entanglement, debris, etc), 4 ) cm), 5 ). Natural, cold s tress, 6 ). Other natural (r ed tide, infectious disease), 7 ). Verified/u nrecovered, and 8 ). U ndetermined. During 2007 2011 approxim ately 450 Florida manatee deaths per year were recorded by MMPL with undetermined (25% of total deaths), cold stress (22% of total deaths), perinatal (20% of total deaths) and watercraft (19% of total deaths) as the leading causes of death The cause of manatee mortality varies from year to year. From April 1976 to to be caused by humans or by an unknown cause with the highest occurrence of death during the winter and in the northeast section of Florida. In addition, Ackerman et al. (1995) examined 2,133 carcasses from the southeastern United States a nd Puerto Rico from 1974 1992 and f ound that manatee mortality increased 5.9%/year with u ndetermined cause of death of 24 41%. Thus, unknown, cold stress, perinatal and watercraft causes of death are currently of utmost concern for the manatee population.
105 C ontaminants have been of a concern in marine mammals, especially that of stranded marine mammals Interest of contaminants in marine mammals began as the frequency of mass stranding s increased and as the repercussions of metal toxicity on reproduction were highlighted. Studies have shown mass strandings of marine mammals to be possibly associated with metals ( Anan et al., 200 2 ; Bennett et al., 2001 ; Siebert et al., 1999 ). Metals have also been linked to immune suppression by examining leukocytes exposed to metals in pinnipeds (Kakuschke et al., 2005; 2006 ; Pillet et al., 2000 ). Moreover, harbor seals with phocine distemper v irus (PDV) had higher concentrations of Cr in the liver and Cu in the kidney (Frank et al., 1992) than unaffected seals. Physiological stressors, such as cold stress and red tide events may suppress the im mune system of manatees possessing high metal acc umulation, which may then affect the overall population of this endangered species. Although we have investigated metal concentrations in blood, examination of metals in organs provides information on metal distribution throughout the body and accumulati on A number of marine mammal carcass publications on metals are available, but (1984) analyzed 54 carcasses from 1977 1981 and found high copper concentrations in the liver of Flori da manatees from areas of high herbicidal use. Due to this report, copper based herbicides were ceased in a popular winter manatee site in Crystal River, Florida. However, m etals have not been monitored in Florida manatee carcass es since 1981. Marine mam mals are long lived and are sentinel species for the health of our waterways. The endangered Florida manatee is the only sirenian in the waters of the United States with a current estimate of approximately 5,000 (FWC, 2011 ). Thus, any
106 information on the biology and physiology of this species is imperative and should be assessed on a continuing basis in order to ensure the health of this species as well as for monitoring the surrounding environment The first objective of this study is to determine curr ent organ distribution of copper, zinc, selenium and arsenic throughout the body of the Florida manatee This will be the first study to examine metal loads in various tissues besides kidney, liver and muscle reported by We hypoth esize that metal accumulation in the liver and kidney will be correlated to cause of death (COD) in the manatees and will be higher in urban locations In Chapter 2 we found significant differences in whole blood between locations in a number of elements with a special interest in copper, zinc, selenium and arsenic Although whole blood is a non invasive form of determining circulating levels of metals, organs, such as the liver and kidney, are best when determining long term metal accumulation and body burdens. The second objective of this study is to determine if metal levels have changed throughout the years by comparing kidney and liver from this study to data from 1978 1984) We hypothesize that metal loads will be lower than 1978 1979 due to an increase in regulations of metal based chemicals used in the state of Florida. As a result, metal distribution throughout the Florida manatee will be determined to monitor metal a ccumulation and health of this endangered species. Mater ials and Methods Carcass Samples Thirteen manatees from the Marine Mammal Pathobiology Laboratory (MMPL) of the Florida Fish and Wildlife Research Institute in St. Petersburg, Florida from 2008 2011 were used in this study (Table 3 1). Necropsies were p erformed at the MMPL
107 un der the direction of Martine de Wit, DVM, and staff members of MMPL. Fresh manatee carcasses of various ages (7 calves, 3 subadults, 3 adults), length, weight and sex (6 males, 7 females) with different causes of death were used in t his study. Manatees were categorized by districts : Northwest (NW), Southwest (SW), East Coast (EC), and Southeast (SE). With a possible seasonal difference in the concentration of metals (Caccia and Millero 2003), sample collection was obtained througho ut the year. A minimum of one gram of several tissues were collected: liver, duodenum, pancreas, kidney, intestines, colon, cecum, heart, brain, bladder, testis (when applicable), cervix (when applicable), skin/blubber, muscle, urine, feces, stomach, sto mach contents, thyroid, thymus, and lung. The primary tissues collected in pinniped trace element analysis include the liver, kidney, and muscle (Gray et al., 2008) with the liver being the key organ in terms of trace element concentration analysis (Becke r et al., 1997). In addition, manatees are hindgut fermenters, where the main site for protein and lipid digestion is in the cecum and colon, where most of the absorptive cells are present (Burn, 1986). As a result, we collected a number of tissue sample s from various part s of the carcass Samples were cut with stainless steel sterile blades and placed in plastic whirl pak bags (Fisher Scientific, Pittsburgh, PA). Measurements, including straight and curvilinear body length, as well as any additional m arkings, were recorded prior to necropsy examination Age categories were estimated u sing body length measurements with age class categories defined as: straightline cm=calf, 226 270 cm =subadult, and >270 cm=adult ( revised from 1985). Live Manatee Samples For this study, manatee health assessments were performed in two locations under the authori ty of the USGS Sirenia Project and Florid a Fish and Wildlife
108 Commission from 2007 2011: 1) King s Bay, Crystal River, Citrus County (C CR; 28 o 53'28"N, 82 o 35'50"W), and 2) Indian River Lagoon, Brevard County (CBC; 28 o 28'13"N, 80 o 45'48"W). Manatees were captured with a 122 m long net by a land set or a boat based capture depending on location. Opportunistic samples of feces, urine, skin and /or milk were obtained from manatees during health assessments. In addition to wild manatee health assessments, fecal samples were collected opportunistically from tagged manatees in Crystal River, Florida (Dory and Ebb) that were used for behavior and fecal hormone studies by Dr. Iske Larkin at the University of Florida. There were a total of 17 fecal samples (4 CCR, 8 CBC), 15 urine samples (12 CCR, 3 CBC), 11 skin samples (7 CCR, 4 CBC) and 4 milk samples (1 CCR, 3 CBC ) from wild manatees Sample A nalysis Analyses of trace elements were completed in the College of Pharmacy at the University of Florida using an inductively coupled plasma mass spectrometry (T hermo Electron X Series ICP MS). et al., (1984 ), Cu, Zn, As, Se Cd and Pb were analyzed in tissues. Samples were thawed prior to digestion if frozen and kept in 4 o C. Tissue samples were wiped with K imwipe s (KIMTECH Science, Kimberly Clark Worldwide, Inc., Irving, Texas) if surrounded by excess mate rial (i.e. feces, blood, etc) and a sample (~500 mg) was placed in a labeled borosilicat e glass tube Nitric acid (500 L) was placed in each tube and heated to 200 o C in an oil bath or graphite block until digested. Additional nitric acid (500 L) was us ed in each sample with the amount varying depending on the sample type (i.e. feces takes approximately 1.5 mL of nitric acid). Once digestion was complete, 30%
109 hydrogen peroxide (250 L) was added. Ten mL of Millipore water was added to each sample. Each sample was filtered using a 13 mm nylon syringe filter (0.2 um, Fisher Scientific Company) and placed in a 15 mL conical tube (Corning Life Sciences, Lowell, MA) for analysis An inductively coupled plasma mass spectrometry (Thermo Electron X Series ICP M S, Thermo Fisher S cientific, Inc., Waltham, MA) in the College of Pharmacy at the University of Florida was used for analysis, with an internal standard of 115 In. Quality assurance for manatee samples included blank samples, repeat samples, and NOAA whale and manatee livers. The standard reference material s for select elements is reported as follows ( meanSEM ) with standard laboratory results in parenthesis: F or beluga whale liver II homogenate NOAA standard reference material (QC97LH2) : As 1.50.19 (0.39 0.03 ), Cd 2.110.04 (2.350.06), Cu 11.350.24 (13.160.4), Fe 62527 (66815), Se 28.82.6 (24.30.85), and Zn 201.48 (26.310.66) For pygmy sperm whale Liver III (QC03LH3 ) NOAA standard resulted in : As 0.40.04 (0.860.08), Cd 5.640.22 (5.940.38), C o 0.060 .005 (0.07 0.003), Cu 2.740.15 (2.740.19), Fe 60548 (69445), Se 10.330.95 (7.871.18), and Zn 17.471.39 (21.151.65). The Triplicate runs were performed on the ICP MS on each sample and the mean was obtained in ppb. The mean was then multipl ied by the volume of DI water the sample was reconstituted with to obtain total concentration in ng/mL. Concentrations of samples were then reported as ng/mg using the original weight of the sample, or ppm wet weight. Reference Conversion Factor Similar t o Yang and Miyazaki (2003), a reference conversion factor (CF) between wet weight and dry weight values for comparative purposes between studies was
110 determined for manatees Seven manatees were used to determine the conversion factor. Liver and kidney sa mples were dried of 65 o C for one week then acid digested as mentioned above prior to analysis with ICP MS. In order to determine the conversion factor, calculations were made with the following equation: Mn = ((Ww Wd)/Ww) x 100 (3 1) w here Mn is mean moisture content, Ww is wet weight of tissue, and Wd is dry weight of sample. CF=1 (me an moisture content/100) (3 2) w here CF represents conversion factor. We then compared our results to other CF values reported for other marine mammal s pecies. Statistical Analysis Descriptive statistics for mean, standard error and range for each element were calculated using SigmaPlot version 11 (Systat Software Inc., Sa n Jose, CA). Samples that were below detection l imit (BDL) were included in statis tical analysis by dividing the BDL by half and defined as 0 if detection was not present. Non parametric statistics was used when the normality test failed and/or the equal variance test failed. A Kruskal Wallis one way analysis of variance (ANOVA) on r a nks was used for no n parametric analysis, while a one w ay ANOVA was completed for samples that passed normali ty and equal variance. When a one w ay ANOVA was completed and passed normality and equal variance and there was a significant difference, an all p airwise multiple comparison procedure (Holm Sidak method) was completed. If a normality test failed and the data had a significant difference, an all pairwise multiple comparison procedure (Dunn's Method) was completed using the median. A Pearson product moment c orrelation was performed to determine if a correlation was present for sex
111 (male, female), age class (calf, subadult, and adult), straig ht length (cm), and weight (kg ) for each metal in wild manatees. A Kruskal Wallis ANOVA was performed to deter mine a significant difference (p<0.05) for each metal to district and cause of death (COD). A t test was completed to determine a significance difference between Dr. a nd liver. Results Liver The liver is the primary reservoir for metal accumulation, thus, will be the key organ when determining metal toxicity. Average trace metal concentrations can be found in Table 3 2. There was a significant difference in district an d Zn concentrations (p=0.018) with highest levels in the SE with a mean SEM of (578.05 0 ppm) with lowest levels in the EC (90.34 57.95 ppm). There was no significant difference in the district from which the animal was found ( Cu p=0.171 Se p=0.921, and As p=0.387). There was no significant difference in age (Cu p=0.159, Zn p=0.618, Se p=0.339 As p=0. 167), sex (Cu p =0.379, Zn p=0.569 Se p=0. 452 As p=0. 454 ) or COD (Cu p=0.096, Zn p=0.466, Se p=0.096 As p=0. 146) with hepatic metal concentrations. Th ere was also no correlation to age or sex to the levels of hepatic Cu, Zn, Se, and As. There was a strong negative correlation ( r = 0.834) to straight length and hepatic Cu, while as length increased, the concentration of Cu t ended to decrease (p=0.005 ). K idney In addition to the liver, the kidney is also a n important site of metal accumulation. Average trace metal values for the kidney can be found in Table 3 2. There was no significant difference in district locations for ( Cu p =0.729, Zn p =0.079, Se p =0 .110 As
112 p=0.136) or COD ( Cu p =0.465 Se p =0.222). There was a significant difference in Zn and As (p=0.047) renal concentrations with COD. The level of Zn was highest in the watercraft COD with a meanstandard e rror of mean at 24 .853.97 ppm>cold stres s (23.06 1.67 ppm)>n atural ( 16.280.73 ppm)>perinatal (8 ppm). The level of As was highest in cold stress COD at 0.10.008 ppm> watercraft (0.10.02 ppm)> n atural (0.06 0.01 ppm)>perinatal (0.03 ppm). There was no correlation with age, sex, or straight l ength to renal metal concentrations. Skin Metal concentration in skin varied by layers of the skin In the skin found dorsally on the animal, there was no significant difference in Cu (p=0.171) and Se (p=0.137). However, there was a significant difference in Zn (p<0.001 ) with outer layer (18.2 ppm) > total (5.6 ppm) > inner layer (2.1 ppm) and As (p=0.0 48) with the outer layer (0.1 ppm) > total (0.04 ppm) > inner layer (0.01 ppm). In ventral sections of the skin, there was no significant difference in As (p=0.064), but there was a significant difference in Cu ( p<0.001) with outer layer (1.6 ppm)> total (0.4 ppm)> inner layer (0.2 ppm), Zn (p <0.001) with outer layer (17.6 ppm) > total (4.2 ppm) > inner layer (3.8 ppm), and Se (p=0.03 ) with outer layer (0.09 ppm) > total (0.03 ppm) > inner layer (0.01 ppm). When examining the whole skin sample without sectioning layers, there was no significant difference in Cu (p=0.140), Zn (p=0.990), and As (p=0.737). On the other hand, Se had a p value of 0.047 with the tail skin the highest at 0.1 ppm, then dorsal (0.05 ppm ) and ventral skin (0.05 ppm). The tail was an excellent site for comparison, as sections of the tail were taken at health assessments for genetic purposes and for Chapter 6. Average metal concentrati ons can be found in Table 3 2. There was no significant difference in Zn
113 (p=0.406) and district, but there was a significant difference in Cu (p<0.001) with a mean SEM with SE (1.70 0.53 ppm)>EC (1.51 0.13 ppm) > SW (1.03 0.17 ppm) > NW (0.72 0.1 2 ppm) > BZ (0.45 0.06 ppm). There was also a significant difference in Se (p=0.01) with the highest levels in BZ with a median of ( 0.38 ppm) > EC (0.16 ppm) > NW (0.15 ppm) > SE (0.08 ppm) > SW (0.07 ppm) and As (p=0.04 ) with a median of 0.15 ppm i n SE > BZ (0.07 ppm) > NW (0.05 ppm) > EC (0.03 ppm) > SW (0.02 ppm). There was no significant difference in COD with metal levels in the tail for Cu (p=0.111), Zn (p=0.631), and As (p=0.427), but a significant difference in Se (p=0.001) with a median of 0.23 ppm in live animals > perinatal (0.11 ppm) > watercraft (0.09 ppm) > cold stress (0.08 ppm) > n atural (0.04 ppm). There was no correlation with sex or length and skin metal levels, but there was a positive medium correlation with age and Se (p=0.0373). With an r value of 0.410, As and Se levels increased with age Feces In regards to feces, there was no significant difference in district and metal concentrations in Cu (p=0.07) and As (p=0.137), but there is a significant dif ference with district and Zn (p=0.011) and Se (p =0.011). The median Zn level was hi ghest in SE (75 ppm) > SW (46.2 ppm) > EC (31.8 ppm) > NW (28.5 ppm) > BZ (8.4 ppm), while the me dian Se was highest in SW (0.19 pp m) > EC (0.18 ppm) > NW (0.18 ppm) > BZ (0.04 ppm). Mean fecesSEM ca n be found in Table 3 2. There was no correlation with age and sex with fecal metal levels, but there was a negative correlation with straight length and Zn levels (p=0.0278). The correlation coefficient showed a medium correlation with an r value of 0. 459.
114 Urine Similar to metal fecal extraction, t here was no significant difference between district location in Cu (p =0.761) and As (p=0.790). There was a significant difference in Zn (p=0.007) with significantly higher levels in SW (0.83 0 ppm) than the E C (0.22 0.13 ppm) and the NW (0.23 0.05 ppm). Selenium levels also showed a significantly higher difference (p=0.021) in EC (0.08 0.03 ppm) than the NW (0.03 0.01 ppm) and the SW (0 ppm). Mean urineSEM can be found in Table 3 2. There was also no corre lation of urine metal levels to sex, age or straight length. Other Tissues A number of other organs were analyzed, as shown in Table 3 2. Figure 3 1 displays Cu, Zn, Se, and As concentrations for each organ from highest concentration to lowest concentrat ion. For Cu, the top three tissues were liver (12.754.42 ppm), feces (10.152.16 ppm), and heart (2.360.26 ppm), while Zn was found in the highest concentrations in liver (170.9357.32 ppm), colon (57.5524.24 ppm), and feces (49.865.2 ppm). As for Se the highest concentrations were found in the kidney (0.74 0.09 ppm), adrenal gland (0.450.02 ppm), and liver (0.350.05 ppm), while As was found in highest levels in feces (1.130.38 ppm), thyroid (0 .310.14 ppm), and urine (0.19 ppm). Conversion Fact or The conversion factor from dry weight to wet weight is shown in Table 3 3. The conversion factor for the ratio of dry weight to wet weight is 0.22 for liver and 0.17 for kidney. Results were also compared to other marine mammal species (Table3 4) with C F similar to other marine mammal species This information can be valuable when
115 comparing results from previous papers where dry weight is used as a measure for metal concentration. Thirty Year Comparison of Metals in Manatees d Pb, Cu, Hg, Se, and Cd levels in carcasses in Florida from 1976 1981. In collaboration with Dr. Tom and kidney (n=20) samples from 1978 1979 were available and compared to the results of this study (Table 3 5) in order to determine any changes in metal levels over time in the liver and kidney. In the liver, there was no significant difference in Cu (p=0.277) and Se (p=0.596). However, the there was a significant difference in Pb concentrations (p<0.001) with much higher l evels in 1979 1980 than 2007 2010. Mercury and Cd could not be compared due to a lack of detection. In the kidney, there was a significant difference in Pb values (p<0.001), where values were significantly higher in 1978 1979. There was no significant di fference in Cd (p=0.592). Copper, Se, and Hg were not able to be compared due to a lack of detection. Discussion The first objective of this study was to determine metal distribution in the Florida manatee. Metal levels in each tissue analyzed can be se en in Table 3 2 and Figure 3 1. Within the first three organs for each metal, there is a site of accumulation and possible storage, as well as a means for excretion. Thus, suggesting the process of trace metal homeostasis is maintained through a fine bal ance of uptake, utilization and excretion in the Florida manatee. Copper The liver is the central organ for maintaining copper homeostasis and is the first target organ after dietary Cu is obtained through the small intestines (Mercer and
116 Llanos, 2003). Copper, as well as zinc, are essential elements used for many physiological mechanisms and enzymatic functions, therefore, it is no surprise that the liver contains the most Cu. Liver values were greater than kidney, which was similar to other marine mam mal species (Table 3 6). The liver contained the highest level of copper in the Florida manatee, as levels differed with age class The highest amount of Cu was found in a perinatal calf who was 114 cm in length, as Cu levels tended to decrease with incr ease in straight length. This high level of Cu in younger animals was higher in the fetus than adult (Fujise et al., 1988; Yang et al., 2004) and in the bottlenose dolphin ( Storelli an d Marcotrigiano, 2000). It has been suggested that Cu and Zn are closely regulated and homeostatically controlled in marine mammals (Law et al., 1991; 1992), while one of the key players involved for homeostatic control o f Cu and Zn is metallothionein A ccording to K gi and Sc h ffer (1988), metallothioneins play an essential role in homeostatic control of divalent metals and in detoxification of heavy metals, such as cadmium and mercury. This elevated Cu level in neonates is most likely bound to metallot hionein or other cuproproteins (Luza and Speisky, 1996). Thus, metallothionein will be evaluated in the Florida manatee in Chapter 6. As the liver is the central organ for copper homeostasis, excess copper is released through bile and feces (Mercer and Lla nos, 2003). The homeostatic mechanism of manatee as no exception. The third highest Cu level was found in the brain of the Florida manatee. Copper is an essential element for the central nervous system and brain function as well. The
117 necessity for this essential element is shown in patients with Menkes or Wilson d isease. The inh erited Cu deficiency in Menkes d isease results in brain degeneration via demyelination and neu rodegeneration (Kaler, 1998; Kodama et al., 1999), while the Cu accumulation in Wilson d isease results in dystonia (neurologic movement disorder), dysarthria (neurologic speech disorder) and other Parkinson like tremors and mental health problems (Ferenci 2004; Madsen and Gitlin 2007). The range of Cu ( 2.53 5.61 ppm) in the Florida manatee brain was within levels observed in other marine mammals. The level of copper in the commo n porpoise was similar at 5.12 u g/g ww in females and 5.29 ug/g ww in males (Falconer et al., 1983) and the harbor seal reported a range of 2.4 4 mg/kg (Drescher et al., 1977). Zinc Similar to copper, zinc is an essential element involved in a number of physiological mechanisms and enzymatic functions. The liver is a predominan t organ with respect to zinc metabolism as regulated by factors, such as epinephrine, interleukin 1, glucagon, insulin and glucocorticoids playing a role in zinc distribution (Cousins 1983 ; 1989). This was seen in manatees in this study, as well as oth e r marine mammals, where liver was greater than kidney in Zn concentratio ns (Table 6 2 ). The Florida manatees were similar to other marine mammals in kidney values with a range of approximately 20 30 ppm, but the Florida manatee exhibited the highest level of hepatic Zn with a range from 117 2658 ppm. The range of Zn (32.4 288.6 ppm) in the liver of the Florida manatee was higher than other marine mammal species. Six species of cetaceans and pinnipeds off of the Wales coast and Irish Sea from 1989 1991 resulted in a hepatic Zn level of 15 150 g/g, suggesting a species difference in
118 Zn concentrations (Law et al., 1992). In addition, Honda et al. ( 1983) had a maximum Zn level ( 109 g/g ) while Muir et al. (1988) resulted in white beaked dolphins with a maximum of 136 g/g. We saw in Chapter 2 t hat manatees had elevated Zn levels in whole blood which may be correlated to the higher levels of Zn present in the liver. Moreover, according to Denton et al. (1980), dugongs also have elevated hepatic Zn levels at 219 4183 m g/g dw (54.75 1045.75 mg/g w w .; CF=0.25). As a result, this elevated level of hepatic Zn may be unique to the sirenians and warrants further investigation. The key organ for Zn homeostasis is the liver with primary uptake through the gastrointestinal tract and method of excretion as feces, hence, the liver, colon and feces contained the highest Zn concentrations in the Florida manatees in this study Katouli et al. (1999) showed the benefits of stability in the intestinal flora and coliform strains due to supplementation of zinc oxi de in post weaning piglets. According to Cousins and Failla (1980), Zn uptake occurs in the small intestines. In this study, the colon had higher Zn levels, followed by the cecum, then the duodenum and intestines as seen in Table 3 2, which may be d ue to the fact that the manatees are hindgut fermenter s with a slow transit rate of passage. The majority of digestion of hindgut fermenter occurs in the cecum and proximal colon of the large intestines (Burn 1986; Murray et al. 1977; Reynolds and Rommel 19 96), thus, suggesting Zn upta ke in the cecum and colon in addition to the intestines in manatees However, due to this small sample size and the possibility of fecal contamination in the colon, additional studies are needed.
119 Selenium Selenium is another essential element important for many physiological functions, as well as for detoxification purposes. Hepatic selenium levels were lower in sirenians than other marine mammal species (Table 3 6), with levels higher in the kidney than liver. The kidney wa s found to contain the highest level of Se which may be due in part to the detoxification mechanism of Hg:Se in many marine mammals (Dietz et al., 2000; Endo et al. 2002; Ikemoto et al., 2004 ; Koeman et al., 1975 ). However, although not mentioned in the results, levels of Hg were below the limit of detection in the Florida manatee, suggesting that manatees are not exposed to a high level of Hg in our study sites. The Se level in the kidney in the Florida manatee may be possibly due to the role of selenop roteins and selenoenzymes, such as glutathione peroxidase. Carmagnol et al. (1983) f ound that, in humans, Se depende nt and non Se dependent glutathione peroxidase was found in equal amounts in the renal medulla, while the adrenal gland and platelets conta ined the majority of Se dependent glutathione peroxidase. Therefore, this could result in the adrenal gland having the second highest Se level in the Florida manatee. Similar to Cu and Zn, the liver seems to be a vital organ for Se control in the Florida manatee, as it is the third highest in Se content. In Chapter 2, we found that manatees had lower levels of Se when compared to other marine mammal species possibly caused by a low Se diet. Therefore, it is suggested that manatees utilize the homeostati c control of Se by utilizing pools in the kidney, liver and adrenal gland with mechanisms unknown at this time. Arsenic Arsenic is a non essential metal, thus, resulti ng in two means of excretion ( fecal and urine ) in the Florida manatee with no significan t difference between districts or from
120 wild and necropsy animals Simi lar to manatees Dutkiewicz (1977) found that elimination of arsenic was mainly through urine and feces in rats as well. Ur ine has been used as a useful biomarker for As exposure in ce rtain areas, such as Montana (Hwang et al., 1997) and India (Das et al., 1995), as well as a main route of excretion. The second most abundant As level in the Florida manatee was the thyroid. There have been a few studies on the effects of contaminants on thyroid function in marine mammals, especially of PCBs, dioxins, and metals, such as Cd, Hg, and Pb (Greg ory and Cry, 2003), but we were not successful in finding the effects of arsenic increases in manatee thyroid tissues Although mechanisms are not understood at this time, thyroid hormones prevent arsenic toxicity in the liver and kidney possibly due to lipid peroxidation and an increase in glutathione peroxidase (Allen and Rana, 2003). Similar to Chapter 2, speciation of As is highly recommended be fore addressing toxicological issues. COD and District Locations The liver and kidney are main sources of metal accumulation in the animal system. Thus, the discussion will be based on the liver an d kidney and additional tissues as needed. It has been s uggested that trace metal accumulation may be correlated to immunosuppression in marine mammals. In this study, we hypothesized a correlation of metal level to cause of death. Those individuals with an assuming weaker immune system (i.e. cold stress) wil l have a higher metal load than those with an anthropogenic cause of death (i.e. boat strike). Health status may influence metal concentrations in the Florida manatee. Although there was no significant difference between COD and hepatic metal concentrati ons, highest concentrations were seen in manatees with a COD of natural, cold stress ( 113.28 ppm) and chronic watercraft (129.11 p pm)
121 compared to manatees diagnosed with natural, other (94.67 ppm) and perinatal (32.39 ppm) There was no significant differ ence in hepatic Zn levels based on location It has been shown that p hysiological stress and health can affect metal l evels in marine mammals (Das et al., 2003 ; Law, 1996). For example Bennet t et al. ( 2001 ) found harbor porpoises that died of an infecti ous disease had an increase in hepatic Zn, Hg, Se, and Hg:Se. Moreover, Das et al. (2004) also observed increased Zn levels in various tissues in those cases that were emaciated or diagnosed with bronchopneumonia in 132 harbor porpoises ( Phocoena phocoena ). Harper et al. (2007 ) found that hepatic Zn levels were lower in California sea lions ( Zalophus califnornianus ) suspected of domoic acid toxicity (84.4 35.7 ppm, ww) with significantly higher hepatic Zn levels in animals that died of disease (i.e. pneum onia, septicemia, abscesses; 103.2 30.2ppm, ww). This study did not take into account time spent in rehabili tation centers and was a result of 9 animals, thus, time in rehabilitation and more samples are needed to obtain meaningful results in terms of COD and metal levels. However, health status may be a contributing factor in hepatic liver values in the Florida manatee, as seen in other marine mammal species. For our second hypothesis, we found that there was no significant difference in metal accumulati on in the liver or kidney based on district location. It is difficult to extrapolate information of environment from manatee carcasses, as the location the manatee is found may not be where the animal spent most of their time. Manatees are semi migratory animals, as some manatees reside in the same location, while others travel hundreds of miles, at times 50km/day (Reid et al., 1991 ; Deutsch et al., 2003 ). One manatee traveled 820 km in Florida (Reid et al., 1991), while Deutsch et al. (2003)
122 reported on e male travelli ng >2,300 miles along the East c oast of the United States from Florida to Rhode Island. Therefore, according to this study, there was no correlation to cause of death or district location to metal levels in the Florida manatee. From Past to Present Our final objective was to determine any changes in metal burdens in the Florida manatee through time. Although there was no significant difference in hepatic Cu concentrations levels in the nine manatees sampled were lower than manatee tissues e valuated in 1978 1979 possibly due to the regulated use of Cu based herbicides there was a significant decrease in the current level of Pb found in the kidney and liver of the Florida manatee. The signif icant decrease in Pb in the manatee suggests an anthr opogenic influence in the 1970s. Lead was commonly found in the environment from paint, pipes, and tetraethyl and tetramethyl gasoline before restrictions were placed in the United States in the 1970s a s shown in past studies Therefore, this decrease in Pb accumulation in the liver may be a product of strict regulations on the use of lead. Our findings corroborate that of Alexander et al. (1993) who collected core samples with a 50 year time span from the St. Johns River and Hillsborough Bay. They found that Pb concentrations reached maximum levels from 1975 to 1981 with a decrease over time in the St. Johns River, while Hillsborough Bay Pb concentrations began to drop in 1969 to 1974 due to the use o f unleaded gasoline. Moreover, water samples from the Everglades taken in October of 1971 measured the highest amount of Pb in the area due to development and agricultural runoff (Horvath et al., 1972) Lead toxicosis in marine mammals has been documente d as a result of anthropogenic influences in a captive bottlenose dolphin who was a victim to air gun pellets (Shlosberg et al., 1997) and an adult harbor
123 seal that ingested a lead sinker (Zabka et al., 2006 ) Therefore, although Pb levels is lower than other marine mammal species (Table 1 1) and lower than in 1979 1980, mon itoring metal loads in wildlife is vital for the conservation of species and the environment. Summary and Significance This study determined trace metals found in various tissues of the Florida was also the first study to exa mine various tissues (i.e. milk ) which have not been examined in manatees prior to this study. We acknowledge that it would be best to homog enize the whole organ to represent the total metal conce ntration in the tissue but due to the large size of the manatee, sections of the tissue were collected in the same location to alleviate such discrepancies 84) The liver is a central organ for trace metals and is the predominan t Cu and Zn accumulation site. The kidney had the highest concentration of Se; possibly d ue to glutathione, while the thyroid had the highest levels of As, with reasons which remain unknown at this time. There was no correlation with metal levels to cause of death or district location as a result of a small sample size and various migratory movement patterns of the manatees throughout the state of Florida. Moreover, health status of the animal should be taken into account when analyzing body metal burdens. There was a significant decrease in Pb levels from manatees in the 1970s to current populations, supporting the importance of decreasing anthropogenic influences and increasing env ironmental regulations and awareness Continual m onitoring of metals is highly encouraged not only for the health of the endangered Florida manatee, but also for the health of our fragile ecosystem
124 Table 3 1. Manatee carcasses included in this study. Mammal Pathobiology Laboratory in St. Petersburg, Florida. Manatee ID Necropsy Date Location District Sex Age Length (cm) Weight (kg) COD MEC0853 7/1/2008 Brevard Cou nty; Indian River; Titusville EC M calf 119 25 Perinatal SWFTm0826b 10/8/2008 Volusia County; Mosquito Lagoon; Oak Hill SW F subadult 261 285 Watercraft, chronic LPZ102639 11/5/2008 Lee County; Estero Bay; Bonito Springs SW M adult 309 478 Watercraft, chro nic LPZ102654 12/5/2008 Citrus County; Kings Bay NW F subadult 261 289.5 Watercraft, chronic MNW0901 1/26/2009 Pinellas County; Tampa Bay NW F subadult 212 176.5 Natural, cold stress MSE0910 1/29/2009 St. Lucie County; Indian River; Ft. Pierce SE F calf 188 133.5 Natural, cold stress MSW0930 3/9/2009 Collier County; Caxambas Bay; Marco Island SW M calf 156 Natural, cold stress MNW0905 3/10/2009 Citrus County; Kings Bay NW M calf 210 201.5 Natural, other MSE 0943 4/2/2009 Broward County; Cypress Cree k; Pompano Beach EC M calf 205 Natural, other LPZ102765 8/6/2010 Collier County; Goodland; Shell Key Bay SW F adult 267 296.5 Watercraft, chronic MEC10210 10/15/2010 Brevard County; Titusville, Indian River EC F calf 114 38.5 Perinatal MEC10224 12/17/ 2010 Brevard County; Florida Power and Light intake canal EC M calf 126 47.5 Perinatal LPZ 102904 4/14/2011 Hillsborough County; Tampa, Old Tampa Bay NW F adult 315 528.5 Watercraft, chronic District: EC = East Coast, SW=Southwest, NW=Northwest, SE=South east COD=Cause of death Additional information on manatee mortality: my.fwc.com/research/mana tee/rescue mortality statistics
125 T able 3 2. Metals m eanSEM in tissues from wild and necropsied manatees from 2008 2011. Element n Liver n Kidney n Skin (Tail) n Feces n Urine n Milk Cu 9 12.74.4 9 20.1 26 0.90.1 24 7.51.3 18 0.1 0.01 4 0.50.1 (2.6 44.4 ) (1.6 2.3 ) (0.2 2.2 ) (1.2 26.4 ) (0.001 0.2 ) (0.3 0.8 ) Zn 9 117.726.5 9 20.5 2.3 26 11.61.4 24 35.44.4 18 0.3 0. 1 4 5.61.1 (32.4 288.6 ) (8 32.8 ) (2.1 29.8 ) (6.6 95.6 ) (0 0.8 ) (3.4 7.9 ) Se 9 0.40.1 9 0.70.1 26 0.20.1 23 0.20.03 19 0.04 0.01 4 0.070.01 (0.1 0.6 ) (0.4 1.3 ) (0.03 1.1 ) (0.1 0.7 ) (0 0.2 ) (0.05 0.1 ) As 9 0.1 0.01 9 0.1 0.01 26 0.1 0.01 23 0.80.1 19 0.2 0. 1 4 0.020.002 (0.04 0.1 ) (0.03 0.1 ) (0.002 0.3 ) (0.1 3.4 ) (0 0.8 ) (0.01 0.02) n denotes sample size Table 3 2. Continued. Element n Blubber n Colon n Duodenum n Intestines n Duodenum contents n Duoden um horns Cu 7 1.20.5 3 1.2 0.3 9 1.40.2 4 1 0. 1 1 1.02 1 2.3 (0.2 3.7 ) (0.8 1.7 ) (0.7 2.8 ) (0.8 1.2 ) Zn 7 5.90.9 3 57. 6 24.2 9 30.15.8 4 26.56.5 1 4.1 1 24.8 (3.6 10.4 ) (22.7 104.1 ) (13.4 69.7 ) (13.4 44 ) Se 7 0.1 0.01 3 0.1 0.01 9 0.10.1 4 0.1 0.03 1 0.03 1 0.1 (0.01 0.1) (0.07 0.1 ) (0.04 0.5 ) (0.1 0.2) As 7 0.1 0.02 3 0.040.02 9 0.1 0.03 4 0.1 0.03 1 0.01 1 0.01 (0.02 0.2 ) (0.01 0.1 ) (0.01 0.2 ) (0.01 0.2 ) n denotes sample size
126 Table 3 2. Continued. Element n Cervix n Ovary n Uterus n Seminal Vesicles n Testes n Adrenal Gland Cu 1 0.7 0.2 2 1.10.2 1 1 1 1.1 1 1.4 1 20.3 (0.7 1.8 ) Zn 1 122 2 6.80.9 1 14 1 5.9 1 9 1 13.92.1 (5 8.4 ) Se 1 0.10.03 2 0.1 0.02 1 0.1 1 0.1 1 0.3 1 0.5 0.02 (0.1 0.2 ) As 1 0.10.05 2 0.10.03 1 0.04 1 0.01 1 0.02 1 0.10.1 (0.02 0.1 ) n denotes sample size Table 3 2. Continued. Element n Pancreas n Lung n Ceca l contents n Cecal horns n Cecum n Brain Cu 7 10.1 9 1.30.1 2 2.90.6 7 1.70.5 6 1.30.2 5 4.90.6 (0.6 1.3 ) (0.8 1.7 ) (2.3 3.5 ) (0.8 4.2 ) (0.8 2.3 ) (2.5 5.6 ) Zn 7 222.9 9 11.21.1 2 16.80.2 7 25.8 3 6 31.22.3 5 13.91.3 (14. 6 30.9 ) (6.5 17.4 ) (16.6 17 ) (19.7 41.9 ) (26.1 40.3 ) (10 17 ) Se 7 0.2 0.02 9 0.1 0.01 2 0.1 0.02 7 0.10.1 6 0.1 0.02 5 0.20.1 (0.1 0.2 ) (0.03 0.1 ) (0.03 0.1 ) (0.1 0.5 ) (0.03 0.2 ) (0.1 0.8 ) As 7 0.030.01 8 0.1 0.01 2 0.030.02 7 0.1 0.02 6 0.10.01 5 0.030.01 (0.01 0.1 ) (0.01 0.1 ) (0.02 0.1 ) (0.002 0.1 ) (0.03 0.1 ) (0.01 0.1 ) n denotes sample size
127 Table 3 2. Continued Element n Heart n Gall Bladder n Bladder n Cardiac Gland n Spleen n Thym us Cu 6 2.40.3 2 10.2 2 1.10.5 2 3.91.7 4 1.4 0.1 7 0.90.1 (1.7 3.3 ) (0.8 1.2 ) (0.6 1.6 ) (2.2 5.7 ) (1.2 1.6 ) (0.5 1.5 ) Zn 6 27 .52.3 2 14.83.8 2 15.32.5 2 19.33.1 4 17.60.8 7 21.36.4 (19.58 34.83) (11 18.5 ) (12.8 17. 8) (16.2 22.4 ) (15.6 19) (8.3 55 ) Se 6 0.1 0.03 2 0.1 0.03 2 0.1 0.03 2 0.10.04 4 0.2 0.03 7 0.2 0.03 (0.1 0.2 ) (0.05 0.1 ) (0.03 0.1 ) (0.1 0.2 ) (0.1 0.3 ) (0.1 0.3 ) As 6 0.040.01 2 0.10.1 2 0.1 0.04 2 0.010.01 4 0.050. 02 7 0.10.02 (0.02 0.1 ) (0.01 0.1 ) (0.01 0.1 ) (0.002 0.0 3 ) (0.03 0.1 ) (0.01 0.1 ) n denotes sample size Table 3 2. Continued Element n Thyroid n Muscle n Stomach n Stomach Contents Cu 5 0.90.2 6 0.50.1 2 0.90.1 2 0.80.2 (0.6 1.4 ) (0.3 1.1 ) (0.7 1.1 ) (0.5 1.3 ) Zn 5 18.13.3 6 22.4 2.9 2 23.35.1 2 5.61.8 (10.3 27.1 ) (13.8 32.2 ) (13.1 28.4 ) (2 10.5 ) Se 5 0.10.03 6 0.10.02 2 0.10.03 2 0.040.01 (0.1 0.2 ) (0.03 0.1 ) (0.03 0.1 ) (0.01 0.1 ) As 5 0.30.1 6 0.10.01 2 0.040.004 2 0.030.02 (0.01 0.7 ) (0.03 0.1 ) (0.03 0.04) (0.01 0.1 ) n denotes sample size
128 A B C D Figure 3 1. M etal concentration in tissues of the Florida manatee A) Copper concentration was highest level in the liver, B) Zinc concentration was highest in the liver, C) Selenium concentration was highest in the kid ney, and D) Arsenic concentration was highest in the feces
129 Table 3 3. The reference conversion factors for liver, kidney, erythrocytes in royal blue tubes (RBC B) and serum separator (RBC TT), and whole blood (WB) in the Florida manatee. Organ n Conversi on Factor Mean Moisture Content (%) Liver 7 0.22 77.90 Kidney 7 0.17 83.38 Erythrocytes B 5 0.27 73.12 Erythrocytes TT 6 0.26 73.96 Whole Blood 5 0.18 81.56 n denotes sample size
130 Table 3 4. The conversion factor (CF) from dry weight to wet weigh t. Organ Manatee a Manatee 1 b Dugong (Mature) 2 b Dugong (immature) 2 b Dall's Porpoise 3 Harbor Porpoise 4 White beaked dolphin 4 Bottlenos e dolphin (FL) 5 b Bottlenos e dolphin (TX) 5 b Liver 0.22 0.39 0.25 0.23 0.3 0.3 0.3 0.2 9 0.2 6 Kidney 0.1 7 0.2 0.23 0.25 0.25 0.23 0. 22 Muscle --0.31 0.28 0.28 0.28 a this study b calculated values from data and publications (from Yang and Miyazaki, 2003) 1 2 (Haynes et al. 2005), 3 (Yang and Miyazaki, 2003), 4 (Siebert et al., 1999), 5 (Meador et al. 1999)
131 Table 3 5. Thirty year comparison of kidney and liver metal concentratins in the Florida manatee LIVER LIVER KIDNEY KIDNEY n 1978 79 a n 2008 10 b n 1978 79 a n 2008 10 b Pb 19 10.08 5 0.050.02 20 0.70.03 5 0.020.01 Cu 19 31.611.4 9 12.7 4.4 ------9 20.1 Hg 1 0.1 ------------------Se 11 0.30.03 9 0.30.07 ------9 0.70.1 Cd ------5 1.10.97 18 6.42.03 6 95.8 a b this study *denotes significant difference (p<0.001)
132 Table 3 6. Liver and k idney comparisons between various marine mammal species ( Revised version of Table 1 1 ) Element n Tissue Mean Range Species Location Reference As 9 Liver 0.08 0.04 0.13 Florida manatee ( Trichechus manatus latirostris ) Florida, USA This study 9 Kidney 0 .08 0.03 0.13 Florida manatee ( Trichechus manatus latirostris ) Florida, USA This study 80 Kidney 0.7 0.5 2 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 80 Liver 0.8 0.5 14 CA Sea Lion (Zalophus californianus) California Harper e t al. (2007) 38 Liver 3 0. 5 7.7 Dugong (Dugong dugon) Australia Haynes et al. (2005) Cu 43 Kidney 0.5 3.2 Dugong (Dugong dugon) Australia Denton et al. (1980) 9 Kidney 1.99 1.6 2.3 Florida manatee ( Trichechus manatus latirostris ) Florida, USA This st udy 54 Kidney 2.3 1.8 3.5 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 16 Kidney 2.3 4 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 43 Liver 2.4 160 Dugong (Dugong dugon) Australia Denton et al. (1980) 30 Kidney 3.1 1.5 6.1 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 5 Kidney 3.4 2.7 3.8 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 58 Liver 2.6 17 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 37 Live r 5.3 2 20.3 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 1 Kidney 5.4 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 57 Liver 8.1 3.6 15.2 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 2 Kidney 8.1 5. 1 11 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 80 Kidney 9.5 3 19.8 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 1 Liver 9.7 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 5 Liver 10.5 6.5 16.5 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) n denotes sample size
133 Table 3 6. Continued. Element n Tissue Mean Range Species Location Reference Cu 29 Kidney 10.6 5 21.8 Ringed seal ( Phoca hispida ) West Greenland Joha nsen et al. (1980) 29 Liver 11.6 4.5 22.3 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 5 Kidney 12.8 10.3 15.6 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) 9 Liver 12.8 2.6 44.4 Florida manatee ( Trichechus ma natus latirostris ) Florida, USA This study 5 Liver 15.5 6.6 20.7 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 2 Liver 16.8 5.8 28.2 Dugong (Dugong dugon) Australia Marsh, 1989 2 Liver 20.4 15 25.8 Weddell seal ( Leptonychotes w eddellii ) Antarctica Yamamoto et al. (1987) 3 Liver 20.3 44.2 Dugong (Dugong dugon) Australia Haynes et al. (1999) 54 Liver 33.7 0.9 230.8 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 80 Liver 41.4 7.6 138 CA Se a Lion (Zalophus californianus) California Harper et al. (2007) 38 Liver 101 9.5 303 Dugong (Dugong dugon) Australia Haynes et al. (2005) Se 19 Liver 0.08 nd 0.21 Florida manatee ( Trichechus manatus latirostris ) Florida, USA O'Shea et al. (1984) 3 Liv er 0.3 0.6 Dugong (Dugong dugon) Australia Haynes et al. (1999) 38 Liver <0.02 3.6 Dugong (Dugong dugon) Australia Haynes et al. (2005) 2 Kidney <0.1 0.1 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 2 Liver 0.1 <0.1 0.1 Bowhead wh ale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 9 Liver 0.35 0.1 0.6 Florida manatee ( Trichechus manatus latirostris ) Florida, USA This study 9 Kidney 0.74 0.4 1.3 Florida manatee ( Trichechus manatus latirostris ) Florida, USA This study 54 Kidney 3.2 1.7 4.9 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 37 Liver 4.1 0.6 8 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 14 Kidney 5.6 Striped dolphin ( Stenella coeruleoalba ) Japan Itano et al. (1984) n denotes sample size
134 Table 3 6. Continued Element n Tissue Mean Range Species Location Reference Se 4 Kidney 7.1 2.3 10 Harbor seal ( Phoca vitulina ) Wadden Sea Reijnders (1980) 1 Liver 7.66 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 1 Kidney 7.69 Dal l's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 15 Liver 48.6 Striped dolphin ( Stenella coeruleoalba ) Japan Itano et al. (1984) 8 Liver 109 3.9 350 Harbor seal ( Phoca vitulina ) Wadden Sea Reijnders (1980) Zn 9 Kidney 20.5 8 32.8 Florida ma natee ( Trichechus manatus latirostris ) Florida, USA This study 2 Kidney 23.8 19 28.5 Bowhead whale ( Balaena mysticetus ) Alaska Byrne et al. (1985) 17 Kidney 27 19.8 40.4 Steller sea lion ( Eumetopias jubata ) Hokkaido, Japan Hamanaka et al. (1982) 5 Ki dney 27.2 22 32 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 2 Kidney 29.1 27.4 30.7 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) 30 Kidney 30.1 22.8 41.2 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 43 Kidney 14.3 53.5 Dugong (Dugong dugon) Australia Denton et al. (1980) 16 Kidney 16.3 32.5 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. (1977) 57 Liver 27 56 Harbor seal ( Phoca vitulina ) North Sea Drescher et al. ( 1977) 1 Kidney 31.5 Dugong (Dugong dugon) Australia Marsh, 1989 1 Liver 36.4 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 1 Kidney 38.2 Dall's porpoise ( Phocoenoides dalli ) Japan Yang et al. (2006) 37 Liver 38.8 24 63.6 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 4 Kidney 40.7 32.9 47.9 Ringed seal (Phoca hispida) W. Greenland Sonne et al. (2009) 54 Kidney 41.1 3.8 85.8 Narwhal ( Monodon monoceros ) Canada Wagemann et al. (1983) 1 Liver 43.6 Bowhead whale ( Bala ena mysticetus ) Alaska Byrne et al. (1985) 2 Liver 44.4 41.7 47 Weddell seal ( Leptonychotes weddellii ) Antarctica Yamamoto et al. (1987) n denotes sample size
135 Table 3 6. Continued Element n Tissue Mean Range Species Location Reference Zn 57 Liver 4 4.5 26.5 109 Striped dolphin ( Stenella coeruleoalba ) Japan Honda et al. (1983) 29 Liver 46 30.7 67.3 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (1980) 29 Kidney 46.2 27.9 78 Ringed seal ( Phoca hispida ) West Greenland Johansen et al. (19 80) 4 Liver 46. 9 34.7 59 Ringed seal (Phoca hispida) W. Greenland Sonne et al. (2009) 17 Liver 47 35.5 86 Steller sea lion ( Eumetopias jubata ) Hokkaido, Japan Hamanaka et al. (1982) 5 Liver 47.4 40 55 Harp seal ( Pagophilus groenlandicus ) Barents Sea Sonne et al. (2009) 5 Kidney 48.4 34 62 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) 5 Liver 55.2 41 68 Hooded seal (Cystophora cristata) Barents Sea Sonne et al. (2009) 80 Kidney 64.3 16.5 973 CA Sea Lion (Zalophus californianus ) California Harper et al. (2007) 80 Liver 96 37.3 184 CA Sea Lion (Zalophus californianus) California Harper et al. (2007) 9 Liver 117.7 32.4 578.1 Florida manatee ( Trichechus manatus latirostris ) Florida, USA This study 2 Liver 363 507 Dugong (Dug ong dugon) Australia Marsh, 1989 3 Liver 529 913 Dugong (Dugong dugon) Australia Haynes et al. (1999) 43 Liver 57.6 1100.8 Dugong (Dugong dugon) Australia Denton et al. (1980) 38 Liver 2658 458 5375 Dugong (Dugong dugon) Australia Haynes et al. (20 05) n denotes sample size
136 CHAPTER 4 COPPER, ZINC, SELENI UM AND ARSENIC DISTR IBUTION IN VEGETATIO N AT KINGS BAY, CRYSTAL R IVER, FLORIDA WITH R ELATION TO THE FLORI DA MANATEE ( T richechus manatus latirostris ) Background Kings Bay, in Crystal River, Florida is a vital habitat for a number of species, especially that of the Florida manatee. The Kings Bay watershed is home to 21 species of amphibians, 47 species of reptiles, 191 species of birds, and 22 species of mammals ( SWFWMD 2004 ) and is crucial for th e survival of the Florida manatee. Manatees utilize Kings Bay in winter months by taking shelter from the decreasing temperatures of the Gulf of Mexico in order to prevent the fatal cold stre ss 1985) as well as year round inh abitance The constant flow from the artisian fed springs maintain s temperatures at 23 24 0 C throughout the year, resulting in waters being 7 0 C warmer than ambient air during the winter months (Hartman, 1979) thus making it an ideal environment for manat ees in winter The Crystal River National Wildlife Refuge was created by the United States Fish and Wildlife Service (USFWS) in 1983 in order to help monitor this important watershed and protect the endangered ma natee (Notestein et al., 2005). Crystal R iver is home to the largest gathering of manatees at a natural refuge (Hartman 1974) with Kings Bay being only one of four natural spring refuges in the state of Florida (Laist and Reynolds 2005) Located in Citrus County on the west coast of Florida Kings Bay measures roughly 600 acres (Notestein et al., 2005) with water from the bay flowing approximately 11 miles to the northwest before reaching t he Gulf of Mexico (Kochman e t al., 1985). Kings Bay is a relatively shallow bay, ranging from one to 10 meters in depth with more than 30 artesian springs (Hartman 1979; Kochman et al. 1985 ) and a
137 wide array of species of vegetation which makes Kings Bay an ideal habitat for manatees Due to the combination of warm, clear waters of Crystal Ri ver and the charismatic megafauna of the Florida manatee, Kings Bay is also an important ecotourism destination. The local economy thrives on the various commercial and recreational activities supported by Kings Bay with an increase in population from 9 ,268 in 1960 to 118,085 in 2000 in Citrus County However, due to the large number of visitors and resident s an increase in anthropogenic influences has adversely affected water quality and the natural habitat (Notestain et al., 2005). As a primary site for manatees, evaluation of metal loads in vegetation of Kings Bay is of utmost importance M etal exposure in marine mammals is thought to be due primarily to dietary intake ( Andre et al., 1991 ; Augier et al., 1993; Das et al., 2003; Law, 1996). Sirenian s have a unique diet, in that they are the only herbivorous marine mammal s and consume vegetation in freshwater, brackish and ma rine environments (Best, 1981; Hartman, 1979 ). Although low on the trophic level, manatees are in direct contact with sediment s and aquatic vegetation which may possess contaminant loads from various sources (Bonde et al., 2004). While Hydrilla verticillat a are capable of growing to 10 m, manatees were never f ound to dive more than 4 meters for Hydrilla and only fed at one to th ree meters on Ceratophyllum demersum and Myriophyllu m spicatu m in Crystal River (Hartman, 1979). Moreover, many plants are bioaccumulators, meaning they absorb and retain metals from the environment, and bioconcentrators, as they are able to absorb and re tain metals directly from the water. S eagrasses found in saltwater are an important dietary source for manatees and
138 dugongs (Burns et al., 1997 ; Dawes, 1985 ) and are able to absorb metals from the surrounding environment. Studies by Lewis et al. (2007) fo und high levels of copper and arsenic in the surface water of the Gulf of Mexico at 13.9 61.1 g/L and 36.3 75.6 g/L, respectively. Mercury, cadmium, nickel, lead and silver were found in more than 50% of turtle grass ( Thalassia testudinum ) and shoal grass ( Halodule wrightii ). This sug gests that seagrasses may be a potential source of metal expo sure in manatees. Kings Bay provides an adequate diet of freshwater vegetation for the Florida manatee, but is exposed to various chemical influ ences and developmental changes These factors make it a useful location to study the levels of metals in plan ts, potential metal exposure in manatees due to plant ingestion and possible exposures to human influences on metal loads in vegetation The first objective of this study is to evaluate metal concentrations in the surrounding environment (vegetation, wat er and sediment) which may affect metal accumulation in the Florida manatee. Stavros et al. (2008 a ) examined 5 vegetation specie s commonly consumed by manatees from the Salt and Crystal r iver, Florida in January 2007. The study by Stavros et al. (2008 a ) provided good preliminary values for vegetation associated with the Florida manatee but was performed on a single time point and resulted in a large range within metal levels in Cu (0.41 9.99 ug/g), Zn (1.90 9.02 ug/g), As (0.09 2.65 ug/g), and Se (0.132 0.383 ug/g). As a result, this study will include varying freshwater vegetation species collected throughout 2008 2011. With the evaluation of metal content in vegetation most commonly consumed by manatees in Kings Bay, we hypothesize that diet is the p rimary source of copper, zinc, arsenic and selenium accumulation in the Florida manatee In addition, due to the historical use of Cu based herbicides, our second objective is to
139 monitor changes in metal burdens of vegetation species by c omparing results from published data) in 1979 1980. This study will not only evaluate possible metal exposure in manatees, but will help monitor the health of this valuable watershed. Materials and Methods Vegetation Samples In collaboration with the University of Florida, Crystal River National Wildlife Refuge and USGS Sirenia Project, freshwater aquatic vegetation was collected from 15 sampling stations (A P, no statio n O) during routine vegetation surveys that were conducted every other month from 2008 2011 (Figure 4 1). A number of species were collected including : Algae (n=7), Chara spp (Muskgrass, n=8), Ceratophyllum demersum (Coontail, n=4), Halodule wrightii (Shoalweed, Belize, n=6), Halophila engelmannii Hydrilla verticill ata (n=3), Lyn g bya spp (n=2), Myriophyllum spicatum (Eurasian watermilfoil, n=30), Najas guadalupensis (Southern naiad, n=15), Potamogeton pectinatus (Sago Pondweed, n=27), Syringodium filiforme (Manatee Grass, n=1), and Vallisneria americana (Tapegrass, n =31). Vegetation samples (1 6 grams, ww) were collected from various depths at different stations throughout the year. In addition to plant survey samples, vegetation samples were also collected from surrounding areas of wild manatee health assessments in Brevard County, Florida (CBC) and Belize (BZ) in 2009 2010 and from Salt River, in Crystal River, Florida (SR) in 2010 2011. Opportunistic samples from the mouth of wild manatees in Citrus County (IM) were also collected during health assessments in Oc tober 2010. Plant samples were rinsed with surrounding water in the field and placed in a plastic whirl pak bag or polypropylene conical tube and stored in a cooler until analysis in the laboratory.
140 Vegetation samples were separated from roots for six sa mples in 2010 2011 in order to determine if metal concentration varied with roots versus shoots with the possibility of manatees consuming the whole plant while grazing. Vegetation samples were immediately dried upon arrival to the laboratory at 60 o C for a minimum of seven days and ground to a powder similar to procedures following Prange and Dennison (2000). Water Water samples (15 50 mL) from various stations were collected in Kings Bay, Crystal River, Florida (n=22) from 2009 2011. In addition to Citr us County, samples were collected in Brevard County in January, 2009 (n=2). Water samples from close to the site of vegetation were taken in order to emulate samples that w ould be ingested by the manatee. Sediment Manatees have been observed to stir the t op sediment with foreflippers when feeding or when consuming rhizomes, thus, sediment may be a possible source of metal exposure in manatees. Sediment samples from various stations were collected at in Kings Bay, Crystal River, Florida (n=13) from 2009 20 10. In addition to Citrus County, samples were collected in Brevard County in January, 2009 (n=2) and Belize in June 2010 (n=1). Sediment samples were immediately dried upon arrival to the laborator y at 60 o C for a minimum of seven days Dried sediment s amples were then placed in polypropylene tube s with equal amounts of 2% HNO 3 in order to oxidize and leach metals from the sediment for an additional seven days to determine possible surface metal loads of sediment
141 Sample Analysis Approximately 0.5 grams of dried vegetation, leached sediment, or water was pl aced in borosilicate glass tube (18x150mm, Fisher Scientific Company, Inc., Pittsburgh, PA) with ultrapure Optima nitric acid (Fisher Scientific Company) and placed in a 45 well graphite digestion bloc k at approximately 130 o C. Ultrapure 30% hydrogen peroxide (Mallinckrodt Baker, Inc., Phillipsburg, NJ) was used to complete digestion of organic matter. Ten mL of Mil li Q (EMD Millipore Billerica, Massachusetts ) deionized water was then added to dissolv e samples. Each sample was filtered using a 13 mm nylon syringe filter (0.2 m; Fisher Scientific Company) and placed in a 15 mL conical tube (Corning Life Sciences, Lowell, MA) for analysis using an inductively coupled plasma mass spectrometry (Thermo Electron X Series ICP MS, Thermo Fisher S cientific, Inc., Waltham, MA) in the C ollege of Pharmacy at the University of Florida Copper, Zn, Se, and As were analyzed with an internal standard of 115 In. Quality assurance for manatee samples included blank samples, repeat samples, and NOAA whale and manatee livers. The standard refere nce material for select elements is reported as follows (meanSEM) with standard laboratory results in parenthesis, for beluga whale liver II homogenate NOAA standard refere nce material (QC97LH2): As 1.50.2 (0.390.03 ), Cd 2.110.04 (2.350.06), Cu 11.35 0.24 (13.160.4), Fe 62527 (66815), Se 28.8 2.6 (24.30.85), and Zn 201.5 (26.3 0.66) The pygmy sperm whale Liver III (QC03LH3) NOA A standard resulted in: As 0.40.04 (0.860.08), Cd 5.60.2 (5.940.38), Co 0.060.01 (0.07 0.0 03), Cu 2.70.2 (2.740.1 9), Fe 60548 (69445), Se 10.33 0.95 (7.871.18), and Zn 17.51.4 (21.151.65). The Triplicate runs were performed on the ICP MS on each sample and
142 the mean was obtained in ppb. The mean was then multiplied by the volume of DI water the sample was recons tituted with to obtain total concentration in ng/mL. Concentrations of samples were then reported as ng/mg using the original weight of the sample, or ppm dry (or wet) weight. GIS Geographic Information System (GIS) was completed using ArcGIS Education Ed ition 10 (ESRI, Redlands, CA) and Global Positioning System (GPS) coordinates (Garmin, Olathe, KS) of each station from the June 2, 2011 vegetation survey. The GPS coordinates were converted to decimal degrees in Albers format for each station An averag e metal concentration at each station was calculated using all vegetation samples collected from 2008 2011 and placed in a comma separated value file. The shapefile map used for this analysis was obtained from USGS Sirenia Project (Dr. Daniel Slo ne) which was taken from the Southwest Florida Water Management District (FL04shoreline, polygon). Data was added (xy data) and displayed with graduation. In order to determine graduation of metal loads from each station with proximity to the nearest station, the spline with barriers spatial analysis tool was used. Spline with barriers interpolation was used because the points were not continuous and consisted of island barriers in Kings Bay The minimum curvature spline was calculated in order to estimate the de gree of metal concentration between stations. The mouth of the river and additional canals were clipped and not included in our analysis. Ten classes were used for each metal and distribution of Cu, Zn and As in vegetation samples in Kings Bay was compl eted.
143 Thirty Year Comparison of Metals in Vegetation B ased on historical use of Cu based herbicides in Kings Bay special interest was given to copper. Copper data from October 1979 and February 1980 on three species of vegetation: Hydrilla verticillata (n=12), Vallisneria americana (n=6), and Ceratophyllum demersum (n=12), for up to six plant survey stations was obtained The average respective vegetation data in this study was used to determine changes over time for Hydrilla v erticillata (n=3 ), Vallisneria americana (n=30 ), and Ceratophyllum demersum (n=30 ) Statistical Analysis SigmaPlot version 11 (Systat Software Inc., San Jose, CA) was used for statistical analysis and visual graphs Descriptive statistics were used to d etermine mean SEM A one way analysis of v ariance ( ANOVA ) and Kruskal Wallis one way analysis of variance on r anks were used to determine a sig nificant difference (p<0.05) between plant survey stations and season with metal concentration levels in each ve getation species, sediment and water. A one w ay ANOVA was performed to determine a significant difference between locations (CR, BZ, CBC) using average total vegetation of Cu, Z n, As, and Se. A Mann Whitney rank sum t est was used to determine a signific ant difference between Cu data from vegetation samples in 1979 1980 and 2008 2011 and to determine significant differences between vegetation with roots and without roots. Results Trace metal concentrations varied with location (Figure 4 2), vegetation spe cies (Figure 4 3), and season, thus, results will be discussed by element. Overall
144 mean SEM for total v egetation in Kings Bay was 9.80.7 ppm for Cu, 65.95.5 ppm for Zn, 2.62.2 ppm for As, and 0.70.04 ppm for Se. Vegetation Copper When analyzing tota l vegetation content the three highest Cu concentrations were found in plant survey stations N, I, and F (Figure 4 2A). There was a significant difference in Cu concentrations between species (p=0.001), with highest levels found in Lyngbya spp (17 ppm) Halophila engelmannii (12.5 ppm) and Vallisneria americana ( 9.2 ppm) ( Figure 4 3A). There was also a significant difference in season (p=0.023), with highest Cu concentrations found in the winter (9.6 ppm) There was no significant difference (p=0.240) in Cu levels between locations (CR, CBC, and BZ). When analyzing individual common freshwater vegetation species within Crystal River, Florida ( Myriophyllum spicatum Najas guadalupensis Potamogeton pectinatus and Vallisneria americana ), there was a sig nificant difference found by season for Vallisneria americana (p=0.038) with levels highest in the winter and Najas guadalupensis (p=0.043) with levels highest in the Spring. However, there was no significant difference in Potamogeton pectinatus (p=0.689) and Myriophyllum spicatum (p=0.482). Copper data from October 1979 and February 1980 on Hydrilla verticillata Vallisneria americana and Ceratophyllum demersum compared to concentrations found in this study. There was no s ignificant difference in Hydrilla verticillata (p=0.829) and Vallisneria americana (p=0.596) but there was a significant difference in Ceratophyllum demersum (p=0.032). Copper concentrations were significantly higher in 1979 1980 with a median of 13.5 pp m, as compared to Ceratophyllum demersum levels detected at 6.9 ppm in 2008 2011. However, overall
145 Cu levels for all three species combined were not significantly different from 1979 1980 and this study. Zinc When analyzing total vegetation content, the t hree highest Zn concentrations were found in plant survey stations I, F, and M (Figure 4 2B). There was a significant difference in Zn concentrations between species (p<0.001), with highest levels found in Vallisneria americana ( 78.2 ppm), Lyngbya spp (71 .3 ppm) and Najas guadalupensis (67.4 ppm) (Figure 4 3B). There was also a significant difference in season (p=0.028), with highest Zn concentrations found in the Spring (63.5 ppm) There was a significant difference (p=0.002) between locations with the highest concentration of Zn in Crystal River compared to the lowest levels in Belize. When analyzing individual common freshwater vegetation species within Crystal River, there was no significant difference in season in Vallisneria americana (p=0.064), Po tamogeton pectinatus (p=0.335), Najas guadalupensis (p=0.281), and Myriophyllum spicatum (p=0.250). Arsenic When analyzing total vegetation content, the three highest As concentrations were found in plant survey stations BZ, N, and SR (Figure 4 2C). There was a significant difference in As concentrations between species (p<0.001), with highest levels found in seagrass species of Halophila engelmannii (15.6 ppm), Halodule wrightii (8.7 ppm), and Syringodium filiforme (8 .3 ppm) (Figure 4 3D). There was also a significant difference in season (p=0.008), with highest As concentrations observed during the winter months (2.5 ppm) There was a significant difference (p<0.001) in As levels between locations with BZ higher than Crystal River and Brevard County When analyzing individual common freshwater vegetation species within Crystal River, there was no significant
146 difference in season in Vallisneria americana (p=0.136), Potamogeton pectinatus (p=0.885), Najas guadalupensis (p=0.396), and Myriophyllum spicatu m (p=0.409). Selenium When analyzing total vegetation content, the three highest Se concentrations were found in plant survey stations N, J, and I (Figure 4 2D). There was no significant difference in Se concentrations between species (p=0.051), while the highest Se content in vegetation was Lyngbya and other algal species (1.985 ppm) with lowest levels found in Halodule (0.299 ppm) (Figure 4 3D). However, t here was a significant difference in season (p=0.003), with highest Se concentrations during the winter months (0.8 ppm ) There was no significant difference (p=0.078) between locations (CR, BZ, and CBC). When analyzing individual common freshwater vegetation species within Crystal River, there was a significant difference in Vallisneria americana (p=0.022) and Potamogeton pectinatus (p=0.016) with levels highest in the winter. On the other hand, there was no significant difference in Najas guadalupensis (p=0.174) and Myriophyllum spicatum (p=0.725). Roots Roots were separated from Vallisneria ame ricana and Ceratophyllum demersum in 2010 2011 to determine metal levels in the whole plant and without roots (Table 4 1). There was no significant difference in Vallisneria americana with and without ro ots for Cu, Zn, As, and Se ( p=1 ) or Ceratophyllum de mersum with and without roots for Cu (p=0.667), Zn (p=1), As (p=0.667) and Se (p=1). Water Based on the results water was found to be negligible in terms of a source of accumulation of metals in the manatee. Twenty nine samples were obtained from
147 Kings B ay, Crystal River, Florida from 2009 2011. Mean standard error was 0.030.01 ppm Cu, 0.180.04 ppm Zn 0.003 0. 00 2 ppm As and 0.0 010.0005 ppm Se. There was no significant difference between stations for Cu (p=0.615), Zn (p=0.663), As (p=0.626) and Se (p=0.320). Moreover, metal concentrations in Citrus County and Brevard County were not significantly different in Cu (p=0.227), Zn (p=0.515), As (p=0.806), and Se (p=0.598) Sediment For leached sediment samples, there was no significant difference in st ations in Crystal River with concentrations of Cu (p=0.759), Zn (p=0.720), As (p=0.6), and Se (p=0.459). Mean SEM for sediment ( n=10) in Crystal River was 0.80.2 ppm for Cu, 3.81.8 ppm for Zn, 0.030.005 ppm for As, and 0.0 20.01 ppm for Se. When compa ring location differences between Citrus County (n=10), Brevard County (n=2 ) and Belize (n=1), there was a significant difference in Cu (p<0.001) with highest levels in Brevard County and As (p=0.007) with highest levels in Belize However, there was no significant difference in Zn (p=0.676) and Se (p=0.055). GIS A geographic information s ystem (GIS) was used to visualize average metal loads of vegetations for each station and the surrounding area within Kings Bay, Crystal River The average concentrati on in vegetation at each station for Cu (Figure 4 4A), Zn (Figure 4 4B) and As (Figure 4 4C) were displayed in 10 classes of concentrations, as depicted in the color shade For all metals, higher concentrations were found in the northern portion of Kings Bay than in the southern stations with special attenti on to stations N, I, and F
148 Discussion Based on this data, diet may influence metal accumulation in the Florida manatee. There was a statistically significant difference in season for Cu, Zn, As and S e l evels, with metal levels depende nt on species, except for Se. Levels in water were found negligible and there was no significant difference in root versus shoot accumulation in Vallisneria americana and Ceratophyllum demersum For leached sediment sam ples, Cu was higher in Brevard County, while As was higher in Belize. Overall concentration of Cu in vegetation did not differ from 1979 1980 when compared to this study. In addition, a trend of metal accumulation in vegetation was found in the northern plant survey stations in Kings Bay. Metals and Vegetation Copper Copper levels have historically been of concern in Kings Bay. Although there was no significant difference in Hydrilla verticillata and Vallisneria americana there was a significant diffe rence in Ceratophyllum demersum with levels significantly higher in 1979 1980. This apparent decrease in Cu may be due to the ban of Cu based herbicides in Kings Bay in the 1980s suggesting that Ceratophyllum may be more sensitive to Cu exposure than Hyd rilla or Vallisneria As described in Keskinkan et al. (2004), the removal of metals from the surrounding environment by aquatic plants is performed by an initial fast, reversible, response called biosorption, and a second, slow, irreversibl e response of bioaccumulation. Authors found that Ceratophyllum were capable of removing Pb, Cu, and Zn from solution. The level of adsorption in species may determine the variation in metal accumulation between plant species found in this study. Moreover, based on T able 4 2, Cu levels from various plants were relatively
149 similar. The levels in Stavros et al. (2008a) may be due to the fact that samples were only obtained in the winter season. Zinc Based on our data, one can speculate that ingestion of freshwater veg etation may play a role in Zn accumulation in the manatee. Although various vegetation species are present in Kings Bay, manatees in freshwater areas of Crystal River, Homosassa Springs and Withlacoochee River, feed predominately on Hydrilla verticillata Elodea densa, Vallisneria americana Ceratophyllum demersum, and Myriophyllum spicatum and while in brackish water, Ruppia maritime and Halodule wrightii were the dominant species (Hartman, 1979). When examining the Zn levels in manatee s, one of the mo st preferred vegetation species, Vallisneria americana also had the highest concentration of Zn. In addition, there was a significantly higher level of Zn in vegetation found in Crystal River than in Belize, which mirrors blood levels at these locations (Chapter 2 ). Zinc levels can vary, as shown in Table 4 2, depending on the species, season, and location. Arsenic In addition to Zn, our data suggest that diet may also play a role in As concentrations in the West Indian ma natee. Based on Chapter 2 whole blood values there was a significantly higher concentration of As in the Antillean manatee found in Belize than other locations of manatees in Florida According to the results of this study As concentration was also highest in seagrasses commonly consu med b y Antillean manatees in Belize and sediment samples. Moreover, As concentrations were significant ly higher in vegetation species from Belize than Florida. Although it is not possible to determine the cause of As in Antillean manatees based on this s tudy metals
150 are present in insecticides, pesticides, herbicides, and fungicides which are commonly used for banana, sugarcane, citrus, papaya and rice industries, as well as by other small farms (Fernandez, 2002) which are present in Belize As stated i n Chapter 2 speciation of As is needed in or der to determine toxicity of As, but found based on the results of this study, that diet likely influence s As accumulation in the manatee. Selenium In addition to As, s elenium levels in Chapters 2 and 3 were lo w and much lower than other marine mammal species. Based on our results of this study Se was highest in algal species, which is not a preferred feed by manatees and low in preferred vegetation, such as Vallisneria americana and Halodule wrightii (Figure 4 3D). Algae does not seem to be a significant source of food and may be consumed incidentally (Hartman 1979) or when resources are scarce during events of a tropical cyclone (Heinsohn and Spain 1974 ). Thus, the scarcity of Se in the diet of manatees likely influences circulating levels of low Se as evident in Chapter 2 and 3. We suspect t he low Se levels found in manatees are due to low naturally occurring Se in areas, such as Florida Low Se levels in tissues were found in 174 white tailed deer ( Od ocoileus virginianus ) in s outhern Florida. The majority of serum samples (75%) were below livestock deficiency concentrations with a mean standard deviation of 0.051 0.004 ppm (dw), as authors suggest this may be representative of low Se intake in the di et (McDowell et al., 1995) In addition, Merkel et al. (19 9 0 ) found soils in Florida to be Se deficient, resulting in low Se in the feed of Charolais cattle and water buffalo, thus, encouraging Se supplementation In addition to feed, Bas u et al. (2007) found low Se levels in the Upper Florida n Aquifer which supports the low Se in water and leached sediment in this study.
151 Opportunistic Herbivory A number of factors may impact metal accumulation in the Florida manatee; including diet preference, foragin g behavior, vegetation density, and natural and anthropogenic factors. Although this study provides insight to metal accumulation in manatees in Kings Bay through diet, diet in an opportunistic herbivore is difficult to assess as manatees consume a wide variety of vegetation consisting of over 60 different plant species in fresh brackish and marine environments (Best, 1981; Hartman, 1979; Reep and Bonde, 2006). Manatees consume a number of different types of invertebrates accidentally with vegetation as well Organisms include amphipods, isopods, tiny shrimp, crayfish, crabs, insect larvae, bivalves, snails, leeches, nematodes, platyhelminths, polychaetes, worms, tunicates, hydroids, a et al., 1991) and a cannonball jellyfish ( Stomolophus meleagris ) (Zoodsma, 1991). Courbis and Worthy (2003) found that manatees in the Ind ian River Lagoon also consumed barnacles, tunicates, bivalves, gastropods, small cetaceans, and other invertebrate s. In addition to invertebrates, fish have been seen consumed by manatees (Jenkins, 1978; Powell, 1978). Hartman (1979) also observed manatees consuming dead plant material and manatee feces perhaps to supplement their diet or by accident Although veg etation accounts for the vast majority of ingested material in manatees, additional studies utilizing s tomach contents and the amount of metal from vegetation ingested is needed to confirm that aquatic vegetation is the major source of trace metal accumula tion in the Florida manatee.
152 Roots, Water, and Sediment Manatees have different foraging habits with graz ing, cropping and rooting depende nt on sediment type, ease of pulling the plant out, or nutritional source of the plant species (Packard, 1981; 1984; Provancha and Hall 1991 ; Zieman 1989 ) which may potentially affect the level of metal exposure and accumulation in manatees However, b ased on our results (Table 4 1), there was no significant difference in vegetation with roots and without roots The re was also no significant difference in metal concentrations in water which appear to be a negligible source of metal exposure for the West Indian manatee. Sediment, on the other hand, may play a role in metal accumulation in manatees depending on the a mount ingested. Based on our observations in the field, manatees often stir up the surface of the sediment while feeding in shallow waters Therefore, further analysis is n eeded to determine the amount and type of sediment ingested in manatees to determi ne metal exposure. Possible Anthropogenic Influences Based on GIS analysis, metal concentrations in vegetation were higher in the northern section of Kings Bay. The highest metal levels were found commonly around station N, I, and F (Figure 4 1). Station N and I are located at the mouth of Crystal whereas F is a n outpocket next to Parker Island where presence of recreational boats are found anchored during low tide, especially in the summer Al though it is not possible to pinpoint the sources of metal loads in Kings Bay based on our study, it has been shown that Cu and Zn are common elements leached from antifouling paint from the hull of boats ( Carson et al., 2009; Schiff et al., 2004; Turner e t al., 2009; Ytreberg et al., 2010). Anti fouling paints have been used for many years to deter organisms, such as barnacles, algae and
153 mussel s from remaining on the hull of the boat which can increase drag and decrease speed resulting in more cost s f or fuel (Champ, 2000). Many forms of anti fouling agents have been introduc ed in the past, utilizing Hg, As, and Cu. Therefore, with the continual use of copper based anti fouling paints and zinc oxide ( Singh and Turner, 2009 ) monitoring of these metals i s highly recommended in Kings Bay with additional studies measuring boat traffic, types of vessels, and seasonal use patterns Zinc in the aquatic environment can be present from industrial and sewage discharges, as well, as from outboard motors a nd sacrif icial Zn anodes (Bird et al., 1996) Automobile associated emissions, such as brake dust, roadside dust and soil, and tire wear can also contribute to Cu and Zn loads in to the aquatic environment. Many past studies on Cu emissions from brake dust have be en a problem in many areas (Thorpe and Harrison, 2008), similar to Kings Bay. Moreover, Florida is known for their variety of golf courses with approximately 25 brands of herbicides used to maintain the quality of turf on Florida golf courses contributin g to groundwater contamination ( Cai et al., 2002). Although wastewater treatment outflow in the northern part of Kings Bay was diverted in 1992, the largest contributor of nutrients i n Kings Bay are spring discharges, which contain residential and golf co urse fertilizers and septic tanks discharge (SWFWMD 2004). As a result, there are a number of possible sources of metal exposure in Kings Bay which warrants further investigation In addition to aquatic vegetation adsorption, the distribution of metals can vary depending on a number of environmental factors, such as pH, tides, precipitation, natural disasters, dissolved oxygen conditions, and temperature (Frazer et al., 2006 ; Terrell et al., 1996 ) therefore, continual monitoring of metals is essential f or the health of Kings Bay.
154 Conservation Impact Kings Bay is an important resource for manatees and humans alike and monitoring for metal levels is recommended for the conservation of this habitat High levels of metals can have detrimental effects on plants causing repercussions i n development It has been found that a quatic vegetation easily absorbs nutrients and other elements from their surroundings and can play an important role in removing contaminants (Boyd, 1970) Unfortunately, this can cause a potential threat to the endangered herbivorous manatee. Although natural biological factors affecting metal accumulation in vegetation cannot be controlled, the negative impacts that humans have on areas, such as Kings Bay, can be prevented. The human population in Florida has increased over the past 40 years, with the threat of residents and tourists impacting the manatee habitats. Anthropogenic activities, such as agricultural runoff, sewage discharge, recreational and commercial activities, boat pr opeller scars, oil spills, and paper mill effluents (Philli ps, 1960; Smith 1993 ; Zieman and Zieman, 1989 ) can impact seagrass beds and vegetation and in turn, negatively affect the ecosystem as a whole When seagrasses are wiped out, sediments are easil y disturbed, thus increa sing turbidity and light becoming less accessible for plant growth Moreover if warm water refuges, such as Kings Bay, are lost due to natural or anthropogenic impacts this can be detrimental to the survival of this endangered s pecies (Laist and Reynolds, 2005) t hereby emphasizing continual monitor ing of the health of Kings Bay and this valuable watershed ecosystems
155 Figure 4 1. Plant survey stations with map of Florida. Revised plant survey st ations from Kochman et al. (1985 ) used in this study. All 15 stations are circled in red with springs denoted by
156 A B C D Figure 4 2. Average trace metal conce ntrations in total vegetation. Mean SEM (ppm, dw ) for A) Copper B) Z i n c C) A r s enic and D) Se lenium levels at each plant survey station in Kings Bay (A P) and B elize (BZ ) during 2008 2011.
157 A B C D Figure 4 3. Average trace metal concentrations per veget atio n spec ies. MeanSEM (ppm, dw) for A) Copper B) Z i n c, C) Arsenic and D) Selenium levels during 2008 2011.
158 Table 4 1. Metals in roots and s hoots. Copper (Cu), zinc (Zn), arsenic (As) and selen ium (Se) concentrations (ppm, dw ) were determined in the whole plant and without roots in Vallisneria americana (tapegrass) and Myriophyllum spicatum (Watermilfoil) in Kings Bay, Crystal River, Florida in 2010 and 2011. Station Sample Date Collected 65 Cu (ng/mg) 66 Zn (ng/mg) 75 As (ng/mg) 82 Se (ng/mg) K Tapegra ss w/o root April 23, 2010 5.5 90.9 0.7 0.4 K Tapegrass w/root April 23, 2010 6.8 57.5 1.1 0.4 I Waterm ilfoil w/o root June 2, 2011 8.7 25.1 4.6 0.7 I Watermilfoil w/root June 2, 2011 8.8 94.7 5.3 0. 7 J Watermilfoil w/o root June 2, 2011 5.9 50. 8 1.4 0 .5 J Watermilfoil w/root June 2, 2011 7.4 14.5 1.8 0.7
159 Figure 4 4 A Geographic Information System (GIS) of average copper concentration in aquatic vegetation at each vegetation survey station in Kings Bay, Crystal River, Florida, from 2008 2011
160 Figure 4 4B. Geographic Information System (GIS) of average zinc concentration in aquatic vegetation at each vegetation survey station in Kings Bay, Crystal River, Florida, from 2008 2011.
161 Figure 4 4 C Geographic Information System (GIS) of average arse nic concentration in aquatic vegetation at each vegetation survey station in Kings Bay, Crystal River, Florida, from 2008 2011
162 Table 4 2. Trace metal comparison of various marine aquatic and terrestrial plant s for zinc, copper, selenium and arsenic. Aq uatic Vegetation Aquatic Vegetation Marine Seagrass (Blades) Marine Seagrass (Blades) Cymodocea nodosa (Blades) Terrestrial Forage Species Florida, USA Florida, USA Gulf of Mexico, USA Port Curtis, Australia Bay of Laryma, Greece Florida, USA this stud y Stavros et al., 2008 a Lewis et al., 2007 Prange and Dennison, 2000 Nicolaidou and Nott, 1998 Emanuele and Staples, 1990 Element Mean SEM MeanSD MeanSD MeanSEM MeanSD MeanSEM Cu 9.80.7 2.5 4.2 9.35.1 10.61.4 9.60.5 10.21.4 Zn 65.9 5.5 4.4 3 1 4.725.7 45.115.3 57.56.2 26.52.3 As 2.62.2 1.1 0.9 5.72.4 Se 0.70.04 0.2 0. 1 1.90.4
163 CHAPTER 5 PURIFICATION AND CAT ALYTIC PROPERTIES OF TWO ISOZYMES OF CARB ONIC ANHYDRASE IN THE FLO RIDA MANATEE ( T richechus manatus latirostris ) Background Elevated levels of zinc are unique to sirenians when compared t o other marine mammal species, with levels of concentrations higher in manatee red blood cells (RBC) than plasma (Chapter 2). As the primary Zn metalloenzyme in erythrocytes is carbonic anhyd rase (CA) (Gardiner et al., 1984; Ohno et al., 1985) the identification of CA and kinematics will be evaluated in the Florida manatee Carbonic anhydrase was first reported by Meldrum and Roughton ( 1933 ) in bovine erythrocytes, with the discovery of zinc predominately in the metalloenzyme by Keilin and Mann (1940). Keilin and Mann (1940) also noted that pure CA in the ox and sheep contained 0.33% zinc and did not contain Fe, Cu, Mn, Mg or Pb, which was later confirmed by Hove et al. (1940). Carbonic an hydrase is the second most abundant protein, next to hemoglobin, in the red blood cell ( Armstrong et al., 1966; Keilin and Man n, 1940; Swenson, 2000). A pproximately 87% of Zn in human red blood cells is found in carbonic anhydrase (Ohno et al., 1985). More over, Zn is the central metal ion found in CA which is bound to three histidine ligands, with the versatile His 64 involved in proton transfer of water ( Lindskog, 1997; Silverman and Lindskog, 1988 ). Thus, one explanation for the high concentration of Zn in manatees is the possible physiological mechanism involving Zn in carbonic anhydrase Carbonic anhydrase is a ubiquitous enzyme that is involved in a number of physiological processes such as homeostasis of pH and CO 2 respiration and transport of CO 2 /HCO 3 in tissues, electrolyte secretion, and functions in gluconeogenesis,
164 lipogenesi s, and ureagenesis Carbonic anhydrase catalyzes the hydration/dehydration of CO 2 as shown below in [Eq 5 1] : CO 2 + H 2 O H + + HCO 3 (5 1) C arbonic anhydrase I and II are the most abundant isoforms in mammalian erythrocytes It has been shown that CA I has a slower turnover but with a greater quantity than CA II in the cytosol of erythrocytes (Maren et al. 1976; Swenson 2000) On the other hand, CA I I is a high activity enzyme (30 fold higher) and comprises only 11% of total CA activity in human red blood cells (Funakoshi and Deutsch, 1971). The amino acid sequences of CA are highly homologous across mammalian species, but the activity of CA can vary. Desp ite the large quantity of information on CA isozymes in mammals, much remains unknown in terms of red blood cell carbonic anhydrase kinetics in marine mammals. There have been very few studies on carbonic anhydrase in marine mammals, as this is the first study conducted on the kinetics of red blood cell CA in sirenians. Yang et al. (2000) examined CA I I activity in the high altitude llama ( Lama glama ) and deep diving, beluga whale ( Delphinapterus leucas) and found that the lack of CA I I in the beluga whal e may be an adaptation to hypoxic environments. In addition to the llama and beluga whale, the subterranean mole rat ( Spalax ehrenbergi ) also lacks CA I I (Yang et al., 1998), as well as primitive vertebrates, such as agnathans (lamprey, hagfish) and elasm obranch (dogfish; Maren et al., 1980). As some species do not have CA I I, some lack CA I without any adverse side effects. T he blue white dolphin, or striped dolphin, ( Stenella coeruleoalba ) was found to have only one high activity enzyme ( Shimizu and Ma tsura 1962 ). Moreover, sheep ( Ovis aries ), as well as
165 bovine and other ruminants, contain one high activity carbonic anhydrase in red blood cells (Tanis and Tashian, 1971), in addition to felines (cat, lion, jaguar, tiger, and leopard), ox, chicken and t he frog (Bernstein and Schrae r, 1972; Carter and Auton, 1975 ). As carbonic anhydrase has been purified and characterized in a number of animals it has yet to be evaluated in the Florida manatee. Thus, the objective of this study is to purify and identif y CA isozymes and assess CA activity in erythrocytes of the Florida manatee. Materials and Methods Blood Samples Health assessments were performed on manatees residing at Homosassa Springs Wildlife State Park in Homosassa, Florida from 2010 2011. Seven adult manatees (1 male, 6 females) were used in this study. Blood was collected from the medial interosseous space of the radius and ulna from minimally restrained manatees by a veterinarian or highly trained biologist. Blood was collected using an 18 g auge x 38.1mm needle and a 7m L royal blue top Monoject tube with K 2 EDTA. Blood samples were then put on ice while in the field and eventually stored in 80 0 C until analyzed. Hemo lysates were obtained by placing whole blood samples in a centrifuge and spinning tubes at 3,500 g for 10 minutes. Plasma and buffy coat were removed and red blood cells were washed three times with cold 0.9% sodium chloride solution Cold Millipore water was then added to the washed erythrocytes at a concentration of 1:1 and centrifuged at 2,000 g for 10 minutes. This allowed a separation of the membrane from cytosol Aliqu ots of hemolysate were obtained and placed in the 80 o C for future analysis.
166 Preliminary Quantification of CA Isozymes in Hemolysate In order to make a preliminary estimate of the presence of CA in the manatee hemolysate ; a Western Blot was performed usi ng a rabbit polyclonal IgG antibody (Santa Cruz Biotechnologies, Santa Cruz, CA) on diluted hemolysate. A comparison of CA II, the most active enzyme, t o other terrestrial species was completed in order to quantify abundance of reactivity to the antibody Blood in K 2 EDTA tubes was obtained from the Clinical Pathology department in the College of Veterinary Medicine at the University of Florida fro m vario us animal species in May, 2011 and hemolysates were prepared from the following animals: 5 equine, 1 caprid (goat), 4 feline, and 8 canines. Total protein was determined using Bio Rad Protein Assay at a 1:4 dilution (Life Science, Hercules, CA) and bovine serum albumin (BSA) standards. Samples were measured in duplicates and absorbance was measured at 595nm on the Spectramax 250 Monochromatic Spectrophotometer (Molecular Devices, Sunnyvale, CA). After total protein was determined in the hemolysates prote in was separated using 1 D sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). Min i PROTEAN Rad) and lab made gels were utilized and wet transferred to a polyvinylidene (PVDF) membrane (Immobilon P Transfer Membrane; Millipore, Billerica, MA) at 20 volts overnight. Ponceau red staining was completed to confirm transfer of protein prior to exposure to antibody. Membranes were probed with a 1:1,000 dilution of a primary antibody, rabbit polyclonal IgG Antibod y for CA II (Santa Cruz Biotechnologies, Santa Cruz, CA) for at least two hours, followed with an incubation of a secondary antibody, goat anti rabbit IgG (H+L) HRP (horseradish peroxidase) conjugate for 90 minutes. Enhanced chemiluminescent (ECL) detecti on
167 was used to visualize the immunoreactive proteins and quantified by densitometry using ImageJ 1.45 (National Institutes of Health). Inhibition of Ethoxzolamide In order to determine presence of CA in manatee hemolysates, the inhibition constants were d etermined from an aliquot of hemolysate. The inhibitor constant (Ki) for iodide binding was estimated using the slopes of two curves from the 18 O depletion method, with the Easson Steadman Plot confirming activity of two isozymes (Figure 5 1). This resul ted in a Ki of 0.7 0.1nM for isozyme I and 30 10nM for isozyme II found in hemolysate. This confirmed the presence of two CA isozymes. In addition, i nhibition titration with ethoxzolamide (EZA) and the 18 O exchange method by Silverman (1973) was used to determine inhibition constants for purified isozyme I and II The inhibitor constant (Ki) for EZA binding was estimated using the slopes of two curves from the 18 O depletion method, with the Easson Steadman p lot confirming activity of two isozymes (Figure 5 1 ). The Ki for isozyme I was 0.04 nM and 0.2 nM for isozyme II. The intercept of the slope gave a value of 47 0.9 nM activity for isozyme I and 12 0.2nM for isozyme II. CA Purification Hemolysates were then used to isolate and purify CA isozymes. Aff inity chromatography was performed following revised p roc edures for purification of erythrocyte CA by Khalifah et al. (1977) and Silverman et al. (1978 ). An affinity gel containing p aminomethy lbenzenesulfonamide attached to agarose beads (Sigma Aldrich, St. Louis, MO ) was washed ten times with wash I (0.2 M Na 2 S O 4 0.1 M Tris Base, pH 9) to remove any azide residue Manatee lysates were pooled (~40 mL) and mixed with 3 mL of affinity gel stirring at 4 o C for 2 3 hours. The affinity
168 gel/buffer/manatee hem olysate suspension was then filtered and washed approximately 20 times with 20 mL of Wash II (0.1 M Tris, 0.2 M sodium sulfate, pH 8.7) in order to eliminate non specific proteins, such as hemoglobin. Wash III (0.1 M Tris, 0.2 M sodium sulfate, pH 7) was then used approximately 11 times to ensure removal of any non specific proteins. The CA I bound to the resin was then eluted with a Kl buffer (0.1 M Tris sulfate, 0.4 M potassium iodide, pH 7) which binds tightly to isozyme I (Figure 5 2A) while NaN 3 (0. 4M) was used to separate isozyme II (Figure 5 2B ). The collected fractions based on the A 280 were pooled and concentrated into an Amicon Ultrafiltration Unit ( 10,000 NMWL; Millipore, Billerica, MA) and stored at 4 o C. Purified isozyme I and isozyme II wer e assayed for catalytic activity via the 18 O exchange method and purity was assessed using SDS PAGE and isoelectrofocusing (IEF) with 2D gel electrophoresis. C arbonic A nhydrase Kinetics 18 O Exchange Method The 18 O exchange method by Silverman ( 1973) was used to determine the presence and concentration of manatee isozyme I and II in erythrocytes. The 18 0 exchange method utilizes mass spectrometry by measuring the depletion of oxygen 18 labeled CO 2 catalyzed by CA and hydration to an unlabelled CO 2 and w ater This metho d described in Silverman (1982), measures the atom fraction of 18 O in CO 2 by membrane inlet mass spectrometry (Extrel EXM 200), where CO 2 passes through a silicon rubber membrane and into the mass spectrometer. Solutions had a total concen tration of 25 mM for all CO 2 species and the ionic strength of the solution was maintained with 0.2M Na 2 SO 4 In the first step of catalysis, the dehydration of labeled bicarbonate has a third of a probability to label the active site with 18 O [Eq 5 2]
169 H2O HCOO 18 O +EZnH 2 O EZnHCOO 18 O COO+EZnO 18 O H (5 2 ) The Zn bound 18 O labeled hydroxide then releases H 2 18 O to the solvent. The labeled water is then diluted by H 2 16 O. The o xygen 18 exchange was used to determine k cat /K M fo r hydration of CO 2 as a result of the interconversion of CO 2 and HCO 3 The first order rate of depletion of oxygen 18 results in k cat /K M for dehydration and hydration and a pKa from the logKa This is a pH dependent step based on the ionization of the Zn bound water. The rate of exchange of CO 2 and HCO 3 at chemical equilibrium equals R 1 [ Eq. 5 3 ] R 1 /[E] = k cat [S]/(K m + [S]) ( 5 3) Where k cat /K M is the rate constant for the conversion of substrate into product, and [S] is the substrate co ncentration of carbon dioxide or bicarbonate. The ratio of k cat /K M measured in this method is the same, in principle, as measured at steady state. EZn 18 OH +BH EZnH 2 18 O+B EZnH 2 O+H 2 18 O+B ( 5 4 ) Equation 5 4 measured the rate of release from the enzyme of H 2 18 O and proton transfer resulting in the rate constant R H2O /[E]. Although this rate constant has been interpreted, its pH profile in catalysis by manatee CA I and CA I I were irregular and could not be interpreted in a straightforward manner (data not shown). C arbonic A nhydrase Purity Assessment Two D SDS PAGE with isoelectrical focusing (IEF) was used to assess the purity of the CA isozymes that were obtained. The purified sample was cleaned using a GE Healthcare 2D Clean up Kit (Piscataway, NJ) fol lowing protocol from GE Healthcare. Briefly, 15 L of purified isozyme I and isozyme II were used with 45 L) was
170 then placed in each sample, vortexed and centrifuged for 20 minutes at 4 o C at 12,000 L) was again added and centrifuged for an additional five minutes. Deionized water (40 mL) was then added and pellet was resuspended in a Rehydration Solution and incubated overnight. T he Ready Prep 2D Starter Kit (Biorad) and 7cm Immobiline with a pH 6 11 (GE Healthcare) dry strips were used for isoelectric focusing and run overnight. The conditioning step began with 250V for 1 hour at 19 o C, with a ramping of 250 3500V for 3 hours at 19 o C, then an initial focusing at 3500V for 3 hours at 19 o C, a second ramp of 3500 5000V for 2 hours at 19 o C and a final focusing period of 5,000V for 15 hours at 19 o C. NuPAGE 4 12% Bis Tris imension and run at 125V for one hour. Gels were stained with SYPRO Ruby Protein Gel Stain ( Invitrogen ) to identify the bands of interest (Figure 5 3). The gel band with the appropriate size of the pr otein of interest was cut and submitted to the the In terdisciplinary Center for Biotechnology Research (ICBR) Proteomics Core at the University of Florida for Liquid Chromatography tandem mass spectrometry (LC MS/MS). The gel band was trypsin digested and run on a LC MS/MS. LC MS/MS analysis was completed o n a hybrid quadrupole TOF mass spectrometer, QSTAR XL MS (Applied Biosystems, Foster City, CA). A scan was completed from m/z 400 to 1500 (1 sec) then a MS/MS (3 sec) with the two highest signal intensity ions. The focusing potential voltage was 275V and the ion spray voltage was set at 2600V, as the ions traveled through the first quadrapole then transitioned to the time of flight region using the two quadrapole filters. As ions traveled through the flight tube, they were refocused
171 to a four anode micro channel plate detector from an ion mirror at 990V. The second quadrapole filtered the ion of interest and the third quadrapole was the collision cell. The collision gas used in this analysis was nitrogen and optimization was based on the rolling collisio n energy from the m/z and the charges of the peptide ion. Database Analysis Data from the LC MS/MS were acquired using Analyst version 1.1 and analyzed using MASCOT (Matrix Science, London, UK; version 2.2.0). The Mammalia n database in the National Cente r for Biotechnology Information (NCBI) (07/29/2011; 886,547 entries) was used. MASCOT searched for a fragment ion tolerance of 0.50 Da and parent ion tolerance of 0.50 Da. The fixed modification was Iodoacetamide, a derivative of cysteine. Variable modi fications included S carbamoylmethylcysteine cyclization (N terminus) of the N terminus, deamination of asparagines, and glutamate and oxidation of methionine. These variable modifications were set to recognize non labeled or inefficiently labeled cystein e peptide product. Protein identificatio n was confirmed using Scaffold version 3.2.0 ( Proteome Software Inc., Portland, OR) and peptides were accepted if identifications were >95% probability as stated in the Peptide Prophet algorithm (Keller et al. 2002) with at least two identified peptides. Protein identifications were accepted if >99% probability based on Nesvizhskii (2003) and had at least 2 identified peptides. Similar peptides that could not be distinguished by MS/MS were then grouped together due to principles of parsimony. Results Preliminary Quantification Prelim in ary investigation using manufactured primary and secondary antibodies on w estern blots was used to determine CA isozyme II in the Florida manatee erythrocytes
172 As shown in Figure 5 4 manatee hemolysate successfully bound to the primary antibody for CA I I In order to semi quantify the amount of CA I I in manatee hemolysate, density of reactivity to CA I I antibody was measured comparing various animal species. CA I was not measured du e to the fact that activity of CA I I is much higher and would be the significant use of Zn than CA I in the Florida manatee. Density was measured using Image J and resulted in the following density from loading of 20ng of protein: 17,157 for manatee, 36,0 23 for feline, 5,182 for equine, 963 for caprid (goat), 16,422 for canine, 15,616 for manatee, 46,568 for bovine standard of 1mg/mL, 42,540 for 0.75 mg/mL bovine standard, and 15,422 for 0.25 mg/mL bovine standard (Figure 5 4) Catalytic Activity The pH pr ofiles for k cat /K m for the hydration of CO 2 catalyzed by isozyme I and isozyme II in the Florida manatee was completed This rate constant describes the catalyzed hydration of CO 2 and depends on the reaction of this substrate with zinc bound hydroxide and the ionization state of the Zn bound water to form the Zn bound hydroxide (Silverman and Lindskog 1988). For isozyme I, t he k cat /K m pH profile range of 5 9 for CO 2 hydration was determined by the 18 O exchange and was best fit b y two ionizations with pKa = 70.1 and 5 0.5 with a maximum k cat /K m of 3 x10 7 (Figure 5 5A) On the other hand, catalysis by isozyme II could be f it to a single ionization of 6 0.1 with a maximum k cat /K m of 6 x10 7 M 1 s 1 (Figure 5 5B ). Manatee Carbonic Anhydrase I and II Identific ation The purified isozyme I and II were confirmed to be CA I and II. The purified isozyme I submitted to ICBR identified two unique peptides and three unique spectra, with a total of 13 spectra (Figure 5 6). Analysis with >99% protein identification
173 pro bability, at least two peptides and >95% peptide identification probability resulted in 16% identity (41/261 amino acids) with Canis lupus familiaris carbonic anhydrase I (gi 223556021; 28,995 Da; Figure 5 7). Purified isozyme II run on LC MS/MS found thr ee unique peptides and three unique spectra, with a total of 12 spectra (Figure 5 8). There was 17% identity (44/260 amino acids) with Canis lupus familiaris carbonic anhydrase II (gi 223556021; 28,995 Da; Figure 5 9). Therefore, two isozymes of CA were s ucc essfully identified in Florida manatee erythrocytes. Discussion Two isozymes of CA in the Florida manatee have been identified Unlike other marine mammal species, such as the beluga whale with only CA I (Yang et al., 2000) and striped dolphin with onl y CA II ( Shimizu and Matsura 1962 ), the Florida manatee appears to have CA I and II. The Florida manatees meters and restrict their diving behavior to shallow waters (Reynolds 1981; Lefebvre et al. 2000) As a result, manatees have close access to the surface and are not conditioned to hypoxic conditions seen in many deep div ing cetaceans w hich may alter the need for CA Deep diving marine mammals may hav e adapted to other mechanisms co mpensating for the lack of CA I or II. For instance, in the CA I I deficient mole rats, Yang et al. (1998) found unique selenium binding prote in (SeBP) and low levels of Se (46 g/L) to account for the lack of CA I I. This is quite interesting, as the lack of CA I has no deleterious effects on humans, whereas CA I I deficiencies can cause osteoporosis, renal tubular acidosis, and mental retardation emphasizing the importance of CA in genetics, bone resorption, and kidney and brain function (review by Sly and Hu, 1995). There are currently 14 CA isozymes in mammals, all with a
174 specific function (Chegwidden and Carter, 2000), with manatees having at least two, CA I and II. We observed that k cat /K m for catalysis by CA I was fit by two ionizations (Figure 5 5A). This is unique in normal CA found in mammals and has been seen in CA of plants and mutant CA. Johansson and Forsman (1993) examined C A in peas ( Pissium sativum ) and found CA activity ( k cat /K m ) did not follow a simple titration curve with increased pH. This difference in manatees may be due to more than one ionizable group in the active site which can affect the pK a of the active groups involved in catalysis. Therefore, this second ionization may be due to the ionization of another residue in the active site cavity which may be unique to manatees This additi onal side chain may affect the catalytic active groups of CA I in manatees all owing for a pka at a pH of 5, possibly to adapt to hypoxic conditions or is a residual product of evolution in manatees. Moreover, t here has been evidence of species differences in CA structure, with horse CA only containing two His residues, as opposed t o three in human CA I (Forsman et al., 1983). As a result, additional studies on the structure of manatee CA isozyme I will help clarify the double ionization that affe cts k cat /K m T he activity of manatee CA, based on k cat /K m is compared to other mammali an species in Table 5 2 The ratio of k cat /K m is b e or the manatee k cat /K m is similar to other mammals and is found in between human (HCA) and rat erythrocytes for both isozymes. Accordi ng to the results of manatee CA isozyme II, where CA I I is the most efficient 2 was slower than humans, but faster than the
175 Manatee isozyme II was less inhibited by ethoxzolamide concentrat i on as shown with a Ki of 0.2 nM compared to isozyme I of 0.04 nM which bound more tightly to EZA In addition, EZA inhibited manatee CA more strongly than other animal species (Table 5 2). These sulfonamide inhibitors such as ethoxzolamide bind to the Zn at the active site. This sensitivity to EZA may be due to the structure of manatee CA as suggested in the increased sensitivity to inhibitors in f emale rats compared to male rat s (Garg, 1974). Again, this emphasizes the need to examine the structure of m anatee CA. Significance and Future Studies This is the first study of CA in sirenians. In addition to manatee CA kinetics, quantitative measurements on the amount of CA I and CA I I should be made in the Florida manatee to further understand its function in erythrocytes. With our preliminary results of calculating density of CA II in various species (Figure 5 4), reactivity to the primary antibody can vary between species. The antibody used in this study was a rabbit polyclonal IgG primary antibody with recommended detection to mouse, rat, human, equine, canine, and bovine. This may be the reason for such low reactivity in the caprid rather than illustrating a quantitative amount of CA II In addition to the Florida manatee, we can examine a number of other marine mammal species in order to compare catalytic properties across marine mammals. A study of the structure of the Florida manatee CA enzyme using X ray crystallography is in progress with Dr. T his will help us to understand the structure of manatee CA, which can, in turn, help explain its catalytic activity and sensitivity to inhibitors. Moreover with a combination of kinetics, sequence knowledge, and structure, we can determine the homology a cross marine mammal species.
176 Figure 5 1. Inhibition by iodide of CA in manatee hemolysate measured by the 18 O exchange method confirmed the presence of two isozymes The Ki was 0.7 0.1 nM for isozyme I and 30 10 nM for isozyme II. *Graph provided by D r. Tu.
177 A. B. Figure 5 2 Purification of CA from hemolysate of the Florida manatee. Hemoglobin elutions were completed with multiple buffers. A). The CA I bound to the resin in the affinity column was then eluted with Kl, while B). NaN 3 was used for el utions of CA I I with absorbance of 280
178 Table 5 1. Carbonic anhydrase activity c omparison. The maximal K cat /K m and Ki against ethoxzolamide (EZA) were compared with various vertebrates (mammals and non mammals). CA Type K cat /K m (M 1 s 1 ) K i (nM), EZA Ref erences Human I 5x10 7 2 Khalifah (1971), Sanyal et al. (1982) Rat I 0.04x10 7 Feldstein and Silverman (1984) Manatee I 3 x10 7 0.04 This study Human II 15x10 7 8 Khalifah (1971), LoGrasso et al. (1991) Rat II 2x10 7 Feldstein and Silverman (1984) Manat ee II 6 x10 7 0.2 This study Guinea Pig I/II 5.12.0 Dodgson and Forster (1983) Ferret I/II 1.70.5 Dodgson and Forster (1983) Cat II 0.60.1 Dodgson and Forster (1983) Dog I/II 7.1 Dodgson and Forster (1983) Horse I/II 1.1 Dodgson and Forster (198 3) Ox II 0.4 Dodgson and Forster (1983) Hagfish I -Sanyal et al. (1982) Dogfish I 10 Sanyal et al. (1982) Sheepshead II 2 Sanyal et al. (1982) Frog II 2 Sanyal et al. (1982) Chicken II 2 Sanyal et al. (1982)
179 A B F igure 5 3. Isoelectrical focusing with 2D gel electrophoresis for manatee CA A). Isozyme I B). Isozyme II Red boxes indicate where selection was made for CA to submit for LC MS/MS at 30 kDa *Overloading of protein presented less separation 50 kDa 50 kDa
180 Fi gure 5 4. Multiple species comparison in CA I I Multiple terrestrial species was compared to manatees at a concentration of 20 ng. Density was measured using Image J resulting from left to right, of 17,157 for manatee, 36,023 for feline, 5,182 for equine, 963 for caprid, 16,422 for canine, 15,616 for manatee, 46,568 for bovine standard of 1 mg/mL, 42,540 for 0.75 mg/mL bovine standard, and 15,422 for 0.25 mg/mL bovine standard.
181 A B Figure 5 5. The pH profile of k cat /K M (M 1 s 1 ) for the catalysis of the hydration of CO 2 determined by 18 O exchange method. Data were obtained at 25 o C with a concentration of 25 mM for [CO 2 ]+[HCO 3 ]. The total ionic strength of solution was maintained at 0.2 M using Na 2 SO 4 A) The dotted line shows a double ionization of isozyme I with a pKa = 5 0.5 and 7 0.1 with a maximum k cat /K M of 2 x10 7 The solid line represents the least squares fit to a single ionization with a pKa of 70.1 and maximum kcat/KM of 3 x10 7 M 1 s 1 B) A single ioni zation of isozyme II with a pKa of 60.1 and a maximum k cat /K M of 6 x10 7 M 1 s 1 was present.*Graphs provided by Dr. Tu
182 Figure 5 6. Purified isozyme I Spectrum. Phosphorylation sites of peptide fragments with the LC MS/MS. Identification resulted in two unique peptides and three unique spectra, with a total of 13 spectra. With a >95% peptide identification probability, one peptide sequence of isozyme I is shown with association of b and y ions.
183 Figure 5 7. Protein Identificaton. Manatee isozyme I wa s homologous to Canis lupus familiaris with >99% protein identification probability. The amino acids in yellow represent 16% coverage while the amino acids highlighted in green are those >95% confidence. This confirms that the isozyme I purified from the Florida manatee erythrocytes was carbonic anhydrase I
184 Figure 5 8. Purified isozyme II Spectrum. Phosphorylation sites of peptide fragments with the LC MS/MS. Identification resulted in three unique peptides and three unique spectra, with a total of 1 2 spectra. With a >95% peptide identification probability, one peptide sequence of isozyme II is shown with association of b and y ions.
185 Figure 5 9. Protein Identificaton. Manatee isozyme II was homologus to Canis lupus familiaris with >99% protein i dentification probability. The amino acids in yellow represent 16% coverage while the amino acids highlighted in green are those >95% confidence. This confirms that the isozyme II purified from the Florida manatee erythrocytes was carbonic anhydrase II
186 C HAPTER 6 IDENTIFICATION AND INDUCTION OF METALLOTHIONEIN IN THE WEST INDIAN MANATEE ( Trichechus m anatus ): POTENTIAL BIOMARKER FOR METAL CONTAMINATION Background Zinc levels in the blood of the Florida manatee are much higher than in most mammals (Chapter s 2 and 3) Zinc is essential for a number of physiological and metabolic functions, including protein structure and gene transcription (Vallee 1983 ). H owever, high levels of zinc can also cause toxicity. Because manatees appear to maintain zinc at thes e levels, it is of interest to investigate as to how they accomplish this without injury. One possible mechanism is homeostatic control by me tallothionein Mammalian metallothionein (MT) was first discovered in an equine kidney by Margoshes and Vallee in 1957. MT is a heat stable protein with a low molecular weight (6,000 7,000 Da), high cysteine content (~20 cysteines), and no aromatic amino acids (Cousins, 1983; Hamer, 1986 ; Kgi et al., 1984; Kgi and Schffer 1988; Palmiter, 1998). In mammals, ther e are four isoforms: MT 1 4. MT 1 and MT 2 have a number of different isoforms and are expressed in most organs, MT3 is predominately found in the brain and MT 4 is found in the stratified squamous epithelium, such as skin (Quaife et al., 1994; review by A variety of functions have b een proposed for MT, including metal homeostasis and detoxification. MTs have been suggested to play a role in zinc and copper metabolism, while maintaining homeostasis for these essential metals. In addition, it has been shown that MT is a detoxification mechanism for non essential metals, such as Cd (Bremner and Beattie, 1990 ; Klaassen et al., 1999 ; Vallee, 1995; Webb, 1987 ). In regards to Zn, MT may be a storage or transport protein in order to maintain
187 homeostasis ( Hamer, 1986; Otvos and Armitag e, 1980 ). Thus, MT may be a key intracellular protein for controlling Zn uptake, distribution, storage 2005). Moreover, under normal physiological conditions, Zn is favored to bind to MT for various structural, catalytic, or regulatory functions (Cousins, 1996; Maret, 2000 ). Thus, the role of MT may be vital to control Zn levels in manatees. Metal binding can occur in a variety of ways in metallothionein. Metals bind to th e thiol group ( SH) of the cysteine residues, with the metal binding affinities an d formation depende nt on the metal ion present. MT can be bound to a number of metal ions, including Cd 2+ Hg 2+ and Cu + as the metal bound to MT varies between individuals and tissues, but it is tightly bound mainly to Zn 2+ (Bell and Vallee, 2009; Duncan et al., 2006; Maret, 2000 ). Moreover, due to the chemistry of the thiol group, many metals may be bound to MT at once, with up to 7 divalent metals or 12 monovalent metal atoms. MT has two subunits: a stable domain (C terminal), which attaches to 4 divalent metal atoms and the reactive domain (N terminal), which binds to 3 metal atoms. Exchange of metals between the two domains and between other MTs may occur depending on the metal ( Amiard et al., 2006; H euchel et al. 1994; Kgi and Kojima, 1987; Kgi and Schffer 1988; Nielson and Winge, 1985; Robbins et al., 1991; Roesijadi, 1996 ), thus, making MT a somewhat elusive metalloprotein with a number of possible functions. Transcription of MT can be induced by a number of biological and physiological factors, including metal exposure. Metal regulated MT gene e xpression is dependent on metal response element transcription factors (MTF1) and metal response elements (MREs). These transcription factors are fou nd on the promoter region of the gene and respond to changes in cellular metal concentrations of Cd and Zn (Andersen et al.,
188 1987; Resijadi, 1994; Smirnova et al., 2000 ; Thiele, 1992 ). The MREs on the promoter consist of a 12 bp sequence which are also re gulated by Zn (review by Giedroc et al., 2001), thus, emphasizing the important role Zn plays in the functioning of metallothionein and other genes Metallothionein has been characterized in many marine mammal species. Das et al. (2002) successfully chara cterized two isoforms of MT in the white sided dolphins ( Lagenorhynchus acutus ): MT I and MT II. Additional studies have been performed in the California sea lion ( Zalophus californianus ), sperm whale ( Physeter macrocephalus Ridlington et al., 1981) bottl enose ( Tursiops truncates ) and stripped ( Stenella coeruleoalba ) dolphins (Decataldo et al., 2004), and harbor seals ( Phoca vitulina Tohyama et al., 1986). However, metallothionein has not yet been identified in a sirenian. It is quite difficult to expe rimentally determine the physiological responses of manatees to contaminant exposure due to restrictive regulations on marine mammals and their large size. In addition there are currently no manatee cell lines and it is nearly impossible to obtain fresh liver tissue from which viable RNA hepatocytes may be isolated, so another cell type was necessary to study the effect of metals on MT expression. It has been shown that in vitro metal exposures of immune cells can be useful to elucidate the response of M T. Studies have found that Cd and Zn can induce MT in cells; however, Pb and Cu cannot ( Mesna et al., 1990 ; Peavy and Fairchild, 1987; Yamada and Koizumi, 1991). Yamada and Koizumi (1991) found Zn to be the strongest inducer of MT in human lymphocytes, wi th a maximal induction after 16 hours at 200 M Zn, resulting in a 9.5 fold increase when compared to other metals. In addition to lymphocytes, monocytes are also good sources of MT expression (Mesna et al., 1995).
18 9 In a study by Pillet et al. (2002), MT 1 and 2 was induced in leukocytes of grey se als ( Haliochoerus grypus ) exposed to CdCl 2 and ZnCl 2 As a result of these studies and additional studies ( Pauwels et al., 1994 ; Sullivan et al., 1998 ), peripheral blood mononuclear cells (granulocytes, monocytes and lymphocytes) isolated from manatees we re used to identify MT 1 and study the regulation of metallothioneins by metal exposure. The first objective of this study is to clone and sequence metallothionein in the Florida manatee from peripherial blood mononuclear cells ( PBMC ) Metallothionein i s a highly conserved gene across mammalian species ( Kgi et al., 1984 ), thus, we predict that the Florida manatee MT will be similar to other mammalian species. Moreover, in order to determine the immunotoxic effects and transcriptional response of MT to metals in manatees, PBMCs, or leukocytes, will be isolated and exposed to metals in order to determine a dose and time response curve. Leukocytes are accessible in manatees through blood and contain nuclei which will allow for induction of MT at the leve l of transcription. We hypothesize that MT will be induced with in vitro exposure of CdCl 2 and ZnCl 2 in the Florida manatee. Metallothionein has been used an as effective biomarker through its specificity and ability to bind to metal ions and has been use d as a biomarker in a number of aquatic animal species, including the yellow catfish ( Pelteobagrus fulvidraco ; Kim et al., 2012), loggerhead ( Caretta caretta ) and green ( Chelonia mydas ) turtles (Andreani et al., 2008), and mussels ( Mytilus edulis ; Soazig a nd Marc, 2003), just to name a few. Skin samples have recently been measured for trace metal concentrations in wild bottlenose dolphin ( Tursiops truncates ; Bryan et al., 2007 and Stavros et al., 2007 ; 2011 ) and Florida
190 manatees (Stavros et al., 2008 a ) in the Florida region. Skin samples are routinely obtained for genetic purposes in wild manatees by United States Geological Survey (USGS) Sirenia Project, so fresh samples are accessible from live individuals for RNA isolation. Therefore, the third objectiv e of this study is to express MT 4 in three populations of manatees in Florida and Belize using skin samples obtained from routine health assessment procedures. Utilizing MT 4 as a biomarker, we hypothesize that manatees residing in areas with greatest an thropogenic influences ( i.e. Citrus County, Florida) will have increased metal exposure, thus, they will have increased induction of MT 4 This will be the first study to characterize MT in the Florida manatee and will help to understand the role metallot hionein plays in sirenians physiology Materials and Methods Manatee L eukocytes Manatee health assessments were completed in 2008 2011 in Kings Bay, Crystal River, Florida, under the supervision of the USGS Sirenia P roject. B lood was obtained from the med ial interosseous space between the radius and ulna fro m minimally restrained manatees by a veterina rian or highly trained biologist and placed in a sodium heparin vacutainer tube. Blood samples were then put on ice while in the field and stored in 4 0 C on ce in the laboratory. Whole blood was collected from 26 manatees and PBMC were isolated using the Ficoll gradient method revised from De Swart et al. (1993) and Pi llet et al. ( 2000; 2002) within 8 hours of collection. Briefly, PBMC were isolated from wh ole blood which was diluted in RPMI 1640 medium (diluted 1:4 ) with 10 IU/mL hepar in and then placed on a Ficoll P aque density gradient. Leukocytes were separated via centrifugation for 45
191 minutes in 20 o C at 400 g. Cells were washed with additional RPMI 1640 and resuspended in 5mL of RPMI 1640. Cell Culture An aliquot of t he cells were dyed with t rypa n b lue to determine viability and counted to make certain of a greater than 90% survival. For cell culture, leukocytes were seeded into 3.8 cm 2 12 well cu lture plates (BD Falcon BD BioSciences, Bedford, MA) at an average of 1x10 5 cells/well in 1mL media solution. The media solution contained 500 L of growth media (20 mL 40% FBS, 1 mL ABAM, and 29 mL RPMI 1640) and ~50 100 L of RPMI 1640. A time response curve was performed from three individuals (CCR 1108, 1109, and 1110) using 2x10 9 M CdCl 2 and 2x0 5 M ZnCl 2 at time 4, 12, 24, and 48 hours incub ated in 37 o C. Controls without any exposure to metals were present at each time point (Figure 6 1A). Four manatees from 2011 health assessments (CCR 1106, 1107, 1111, and 1112) were used for the dose response curve. The dose response curve was created exposing cells to ZnCl 2 from 2x10 7 M to 2x 10 3 M, as well as a dose response curve for CdCl 2 from 2x 10 11 M to 2x 10 7 M exposures. Cells with no exposure to metals were present as a control and cells were incubated at 37 o C for 24 hours (Figure 6 1B) Cells w ere harvested at each time point by removing the culture media and centrifuged cells at 10,000 g for 5 minutes The supernatant was removed and 1mL of TRIzol was added to cells and stored in 4 o C for total RNA isolation. In order to determine viability of cells, a duplicate plate with each treatment group was used with alamarBlue (Invitrogen) assay at each time point. The cells were incubated for 1 4 hours and absorbance was measured at 570nm. Absorbance of
192 treatment cells were then divided over absor bance of control cells and subtracted from 1 and multiplied by 100 in order to determine the percent reduced in cells and assess viability (Figure 6 2). This was verification that the cells were still viable or not under treatment conditions. Manatee Skin Manatee health assessments were performed in two locations in Florida from 2008 2011: 1) King s Bay, Crystal River, Citrus County (28 o 53'28"N, 82 o 35'50"W) and 2) Indian River Lagoon, Brevard County (28 o 28'13"N, 80 o 45'48"W), under the authority of the US GS Sirenia Project and Florida Fish and Wildlife Commission. In addition to Florida, manatee health assessments were conducted in Belize City, Belize (16 0 0 in the summer of 2011 with collaborations from Sea to Shore Alliance USGS, and Belize Forestry Department Thirty one wild manatees were used in this study, with 14 samples from Citrus County (12 males, 1 females, 1 unknown), 13 samples from Brevard County (7 males, 5 females, 1 unknown), and four samples from Belize City (3 males, 1 female). Manatees were captured using a long net and brought to shore or loaded onto a boat, depending on capture location and proximity to land. Skin biopsies were obtained from the tail margin and a small thin piece of skin was placed in 10mL of RNA later (Applied Biosystems, Ambion, Carlsbad, California) in a Corning polypropylene conical tube (Fish er Scientific, Pittsburgh, PA). Samples were kept at room temperature for a minimum of 24 hours and then placed in the 80 o C until analysis. Skin sam ples in RNAlater were thawed at 4 o C prior to RNA isolation In order to isolate RNA, s kin was frozen in liquid nitrogen and pulverized in a stainless steel mortar and pestle.
193 RNA P urification and cDNA T otal RNA was isolated from PBMC and skin using the p henol/chloroform extraction method ( TRIzol Reagent, Invitrogen, Carlsbad, CA) following the TRIzol manual. Briefly, samples were incubated in TRIzol at 15 30 o C for 5 min Chloroform (0.2 mL) was then added, incubated at 15 30 o C fo r 2 3 min, then centri fuged at 12,000 g for 15 min at 2 8 o C. The supernatant was then placed in a fresh tube with 0.5 mL of isopropyl alcohol and incubated at 15 30 o C for 10 min Samples were then centrifuged at 12,000 g for 10 min at 2 8 o C. The pellet was then washed once wit h 1 mL of 75% e thanol, vortexed and centrifuged at 7,500 g for 5 min at 2 8 o C, then dr ied for approximately 10 min The pellet was reconstituted with 20 Resuspension Solution (Applied Biosystems/Ambion, Austin TX ) and RNA was measured using a NanoDrop 1000 Spectrophotometer (Thermo Fisher Scientific, Inc., Waltham, MA). To ensure DNA contamination was not present, RNA s amples were treate d with DNAse using the DNA free systems/Ambion, Austin, TX ). RNA samples were then converted to cDNA by RT PCR using MMLV reverse transcriptase (Promega Corporation, Madison, WI ) and following similar procedures from Doperalski et al. (20 11) RT PCR was performed to obtain cDNA synthesis using a minimum of 0.5 g total RNA. Total RNA was combined with 1 L of random hexamer (Promega Corporation, Madison, WI) and brought up to 10 L with nuclease free water. The RNA/primer solution was then heated to 70 o C for 5 min and then immediately placed on ice. S amples we re then mixed with 5 L MMLV 5x reaction buffer, 5 L dNTP mix (10 mM), 0.2 L of RNAsin (40 U/ L), and 1 L of MMLV RT (200
194 U/ L) and heated at 37 o C for one hour (Reagents from Promega). The cDNA product was stored at 20 o C. MT 1 : Cloning and S equence D e termination In order to design primers for manatee MT (TmMT) a 183 bp partial sequence of bowhead whale ( Balaena mysticetus ) metallothionein from the National Center for Biotechnology Information (NCBI) Nucleotide D atabase (GenBank AF022117.1, GI: 2462852 Accession #AF022117) was used as a template. A forward primer and degenerate reverse primer were selected using Primer 3 (Rozen and Skaletsky, 2000) and conserved MT sequences of the bowhead whale and additional mammalian species (Table 6 1). Cloning an d sequencing procedure were similar to Doperalski et al. (2011). PCR was performed with 100 ng TmMT cDNA template, 2.5 L 10xPCR buffer, 0.5 L dNTP (10 mM), 0.5 L forward primer (10 M), 0.5 L reverse primer (10 M), and 0.2 L Taq DNA polymerase (1 U/ L) (Life Technologi es Corporation/Invitrogen). Thermocycling parameters were set to : 94 o C for 3 min, 35 cycles of 94 o C for 30sec, 50 65 o C for 30 sec (in the case of Tm MT 1 56.2 o C ) and 72 o C for one min with a final extension at 72 o C for 7 min. Amplificat ion products were then run on a 2% agarose gel with 1 ug/mL of ethidium bromide at 1 00V for approximately 45 min Products with a correct length of approximately 150 bp were then ligated into the pGEM T Easy plasmid vector (Promega Corporation) and trans formed into One Shot TOP10 chemically competent Escherichia coli (Invitrogen) cells Plasmids were then isolated using the PureYield Plasmid Miniprep Kit (Invitrogen) and samples were submitted for Sanger sequencing at
195 the Interdisciplinary Center for Biotechnology Research (ICBR) at the University of Florida. Tm MT 1 Three additional MT nucleic acid sequence. Upstream primers were designed using Primer 3 (Rozen and Skaletsky, 2000) from the partial 153 bp sequence results from the submitted Sanger sequencing from the first cloning procedures of TmMT (Table 6 1). The FirstChoice RLM RACE kit (Ambion) was used following the protocol from Ambion and Doperalski et al. (2011) B riefly, 1 g of total RNA was mixed with 2 L 10x RT Buffer, 3 L dNTP (2.5 mM) mix, 2 L RNase Inhibitor (10 U/ L), 1 L M MLV RT, and 9.25 L nuclease free water. First strand synthesis was run for one hour at 42 o C. RACE PCR forward primers were designed from cloned MT RACE Outer primer as provided in the kit. PCR was again performed using similar parameters as above and the PCR product was then ligated and transformed. Using a p GEM T Easy Vector the sequence was extended Manatee MT 1 was aligned using Clustal W2 with a number of species from NCBI: 389 bp Rattus norvegicus MT 1A ( NM_138826 ), 398 bp Pan troglodytes MT 1E ( NM_001252596 ), and 183bp Balaena mysticetus MT (AF022117) as shown in Figure 6 3. We also used BLAST to confirm our gene of interest. Tm MT 4: Cloning and S equencing Methods were similar to MT 1 cloning and sequencing as mentioned previously. T otal RNA was isolated from wild manatee skin by phenol chloroform extraction
196 ( TRIzol Reagent, Invitrogen Corporation, Carlsbad, CA) and resuspended in RNAsecure Resuspension Solution (Life Technologies Corporation/Ambion, A ustin, TX). RNA was purified and cleaned to remove any DNA contamination. Samples were m easured for nucleic acid concentration and purity by a spectrophotometer (NanoDrop ND 1000, Thermo Fisher Scien tific, Inc ). First strand cDNA synthesis was performed using 1 g of total RNA and degenerate primers (Table 6 1). A partial 182 bp manatee MT 4 (Tm MT 4 ) sequence was obtained. Sequences of MT 4 were obtained from various species using the NCBI Nucleotide database and aligned using Clustal W2 (Figure 6 4) to confirm our gene of interest : 294 bp Macaca mulatta MT 4 (XM_001096721, p redicted), 294 bp Pan troglodytes MT 4 (XM_001137744, predicted) and 294 bp Homo sapiens MT 4 (NM_032935). Sequences were also confirmed using BLAST. RACE was not performed on MT 4 as our primary objective was to use MT 4 as a biomarker for metal exposu re and an elongated sequence was not needed for quantification purposes using qPCR. H ousekeeping G ene A standard control is needed for qPCR in order to correct for any variations, thus the reference gene used in this st udy was 18s ribosomal RNA ( rn18s ) The primers used for rn18s were from a largemouth bass ( Micropterus salmoides ) with sequence from Blum et al. (2008) as shown in Table 6 1 We obtained a fresh liver from a euthanized manatee (LPZ 102654, December 5, 2008) and isolated total RNA from sim ilar procedures as above. We cloned and sequenced for the housekeeping gene and found the sequence to be highly conserved (Figure 6 5) The rn18s sequence used for largemouth bass was the same as that found in the liver of the Florida manatee, thus,
197 prime rs from Blum et al. (2008) were used in this study to detect the housekeeping gene. Average efficiency SEM for rn18s of MT 1 standard curves was 111.25.5 with a r 2 of 0.990.01 and a slope of 3.090.11, while the average efficiency SEM for rn18s o f MT 4 was 132.776.6 with a r 2 of 0.990.01, and a slope of 2.740.14. Real time PCR of MT E xpression In order to quantify the amount of MT transcript copy number in each treatment of leukocytes, real time PCR (qPCR) was utilized using the Bio Rad My iQ Single Color Real Time PCR Detection System. The quantification of MT transcript copy number was determined using an absolute standard curve made from s erial dilutio ns of pGEM T Easy plasmids of MT 1 MT 4, and rn18s Expression of MT and rn 18s was measured in duplicate using the following protocol in a 96 well plate (Doperalski et al., 2011) : 5 L cDNA or plasmid standard or no template control (NTC) of water with 0.5 L forward and reverse qPCR primers (10 mM), 6.5 L nuclease free water and 12.5 L of Absolute SYBR Green Fluorescein (Thermo Scientific, Pittsburgh, PA). Real time PCR primers we re designed using Primer 3 (Rozen and Skaletsky, 2000) from the MT 1 and the partial MT 4 sequence (Table 6 1). Real time PCR thermocycling parame ters began with a denaturation at 95 o C for 3 min, 40 cycles of 10 sec at 95 o C, then 60 sec at 64 o C, with a final melting curve at 55 95 o C. Data was analyzed using the iQ 5 Optical System Software (v ersion 2.1, Bio Rad). The standard curves were evaluated to ensure proper calculations of our data, as well as making sure the threshold values were placed in the area of logarithmic amplification. Moreover, the melting curve was used to validate the PCR product of interest in each assay. MT values were norma lized to rn18s (MT/rn18s) using the starting quantity
198 mean The delta delta CT method (PE Applied Biosystems, Perkin Elmer, Forster City, CA) was used to determine a fold change for each treatment utilizing the mean CT (cycle threshold) for your gene of i nterest, housekeeping gene and control. The difference of the mean CT for MT from rn18s was calculated for each treatment and subtracted from the mean control CT. The exponential fold change was dete rmined from the control, which was 0 resulting in the relative quantification Average efficiency SEM for the MT 1 standard curv es for all runs was 105.77.9 with a r 2 of 0.990.001, and a slope of 3.210.18. For MT 4 the ave rage efficiency SEM was 106.75.3 a r 2 of 0.9950.002, and a slope of 3.19 0.012. Statistical Analysis Statistical Analysis was performed using S igmaPlot version 11 (Systat Software Inc., San Jose, CA, 95110). TmMT absolute copy number was presented as meanSEM for each treatment group a nd location. A Kruskal Wallis one wa y analysis of variance on r anks was used to determine a significant difference (p<0.05) between treatment groups for Tm MT 1 metal exposures and location differences with Tm MT 4 expression. A Pearson Product Moment Correlation (CCR, CBC) and a Spearman Ran k Order Correlation (BZ) was run to determine a relationship between Cu, Zn, As, and Cd in blood and Cu, Zn, and As in skin from values in Chapters 2 and 3 with Tm MT 4 induction for each animal in this study. Results Tm MT 1 A 381 bp sequence representin g MT 1 was cloned from peripheral blood leukocytes of Florida manatee (Tm MT 1 ) The sequence was confirmed to be MT 1 based on identity with previously identified MT 1 sequences and aligned with Clustal W2
199 (Figure 6 3). I t was 84% identical to predicted Pan troglodytes MT 1 X (E value 2e 95, XM_003339281.1 ), 83% identical to Homo sapiens MT 1 X (E value 6e 95, BC032338.1 ), and 82% to Homo sapiens MT 1 A (E value = 2e 89 NM_005946.2 ) and 80% predicted Maca ca mulatta MT 1 E (E value = 1e 79, XM_001088023.2 ) This sequence will be submitted into the NCBI database for assignment of an accession number. Induction of metallothionein was measured in leukocytes using absolute copy number normalized to 18s in real time PCR. MT 1 was induced by cultured manatee leukocytes with exposure to CdCl 2 and ZnCl 2 When utilizing relative quantification m aximal induction of CdCl 2 was observed at 24 hours with a transcript abundance of (6.58 4.54)x10 6 copies. Under these conditions, steady state MT 1 message levels increased by 7 fold change from control (Figure 6 6A) Manatee PBMCs responded to exposures of CdCl 2 within 24 hours at an exposure as low as 2x10 11 M concentration resulting in maximal Tm MT 1 expression of (4.61092.8505)x10 4 starting quantity and a 3 fold increase from control (Figure 6 7A). Induction of Tm MT 1 began decreasing with increasing exposure, with a 1 fold change from control when exposed to 2x10 10 M with no change in expression of Tm MT 1 with higher doses of CdCl 2 The time response of ZnCl 2 induction of Tm MT 1 in manatee PBMCs was similar to CdCl 2 exposures. Maximal induction by Zn Cl 2 using relative quantification, resulted in a steady state Tm MT 1 message level increasing by a 13 fold change from control (Figure 6 6B) Manatee PBMCs responded to exposures of Zn Cl 2 within 24 hours at an exp osure of 2x10 4 M concentration This resulted in maximal Tm MT 1 expression of 9.8510 3 copies and a 6 fold increase from control (Figure 6 7B).
200 Tm MT 4 We successfully cloned and sequenced a partial sequence (182 bp) of Trichechus manatus MT 4 (Tm MT 4 ) Using BLAST, our sequence was 91% identical to predicted Loxodonta a fricana MT 4 like (E value = 8e 64, XM_003416304.1 ) 88% identical to predicted Macaca mulatta MT 4 (E value = 3e 57, XM_0010 96721.2 ), 88% identical to Homo sapiens MT 4 (E value = 3e 57, BC113444.1 NM_032935.2 ), 86% identical to Canis lupus familiaris MT 4 (E value = 6e 53, NM_001003150.1 ), and 86% identical to Bos grunniens MT 4 (E value = 7e 52, EF141034.1 ) as seen in Figure 6 4 When q uantified MT 4 in wild manatee skin from three locations (Figure 6 8), there was no significant difference in MT 4 expression betwe en locations (p=0.903). We found a mean absolute copy number normalized to control of (9.395.38) x10 6 in Citrus County, Florida, (8.273.6) x10 6 in Brevard County, Florida, and (1.491.12) x10 5 in Belize City, Belize. According to Table 6 2 there wa s no significant correlation to absolute copy number with Cu (p=0.114), Zn (p=0.259), and Cd ( p=0.917) levels in whole blood and Cu (p=0.290) and Zn (p=0.389) concentrations in skin. Discussion This was the first study to identify and induce metallothionei n in a sirenian. We have successfully cloned a 381 bp sequence of Tm MT 1 and a partial 182 bp sequence of Tm MT 4 Moreover, Tm MT 1 mRNA was induced by exposure to CdCl 2 and ZnCl 2 in manatee PBMCs, while Tm MT 4 was found to not be a good biomarker for met al exposure in whole blood and skin. Tm MT 1 and Tm MT 4 Metallothionein is a highly conserved gene across mammalian species, with the West Indian manatee as no exception. According to our 381 bp sequence of Tm MT 1
201 there is high degree of identity to other mammalian species as shown in the BLAST results and Clustal W2 alignment (Figure 6 3). In addition, there was high homology of Tm MT 4 with other mammalian species (Figure 6 4). This is not surprising, as Moleirinho et al. (2011) found that MT 1 4 all ev olved from one duplication event as mammals began to evolve. Thus, based on our sequence of manatee MT 1 and MT 4 cDNA, we can predict that MT will be similar to other placental mammalian species. Further detail of Tm MT 1 phylogeny will be discussed in Cha pter 7. Induction of MT 1 by CdCl 2 Tm MT 1 mRNA expression was seen in manatee PBMCs exposed to zinc and cadmium using qPCR analysis. Manatee leukocytes were quite sensitive to CdCl 2 exposure. Induction of MT was seen with CdCl 2 exposures with an optimal time of 24 hours with expression of Tm MT 1 induction with exposures as little as 2x10 11 M. Metallothionein expression was highest at lower concentrations of CdCl 2 and decreased with increased exposure. As mentioned above, in human lymphocytes, induction of MT occurred at an optimal concentration of 10 M (1x10 5 M) for Cd, Hg, and Ag (Yamada and Koizumi, 1991), while human monocytes induced MT at an ideal concentration of 10 M (1x10 5 M) for CdCl 2 (Mesna et al. 1995). In addition, Yurkow and DeCoste (199 9) exposed Cd (5x10 7 M) to human lymphocytes which increased MT levels. However, Pillet et al. (2002) did not have any increase in MT when exposing grey seal peripheral blood lymphocytes to 10 5 M. T his high threshold for Cd may possibly be due to Arctic marine mammals conditioning to high levels of Cd. Arctic ringed seals reported renal Cd levels of 200 g/g (ww ; Dietz et al. 1998), and 25 g/g (w w) in the kidneys of harp seals (Ronald et al., 1984) and narwhals at 205 g/g (ww; Wageman et al., 1983).
202 These elevated levels of Cd in the Arctic may be potentially making grey seals less sensitive to effect s of Cd toxicity (Pillet et al. 2002). Manatees, on the other hand, had low levels of Cd in the kidney, with a mean standard error of 94.7 ppm (ww ) and blood at <0.01 ppm (Chapter 2). Alternatively, manatees may be exposed to low levels of Cd in the en vironment and accumulate low levels in the kidneys, thus, making them more susceptible to Cd toxicity and sensitivity to Cd exposure. This is of concern for any endangered species with low genetic diversity and low reproductive rate. Cadmium is commonly used in a number of products including batteries, semiconductors, plastic stabilizers, and plating of iron and steel (Hooser 2007) and can enter the environment from zinc smelting and refineries, coal combustion, mine wastes, iron and steel production, fertilizers and sewage sludge (NRC 2005). Thus, emphasizing the importance of monitoring metal loads in manatees and the environment with the potential of Tm MT 1 in leukocytes as a useful biomarker for Cd exposure Induction of MT 1 by ZnCl 2 Metal conce ntration and duration of exposure may be important parameters for MT induction in manatee leukocytes. In both CdCl 2 and ZnCl 2 we saw maximal relative Tm MT 1 mRNA expr ession at 24 hours and decreased at 48 hour s relative to control (Table 6 2 ). In Pillet et al. (2002), maximal induction of grey seal leukocyte MT levels occurred at 3 hours and remained elevated to 24 hours with an exposure of 10 4 M concentration of ZnCl 2 Moreover, in human lymphocytes induction of MT occurred at an optimal concentration of 200 M (2x10 4 M) for Zn, Cu and Ni (Yamada and Koizumi, 1991), while human monocytes induced MT at an ideal concentration of 125 M (1.25x10 4 M) ZnCl 2 (Mesna et al. 1995). For this study, the time response curve was
203 exposed to 2x10 5 M of ZnCl 2 resulting in expression of Tm MT 1 at four hours, remaining elevated at 12 hours and peaking at 24 hours (Figure 6 6B). Thus, utilizing a higher concentration of ZnCl 2 is needed to elicit a response of MT expression in manatee leukocytes similar in other animals T his is shown in Figure 6 7B, where the maximal induction of Tm MT 1 is present at a dose of 2x10 4 M. Therefore, ideal induction of TmMT with exposures to ZnCl 2 is within the 10 4 M range and is expressed <24 hours, similar to other studies. Cell viabilit y and saturation are also important factors to be taken into account at levels above optimal. One of the main challenges for cell cultures is to maintain viability of cells throughout treatment. As shown in Figure 6 2, the percent cell reduction did not change with treatment or time and cell viability was maintained throughout this experiment. Therefore, a reduction in cell viability was not an issue. The decrease in MT expression at high Zn levels may be due to saturation of transcription factor s Man y transcription factors regulate gene expression, therefore, the metal regulated transcription factor 1 (MTF1), may be acting as a cytoplasmic sensor through the us e of MREs (Heuchel et al., 1995 ; review by Giedroc et al., 2001). With high levels of Zn, a vailable ligands of MT are not present for Zn to bind. Moreover, MT degradation due to the release of Zn to MTF1 or oxidative stress may have occurred. The reduction in MT expression may be due to the binding of Zn to MRE of MTF1, resulting in apo MT (thi onein), and potential degradation. In addition, oxidative stress may be present in the cells, resulting in apo MT and degradation (Davis and Cousins, 2000 ). Tm MT 4 a s a Biomarker Skin has been used as a biomarker for contaminants in marine mammals in th e past (Fossi et al., 1997; 2000). We investigated the relationship between MT 4
204 expression level in manatee skin with levels of metals in whole blood and skin to determine viability of Tm MT 4 as a valid biomarker. There was no difference between Florida and Belize locations in terms of Tm MT 4 expression, with no correlation of MT 4 levels in skin to that of metal levels in skin or blood. As a result, our data suggests that MT 4 may not be a viable biomarker for metal loads in whole blood and skin in man atees. In addition to skin, Quaife et al. (1994) characterized MT 4 of mice in the footpads, tongue, upper stomach, and vagina, which are not practical sample options for live manatees. Manatee skin is thick (~2.5 cm), adds to the negative buoyancy, and lacks low density lipids (Kipps et al., 2002; Reep and Bonde, 2006), thereby, differentiating manatees from other mammals, where MT 4 may be used as a biomarker to metal exposure. Not much is known in regards to MT 4 Quaife et al. (1994) suggested that the MT 4 present in skin may be an additional barrier to metal exposure by sequestering metals and limiting the contact into the bloodstream. Cadmium levels were extremely low in manatee skin and blood, thus, suggesting a possible role of TmMT 4 regulati ng metals and reducing toxicity from the external environment. Zinc and Wound Healing One possibility in regards to the Florida manatee is the utilization of Zn for wound healing. It has been shown that manatees have an extroadinary capability for wound healing which was briefly discussed in Chapter 2. It has been found that MT in the epidermis may play a role in transporting Zn to wounded tissues and assisting in triggering proliferation of new skin cell growth in mice (Iwata et al., 1999). A number of studies have been conducted to prove the efficacy of Zn for wound healing in other mammalian species, both topical and oral Zn, as stated in a review article by Lansdown
205 et al. (2007). Zinc is vital for cell membrane integrity and is an important cofacto r, as well as for mitosis, migration and maturation of epidermal and dermal tissues. The human epidermis has a higher content of Zn than the dermis, as was seen in the manatee (Chapter 3). Some future studies to determine the role of Zn in manatee wound healing can examine zinc metalloenzymes, such as metallothionein (interleukin 1 and regulation of MT), alkaline phosphatase (marker for dermal blood vessel and angiogensis), RNA/DNA polymerases (cell proliferation), and matrix metalloproteinases (MMPs). By utilizing rehabilitating manatees with a fresh boat propeller wound or injury, we can determine the sequential change in the level of Zn at the wound margins, as seen in rats using immunocytochemistry, where Zn levels increased from one to five days post wound then decreased to normal levels at 7 days (Lansdown et al., 1999). Moreover, Lansdown et al. (2007) discussed in detail the role of the Zn dependent enzymes: MMP. There are many forms of MMP that are involved in wound healing, cell migration and res tructuring of the extracellular matrix, such as MMP 1, 8, 9, and 10. C loning and sequencing of MMPs, as well as in vitro studies on cultured necrotic tissue and healthy tissue to determine MMP regulation may also help determine the role of Zn in wound hea ling in manatees Future Studies In addition to metal exposure, MT can be induced by a number of other factors. MT can be induced by glucocorticoids, cytokine IL 6, bacterial infection, and inflammation ( Kgi and Schffer 1988; Waalkes and Goering, 199 0 ), as well as viral infection s and UV and X irradiation may also induce MT (Andrews 1990; Heuchel et al. 1 994; Searle et al. 1984 ). The most studied inducers are metals and glucocorticoids, which can induce different isoforms of MT depending on the s pecies
206 (Miles et al, 2000). The fluctuations in MT expression may be due to roles of various isoforms. Yagle and Palmiter (1985) found that in mice, receptors for glucocorticoids and metals for MT 1 and 2 are co regulated, although MT 1 transcription is higher than MT 2 In humans, on the other hand, it has been found that MT 1 and 2 are regulated separately. As a result of this difference, Yagle and Palmiter (1985) suggested that the promoter region of human MT may have diverged at some point in evolut ion. To expand on this point, Moleirinho et al. (2011) found that all four classes of MT have diverged from a single duplication ; however MT 1 in primates have resulted in further deviations resulting in 13 isoforms, 5 pseudogenes and 8 functionally acti ve isoforms. Therefore, evolution may be a driving factor in how MT is regulated in different species and functioning of various isoforms which we will address in Chapter 7. Leukocytes are a valuable resource in regards to assessing immune function and health in an animal, as well as the induction of MT. However, according to Palmer et al. (2006), blood is a multifaceted tissue comprised of a number of different cell types, including T and B lymphocytes, monocytes, natural killer (NK) cells and granu locytes, which can vary with an individual and the health of the animal. Moreover, the response to MT can also vary by cell type. For instance, studies have shown that monocytes elevate the expression of MT with the exposure of Cd and Zn most effectively when compared to lymphocytes with granulocytes showing no induction of MT (Yurkow and DeCoste, 1999). Although analysis of PBMC is useful, separating manatee immune cells by flow cytometry may help us further understand the response of MT in the manatee l eukocytes.
207 Very few studies have been performed to investigate any association of metal level to health effects in marine mammals (Bennet t et al. 2001; Das et al. 2004 ; Reijnders 1986 ) due to the difficulty of preparing laboratory conditi ons, obtaining long term samples, and executing in vivo studies on marine mammals Therefore, studies in the past have focus ed on stranded animal tissues which may be a subsample of an unhealthy population. With the advancement of molecular techniques and technology, in vitro cell cultures have allowed us to expose marine mammal cell lines to toxicants without hindering the health of the animal. In addition to leukocytes, other tissues accessible from manatees may be used to clarify the role of MT in manatees, such as urine and erythrocytes Lee et al. (1983) examined the effects of Pb, Cd, Hg, Cu, and Zn exposure on urinary MT. Lee et al. (1983) found urine MT in rats increased with an exposure to Cd, Hg, Cu and Zn, but not Pb. Erythrocytes and dried blood have al so been used to determine MT expression as well (Aydemir et al., 2006; Cao and Cousins, 2000; Sullivan et al., 1997). Although the physiological mechanism of MT in manatees remains unknown, we have confirmed the presence and induction of MT 1 and MT 4 in manatees, with possibilities of utilizing other tissues in conjunction with molecular techniques to further our understanding of the role of MT
208 2x 10 9 M CdCl 2 2x 10 5 M ZnCl 2 A. CdCl 2 --------------ZnCl 2 ---------------------B. Figure 6 1. Schematic diagram of CdCl 2 and ZnCl 2 exposures. A ) Time response curve with control (c) at each time point and B ) Dose response curve for a 24 hour exposure with control (c). Blank wells were empty. c 2x10 11 M 2x10 10 M B lank 2x10 8 M 2x10 9 M c 2x10 6 M 2x10 5 M Blank 2x10 3 M 2x10 4 M c 4 hours 4 hours 12 hours 12 hours c c 24 hours 2 4 hours 4 8 hours 4 8 hours c
209 A B Figure 6 2. AlamarBlue d ata. A ) Time response of alamarBlue shows very little change in reduction of cell numbers. B ) Dose Response time points after 24 hours show little change in cell number as treatment doses increased (1 4) This data shows that PBMCs remained viable during treatment conditions.
210 Table 6 1. Oligonucleotide primers used for cloning and real time PCR. Forward 5' 3' Reverse 5' 3' Designed f rom CLONE MT ATGGACCCCAACTGCTCCT YTTGCAGAYRCAGCCCTG Bowhead MT in NCBI 3'RACE MT ATGGACCCCAACTGCTCCT GCGAGCACAGAATTAATACGACT cloned sequence/RACE Kit (reverse primer) qPCR MT GCTGGTGACTCCTGTGTCTG CACTTGTCAGATGCCCCTTT cloned RACE sequence CLONE MT 4 ATGGACNCYRGGGAATGYRY CAGCAGCTGCARTTGTCRGA other MT 4 sequences qPCR MT 4 GAATGCGTCTGCATGTCTG CAGCAGGAACAGCACCTTT cloned RACE sequence 18s LMB CGGCTACCACATCCAAGGAA CCTGTATTGTTATTTTTCGTCACTACCT Blum et al. 2008 P rimers were ma de by Integrated DNA Technologies (Coralville, IA).
211 BowheadMT -----------------------------------------------------------Rattusnorvegicus MT 1 A TCCCGACTTCAG CAGCCCGACTGCCTTCTTGTCGCTTACACCGTTGCTCCAGATTCAC 58 Pantroglodytes MT 1 E ATTCCGCTTTCCANCTGCCTGACTGCTTGTTCGCCTCACTGGTGGGAGCTCCAGCATCCC 60 ManateeMT -----------------------------------------------------------BowheadMT ----------ATGGACCCCAACTGCTCCTGCGCCGCGGGTGGATCCTGCACGTGTGCCG 49 Rattusnorvegicus MT 1 A CAGATCTCGGAATGGACCCCAACTGCTCCTGCTCCACCGGCGGCTCCTGCACCTGCTCCA 118 Pantroglodytes MT 1 E CTTTGCTCGAAATGGACCCCAACTGCTCCTGCGCCACTGGTGGCTCCTGCACGTGCGCCG 120 ManateeMT ----------ATGGACCCCAACTGCTCCTGCGCTGCTGGTGACTCCTGTGTCTGCGCTG 49 ********************* .* ** *..***** ** BowheadMT GCTCCTGCAAATGCAAAGAGTGCAAATGCACCTCCTGCAAGAAGAGCTG CTGCTCCTGCT 109 Rattusnorvegicus MT 1 A GCTCCTGCGGCTGCAAGAACTGCAAATGCACCTCCTGCAAGAAGAGCTGCTGCTCCTGCT 178 Pantroglodytes MT 1 E GCTCCTGCAAGTGCAAAGAGTGCAAATGCACCTCCTGCAAGAAGAGCTGCTGTTCCTGCT 180 ManateeMT GTTCCTGCAAATGCAAAGAGTGCAGATGCACT TCCTGCAAGAAGAGCTGCTGCTCCTGCT 109 ******.. *****..* ****.****** ******************** ******* BowheadMT GCCCCCCGGGCTGCACCAAGTGTGCCCAGGGCTGCGTCTGCAAAGGGGCCTCCGACAAGT 169 Rattusnorvegicus MT 1 A GCCCCGTGGGCTGCTCCAA ATGTGCCCAGGGCTGTGTCTGCAAAGGTGCCTCGGACAAGT 238 Pantroglodytes MT 1 E GCCCCGTGGGCTGTGCCAAGTGTGCCCAGGGCTGCGTCTGCAAAGGGGCATCGGAGAAGT 240 ManateeMT GCCCCGTGGGCTGTGCCAAGTGCGCCCAGGGCTGCATCTGCAAAGGGGCATCTGACAAGT 169 ** *** ****** ****.** *********** .********** **.** ** **** BowheadMT GCAACTGTTGTGCA ---------------------------------------------183 Rattusnorvegicus MT 1 A GCACGTGCTGTGCCTGAAGTGACGAACAGTGCTGCTGCCCTCAGGTGTAAATA -ATTTC 296 Pantroglodytes M T 1 E GCAGCTGCTGTGCCTGATGTGG GAACAG -CT CTTCTCCCAGATGTAAATAGAACAAC 296 ManateeMT GCAGCTGCTGCGCCTGACATGG ---GAGAGCC CTGCCC -AGATGTAAGCAGAGCAAC 222 *** ** ** **. Bo wheadMT -----------------------------------------------------------Rattusnorvegicus MT 1 A CGGACCAACTCAG -----------AGTCTT --GCCGTACACCTCCACCCAG -TTTAC 339 Pantroglodytes MT 1 E CTGCACAACCTGG -----------ATTTTTTAAAAAATACAACACTGAGCCA TTTGC 342 ManateeMT CTGTACAAAACTGGAGGGTTTTTTTAATTTTTTTTTTATACAACCCTGACCCGTTTTTGA 282 BowheadMT ----------------------------------------------------------Rattusnorvegicus MT 1 A TAAACCCCGTTTTCTACCGAGCATGTGAAT --AATAAAAGCC TGTTT ATTCT ----389 Pantroglodytes MT 1 E TGCATTTCTTTTCATACTAAATATGTGACTGACAATAAAAACA ATTTTGACTTTAA --398 ManateeMT TACATTCCTTTTTCTACGAAATATATGA ATGATAATAATAAAAGTTGATGACTTTAAAAA 342 BowheadMT -----Rattusnorvegicus MT 1 A -----Pantroglodytes MT 1 E -----ManateeMT AAAAAA 348 Figure 6 3. Alignment of Tm MT 1 ( Trichechus manatus MT 1 ). Clustal W2 alignment of the 381 bp TmMT sequence with a 389 bp Rattus norvegicus MT 1 A ( NM_138826 ), 398 bp Pan troglodytes MT 1 E ( NM_001252596 ), and 183 bp Bala ena mysticetus MT (AF022117)
212 Pantroglodytes MT 4 ATGGGGAGCCTCTGGCTGCTGCTCACTCAGCCTCCCTTCCCCAGCCGTGACAGCACTGGA 60 Homosapien MT 4 ATGGGGAGCCTCTGGCTGCTGCTCACTCAGCCTCCCTTCCCCAGCCGTGACAGCACTGGA 60 Macacamulatta MT 4 ATGGGGAGCCTCTGGCTGCTGATC ACTCAGCCTCCCTTCCCCAGCCGTGACAGCACTGGA 60 Tm MT 4 -----------------------------------------------------------Pantroglodytes MT 4 GCCTTTCGGACACCTGGACCATG GACCCCAGGGAATGTGTCTGCATGTCTGGAGGAATCT 120 Homosapien MT 4 GCCTTTCGGACACCTGGACCATGGACCCCAGGGAATGTGTCTGCATGTCTGGAGGAATCT 120 Macacamulatta MT 4 ACCTTTCGGACACCTGGACCATGGACCCCAGGGAATGTGTCTGCATGTCTGGAGGAATCT 120 Tm MT 4 ------------------ATGGACGCCAGGGAATGCGCCTGCATGTCTGGAGGAGTCT 40 ****** ********** ****************.*** Pantroglodytes MT 4 GCATGTGTGGAGACAACTGCAAATGCACAACCTGCAACTGTAAAACATGTCAGAAGAGCT 180 Homosapien MT 4 GCATGT GTGGAGACAACTGCAAATGCACAACCTGCAACTGTAAAACATGTCGGAAGAGCT 180 Macacamulatta MT 4 GCATGTGTGGAGACAACTGCAAATGCACAACCTGCAACTGTAAAACATGTCGGAAGAGCT 180 Tm MT 4 GCACCTGTGGGGACAACTGCAAATGCACAACTTGTAACTGTAAGACATGTCAGAAAAGGT 100 *** *****.******************** ** ********.*******.***.** Pantroglodytes MT 4 GCTGTCCCTGCTGCCCACCGGGCTGTGCCAAATGTGCCCGGGGCTGCATCTGCAAAGGAG 240 Homosapien MT 4 GCTGTCCCTGCTGCCCCCCGGGCTGTGCCAAATGTGCCCGGGGCTGCATCTGCAAAGGAG 240 Macacamulatt a MT 4 GCTGTCCCTGCTGCCCGCCAGGCTGTGCCAAGTGTGCCAGGGGCTGCATCTGCAAAGGAG 240 Tm MT 4 GCTGTTCCTGCTGCCCCCCAGGCTGTGCCAAGTGTGCCCGGGGCTGTGTCTGCAAAGAGG 160 ***** ********** **.***********.******.******* .*********..* Pantr oglodytes MT 4 GCTCAGACAAGTGCAGCTGCTGCCCATGAAACCCATCCATCGTGCCCACCCCTT 294 Homosapien MT 4 GCTCAGACAAGTGCAGCTGCTGCCCATGAAAGCCATCCATCGTGCCCACCCCTT 294 Macacamulatta MT 4 GCTCAGACAAGTGCAGCTGCTGCCCATGAAACCCATCCATCGTGCCCACCTCTT 294 Tm MT 4 GCTCCGACAATTGCAGCTGCTG -------------------------------182 ****.***** *********** Figure 6 4. Alignment of Tm MT 4 ( Trichechus manatus MT 4 ). Clustal W2 alignment of the 182 bp partial Tm M T 4 sequence S equences were aligned using Clustal W2 from species in the National Center for Biotechnology Information (NCBI) Nucleotide database: 294 bp Macaca mulatta MT 4 (XM_001096721, predicted), 294 bp Pan troglodytes MT 4 (XM_001137744, predicted ) and 294 bp Homo sapiens MT 4 (NM_032935).
213 LMB ----CGGCTACCACATCCAA GGAAGGCAGCAGGCGCGCAAATTACCCACTCCCGACTCG 55 LR2B18 CGATTCGGCTACCACATCCAAGGAAGGCAGCAGGCGCGCAAATTACCCACTCCCGACCCG 60 LR2B14 ----CGGCTACCACATCCAAGGAAGGCAGCAGG CGCGCAAATTACCCACTCCCGACCCG 55 LR2B17 ----CGGCTACCACATCCAAGGAAGGCAGCAGGCGCGCAAATTACCCACTCCCGACCCG 55 **************************************************** ** LMB GGG AGGTAGTGACGAAAAATAACAATACAGG ACTCTTTCGAGGCCCTG TAA TTGGAATG 114 LR2B18 GGGAGGTAGTGACGAAAAATAACAATACAGG ----------------------------91 LR2B14 GGGAGGTAGTGACGAAAAATAACAATACAGGACCCCCCCGTGGCGGCGACGACCCATTCG 115 LR2B17 GGGAGGTAGTGACGAAAAATAACAATACAGG ----------------------------86 ******************************* Figure 6 5. Alignment of housekeeping gene, 18s. Largemouth bass ( Micropterus salmoides ) from Blum et al. (2008) and manatee liver ribosomal 18s were aligned using Clustal W2. This housekeeping gene was highl y conserved and primers were the same in the manatee and large mouth bass.
214 A B Fig ure 6 6 Time response curve. Time response curve for the induction of Tm MT 1 with an exposure of A ) 2x10 9 M CdCl 2 resulted in a maximal induction at 24 hours with a 7 fold increase from control in Tm MT 1 and B ) 2x10 5 M Zn Cl 2 resulted in a maximal induction at 24 hours with a 13 fold increase from control Relative quantification was based on delt a delta CT method (Livak and Schmittgen, 2001).
215 A B Figure 6 7 Dose response c urve. The dose response curve after 24 hours for A ) CdCl 2 resulted in a maximal induction at 2x10 11 M with a 3 fold increase from control in Tm MT 1 and B ) Zn Cl 2 resulted in a maximal induction at 2x10 4 M with a 6 fold increase from control in Tm MT 1 Relative quantification was based on delta delta CT method (Livak and Schmittgen, 2001).
216 Figure 6 8 Metallothionein 4 expression in wild manatees from Citrus County, Florida (CCR), Brevard County, Florida (CBC) and Belize (BZ) with no significant difference ( p=0.903 )
217 Table 6 2 Correlation of Tm MT 4 transcript in relation to copper (Cu), zinc (Zn), and cadmium (Cd) levels in whole blood (WB) and skin. Location n Cu WB Zn WB Cd WB Cu Skin Zn Skin Cd Skin CCR 14 R 0.352 0.120 0.098 ---p value 0.238 0.695 0.750 ---CBC 11 R 0.437 0.558 0.131 0.503 0.979 -p value 0.179 0.0747 0.701 0.664 0.131 -BZ 4 R 0.000 1.000 -0.200 0.400 -p value 1.000 0.083 -0.917 0.750 -No significant correlation was present
218 CHAPTER 7 TRACE METAL CONTROL IN PAENUNGULATA WITH PHYLOGENY OF METALLOTH IONEIN CDNA IN FLORI DA MANATEE ( T richechus manatus latirostris ) AND ASIAN ELEPHANT ( E lephas maximus ) Background Simpson (1945) first grouped orders Proboscidea, Sirenia, and Hydracoidea into clade Paenungulata based solely on fossil records, with a possibi lity of Hydracoidea being closer to clade Perissodactyla. Studies began combining fossil records and anatomical features in order to construct phylogenetic trees, questioning the classification of all placental mammals (Novacek, 1992). Aardvarks, elephan ts and hyraxes, for instance, were once thought to be associated with ungulates, while the golden mole and tenrecs were categorized with Insectivora, and elephant shrew morphology resulted in classifications with Lagomopha or Rodentia (Hedges, 2001). Sup erorder Afrotheria is currently comprised of six orders: Proboscidea (elephants), Sirenia (manatees and dugongs), Hyracoidea (hyraxes), Tubulidentata (aardvark), Macroscelidea (elephant shrew), and Afrosoricida (golden mole and tenrecs) (Stanhope, 1998). However, with the advancement of molecular techniques and technology, reconstruction of the phylogenetic tree continues. van Dijk et al. (2001) analyzed nuclear and mitochondrial protein sequences ( A crystallin (CRYAA), aquaporin 2 (AQP2), interphotoreceptor retinol binding protein (IRBP), von Willebrand factor, 2B adrenergic receptor, fibrinogen, hemoglobin and and cytochrome b) and found that the African insectivore, the otter shrew ( Mic ropotamogale lamottei ) should also be included in Afrotheria. Researchers began incorporating molecular characteristics with fossil records and anatomical relationships. Protein sequences were in agreement with Simpson (1945)
219 and it was found that clade P aenungulata was not closely related to ungulates, as previously thought (Goodman et al., 1985; Kleinschmidt et al., 1986; Miyamoto and Goodman, 1986). Kleinschmidt et al. (1986) examined and hemoglobin sequences and further confirmed the grouping of Proboscidea, Sirenia, and Hydracoidea in Paenungulata. In addition to hyrax, elephants and manatee s mitochondrial (mt) DNA, von Willebrand factor (vWF) gene, and 2B adrenergic recept or gene (A2AB) have categorized golden moles, elephant shrews and aardvarks ( Orycteropus afer ) with Paenung ulata (Springer et al., 1997). OF t he five placental order s, the golden moles most likely originated from Africa, whereas sirenians originated from the Tethys Sea (de Jong et al., 1981; Springer et al., 1997; Stanhope et al., 1998). This supports the spread of the African animals to the Southern Hemisphere d ue to the break in Gondwanaland with Paenungulata originating from Africa (Springer et al., 1 997). Divergence occurred within the sirenians during a 4 million year time period with divergence of Paenungulata from other non Paenugulata at 80 mya according to chromosomal evolution (Pardini et al., 2007). Chromosomal painting confirms that manatees belong to clade Paenungulata within superorder Afrotheria and support a Tethytheria association (Kellogg et al., 2007). Amino acid sequences from the eye lens protein, a crystallin A, were analyzed and confirmed the categorization of aardvark with elephan ts, manatees and hyraxes, as well as early divergence from placental mammals (de Jong et al., 1981). Springer et al. (1999) analyzed four mitochondrial genes (12s rRNA, tRNA valine, 16s rRNA, cytochrome b) and four nuclear genes (aquaporin, a 2B adrenerg ic receptor (A2AB), interphotoreceptor retinoid binding
220 protein (IRBP), von Willebrand factor (vWF) from 11 eutherian orders and found that nuclear genes showed solid proof of Afrotheria and Paenungulata. Kuntner et al. (2011) examined mitochondrial cytoc hrome b, 12s, 16s, and NADH2, nuclear a 2B receptor (ADRA2B), androgen receptor (AR), growth hormone receptor (GHR), von Willebrand factor (vWF), and interphotoreceptor retinoid binding protein (IRBP) and provided evidence of hyraxes, manatees and elephan ts comprising Paenungulata but showed a closer elephant hyrax relationship than with Tethytheria. Due to the elevated circulating zinc level in manatees, our first objective was to determine if high zinc levels were unique to members of Paenungulata. Acc ording to W i e dner et al. (2011), elephant whole blood Zn levels were not similar to manatees but we also wanted to compare metal levels in plasma, erythrocytes, and liver of elephants to manatees. Due to high Zn levels found in manatees and not elephants we hypothesize that the physiological need for high levels of Zn is unique to sirenians. Because of the importance of metallothionein for maintaining metal homeostasis, we will also determine the sequence of metallothionein in elephants and use this seq uence to examine the relationships in Paenungulata between the elephant and manatee. Mammalian metallothioneins are four tandem grouped genes ( MT 1 2, 3, 4) consisting of 20 cysteines (Villarreal et al., 2006). In addition, MT sequence is highly conserv ed with a strong homology between various species (Cousins, 1983), with all four genes originating from a single duplication event before the spread of mammals (Moleirinho et al., 2011). We have successfully cloned and sequenced metallothionein in manatee s (Chapter 6) and hypothesize that EmMT ( Elephas maximas MT) and TmMT ( Trichechus
221 manatus MT) sequences will be similar to one another due to the relatedness of the species in Paenungulata. Materials and Methods Trace Metal Samples Blood was collected fr om 139 wild Florida manatees (see Materials and Methods in Chapter 2) and 33 captive Asian elephants (Wiedner et al., 2011) Blood was collected using an 18 gauge x 38.1mm needle and a 7m L royal blue top Monoject tube with K 2 EDTA designed for trace elem ent analysis. Plasma was collected, buffy coat discarded and erythrocytes were collected. All blood samples were then put on ice during the field and stored in 4 0 C or 80 0 C until analyzed. Sample Analysis An aliquot of plasma or erythrocytes (250 1000 L) was placed in borosilicate glass tubes (18x150mm, Fisher Scientific Company, Pittsburgh, PA) with ultrapure Optima nitric acid (Fisher Scientific Company) and placed in a 45 well graphite digestion block at approximately 130 o C. Ultrapure 30% hydrogen peroxide (Mallinckrodt Baker, Inc., Phillipsburg, NJ) was then used to complete digestion of organic matter. Three to ten mL of Millipore deionized water was then added to dissolved samples. Each sample was filtered using a 13 mm nylon syringe filter (0. 2 m, Fisher Scientific Company) and placed in a 15mL conical tube (Corning Life Sciences, Lowell, MA) for analysis using an inductively coupled plasma mass spectrometry (Thermo Electron X Series ICP MS, Thermo Fisher Scientific, Inc., Waltham, MA) in the Co llege of Pharmacy at the University of Florida. Using ICP MS provides sensitive analysis on a larger number of elements than using atomic absorption spectrophotometer as used in the past (Law 1996). Although X ray fluorescence spectrometry can also be u sed
222 (Griesel et al., 2006), IC P MS was accessible for our use, more quantitative, and commonly us ed for multi element analysis. In this study, we concentrated on the divalent metals: Cr, Fe, Cu, Zn, As, Se, and Cd with an internal standard of 115 In. Qual ity assurance for manatee samples included blank samples, repeat samples, and NOAA whale and manatee livers. The standard reference material for select elements is reported as follows, meanSEM with standard results in parenthesis, for NOAA Liver I II (pygm y sperm whale): As 0.40.04 (0.860.08), Cd 5.60.2 (5.940.38), Cu 2.70.2 (2.740.1 9), Fe 60548 (69445), Se 10.330.95 (7.871.18), and Zn 17.51.4 (21.151.65). The beluga whale liver II NOA A standard resulted in: As 1.50.2 (0.3910.027), Cd 2.110. 04 (2.350.06), Cu 11.40.2 (13.160.4), Fe 62527 (66815), Se 28.8 2.6 (24.30.85), and Zn 201.5 (26.310.66). Concentrations of samples were reported as ng/mg or ppm wet weight. EmMT C loning and S equencing Manatee MT sequence from Chapter 6 was use d in this study. Also, similar to Chapter 6, we cloned and sequenced MT from Asian elephant peripheral blood mononuclear cell (PBMC). Total RNA was isolated from peripheral blood leukocytes using phenol/chloroform extraction ( TRIzol Reagent, Invitrogen, Carlsbad, CA). Samples were incubated in TRIzol at 15 30 o C for 5 min Chloroform (0.2 mL) was then added, incubated at 15 30 o C for 2 3 min then centrifuged at 12,000 g for 15 min at 2 8 o C. The clear supernatant was then placed in a fresh tube with 0.5 m L of isopropyl alcohol and incubated at 15 30 o C for 10 min Samples were then centr ifuged at 12,000 g for 10 min at 2 8 o C. The pellet was then washed once with 1 mL of 75% ethanol, vortexed and centrifuged at 7,500 g for 5 min at 2 8 o C and pellet was dr ie d for approximately 10 min. The pellet was reconstituted with 20
223 Resuspension Solution (Applied Biosystems/Ambion, Austin, TX) and RNA was measured using the NanoDrop 1000 Spectrophotometer (Thermo Fisher Scientific, Inc., Waltham, MA). Samples were cleaned using the DNA Biosystems/Ambion, Austin, TX) to remove DNA contamination from samples. RNA samples were then converted to cDNA by RT PCR using MMLV reverse transcriptase (Promega Corporation, Madison, WI). RT PCR w as performed to obtain cDNA synthesis using 0.5 g total RNA. Tota l RNA was combined with 1 L of random hexamer (Promega Corporation, Ma dison, WI) and brought up to 10 L with nuclease free water. The RNA/primer solution was then heated to 70 o C f or five min and then immediately placed on ice. Samples were then mixed with: 5 L MMLV 5xreaction buffer, 5 L dNTP mix (10 mM), 0.2 L of RNAsin (40 U/ L), and 1 L of MMLV RT (200 U/ L) from Promega reagents and heated at 37 o C for one hour and then stored at 20 o C to be used for cloning purposes. In order to clone and sequence MT from the Asian elephant, we used primers designed from Primer 3 (Rozen and Skaletsky, 2000) and a 183 bp partial sequence of bowhead whale ( Balaena mysticetus ) metallothionein from the National Center for Biotechnology Information (NC BI) Nucleotide database (GenBank AF022117.1, GI : 2462852, Accession #AF022117) Cloning and sequencing procedure were similar to Doperalski et al. (2011). PCR was performed with 100 ng EmMT cDNA template, 2.5 L 10xPCR buffer, 0.5 L dNTP (10mM), 0.5 L forward primer (10 m M), 0.5 L reverse primer (10m M), an d 0.2 L Taq DNA polymerase (1 U/ L) (Life Technologies Corporation/Invitrogen). Thermocycling parameters were: 94 o C for 3 min, 35 cycles of 94 o C for 30se c, 55 o C for 30 sec, and 72 o C for one min with a final extension at 72 o C for
224 7 min. Gel electrophoresis was run with 2% agarose gel and 1 g/mL of ethidium bromide and products with the estimated length were then ligated into the pGEM T Easy plasmid vecto r (Promega Corporation) and transformed into One Shot TOP10 chemically competent Escherichia coli (Invitrogen) cells Plasmids were then isolated using the Plasmid Miniprep Kit (Invitrogen) and Sanger sequencing was performed at the Interdisci plinary Center for Biotechnology Research at the University of Florida. EmMT R ACE Three additional MT nucleic acid sequence in the Asian elephant. Using Primer 3 (Rozen and Skaletsky, 2000) left primers were designed using the partial 152 bp sequence obtained from above. The FirstChoice RLM RACE kit (Ambion) was used following manufactures protocol. Briefly, 1 g of total RNA was mixed with 2 L 10x RT B uffer, 3 L dNTP (2.5 mM) mi x, 2 pter, 1 L RNase Inhibitor (10U/ L), 1 L MMLV RT, and 9.25 L nuclease free water. First strand synthesis was performed for one hour at 42 o C. RACE PCR forward primers were designed from cloned MT sequence GCAAATGCAAAGAGTGCAAA RACE Outer primer as provided in the kit. PCR was again performed using a 60 o C annealing temperature and the PCR product was then ligated and transformed. Using a p GEM T Easy Vector, plasmid samples were submitted to the Arizona State University DNA Laboratory, headed by Dr. Scott Bingham. BLAST was used to confirm our gene of interest.
225 Phylogenetic Analysis In order to determine the evolutionary relationships between EmMT and TmMT which have been cloned and sequenced, the mRNA nucleot ide sequences from other species were used. Following revised methods from Maness et al. (2011) and Moleirinho et al. (2011), 38 mammalian MT sequences ( MT 1 and MT 2 ) and one avian MT sequence was used to align EmMT and TmMT from this study using MT mRNA sequences from NCBI GenBank (Table 7 3). MUSCLE (Multiple Sequence Comparison by Log Expectation) and MAFFT (Multiple Alignment using Fast Fourier Transform) were used to align sequences in Nexus and Phylip format. MUSCLE and MAFFT alignments were the s ame, thus MUSCLE was used due to ease of formatting outputs into Phylip and Nexus. Sequences from GenBank were aligned using MUSCLE and incorporated into Cyberinfrastructure for Phylogenetic Research (CIPRES) Science Gateway 3.1 ( http://www.phylo.org/ ; Miller et al., 2010) MT sequences from a mallard were used as the outgroup from ma mmals and sequences from the gre y short tailed opossum and platypus were also included as non eutheria n mammals. MrBayes on TG version 3.1.2 was used for Bayesian analysis of MUSCLE alignment in Nexus format with Trestles as the NSF TeraGrid. The Bayesian phylogeny were completed in a 4x4 nucleotide model with 6 nucleotide substitutions in two runs (one million generations each) with a c lade credibility of 0.5. One million generations were run with tress sampled every 500 generations. Bayesian deduction was based on Markov chain Monte Carlo (MCMC) in order to determine the posterior probability of trees. Once the Bayesian tree was dete rmined, RAxML HPC BlackBox (7.2.8) was used to determine maximum likelihood and bootstrap values which was then placed in Consense (Phylip 3.66) in order to obtain the posterior probability, or the likelihood the tree is accurate.
226 Bootstrap sampling was c ompleted using 800 bootstrap replicates, and all tree o utputs were edited in FigTree version 1.3.1 ( http://tree.bio.ed.ac.uk/software/figtree/ ). Statistics D escriptive statistics for mean and stand ard error for each element were calculated using SigmaPlot version 11 (Systat Software Inc., San Jose, CA). A t test was used to find a significant difference (p<0.05) between Asian elephant s and Florida manatee s f or each element in whole blood, erythrocy tes, plasma, and liver samples Results Blood and Liver Comparisons Blood parameters from the Asian elephant and Florida manatee were compared (Wiedner et al., 2011) to determine if the concentration of metals were similar between the species (Table 7 1). In whole blood, there was a significant difference in Cr (p<0.001) with levels in elephants 4x higher than manatees, Zn (p<0.001) with levels twice as high in manatees than elephants, As (p<0.001) with manatees having 14x more As than elephants, and Se ( p<0.001) where levels were double in elephants than manatees. In red blood cells, there was a significant difference in As (p<0.001) with levels 19x higher in manatees, Cr and Se (p<0.001) where concentrations were 3x higher in elephants, whereas Zn (p<0. 001) was 3x higher in manatees. In regards to plasma, there was a significant difference in As (p=0.004) with levels 4x higher in manatees. Zinc (p<0.001) was 4.5x greater in manatees, while Cr (p<0.001) was 4.5x greater in elephants. Selenium (p=0.009) was higher in elephants, while Fe (p=0.002) was higher in manatees. There was no significant difference in Cu between Asian elephants and Florida manatees when analyzing whole blood (p=0.982), red blood cell (p=0.135) and plasma (p=0.176), and Fe in whol e blood (p=0.431).
227 In addition to blood, liver samples from the dugong (Haynes et al., 2005) were also utilized (Table 7 2). Although blood results are unknown in dugongs, liver values in the dugong were significantly higher in dugongs than the Florida ma natee for Zn (p<0.001), Cu (p=0.036), and As (p<0.001). EmMT Sequence A 152 bp sequence of EmMT was successfully cloned and sequenced. EmMT was 97% homologous to Loxodonta africana metallothionein 2 like (predicted; XM_003416302), 93% identical to Macac a mulatta metallothionein 1E (NM_001195830.1), and 92% homologous to Pan troglodytes metallothionein 1E like TmMT, as shown in Figure 7 1. When aligned EmMT to TmMT, it was 91% i dentical to each other with 336 out of 376 base pairs the same. BLAST results were 85% identical to Homo sapien MTF (AF348998.2), 86% homologous to Pan troglodytes MT 1 X (predicted; XM 001092340.2), and 84% homologous to Homo sapien MT 1 E (NM 175617.3). P hylogenetic Analysis A conserved region of 1 35 bp across all 39 species was found. The results of our MT phylogenetic analysis with nuc leotide sequences indicated that elephant and manatee were closely related As expected, the outgroup mallard, was sep arated, as were the other non placental animals. The three Eutherian groups (Afrotheria, Euachontoglires, Laurasiatheria) fell into distinct categories and separated by an isoform. Bayesian values and posterior probabilities are shown at each node in Figu re 7 2.
228 Discussion Zinc in Blood Manatees and elephants are in superorder Afrotheria, and more specifically, clade Paenungulata. Due to this evolutionary classification, we hypothesized that the elevated level of zinc in manatees (Chapter 2) is a physiolo gical mechanism that may be a shared trait in all members of Paenungulata. However, according to our results, the level of zinc in the Asian elephants in this study did not show similar levels as in the Florida manatees. Zinc levels in manatees were sign ificantly higher than elephants suggesting a physiological mechanism specific to manatees (i.e. wound healing) or perhaps to sirenian s as we see very high levels in the liver of dugongs. Metallothionein Metallothionein is a highly conserved gene within mammals. Based on phylogenetic analysis of MT 1 and 2, our results indicate clustering of Paenungulata species. The platypus, a monotreme, was grouped with the opossum and mallard, as expected for they are non placental mammals Using mitochondrial DNA (mtDNA), monotremes and marsupials have been linked together, excluding placental mammals (Janke et al., 1997; Penny and Hasegawa, 1997). Moreover, the classification of the various primate species agrees with Mole i rinho et al. (2011), who found 13 isofor ms of MT 1 in primates, with 5 pseudog enes and 8 active genes. The MT 1 and MT 2 in primates were grouped together, as shown in Figure 7 2. However, we did see some variability in terms of groupings of isoforms. The discrepancies in our results may be du e to the fact that predicted metallothionein like sequences (Table 7 2; Eleph MT 2 Oppossum MT 1 Marmos MT 1 E, Platypus MT 1 Panda MT 1 F, Mouse MT 2 Gibbon MT 1 E) were used for seven species and may not be true indicators of MT classification.
229 As indicated in our weak bootstrap values, additional studies are needed with elongated sequences, more species, and different isoforms of MT. Despite the debates on phylogeny within Afrotheria, evolutionary biologists have classified manatees and elephants together i n Paenungulata. This is the first detailed examination using phylogenetic analysis of MT in sirenians. Manatee and elephant MT were grouped close together, corroborating previous studies of clade Paenungulata. In addition, EmMT may be of MT 1 isoform wi th close relationship to MT 2 of Loxodonta spp. (XM_003416302) with 97% maximum identity and a difference of 4 nucleotides out of 152 bp. Strong Bayesian (100%) and bootstrap values (99.63%) also confirm this idea. Further studies are needed to determine the complete MT sequence in species found in Paenungulata, as well as the different isoforms. At this time, only partial sequences have been cloned, suggesting MT 1 in the Florida manatee and Asian elephant. Further analysis with additional isoforms and populations of manatees and the dugong would be helpful in understanding the phylogeny of MT in Paenungulata. Within sirenians, Kunter et al. (2011) found a closer association of the Amazonian manatee to West African manatee, which contradicts the theory proposed by Vianna et al. (2006), that the freshwater manatee is a sister species to the West African manatee. Manatee subspecies came about due to biogeographical separation. Manatees were thought to have originated in South America with the Family Dugo ngidae in the Caribbean and West ern Atlantic. Due to the competition pressures, dugongs were outcompeted and became extinct in the West Indies during the Pl ei stocene (Domning 1982) Thus, further analysis within sirenians would be interesting in terms o f contaminant
230 detoxification mechanisms and metal homeostasis. In addition to the sirenians and elephants, further analysis of the four other orders in clade Paennungulata would be interesting. Obtaining MT sequences from the orders Hyracoidea (hyrax), Af rosoricidea (golden mole and tenrecs), Macroscelidea (elephant shrew), and Tubulidentata (aardvark) would allow better understanding to the role of metallot hionein in S uperorder Afrotheria. Additional studies may be performed in order to clarify Tethyther ia (Sirenia Proboscidea) and Hyracoidea Proboscidea association within Paenugulata, as shown in Pardini et al. (2007). It has been thought that over 35 spec ies in O rder Sirenia existed within the last 50 million years with only four species remain ing (Domn ing, 1994). Colonization of Florida by the manatee is a relatively recent event possibly due to limited habitat conditions, biogeographic barriers glacial episodes, and the natural events (Garcia Rodriguez, 1998). Molecular studies will help to unravel the evolutionary history of manatees, in addition to clarify fossil records. Continue d conservation of the species is needed to help recover this endangered species. Understanding phylogenetic relationships will play an important role in comparative biolo gy, as well as conservation biology (Kuntner et al., 2011), has been illustrated in the critically endangered and poorly understood, Northern shrew tenrec ( Microgale jobibely ). Phylogenetic analysis provides information on evolu tionary history, and will i mprove our understanding of the ev olution of Afrotheria with advancement in molecular techniques and phylogenetic analysis tools.
231 Table 7 1. Blood comparisons of captive Asian elephant and wild F lorida manatee. Whole blood (W i e dner et al., 2011), eryth rocytes (RBC), and plasma values for Cr, Fe, Cu, Zn, As, Se, and Cd mean standard error are provided. Type Species n 52 Cr (ng/mg) 56 Fe (ng/mg) 65 Cu (ng/mg) 66 Zn (ng/mg) 75 As (ng/mg) 82 Se (ng/mg) 111 Cd (ng/mg) Whole Blood Elephant 33 0.04 0.0 1 + 3 91.527.1 0.80.01 6.10.8 0.02 0.001 0.4 0.0 2 + BLD Manatee 129 0.01 0.001 414.413 0.80.02 12.9 0.4 + 0.3 0.01 + 0.20.01 BLD RBC Elephant 30 0.06 0.0 1 + above detection 0.50.01 7.60.6 0.03 0.001 0.7 0.0 3 + BLD Manatee 69 0.02 0.003 945.586.9 0.60 .02 21.3 0.8 + 0.5 0.0 4 + 0.20.02 BLD Plasma Elephant 30 0.030.01 1.80.05 10.03 0.70.07 0.01 0.001 0.10.01 BLD Manatee 47 0.01 0.001 + 2.80.2 ** 10.05 3.1 0. 2 + 0.030.01 ** 0.10.01 ** BLD Below limit of detection (BLD) is <0.25ppm for Cd. All value s are in ppm (ng/mg) wet weight *denotes significant difference (p<0.05) **denotes significant difference (p<0.01) + denotes significant difference (p<0.001)
232 Table 7 2. Liver comparisons in Paenungulata. Mean standard deviation of Zn, Cu, Se, and As lev els in the Florida manatee, dugong and elephant. Liver Liver Liver Manatee Dugong Elephant n=14, ppm ww n=18, ppm ww NA Element This study Haynes et al. 2005 Zn 143.8145.1 1676.5900 + ----Cu 35.259.2 9281.5 ----Se 0.50.5 <0.02 3.6 ----As 0.1 0.01 2.6 1. 8 + -------*denotes significant difference (p<0.05) **denotes significant difference (p<0.01) + denotes significant difference (p<0.001)
233 TmMT ATGGACCCCAA CTGCTCCTGCGCTGCTGGTGACTCCTGTGTCTGCGCTGGTTCCTGCAAA 60 EmMT ATGGACCCCAACTGCTCCTGCGCTACCGGAGGTTCCTGCGCCTGCCCCGGCTCCTGCAAA 60 ************************ ** ***** **** ** ********* TmMT TGCAAAGAGTGCAGATGCACTTCCTGCAA GAAGAGCTGCTGCTCCTGCTGCCCCGTGGGC 120 EmMT TGCAAAGAGTGCAAATGCACTTCCTGCAGAAAGAGCTGCTGCTCCTGCTGCCCCGTGGGC 120 ************* ************** ****************************** TmMT TGTGCCAAGTGCGCCCAGGGCTGCATCTGCAAAGGGGCATCTGAC AAGTGCAGCTGCTGC 180 EmMT TGTGCCAAGTGTGCCCAGGGCTGCATCTGCAAAGGGGCATCAGACAAGTGCAGCTGCTGC 180 *********** ***************************** ****************** TmMT GCCTGACATGGGAGAGCCCTGCCCAGATGTAAGCAGAGCAACCTGTACAAAACTGGAGGG 240 EmMT GCCTGATGTGCGAGAGCCCCGCCCAGATGTAAATAGAGCAACCTGTACAAAGCTGGAG -238 ****** ** ******** ************ ***************** ****** TmMT TTTTTTTAATTTTTTTTTTATACAACCCTGACCCGTTTTTGATACATTCCTTTTTCTACG 300 EmMT --TTTTGTTTTGTTTTTCATACAACCCTGGCCCATT -TGTTACTTTCCTTTTTCTACG 293 **** *** ***** *********** *** ** ** *** ************** TmMT AAATATATGAATGATAATAATAAAAGTTGATGACTTTAAAAAAAAAAAA -CCTATAGTG 358 EmMT AGATATATGAAT GATAATAATAAAAGTTGATGACTTTAAAAAAAAAAAAAACCTATAGTG 353 *********************************************** ********* TmMT AGTCGTATTAATTCTGTGCTCGC 381 EmMT AGTCGTATTAATTCTGTGCTCGC 376 ********************* ** Figure 7 1. MT alignment in the Asian elephant and Florida manatee. MT alignment for manatee MT (381 bp; TmMT) and elephant MT (376 bp; EmMT) was performed using CLUSTAL W2. Nucleotides aligned 89% to one another with a 16 nucleotide difference.
234 T able 7 3. Phylogenetic analysis of MT 1 and 2 nucleotide sequences. Using GenBank in National Center for Biotechnology Information (NCBI) database, a 135 bp conserved region in 39 mammalian species with one avian species as an outgroup (MallardMT) was use d for phylogenetic analysis. Animal ID Common Name Species Length (bp) GenBank Accession Number Harbor MT 2 Harbor seal Phoca vitulina 91 AY919325 OrcaMT Killer whale Orcinus orca 117 GQ141086 BowheadMT Bowhead whale Balaena mysticetus 183 AF022117 Yak MT 1 Domestic yak Bos grunniens 183 AY513744 Hamster MT 1 Chinese hamster Cricetulus griseus 186 NM_001244576 Eleph MT 2 African elephant Loxodonta africana 186 XM_00341630 2 Gibb MT 2 Northern white cheeked gibbon Nomascus leucogenys 186 XM_003263081 Oposs MT 1 Short tailed opossum Monodelphis domestica 189 XM_001365082 Mallard MT 1 Mallard Anas platyrhynchos 192 AB258230 Marmos MT 1 E* White tufted ear marmoset Callithrix jacchus 255 XM_002748684 Mouse MT 1 House mouse Mus musculus 283 NM_013602 Platypus MT 1 Platypus Ornithorhynchus anatinus 321 XM_001510657 Horse MT 1 A* Horse Equus caballus 334 XM_003364598 SheepMT Sheep Ovis sp. 342 X00953 EmMT Asian elephant Elephas maximus 376 this study Pig MT 1 A Wild pig Sus scrofa 378 NM_001001266 TmMT Florida manatee Trichechus manatus latirostris 381 this study Rat MT 1 A Norway rat Rattus norvegicus 389 NM_138826 Chimp MT 1 G Chimpanzee Pan Troglogytes 394 NM_001252595 Human M T 1 G Human Homo sapiens 396 NM_005950 Pan MT 1 H Chimpanzee Pan Troglogytes 396 NM_001252040 Human MT 1 H Human Homo sapiens 397 NM_005951 Chimp MT 1 E Chimpanzee Pan Troglogytes 398 NM_001252596 Chimp MT 2 A Chimpanzee Pan Troglogytes 408 NM_001252594.1 Pan da MT 1 F* Giant panda Ailuropoda melanoleuca 414 XM_002912252 ChinMT Chinchilla Chinchilla lanigera 416 AY533220 Rhesus MT 1 E Rhesus macaque Macaca mulatta 416 NM_001195830 Cow MT 1 A Cow Bos taurus 419 NM_001040492 denotes metallothionein like sequenc es
235 Table 7 3. Continued. Animal ID Common Name Species Length (bp) GenBank Accession Number Cow MT 2 A Cow Bos taurus 421 NM_001075140 Dog MT 2 A Dog Canis lupus familiaris 430 NM_001003149 Orang MT 2 A Sumatran orangutan Pongo abelii 430 NM_001133593 C ow MT 1 E Cow Bos taurus 431 NM_001078134 Dog MT 1 E Dog Canis lupus familiaris 434 NM_001003173 Dog MT 1 Dog Canis lupus familiaris 434 D84397 Human MT 2 A Human Homo sapiens 466 NM_005953 Human MT 1 A Human Homo sapiens 468 NM_005946 Human MT 1 E Human Homo sapiens 519 NM_175617 Mouse MT 2 House mouse Mus musculus 556 NM_008630 Gibb MT 1 E* Northern white cheeked gibbon Nomascus leucogenys 708 XM_003263076 denotes metallothionein like sequences
236 Figure 7 2. Bayesian tree of MT 1 and 2. Bayesian values are given in bold with posterior probabilities adjacent with the order of nodes in increasing order. Groups were separated into Afrotheria, Euarchontoglires and Laurasiatheria
237 CHAPTER 8 CONCLUSION The presence of elevated zinc levels is unique to sire nians. Zinc levels in the blood and liver of sirenians are much higher when compared to other marine mammal species and have created a reference range for wild West Indian manatees in Florida and Belize. Diet may contr ibute to this increase in zinc but m ay not be the sole factor. Carbonic anhydrase, a major Zn metalloenzyme, was evaluated in manatee erythrocytes and found to have k cat /k m similar to other mammalian species. Manatees have CA isozyme I and II and are sensitiv e to inhibitor, ethoxzolamide. We examined induction of MT and have found that at high levels of zinc and low levels of cadmium resulted in the expression of MT 1 in manatees. The cloning and sequencing of metallothionein in the elephant and manatee showed similar homology based on th e short cDNA seq uences. This elevated Zn level in the West Indian manatee is a result of a number of biological and physiological mechanisms which warrants further investigation Chapter 1 Chapter One provided background information on manatee evolution, physiology, and metal loads found in sirenians, as well as the role of carbonic anhydrase and metallothionein. Chapter 2 A baseline reference range was established for the West Indian manatee. Trace metal concentrations vary between manatee sub species and populations. There were sig nificantly higher Cu levels in captive/rehab ilitating manatees when compared to wild manatees, as well as higher concentrations in more urbanized environments i n Florida
238 than in the Everglades. Selenium levels were lower th an other aquatic species in the Florida manatee. Selenium was also lower in captive manatees which can be of a concern for husbandry purposes. The diet of wild manatees versus captive manatees differ drastically, thus, further analysis of captive manatee diet in terms of essential metals should be performed. Arsenic levels were mu ch higher in manatees in Belize; however, speciation is strongly recommended in order to differentiate toxic As in species Manatees have an elevated level of zinc in whole blo od that is found primarily in the red blood cells. There was no significant difference between wild and captive manatees As a result, we hypothesize d that there is a physiological need for zinc and zinc may be obtained from the herbivorous diet unique am ongst the marine mammals Chapter 3 In addition to whole blood samples from live manatees we examined trace metal loads in organs from necropsy individuals as well. We wanted to examine metal loads in various groups and whether or not there was a relatio nship between metal loads and cause of death. In addition, renal and hepatic lead concentrations were significantly lower in manatees examined from 2008 2010 compared to manatees in 1978 1979 likely due to the decrease of anthropogenic introduction of Pb into the environment. Manatees are sentinel species to the health of our wate rways with strong evidence that contaminant loads should be monitored to protect this endangered species. Chapter 4 Kings Bay, Crystal River, Florida is one of the largest natura l, winter manatee aggregation sites in the United States. Due to the historic concern of elevated copper levels in this area and our main hypothesis that diet i s the primary source of metal exposure, we evaluated vegetation species commonly consumed by ma natees with
239 concurrent vegetation surveys. There was a significant difference in vegetation species and location within Kings Bay. It was difficult to estimate the amount of metal consumed from diet, as manatees are opportunistic generalist herbivores co nsuming a variety of vegetation and it is suggest ed that stomach sample analysis be conducted to determine the metal accumulation from diet. From the GIS results, higher metal concentrations were found in the northern part of Kings B ay which suggests anthr opogenic influences from boat traffic coming into and out of the bay However, additional studies are needed in order to determine sources of metal exposure in the aquatic vegetation. Copper levels in aquatic vegetation has decreased from 1979 1980 and have decreased due to the restrictions on the use of Cu based herbicides. As a result, we conclude that diet may play a role in metal accumulation in the Florida manatee; however, there are likely physiological functions which utilize and factors which co ntrol the level of Zn in manatees. Chapter 5 Carbonic anhydrase is the most abundant Zn metalloenzyme in erythrocytes. Therefore, we hypothesize d that manatees have elevated CA activity compared to other mammalian species due to the elevated Zn levels f ound in manatees Unlike other marine mammal species, the Florida manatee had two isozy mes in erythrocytes which were confirmed to be CA I and CA I I by LC MS/MS. Moreover, the Florida manatee K cat /K m was comparable to other mammalian species, but was mor e sensitive to the inhibitor, ethoxzolamide, suggesting a conformation different from other mammals. The pKa also resulted in double ionization in CA I possibly due to additional histidine or amino acid attachment to the active site. We strongly suggest f urther studies in manatee CA structure, as well as identification of additional isozymes.
240 Chapter 6 Metallothionein is a small protein invo l ved in binding to divalent metals to prevent toxicity and maintain metal homeostasis in mammals This is the first study to characterize MT in manatees, with successful identification of cDNA MT 1 and 4 in the Florida manatee. MT expression in manatee peripheral blood mononuclear cells was sensitive t o low doses of CdCl 2 and higher doses to ZnCl 2 with peak induction at 24 hours of exposure. There were no significant difference s in expression of MT 4 between manatee skin from Belize and Florida. Metallothionein 1 and 4 to be present in the West Indian manatee with induction of MT expression exposed to CdCl 2 and ZnCl 2 Chapter 7 Sirenians belong to clade Paenungulata and are closely related to the elephant and rock hyrax. Thus, trace metal loads in plasma and red blood cells were examined in captive Asian elephants, as well as the identification of metallothionein. M etal levels, with the exception of iron, were significantly different in manatee and elephant. Metallothionein was successfully cloned and sequenced from the elephant and was used to conduct molecular phylogenetic analysis which showed that manatees and e lephants were closely related as has been previously hypothesized. Significance This study evaluated trace metals in the West Indian manatee comparing values from past monitoring efforts conducted monitor the health of the populations During our efforts to determine the potential impact of metals on the health of manatees, we have discovered an interesting physiological finding in manatees. Although we found that metals were not of a toxicological concern, they are un usual amongst other marine mammals in their
241 elevated l e vel of circulating zinc. Zinc is an essential element that is needed for growth and development, immune functions, and wound healing. This essential element may be obtained through diet wi th high levels maintained in the animal through a number of physiological mechanisms. We have evaluated carbonic anhydrase and metallothionein, but this is only a small part of the process As with any fine tuned animal studies a number of physiological and biological factors are involved in order to create a successful and effective system. Essential metals work in conjunction with each other and/or can be dependent upon one another and any deviation above or below baseline levels can cause a deleterio us shift in the system. Manatees are an endangered species exposed to a number of natu ral and anthropogenic influenced factors which may contribute to this shift in normal metal loads. Belanger and Wittnich (2008) stated best; conservation of species is most successful when prevention, rather than reaction, occurs. This research was performed to help management officials and agen cies monitor metal accumulation in the aquatic environment, as well as to further our understand ing of the physiological mechan isms of utilizing and controlling metal loads in manatees.
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272 BIOGRAPHICAL SKETCH Noel Takeuchi was born in Los Angeles, California and was raised in sunny Southern California. Her love for animals began at a young age. After graduating from Palisades Charter High School, she attended the Universit y of California, Davis, majoring in Animal Sciences with a specialization in Companion and Captive Animal Management and a minor in Japanese. The turning point towards a career in marine mammals began as a volunteer at the Marine Mammal Center in Sausalit o California and continued as an intern at the Natural Wildlife Natural Care Centre in Salt Spring Island, BC, Canada Alaska Sea Life Center in Seward, Alaska and as a volunteer at the Marine Mammal Care Center in San Pedro, California. Noel worked as a veterinary technician in a few veterinary hospitals, including Boldy Animal Eye Care, Topanga Animal Clinic, an d Harbor Animal Hospital until she attended graduate school at the University of New England in Biddeford, Maine. Her love for pinnipeds guide d her to work on her Masters in Marine Science under Dr. Kathryn Ono. thesis Harbor Seal (Phoca vitulina) Pups her self in the next chapter of her life at the University of Florida in Gainesville, Florida. Noel was in the Aquatic Animal Health Program and Physiological Sciences in the College of Veterinary Medicine under the direct supervision of Dr. David Barber Noel c ompleted her PhD from the University of Florida in the Spring of 2012.