Title: Sugar transport in the maize scutellum
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 Material Information
Title: Sugar transport in the maize scutellum
Physical Description: 91 leaves : ill. ; 28 cm.
Language: English
Creator: Whitesell, Joseph Henry, 1936
Copyright Date: 1971
 Subjects
Subject: Sugars   ( lcsh )
Corn   ( lcsh )
Plants, Motion of fluids in   ( lcsh )
Botany thesis Ph. D
Dissertations, Academic -- Botany -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis (Ph. D.)--University of Florida, 1971.
Bibliography: Includes bibliographical references (leaves 87-90).
Additional Physical Form: Also available on World Wide Web
General Note: Typescript.
General Note: Vita.
Statement of Responsibility: by Joseph Henry Whitesell.
 Record Information
Bibliographic ID: UF00097697
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000468971
oclc - 37786673
notis - ACN3671

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..- r 1r ,,:per ir. the if.; e 1.:utells.J.


1. UIL: F Tel <. I?1 F h l;'1 TED ti TH~E C:f Ls tIT L .s.IE t










100 10lP I:F FHI LOIPH,'I~


U']IVETIT I if FLC' C arL
I '1












P lI. IJOULE IGE n l lTS


The authjr IxrerZSies his since-*** rhaniks to- [rr. T. E. Hu.nIphre.ls

forT hir 41uidncz throughohut thr. graduote Iprogi'ri m and fo~r hi5 red ice,

pa~tiencei and help ;n conducting e...perimecnts and Tpjrept.rin the r-a~nu-

ECr i p.. It is j pleasure to ....*ork in h~iE IdjTlabor Tor bTnd ch;are h

e~quiprrien t. The hEp oF 1.* rs. D. S. IAnthcr,, F., L. 5irat h ;ind r.. H.

b~cggs a roalitta.;r~ i,,chllers ;s jlEC ajppriciated. The. Forjn= D department[















FABLE OF CONTENTS



Page

ACKNOWLEDGEMENTS .. .. . .. .. ... . ii

LIST OF TABLES .. .. .. .. .. .. . iv

LIST OF FIGURES .. .. .. .. .. .. .. v

ABSTRACT ,,. . . .. .. .. . . .. vi

INTRODUCTION

LITERATURE REVIEW . .... .. .. .. .. .. .. ..

METH1ODS AND MATERIALS . .. .. .. . . 5


Preparation of Scutellum Slices .. .... 25
Analysis of Sugars .. ... .. .. ... 25
Manomectry . . . . . . . . . . 26
Metal Analysis ....... ... ... 27

RESULTS . ... .. .. . ... . .... . 2?

Kinetics ... .. .. .. .. .. ... 29
Sucrose Uptake . ...... . . S
Ga: EvChange .. .. ... .. .. . .. 2















LIST OF Trs3LE J


abli page

I, lehod of Cajlculjting Data ,, ,. .. . .. 31

2. Gluicrt UIptijke jS e'ifated b, Ulrjn*,l
loa n thieBatlhing Solution ....,....,, LS

3.Fermrentct onl in Water And Suigar
:olutions .. .. ... ... .. .. .. S

4. Thc E ffec t o f Uran,1 Iri t -ae Pre rea t-
me~nto~n ~uci'c w~ptjCe ............. 56

5. InhibitiOn of lugar Uprake b, Phlcridrin ,. j3

6. The linhibition b, 00lP of Uptake fromi
0.0111 Eugar SoluIon1 .. ... .. .. .. 59

7. ljltose Uptne . . , . . . . .. I61

?. Thez EiFfcts of' Turaneose and flanni rol
ojn Sacro; e U~prLke . .. ... ... .. 03

1. Suc~Tros TiiSue Lee I and CSuirise Uptake~ ,, . O'r

10, Sucrsse Uptake a Affected h, Various
Cations ... .. .. . ..... . .. . 701














LIST OF FIGURES



Figure Page

1. Sucrose Uptake Vs Time .. ... .. .. ... 30

2, Sucrose Uptake Vs Time .. .. .. .. . ... .. 35

3. Sucrose Uptake Vs Time . ,. .. .. . ... 36

4. Sucrose Uptake Vs Concentration . ... .. .. 37

5. Sucrose Uptake at Constant Sucrose
Concentration .. .. . .. .. .. .. ... 40

6. Glucose Uptake Vs Time .. .. ... .... 41

7. Glucose Uptake Vs Tinie .. ... .. .. .. .. 42

8. Rates of Fructose and Glucose Uptake
Vs Concentration ,. ... .. .. .. . .. 43

9. Glucose and Fructose Uptake as Affected
by Uranyl lon Pretreatment ,. .. .. . 44

10. Uranyl lon Pretreatment ard Glucose
Uptakte . ... .. .. .. ... ... . 48

11, Cluroze Uptakle at Constant rCo~ncntraton .. .. 50

12, Fi rre n rjt i on i n r Ij e r and Su; r ose .. .. .. 6b

13. Gas E chjlnge in r'jucr snd 0. 111 Surore ,. . .. 70

IL. Cjf Echangc in riata ,-ndj 0.lrIGlucee .. .. .. 7l

IB. Ecccr.ercatson ir. Eve:lar :Llurion .. .. .. .. 72

Ii. r~crsl tsin.~lr.:i ..............,.... 75

II, Effeci of Urari,I I;n Pretrtr c rncir ConrcLntra-
tiojn or. Supr Uptake, .. .. .. .. . .. :7

15. Fletal Einding Fo~llrow~ig ar. Acd P~ctreateentr . .. 78






Abstrjct of' Dircertation; Presenred to the
Graduate Council of the University of FloridJ in Parr;al iulfillImen~t
of the P~equirements for the Degree oi Doctor of Phillosophi

SUZG'.f. TP. USPCIFT lu, THE 1141:;E SCUTELLUM;

B;

JoscFph Henr, Wn~tosell

June, 1971


Chairman: Dr. Thioma~S E. H~umphre-:s
Major Deparrreeent: Ecn

Characteristics of the uptaki- of sucrose, gluicoe and frucloto b,

maze scutellum slices are pre~sented. CSugarj Iere taken up at alm~oi!

a conrstnt raite until thej bjthing jclullo~n wal depie.edl e.cn at co~ncen-

[rations+ u:11 belou those whlich saturated the uptar.0 rmechanirms. Th

effect of DUP1Y, phinf'idrir, uran, I ion, jnd anor.io twas to ir.h~ibit r e

uptake of ucrorr e appro-.ii satel mic a~iE s bmuch as the UpEra ke ot h;hl5se.i.

Malrics wasr talen up wi; hoiur hydroli sis. TurCAnoSe I-.i1 not taken up

but slighri, inhiibiced the uptal.r of jucirose. The following conclulsions

are c~r awn. (a: Eucrore- is taken~ up -jCrivcl, aithiout in.erjion. (b)

Hesxose; are taken up bi 1'0 pr3 ~ocesce operating Simultadneou5i,, dirffu-

sion and cci'..*e transport. (c) The actise uitake mechianisms for sucrose

and the he.:-.oses arre locate at the plasmalerr~ain (dj The acti.; uptar."

mechasnisrms for bothi sucrose and thL he>;ose5 are driven by glicrlysiC.

(2) hotel binding chiarac reristics of the scutellum art different from

those of ;east in that binding is not specific to the urptaker rtes and

bound ralttal ionis aire apparently not released during :ugaJr uptalke.


















Much research has been conducted on the movement of sugars in the

cells of animals and microorganisms. Stein (1) reviews this work in a






p~ljnE?, jrn.; ,r the Probt le.. is I:jhtrj l II0 [hi L..II r~: L rldin3 ilf plinE

ph,.CIMAt least it.. rcsprcr ;c. h;lhcr :r-3.n;:r~:I;i th.. re ..Trt orr



;) up :.-.1 c.-nos acc.:1.ride 12 Sucrose 'i 1, Fir the ireson .ii:Crver

st...I ib .~i~lr i i, rr- ,.10 -t d .. plan i [" IId IL.









rea.o :I ~ i:: ,*5. 0 .;r uni lil I: IIIln:.n-s of ~Ch.-- [rITI:.s.5 of 00 e.-:







su r: pro 1 .se .3irth iU.. Lhd th Lr I:E.i: ?nh:...~T~ rt ::in ii( i reser


Fr~lia c r ~ ~ ldl, 'Ir *:ced:,; fru l- .-cor and.lP:.ter partE of lj ants-~ J h)L are-


I NTRODUICT ION







neeir;al to supprrt juch concepts ir 50.11 grear.1, inedcquar-_. ILc iljo

5ta!Cs that the verry exists.*nce of~ c`rri rs has not: tie1 pro;.cn.

studir?5 or BiideSki (:) orn the~ acculrsulation of~ sugars b, plhlolm~ L1ssue

jdd support to th( CO[Lncentin that an acrlt., mostment or su~croSE ;s

probabl, a part of phlopm transport.

The rrork reported herein wa~s underrtake:n rrO 3-in a better ulnder-

sranding or thea process ofi sugjr uptake;,, espc~i;Jlly t."r.;t of ucrTe.

Several .h-racterscists makeZ the c..rn ;s~cullum well F.II;.:Jl for Lhe.

sHudy of iugar uptake.: 1,.3) Ths uptak3 of sucars is real oilorwing



in rhe- Form of sucrose rather rhan~ itarch: alucsse :s not -accur~Iulated:

(c) there ij nro aJeinJ phenomenon durirag which 4n adjustnerr~t in thr-

reSpirtory rT3[ ccurs;~j jnd (0) mOrphologicall,, the scutellun i:

leaf rissua which functions ir. cha mosement. Gi sugar r'r001 Ehe end~~iperm

to .he Je.loping seedling.













LITERATURE REVIEW


Several systems have been described in which sucrose is taken up

without prior inversion.

Weatherley (6) measured sucrose uptake by floating leaf disks of

Atropa belladonna on 10% sucrose solutions and taking dry weights be-

fore and after uptake. At times the amount of hydrolysis was very lower

and the amount of hydrolyzed sucrose in the bathing solution varied

independently of uptake. Whereas pH affected the amount of hydrolysis

it had very little effect on uptake. The amount of hydrolysis was

greater whien older leaves were used. Washing disks prior to treatnment

decreased the amount of hydrolysis. He concluded that sucrose was

absorbed as such. He found (7) that the uptake of glucose and sucrose

on a per mole basis was nearly identical.

Iweatherley (8) also found that the uptake of sucrose wras revers-

ibly inhibited about 75% under nitrogen. He followed the loss and up-

take of water as well as dry weight and included a discussion of the

osmotic situation prevailing in the tissues. He concluded that thle

uptake of sucrose was probably an active process.

Experiments by Pennell and Weatherley (9) showed that sucro:- up-

take was in~hibite-d about 5070 by 2,4-dinitrophenal (DNP) and not at all

by phloridzin (both at 1 mM). In this paper the amount of dry , 2.ht

increase was shown to be caused partly by an increase in s ar;se.

glucose and fructose. The amount of increase not due to th:.:- siy r

a 5.1 jssur.. *J t h. .: E .(. st -ar th ferrat ioi:.- s= .t s g F r..






aenou~nr of .insight inre.=.*~d rr:. jlas due ;o starh ;t w93 iArluLed thatL no

"uphalll" mrjl~ncnt. of sucrore need Occur,

Pojrter a4nd liev, I' 1) wo~rrked rwi h to~bsico leaf disks~ jndi measures

uptake, accumulation and Lgaj errhange in SE solurio~ni of juccose~ andl

in.*err sugaJr. Wrhen ;nterE 5uqrr was5 supplied, ?luicse dis3F~appeard a

3 faster rate thiar. Fruirtose. InvrrE sugjr cjiusedj ~a re rapid a.:cumu-

latio~n of starch than did juCrjse. The totajl uptake~ ojF 5ugar vaS [he

samie wrhethe'r indfrt 5Jgar Or SUCTCIse w35s Suppl;ied symual

late led sucrose could be r~co*.red fromn the le~af disks jfrer bei~ng

jpplied in the~ bathing solution ;hroling that juirose could be taken up

without ;ns\erjion. Thla! around ,n PQ? oF 0.74 du~ring ixubatiojn of tijjue

in varer, but this ;Increased to aboute 1.1 when [he Lilsue' was incubated

in ?ucrose' or he.*ose. The speCi fic ac t i it*I Of th;- CO2 c.o=.ed was5

about Ihe jiame aS thjt Of thC applied iugar leading thrm ra belireve

rhac rhe Obser~~td rate of gss l.changz .-jos noi the result of a hiigh

rare of formn.tnacior soverimposed on the 9.3' exrchange" i rraterl. They

ruggelead~ rather a crhif[ in subjrrarste LO~ Suyr win j,...prs wrCe jddedd

to the bathin3 solcrion.

Viccer: and fIerrcer (II) studied the urt'l:.? o' jurrose by bean

lea tee.-.The bjrhir.g Iolution contajined1 e-l; Sucro-e andj a !rjce

of fractateC jf t incubation, in';:aring that ex.trartellulj r .r,drclasi s

..Ja= ;mall or no~neiictnt. Wrhen tijjue sampFles Nere ant.lued .roit of

rhe Sugary woSS Sucrose I*;th small Snounts of reducing sugars present.

Gas e.*.changel was5 measured jnd1 rh-. P.2 increased fromi about nS to I.0)

r.hln sucrosee was Addd to .he barhing solution, The notiiced a liner

phase2 of jucrJSe Iip(? e wirth lime2 despite large~ concentration diffe-r-

ences in the bjfthJr jcj].jo;in. Tht ste.ao l ract ofi jsaro~se uotae Iwaj







about 9 umoles/g fr wt hr from 1% (0.028M) sucrose. An inhibition of

sucrose uptake of 55% was noted wi th 2.4 x 10dMW DNP. Uptake was mnea-

sured over periods of 8 to 26 hr.

Vickery and Mercer (12) reported increases in 02 consumption upon

the addition of surcrose that were of short duration and independent of

concentration. They stated that the rate of C02 production showed no

correlation with the concentration of sucrose in the external solution

(and hence, in the free space) but was strongly correlated with concen-

tration of sucrose in the apparent osmotic volume. This is used as an

argument that the sites of carbohydrate metabolism are included in the

asmotic volume for sucrose and that part, at least, of the cytoplasm

is included within the membranes involved in sucrose transport. Su-

crose accumulated against a gradient and the initial rates of sucrose

uptake followed a concentration vs uptake curve adaptive to Michaelis

and Menten kinetics, After several hr of uptake the rate decreased.

This decrease was attributed to inhibition of further uptake by sucrose

inside the cell. They argued against the possibili ty that sucrose

pumps occur only at the tonoplast.

Hardy and Norton (13) studied the uptake and utilization of 14C-

labeled sucrose, glucose and fructose by slices of potato tubers.

Glucose was taken up faster than fr-uctose. All three sugars were found

when untreated tissue was analyzed for sugars. It was suggest--I o,n tha

basis of the labelina of various intermediates that sucrose wa- asre.

unchanged and transported to storage where part of i t was hydro~l,:-c

resulting in storage of all three sugars.

Sacher (14), using bean pod tissue, found an extracellules ;I

o~uter p;ci ..-,.:rr a~i c ..n e- ricd .cas~n jl I n i ts activi ty. Hot-rei .-c







suiroie uptak~e ass njLe depenldent on in~tertsiF act..i C a; Snealrn b, the

obser.ation rhat :Jiose wajs taken up in rth abse~nce of ourc~r :pace

irler tose a;t; vi ttl. ClucO-;e uptate <--.;; thre times as5 Ifat J: Frur. CoSi

uptakte from 0.030l solutionl.. There L4-Sa no aiitct o: 10~ t o 10 'tI

uranyl nitrate on uptral.e ofi 0.0?11 glucosa or sucrjas. The Fact that

Sucrose~ wajS tken as as 5suich.j jlii als~OhST[ deosr trd bySholi~ng thjt the

giveme/frucT~i tose rljdoiour i .It rtjio kzs l iti ct:hajngd b:; Iiptjl.e a~han

us ii n, fruc tose -labr led SuCrose, Uni forlily labeler d sacrose relmaincd

unifo-ml, ljbeled ic .n in the presence of unlabe led fructose or glucose

in the~ ha .hing solution. DlrfP (: n 10- 11) inhtibied uprakei from 0.0003Hl

jucrosc 6b ,and ircm 0.0!n suc~ros e 881, In Freshl; cut !;jssue the

endogenous Sugun5 cnisted4( lajrgell of glucose a-nd :ruicts. dnd only

trjici jrounts of suiTrOe. Upon incubation in sugqar silurionn juc.-esee

Wji storedJ, apparentl i ini ths .acule, and the suloC.C/reducingnl jllljr



wrLd the sucrose .-as hyorollzed and the r~tic rjreiltl decreased.

jacher jrouei on cnhe bjsjisl ofSe.eral linesj of I::;jrdence thb[ L:-a rate

l im' rin1 5 tp in hcrose uprake lilj i n Ehd Formjtioi of ;uCTC;2 ind

that the cit~plicam iS frae space to the ta.(ese.



In the gterminating~ :astor bcan, suirose 15 syntrhsi.zed In the; iidospirsT

jt '.h e apensi of ijt. Thr suicree is ca'-.en uoj b, the- ijt**lldon5, and

It ii transplorted- fromr thean into the de.elc~oing ieadlling ar;s. In the



lui... Isest of thr .ugar~ is in the iorn of ;Lucrose with ..irtu-lll ro free

Iietuies present. h;heds ner.pa-o oreriht b

th~e rotyledoins and' suc:rose .>a accurT;ullated aginer olCentl. tion







gradient. DNP partially inhibited the uptake of sucrose. Sucrose was

shown to be taken up without inversion by several lines of evidence

including the retention of asymmetry of labeled sucrose applied in the

bathing solution. In this tissue sucrose was taken up at a higher rate

than either hexose and, more unusual, the r-ate of fructose uptake was

considerably greater than that of glucose uptake.

Kriedemann (17), on the basis of microautoradiographs of castor

bean cotyledons exposed to labeled sucrose for 20 min, suggests that

the cell walls and intercellular spaces provide a diffusion pathway

by which solutes can gain access to the vascular system from an external

source,

Kursanov (3) refers to work in which it was shown that the fibro-

vascular bundles from sugar beet petioles took up sucrose, glucose and

fructose but exhibited a much higher affinity for sucrose.

Grant (18) studied the JptakC of glucose, fructose, and several

other monosaccharides by carrot and corn root tissue. Some of his

results were as follows. Carrot root tissue exhibited a )ag of several

br before uptake began. The uptake of glucose under N2 was less thouI

2E~o tha in ir.He sho.--ad that Jlucor entcred the ice II re jccu-

v~ulated as thc l'ree; sugjr jgjinst .j conecnrtrjrion gradient~. t l-

i'Cas co-~ernicr.11;Cr in the carrOI. ti5Clle oC~iEedd 1!.0!5tt j51C.rir~3 Squjl

d i r ribu! io~ r; aLh.;r [th ire: h us5 i ght o:f the t i .u-. Uptated of glueseI.

rroceededj at j conr rant ratec from~~ 0.0010II sclutionn urst" the batting

solution ~ ~ l ase-as e.H how' e Ehjt th~e ur Eal e OF 3luiiGSGI )nrJ

:e*,e~ril nwhrr csuaors folion- uFptake .: Concen[ trat~C1Tio curse accrdi

t~ liichi eiI ar..i rfierer r, I.iraticl.. 110: did n:t ferii rc. be co~n.; rni d

w~ith rth facr that! a coni cant irat c.1 uputjle t*Jih tiii6, in Fpite OF i






declining sugar' cor..:"'retra on, i r incon sir E::n t .-ai h reactio n~ ratci. ;a

pred~i ted t., rlchaeli5 anid hcntrn k;itt i cs. The mar i nes. ra r-i GI

surgjr uprjl.e b*; carror d-isc; werer frorc 3. to 10 unnolclc*'g b~r and frGD=~

corn roots sure 1ro.0? to 24 umolc.'g br (1 l. I t wa ElIcO:.n th;;t in

carrotl t;Isue the repIredT~ CO., wasr der;.*d preferrentiall*, fror, thi

e nte Pran I sjiuga r L.

Apee..s jnd Eee~ers (203) userng iarro[ and pOtato slices mieasured

0-, consulptionl 3nel C0-. ev~Il[olutio ;i r. o (0.5 umoles m~i) cor~c.-nrati;. ns~

of glui'ose, Thle T.Q did noj :..ar,* Li r.irr fiicanti ,l fromn ..aci: jnd the

addiction of glutose did rootL induci iign~tf cjnt changes~~ ;Ir 02 upruse or

C02 cutpu?.

PE i nihold and i~nhar i 'I dtlror.5:ra~ed ;in jci rie uptak~e me~chan nis

i n car rot root tIssu wC\hic was capal of~j atCI CCrIITmulat in rl -o-meth-,*gl('1]u-

cose. TIhe rate of uptake~ of ,-o-r..ath*,dglu.:ose -.-.ried uith con~ce.-.ra-

Si on approxima tEly a; pirtdicedL b iiichje i njyd fIern itn k~i netfi cs A .

a period of uptal.E the rirnue \ia rinse~d for !0 min ;rnd Lther plactJ in

uater and a concentrationi ratio of ;5: 1 ras mjirtair.=d britsmEn theI Can-

centrations in the ticsue and a-.ele. Chron.oOrlgraphy and jnd lis oif

C02 i ndi cj ed rhat r -r -w thlg iacose rra not ~~ rnetaolIized.

Harley prnd Jeranirage (22) Studied the uptake; of jugari by. becch

mycorrh; :as. They fournd that the~ rate c*1 uptak~e *. concentration

curses for glucsejs and fructo'e formed rectailgular h**pertolat butr the

shapes o~f thi curses wcre different, the m.iir:mum rcat for fruCrGle

bi i ng h;9ghr thar the me..imium rate for gluicesc. In rlhi; rssu ch re-c

is considerable hydrolysis :Ihen sucrose is supplied. iPmrd,

i nh ibi td the abjOrp [i on oi: he.-.oi-.i. When lnoitures of glu~cose2 and

Sr uc toid~ s-tre ;u~p pi ed g lu~c~te w~s prefeiren t;i I ly absorbe-d. The

addition of sugarr raused a re:.pirjrar, siuaie n rmeuooa







concentrations the stimulation caused by glucose was considerably

greater than that caused by sucrose in spite of the fact that a roughly

equal amount of sugar on a weight basis was taken up during the measure-

ments.

Mlorgan and Street: (23), studying the carbohydrate nutrition of

excised tomato roots, found an RQ of about 0.75 in water and about 1.0

in sucrose. The root segments had been starved prior to measurement

and the uptake of 02 was stimulated by the addition of sugars. The RQ

of root tips supplied with sucrose, dextrose, galactose, or reffinose

was within the range 0.90-0.96. The endogenous respiration had an RQ

as low as 0.70 and in mannose as low as 0.60.

Thomas and Weir (24) measured the uptake of sugar by tomato root

segments from solutions of 0.05M glucose and 0.025M sucrose. It was

found thjr mord~ Suqjr Co i rriighl basgi2 Irj Ejiin up arh;r suirOlt \ ii

zupp~lied! a co~mpar~ di to ucO-;t. Sucrose ii mortedI; SUpCTrO [r t

gluci.Zd ini 5urpoT[r tJ ng gro[h :I deCi fed [.:rnl.m l roo:[ .

Whenr radi Ih rec.([ ilicGE firr IFICu~baE.1 ir. Euiroie thereT if i COF.i-

-ider~abl. jmmount of :.
a hoerh~ or nojr 3-, zucrczC is t aler. up a 1 ho~ut ;n.trilon. .ac~rose at

0.029tri and 0.i05rf 1 hroh rirnulated the i-.luciion ofl CO, und i t rw-- rug-

cie_ d F.MEr this vjs duc to~ j ;1Uturade..i ofi respirT~jOTrZ, enz*tn

BIald:Ci (5) areasurtd the upukel; 01i iuiirot b eciterd .cEcular

buindle: Or phI~eile thf~ue: iriii a *jiC.rit* ilf plards.. II. appFl- phlomi

and celtr, .Jc'uljr bundleCS abou~ ;C.~ .0l [r. of L6. th ptk rom~ 1 1 suirose

could bei fourid ir. the- til.ue ii [he form of :u.:rose. ureupa,

irom 0.0031 andj 0.011: tolution, proiedLedd at 6 priogressi-.el, skwarr

race until rhe e-.:er nal sollut;ion contaiind abou[ 10: r of h- original

amoT~unt iof Iucre't.





101

Sucrose waSj takeni up, jgainst icncsntration gr..Jlents of the jrdcr

of 103. Thi ,rates o accumuljtionn t. .aScular LbundlL'; cr phlocle ti;s be

weire muCh higher th~an rates b; pjreracn,ma froml the samie plant. Vsua

cissue jccu-.aul3Led~ Microse at ratej of J to- 16 orales.i'g El- vt br from



P-i.haldJ aid Ellsion (2.; addresled. the qlucstion as to *.*hrether thr:r

wajs j difiusion barrier bet.-seen irternal jubstrjt: ~nd i i~es of resps-

rur.The ,* applied SurnilOw-r hrpojCot,*I segme~nts usi r labeled :3lucose

o~r Iluitamric aci.1 lrn the preihhnce or absence oi 00N ar~d liCO3Ured thC

total jnmoint of i.12 r.ol.id and l'd spec Ii I ac ti ,i t,. The,* .uibj ected

the data tr lrerlce arsalysis and concludedj that !here .*:35 110[ an affe~c-

ti-.c d; ffus~an barr;er beltween thel eaternal subs~rite and! thrIe '.s t

ritich jubjrrates Lre res.pircd. n lt ra a ie I re-a n

JU-'t possiible, ho.ae;er, that sorch j mechanism L(act;i:e rr.miip:.rC) d~f

oi"erate in Use- ;bsen.ce of EdIIP, buc that in its presence !he irrojecules






Euga~r car~e Ic probat.1,~ the ii.ost .tudJied of higher plints ,n

regrdsto uga naecets.Biolass.. (27, p ?i00) state the uptake.

prole a fales:"...IL was~ (cun.1 ihat d.:iI:. i f ju,3di jltr [ I IUC

plj:.d i7 acrarted de cillEd .vate, lus. **er, lircle of their enjogenousi

sug1-r to- the *,ater. Tniis e-ither the~ toniopiast ir retr.:mel.iprm.l

to :ula.* c~.oge..*:r. 01 rhare I Le aC'ri acumuiLatin trach~?ljm in the tell

which a~;...i.el oppose:; the Cui r.Trr' Jlrrusi;nal mn*.ement of iu3dr.

The firot is per~haps r!h. jlapJ.p r Cplanatiucn, but ra~ier the irotica.

o: r-plaJi n i ng not. the rougar c r ignl, be,~ II; came arcumu~ilated behi;nd thle

iniptermeable tOnorljst."






Sugar cane exhibits a large, rapid (1-br duration, 8-min half

time), apparent-free-space uptake followed by a slow uptakte which can?

occur against a gradient and which results in sugar accumulation. The

accumulation uptake will1 proceed over a period of 72 hr. In comparing

rates of uptake of various sugars he found that glucose uptake was mtore

than double that of sucrose uptake on a molar basis. Uptake of fructose

was similar to that of glucose.

Bieleski measured respiration during sugar uptake and found an

increased 02 uptake upon the addition of sugar to the bathing solution.

He does not mention any change in RQ associated with sugar uptake.

Bieleski (28) found that sugar accumulation was completely inhib-

ited by 10-SM DNP, Phloridzin at 2 x 10-3H caused from 10 to 80%/ inhi-

bition of the uptake of glucose. Wlhen tissue was prewashed in 2 x 10-3M

magnesium chloride it caused a 0-20%/ increase in the amount of glucose

accumulated. Double reciprocal plots of sucrose, glucose and fructose

uptake rates vs concentration yielded straight lines (29). The Vmax

reported for sucrose was 0.7 umoles/g hr.

Glaszlou (30, 31) suggested that the outer space consists of the

cell walls and cytoplasm and is in diffusion equilibrium with the ex-

ternal solut ion. "Hence the cytoplasm is part of the outer space

where outer space is defined as the tissue volume which comes to rapid

diffusion equilibrium with sugars in the external solution (the outer

and inner space for this tissue may be quite different for solutes

other than sugars)" (31, p. 178). Tracer studies showed that the

hexoses in the inner space came from hydrolysis of stored sucrose,

Hatch etal. (32) reported on some of the enzynies involved. TI- ,

report characteristics of sucrose synthetase in the direction of su-







rose 5,n the~s;s. / i ~cti titi n th- rie-. rse J Ireci Ion coulId notr beL de-

Eccred becauISi. 3' thE presence or i phosphcetsse which r pidl, hl;Jrol; ic

UDP to UJMP. Stidence For the prrtsence of SUCrG~c--P 5,ntheLr.i 10 wras pre-

3enred, and acdJ jnd jl kaline in.ir Ljces ...reT dcr~CCTbed. The;, couIld not

f indr Sucratre phO ~hor* I as,] En_-jmes for the C,ntheSi-,, ir.te~.rce~n.*ersion

nnd breakdiot-en of hccoce phosphst tes erre identified. The Jamounts 3f

scld and ilk.alineL in'.ls*F.35i S .jry wri h the growth ruC and~ Zhe SUCrose~

scorarge rare (.33) suggesting a 1.0,? role- for insecrt.ise in rejulating rhe~

meo.esnen[ and utiliijtion of uCriioje. Sjcher ct al, (34) p~resen~t a

schemer for' the sugar jccurnuljtion C,cle in immirure 3ugar ceni. Acid

in.ertate occurs both in thce outer CpaCE andj rhlo jtorjgC iC~impa1rtii l'-nt,

Sucrose is h ydrol,-- fd prior to up[JIkE. and, glu~coJ i:. [al.en iip SC..ral.~

times~ us Last as fructose. Sucrose is re-leased tro.T. ;toljgge .;a

ht~drol,sis 0..3 dif'fu'.lon of the booses~t Outt of 3iOrage.

Ilatchi (35) dc--imontra'ted rhe pretence oi iucrose-P syntheta~se in

bjoth lefi andl storage tissui of 'ug-r cane. H!e also showedJ thL; 5,r-

thesis; of Suirose-P by tisslue supplied .4twil luccee. Scoea

r tored nmore ri-pdl, fewii -uirose tha~n froma suerose-P an~d Irere rjpid ,

froml fructose~ th;n r m :r3~ iucrose-P.. Thi5 ic CongiStrTCent~ wih t prop-

ojitionn thjt sugar phaseshares do not penerrat iembra.ws~ as eaiil, as

do non~-phas~osphor~lat suga,-s. Age~nietr, of labeled Jucrcse -a~s lo~st

during storage. Imrile onl/ :Inj.ll qu~anLt S of Sucrose~ --.er Ctored

wrhin iuirosc-P \*.J: supplied t~he s-mmetrr of labell wa: large lly na-in-

acie.Thi-; w-as coil. is tenet w*i h a sc 6.10 or, a-hichi ;ucro ,e-P is

formedc b\ thei actioli Of rucroseC-P c,ithetse ;Ind 5uiroseC i5 stoed

jgainst a sucrose :orcentrraicsl gridiene *.ia the hiJrolesi; of suciase-P

to ;ield Sltored iucrose.




13

in further support of such a scheme Hawker and Hatch (36) demon-

strated the presence of a specific sucrose phosphatase in sugar cane,

carrot roots, etiolated barley, oat, and pea seedlings, parsnip root

and potato tuber. The enzyme was associated with particles which be-

haved l ike mi tochondri a duri ng di fferent ial centri fugat ion. Mend ic ino

(37) had earlier described enzymes in wheat germ and green leaves that

included sucrose synthetase, sucrose-P synthetase, and a nonspecific

sucrose phosphatase.

Hawker and Hlatch (38) present a scheme for the mechani sm of sugar

storage in mature sugar cane tissue. Evidence was presented to show

that the hydrolysis of sucrose is a prerequisite to storage and a rate

limiting step. Mature cane tissue contains an acid, wall-bound inver-

tase and a neutral invertase apparently located in the cytoplasm. The

storage compartment invertase found in immature tissue is absent in

mature tissue. Sucrose storage takes place more rapidly from hexoses

than from sucrose. Uptake of both glucose and sucrose as a function

of the concentration of the bathing solution had the kinetic properties

of an enzyme-catalyzed reaction. In studies on the localization of

ctlr, fir; ii e-r-.. foun j rlh.-lit .mos if n~o[ all of thef Iucr oser s,*nthat-.jse

s.=ar loca ted ir. rhe condulcr ing tiissue, .srd i r i.' poiin ted out th3t i t



Hatchj an ljridou IJ7) prtltented direct evidenic th3e sucrote i.

thet prudJo~nin=.at mornner~lrrs of traniloCatc d pjhow~iiTrthjre ilc. :ugarj care.

71.- jsi.nrncr ofr Ilabelrd Iucrore Ius. .ma~intained through theC siculjr

tis~c v th la. chath and.ter..Pardonizjtion did occ~ur duiring



3iche-r (40)) p~c~rll.cotd -.. .-ar!.-0.nln for e: [TractioPlelrnic I1ucro..




14

Unthesis in the bean endocarp. He supplied UDPG and labteled~ ructose

ind obtlained sucroise ;n wrhcich the labl *r:- predomin~atcly ;n the iruic-

lose moler,. Exper-imennts alrso indicated thE CprcencCe Of UDrPG pyropho;-

ph~or,ldse in the ex.tra3c;[ioplasmic spaci. \lthn latealed fructose nias

sulpplied and suicrol synthsisi occurred i r. he citopls asm~ ;he 1 glu-

case/114C fruitose ratio was apprsroimatell one; thi; sucrose remin~ired

in the tissue e'.Cn aftlcr eve~lnsi-.e w~aching.

B, usinS aceton-extracted chloropljsst from ugjr cjne-, Ha,, and

Ha~Sid (4I) wlere able 10~ ShOu the srnthesi5 OF Sucrose-P fromi UDPC. and

fructose-P and the synthesis of su~crose fromi~ UE=FG jnd fructosr:. The

preparjtion contained phc.5phatajses that h;Jrolyzedd sucrose-F jnd frac-



Schoolar and Edeliia.n (L2) mieasur d stcrete~d iLugar, CO., fi;xicn,



ficated oni \ar~ious solutions. The amount of sucrose rccreted intLo the

bathing solution wasr ineirsease by 10 ft s~odium lodoactate (10-'.

About one-third of the E0E81 Eucrose synthlsizcd during .j 4-d.i, period

ras sre re ted. The ;nh~ibi ter caused no change in rhe- amiount of soluble

sugar \,ithin th-e dist.s .nd i t caused an inrcrsi in the amount of total

soluble: phorns,~n:hate produlcrd. Faspi ration leasurcd in the J.ir).

shoved an FQ of considerable less than I.0 snd this wajs reduced even

furherby 0A.Otherr respiratory inhibitors did not ilicir similar

responses.

Mlany investigations hJ.te been made ol various cn;~mes in~ol:ed in

sugar translorm tionsr~. Onl,; : few will e ment~ioned h~ere. In h-is

re,ica arricle on jugar transfori..ations in plants, Hajssid (Iy,) jis-

cussed the chjracteristics of sucrose SlnthPLjSE anid -ucrose-P c/n-







thetase, the two enzymes most likely to be involved in the synthesis

of sucrose fromn glucose and fructose or from either hexase alone.

Putman and Hassid (44) studied the transformation of sugars in

vacuumn-infiltrated diskts of Canna leaves. When labeled fructose or

glucose was provided, labeled sucrose was recovered which was labeled

in both hexoses; however, no free la'oeled glucose could be found when

labeled fructose was provided and vice versa, an indication that sucrose

was formed via phosphorylated hexose intermediates. When sucrose was

provided in the bathing solution there was rapid inversion of the su-

crose with the appearance of hexoses in the bathing solution followed

by a resynthesis of sucrose within the tissue.

Cardini et al. (45) point out that the equilibrium constant of

sucrose phosphorylase lies in the direction of sucrose hydrolysis and

that sucrose phosphorylase has not been found in higher plants, A

study of the characteristics of sucrose synth~etase from a variety of

plant tissues is reported. The equilibrium constant, K = (sucrose x

UDP)/(UDPG x fructose), varied from 2 to 8 at 370 and pH 7.14 in dif-

ferent experiments.

Leloir and Cardini (46) studied the properties of sucrose-P syn-

thetase but point out the difficulties caused by the presence of in-





IG

ber.tween sucrose conrent jnd jcid ins~ertise actritic,. cdinets

ac Cini; L: .,j high .~iur In3 cr~nas of hi h sugar usage snd 1-.r. dur ingl times

o~f hiigh -ucrosez sto;rage. The, sulggest that~ high i~ver~tueS aCti*ity

pl~re.n~i suirojSe -.Lorage and1 that during periods of 10=;1 hc ost: dema-nd

hydroljjts is due toj ~)alkalin ;ra=ertaic br-;hch ;s not, assoC Dscd **;ith

the ..acuille but locrated in rlhe c*;top~Fleam. ;he; jcuggenr rhat rhe -acidj

Inerrrl se ;j located ir. [hS rrll and~ ;1; the tienopl jgt.

YKurianl. ct al. (4j) ;omosied the locali4liat~innd p~r...erl.ies of'

herok~injje .rithl upatak chjrscterisre c~i ofco~~~cndutn rirsus ircAln sugar

bee-t. TIhis lissues takes; up glucos~' e rust!sr th:lrl irructjSF andc ihe: boIXi-

kinese- jssociated vi ch the; sru~ctural 2lements~ of the rells h:1s a highe-r

afillnit, for gluCcje thjn iiDir frlctose. On rhis basis rhei ;lugge~st

that. he.,so.irase on1 [h-- ilmemrin mre m be part of the uprej'.e process.

The uprjke o; sugars :nd~ the Inrsetl binding choairacteristcs r

;ee,[ I-avre been Srud;'ed ;ntensi.ely.

P.0thst-;n (5Sr' ~resents~ s.eral l~ines of~ e.idenTce LO sh;eu that[

uranl icr. aifecits the up[;Ike ojf glo-ICose I0, east due to: ;ts bihinfrg

to-. rhe zurface and nor io an uotake~ into the iatoplarSm of the Ce 11.

Rathsrtin and Mcier 151) describe the com:pedE~c on fr urBan,I ;or, b;-

rrran thre :east cor~plrrming Ir;:; .arrd rar'ous~ c;.-le;raq agents 3dde*Ul ro

the baithiig solution. On1 rne basis of rhis ..,rk [he*; cond.uded th::E

the" banding sires on the suresee 01the east cag[ Cllj rere pal~pr ophaaces,

UJ~;.-aii.. blrck.l jbour 40~.; jf the uotie of glucose in ,part I50).

Se-.eral other iorions, iincluding io2 ng Ci *,nd win ,trdt

rhe s1 'aice of y/fdit ells butr ujrarl ;or. fOrms ? much l.cori stable-

romp le- 152). Data ..ere presenr-. to Shiou r'lat .hreas~l thC other

cations rere bound to the ina ;rne sic hjt b~nrd ur n~il lon, rhG,- did

nMr Inhibit the upr!tak of 31ucose.;






Data showing the amount of various ions bound to the surface of

yeast cells as a function of the ion concentration are also presented

by Van~teveninck and Booij (53). They showed that in the case of

N2+ or Co2+ when glucose was added to the cells the metal was dis-

placed from the surface of the cells and appeared free in solution.

When the glucose had been taken up by the cells the metals were again

bound. If cells were first poisoned with 10A and then supplied with

glucose a small amount of glucose uptake occurred but was complete in

15 min. The amount of glucose uptake by the poisoned cells was the

same (on a umole basis) as the amount of uranyl ion bound (on a uequiv-

alent basis) by nonpoisoned cells. It was possible by adjusting the

growth medium to vary the amount of phosphorus per yeast cell without

causing irreversible damage to the cells, The amount of uranyl ion

bound and the amount of glucose taken up after poisoning were both

reduced in phosphorus deficient yeast. 'There was a good correlation

between the amount of uranyl ion bound and th~e amount of glucose taken

up by poisoned cells. When yeast was poisoned and then provided with

glucose the uranyl binding capacity disappeared. The addition of 10A

alone caused a 50%0 inhibition of cation binding which could be reversed

by washing the cells in water.

VanSteveninck and Rothstein (54) present an argument to show that

in yeast, sugar uptake can proceed by facilitated diffusion or by an

active uptake mechanism. The faci 1itated diffusion systerc-c r, bei

demonstrated wi th gilj; rosec upr jke~ by uni nduced cel ls and e i h g luii:e



thnl Cneryj re please b, !l,CC I,si. i r. sire of~ [he f at that gluc65i






,s~stms are diff~erent rrlth rellpect to I[Jln bind~na, iclFcr o fi. on;:

upE.-rke, concentration-, of uran,l ion requirid to ir~hitbit uprjake, k~inetic

psramerers, and pjtterns of pecificiti.

Fothui r n Andl Vanirtevennind : () sulnrnarized wrork. donc on, uIprake.

jnd mental b~ilding~ t, ,east cells. It ~as p~ointed out tha. r .e ;nisii~i-

Ctr, CfifcI' of ur?... I on jnd NliL jrl: n1ot du to diTFpClicefler of: i

requi red car for.. 1he corac lusion is r TCjh- d that II.5 phoCphOTr, I i tes

to which uran, I o,i binds, are used continuoulsl, il. gluicoi- tra..sp~ort

and are; rc'ciinerTa td cont i nuouslyI b; j, glCol ,''C. In the ,east s,rtem

a close corlciaticn is pictulred b~r~etwen gl~ccolsis and uptak~e ;rnd

gl~oi*, tic ATP ;E arsumetd to be the: encrg, source for dr;.ingJ uptake.i

Cjrrier jnd gl,Col,tic reactions are thought to be in close geegreph~ic

prox~imi t,. In their Chscre~ to Explain the trsr.5portt of sugars the

cjrriers for fac;l;tated d;i."usion and3 for icti.e Ltrnjport jre ion-

silered to be the s.-c. WIhen act;.e tranlsport occuri the jmouunt of

carr ier jmai l jble for fac il1itra ed difuior I' s rO Edu1ced.

Wheeler and Hancher, (561 p~laced oat roots into n. I and 1.0 mM~

uranil acerate for ..arling periods of time and then made- ilcctron

reiierogrbphs in rwh ch cristjls, apparenli, comlposed oi a ur;anium~ complex,

could e abl, be iecn. Afer A 30-mir. treaciment fo~llorwed b, a :0-min

desorpt~ion the u~ran.71 complex wasi sharply; local;zed its Ceii rrillk

irsteircllular spaci-t jnd secretor, products ir. dirctr contact 4.ith c~il

w~alls. Wlith lonij.r L~-tretment times, up to 50 br anid the iowetr concenl-

tration, thec uran*,i comTple. Crystlalb could be: found in .e~;cls in rlhe

cICt6rl~ater3a in the .j-uole, Othcrs-sise the ccleli \ere nomasl w~i t' no

uran,l ion free ;n Lth c~toplsmi or in ccall orgajnillei, Lrn o

applrent;, caused a deiinite dilatic~oreo the~ mmbranes~ from a normal






width of 90 A to a width of from 150 to 200 A. This effect could be

seen on the plasmalemma of treated cells and in vesicles which con-

tained uranium. They concluded that few, if any, free uranyl ions

passed through the protoplast and that uranyl ion in addition to being

bound to the plasmalemma is bound to cell walls and to secretary prod-

ucts along its surface.

Roseman (57) has reviewed the literature on a bacterial phospho-

transferase system that is thought to be responsible for the uptake of

sugars. The system as it operates in Escherichia coli consists of

three protein fractions: Enizyme 1, Enzyme II, and a low molecular

weight protein designated HPr. Phosphoenolpyruvate (PEP) is the phos-

phate donor, and a variety of sugars including some disaccharides can

serve as acceptors.

Enzyme I and HPr are found in the cytoplasm and Enzyme 11 is

associated with the membrane. Enzyme I and HPr are constitutive where-

as Enzyme 11 is constitutive with respect to glucose. Most Enzymes 11

are inducible. The specific sugar requirements of the system are due

to Enzyme II. Enzyme I and HPr are common to all sugars phosphorylated

by the system. Enzyme I catalyzes the transfer of phosphate from PEPP

to HPr which serves as a phosphate carrier. Thi specific Enzyme 11

then~ cu tl onesr~ 1~1-. Errinster ced" pl-.cr Fphate f'ri.T ph~or phate-li-frr to th








exagernO.Ou iuqri -nteir thli cell ias Fugar Fho~Sphates ar.J this i-. d-



proceiC ; ij.Cll-3 jcti'.e traiport.






Ctlp loocu Jureu'- jcTcullated SUCrose1-P when ;ncuba~ted in

sucrose anJ it i: thought ;Ihat the phi'SphotranSferaS' Sjiem is opera-

Si ve 'T thv uptuike aInd FhospihoriIh[ion (5.0).

Edeslmjn et al. !.ES) wo~rl.e~l rwith scutlle,; roots and shots of CoLs,

rpie, whea~r, jand borln:,, Thiey ShiJwed that the scutellum Contrained a

higher rjtior of salcr350 to heicose thAn did the~ rOOt or 5hoort. HomGe

absorcplion wasd ;r.hibltedd by about h~alf wheln e.-.perimieints Ivre run under

reitrogen. :ubstantial sucro~se form~ation rcok place ii, the scuttiliuni

under rlitroge~~r., whreos incorporation~ into jmino-acidr, Dr..Ides, mralii

jcid, jnd sugar Iph:-sphaeS waS co~nsiderabl, reduicd. In t1.850 li.Lu?5

frucrosP is ib~srbedl ;t aIbo~t half the rare of glucoir. ur o-

phates, sucrose, gluci;e, rruc tase glutarnic and asparrtic acids and

their ;miic~e,, mnalii acid, i02, jnd pol,*sacchairide wreT found to contain

label after appl,ing trrccr bmounit5 of labc led f'ructose or glucoje.

The scurlclumT C.js :hour.ll to contin I;Ichl lowei(r lE.elS of~ h~Cdroi;tc

enz,.ne= than th~e r~orl or Shoots. All of the en-,*nles necessal,; for

the fouraition of so.:rosi fror, herose wercr found ;n [be Siutellum and.

ir jchenP is presen~ted to Ehowr (hC path of SUCr.oSe 5,nthe-5iS wh;Ch in-

.oldes5 thi entimi sac3rose-P S,nthe tase.

Hurophre;s and Carrard hia~e publiihcd a series of paperj dealing

w~i h 110i uptake productLion, s toraqe and lealkage of Sugari b,. the

corn scute lIlure Thci dlemronstiritd Ehat glvcose Iiprsae pro~ceeded jt a

ionstant rare e.ea through glucose in [be bat~hing SolutiGO was Iargeli

deple red of gl~ucose ai ar risult of uptjlke (60). The racir of givCose

urptake ,ras shown to war,- depending7 on the conditions anid length of the

prior incubation of the L;lsue. Changes in the tissue content of

various csugarS and -.urjr phosphatss jfrer ,erving periods of tilie in





21

water were presented, and it was shown that mannose inhibited the up-

take of glucose. Data were presented to show that the corn scutellum

accumulates carbohydrate mostly in the form of sucrose, the content of

starch and hexose being low,

Experiments concerning the glucose-free space of the scutellum,

which involved measuring the amount of glucose in the tissue after in-

cubation in various concentrations of glucose in the presence and

absence of DNP and mannose and the measurement of glucose exi t fol lowd-

ing transfer into water, indicated that the space was intracellular

and that a carrier was not involved. Fructose and mannose occupied

a space of similar size (61).

When incubated in high concentrations of fructose (0.1-0.9M),

scutellum slices synthesized sucrose, some of which was stored and

some of which leaked into the bathing solution (62). The leakage of

sucrose was reduced in th-e presence of Mg2+, r,2+ or Ca2+ and EDTA

increased the leakage from the synthesis compartment (63).

When sucrose storage was measured after incubation in fructose


im. lurLITe .hit in =0und~i EMEi the O lufj IjCe 2n ut ation .T.@J urn un. .. re~




abo t a lo, dcre se in cor d ucrole air.-c Iruics c r jr .5 l;-. e-o-enousi







Irlltj ; el :1he-n Iu.:rilj e .ij -dIrJd rio the barh-,n.) ;;lu~ti j.. .:onr:.ni n..)

Ops.I.Tau' .. il''unts .JI' he-,it. ThIs *:.tul dj not look. beer, Ilhe iase if jn.cros

.i.-ru twi~n.; ~...Jr Cl ..=3 ,r:sr- r : I p tal~e .:.r .b rin3j [l process-i r upt-si'-e.




22

The loiSs from~ st.ragi e was mecasured b, loading thie Stora'ge CompF~rtmen[

uith~ o Euirose andj then ;ncubating the tissues at different pH \jlves

and ri th- ,nd wi thout "cold" su.:rose. Ilore sucrose wras lost jt the

higher pH Lalues and th~e loss was greater in the presence of "cold"

sucrose than in wraEtr ind;cating an erch .n7gi betueecn errornal iind

c tored sucroe.

The addition of Fructose or Jlucose to s~~caeilum sl~cice (L)

resulttd ;n a strong, aErObic Fermenration and the conccmmicant pro-

duction oF ethanol. Increase jucrose i,nthesis~ upo~n ;rcubation ;n

fruCtoseE accompaniid an inlcreasee In gl.iol.sis i cholrt an increase ;rl

0., uptake~. This sujpiorted- the ;de3 that tli,col,tic C.TP 11.ugh1t be re-

sponiible for sucrose- synthesir. ihen ;ncubated in rnrir thef Fi: ior

intact scutElla wras about ), while that for slices wras near Lnit,*

It rwrs cone lud-.d, on th~E bisis of the lete It of ad;Ous phosphO-

fructokinese regulators during d~iffrent rates of gl,col;sis, th~at

control ofi glcolsis ;n rhs sctiure 11.1 a c -crtetd through thea ;avil-

abi lit, of SUbstrteC a-ld th~e distritu;uton o~f aden:n- nuleoti~es and

inojrganic phosphate.

Prcticatmncit s.'ith tr; S!hldro> .nethil I)aminlOnethane (trisi pjretenltd

the StorGTe~ of exog~nous su!crose bult the inhibition could be reserred

b. h1,drogen ion or L,- fit Mn2+, and to d lesser Ea tent tig andl (O

Sucrose storage from fructose was5 little affected b, the pretresatiment

rl th tris (66).

Pretreatruent wri h uran*,I ni trate (67) <--eS Simi lar in i rs effects

to pre[treament with triS in that storage of: eogenous sacirC-a was

inhibi ted and the inihhibitin could be rev-ersed by. H, HI+ and~ lo Soile

er tent Mrl21- Uran,l ion pretre~arment only slightl,- inhibi ted sucrose





23

synthesis from hexase and the inhibition was not thought to act through

the uptake of hexose.

It is possible, by incubating slices in high concentrations of

fructose, to build up considerable concentrations of sucrose in the

synthesis compartment. That this is sucrose and not sucrose-P has

been demons tra ted. Upon reducing thle external sugar concentration and

inhibiting leakage, the free sucrose in the synthesis compartment will

be transferred to the storage compartment. Experiments with mannose

(68) indicated that whereas mannose inhibited the storage of exogenous

sucrose, it did not affect the storage of sucrose which had accumulated

in the synthesis compartment. The suggestion was offered that the

storage of synthesis compartment sucrose involved a non-nucleotide

phosphate doner such as occurs in the bacterial phosphotransferase

system.

Pretreatment of scutellum slices with HCI (0.01M) did not inhibit

the storage of exogenous sucrose or the synthesis and storage of sucrose

from fructose (69),

Recently Humphreys and Garrard (70) suggested that leakage is

from the sieve tubes and is the end result of a series of events which

include intercellular sucrose transport, vein leading and phloemn

transport, Several compounds, all of which can either displace or

form complexes with Ca2+ and Mg2+, protect the leakage process which

is labile at 300 in water.

Since some confusion exists in the us;. of v~ri;,ii-..o!, cjrcerning

uptake studies, definitions of several ter...s ui-j n the,? -r. -e:ntrn

of data and the discussion are given -.ere.

Ilpr~lak--Th 5 tcr-in i uJ d ijr the disapp..:ranc- e of a iet -.ace~







from the b3thing solution and ;r not nearnt to ;mpl, a parricular neech-

anirm.. 50oe duthors should uie abrorprionr.

Diffiujion--TheP net nso?,ement of molecules as a res~ui t 01' rhC i f

thermal nl.tior. Fromi a region of higher LO One of 10,.r0( concentrration,

Wrhzre a miembtrane 15 r ro ssd rE:istance mayI be due to the l im; ted number

and rize of PoreS in thE miembrane~ or tc the rolubilIi ,* C harac teri stics

of the jolutE in the Intmbrane.

Faciliti ated di fFusion--Thi s is a procerr in which a co~nitr ntratio

grajdient is the dr;.ing forrce as in diffusion and the proics s.lads to

a disapipearan~ce of thec gradien~t. The process is thought LC in.ol~e j

membrane conntitucrnt (carrier) locj;ed o~n or in the Is..embranrr Hhich

"fiac i li tatLs diffu srLi on. Faclitated diffusion of a soluito jiroir J

membrane; requircs ne input of' energ, other than that nee~de to na;ntain

rtructure. Itr me, showr a high1 degree of spC~Cifcicit and Ikinaticf are

likely,* to :hhou rjcurjtion thus n~ot conForl..ung to Fick'=. law. of d~iff-

si100.

Actrive- rransport--This process in*~.ol.S the csz of metabolic cncrg,*

3as dr;.;ng force. Ir. ls capatie of bringing about the accumulat~ion

of a SubStance. agjir=1 its concentration gradient. It ij ?enerally

characterize b; a hi:7h degree of specific~t, and sj~rationo kin-tics.













METHODS AND MATERIALS


Preparation of Scutellum; Slices

Corn grains (Zea mays L., cy. Funks G-76) were soaked in runninJ

tap water for 24 hr and then placed on moist filter paper in the dari

at 24-250 for 72 br. The scutella were excised and cut transverse 1,

with a razor blade into slices 0.5 mm or less in thickness. The 1i~ceJ

were washed in distilled water until the wash water remained clear snd'

then were blotted on filter paper and weighed into groups of from :*,1

to 1.0 g depending on the type of experiment.

During IrFpr jarain,, th- Slier vetre [hroutlhl nli)."*I C0 thjt gjch

groups o f Ille r .*6j: a r indon~ r I, le i onl fromn S :- 10 0 Icu rt Ill Thli

resulted i nr. i cI IeI 3cr.Earemnt rwhcn m~easurem~: nS Oi uptakei .:r &c.;u-

mu~~lationl wrITI .m..,dei~ o. upl~ijca rgrups~ 01 Eslices fr~~ro.. OeJa,'s prcp..-

ration. e uLts werET notl as. cons i i-tnt w.ht n dup lct .e are compaFredl



Urnlu:r cirherrwise nored, iniiubsticon r.Evre carried Out vi th 1,CI r



EralnsuicL icienrif it (r..npar,, rNew truns .ick, II. J.i rotating jt jpp.rorr

imael 10 e*amnThe :LOiu.e oi Soluti~on was~ Uujulli ]Td *il








iC m leS tare i nc la e ri(chi"J '' .r hr .;. i re w rIa inte tas p' "oI ~I I ! lr LO)E






rrucrose jrnd reducinlg disacchairides Here jnalyzed jccording to

thle rielson-So,~c?~ogCi cpper reduction michod I:71, 7-?) as reported h,-

5pio 13).The alternate copper Ieagent suggested b:, C~omog3 I ra

sEid.

L'hin samipling the: barhi~ng solutio;lnS for 511gers, amorunts[ beCs**eer

0.1 ain 2.0 mi wrer tak~en depending on rl~e ioncenrr. ti~on, and appro-

prjiat d~lutions wrerc madr so thar betueer. O jnd 140 ug of gluio:e or

fructose erecr used fo~r an1al,sis. T.Jrice this jmount wasr usd for disac

ch~arider other tha~n rucrose Ab~srban~c e wa rejd Or, a F~.letLL~t-Summeror,

flaoel 5.005 photoelctrirrc colrirrreter.

Ti5Elue 5ucro"e r:.-s etr[a[ted b; pouring 20 ml of boiling 20,:

ethajnal over thr cliCes and cOntInuin~g the boiling fo~r ;0 sec. iThC

slice: nrre usrepdo in thc jilcohol folr .0 nain, the allohol 1-35 dectntifd

anid thes pracedure repeated.j Thi 5 li cs r -*6re ther. rinsed three I ithn

rr; h 5 mi portlan of Citahol. The com~binecd C.*.LraC~ing solut ons wrecr

evjporated almnort to drincrs oil a steam bath. \.'ater vra-: addcd to a

voilumc of 50) mrl jnd 10 darops of 0.1.* Ii Ia0 added ro adjust thes yn. Th~e

Treulting ago~us solu=:ion~ was~ frozen, Afrtr rthandiig rh 50 uri~l n U.9

ccntrifuged for 10 min ir. j clinical icntrifuge. for the de-tereda;ritio-

of' CucrsE~, 0.1 fr1 olf this jolutio~n wa~ u~sed.





Experlments welre carried out r. I warbur? DEspiremlCetr ati j30

Thle direct method~ for CO, uWE used 174). The amount of rissue added

to the flasks~ <.as either 100 or 500 iig. when the sli~cs werrp prcpared

the,; sriE placed <-.i thout weighing~ ;nto 25 mi Eriennme,er fla;ks in 10 mi

of rater and incubiated for 1 br at j00. The wrater incubatiorn remo.en

leakatalr sucrose (64). Foliclw:i ng the i ncubtjlor, he slIi ces re re blot ted






and weighed into Warburg flasks. The sugar solutions were either added

at the time the slices were placed in the flasks or added from the side

arm during the course of gas exchange measurements.


Metal Analysis

Uranyl ion was determi ned by the method described by Rulfs et al.

(75). Absorbance was read at 400 nm as suggested by SilIverman et al.

(76). Aluminum was determined by the method of Gentry and Sherrington

(77) as reported under procedure A by Sandell (78). The extraction

was made at pH 5. The purpurate method of Wi lli ams and Moser (73) as

described by Sandell under procedure A (78) was used for the determina-

tion of calcium. Magnesium was determined by the Eriochrome Black T

Method (80). The permanganate method of Nydahl (81) reported by Sandell

(78) was used for the determination of manganese. Cobalt was determined

by a modification of the Nitrosc-R salt method of Marston and Dewey

(82) as reported under procedure B by Sandell (78).

The methods used for uranyl ion and aluminum are not specific;

however, since samples from untreated controls showed zero values

interfering ions were not present. The methods used for manganese

and cobalt are specific. Magnesium, in amounts that would be present

in the solutions analyzed in these experiments, is reported not to

interfer-e wi th the purpur-ate method for calcium. Copper, iron, and

manganese do interfere to some extent. The value obtained for calcium

in the control samples was low but not zero; however, some calcium

would be expected to leak from the control slices. The method for

magnesium is not specific, but the amounts of interfering metals in

these experiments were too low to cause significant error. The aRouTilsl

of calcium and miagnesiumi flounj b, u:ir.3 these methods agree very cloel,-







\rith tho~e found b, ato~mic absorption FpecCtreacep, in tearler wlork b,

ilumchr-r s r~d C..rrjrd 1.70).













RESULTS


In the first section kinetic data will be presented to show the

rates of uptake of sucrose, glucose, and fructose with time and the

variation of uptake rate with concentration of the bathing solution,

it being assumed thiat sucrose uptake occurs without inversion. In the

second section the assumption that sucrose is taken up as such wrill be

justified and the effects of several inhibi tors on7 sugar uptake will be

presented, In the third section gas exchange data will be presented

and it wi ll be shown that fermentation accompanies sugar uptake. The

fourth section presents the results of a study of metal binding charac-

teristics of the scutelluml slices and the effects of several cations

on the uptake of sugars.


Kinetics

Figure I shows the cumulative uptake of sucrose from two concentra-

tions of sucrose over a 2 br period. In these experiment lth fiirs

sample was taken I min after adding the sugar solution =.0 rte iliice.

When the bathing solutions were analyzed for sucrjic .j s..all

amount of glucose was usually found except in the sample. I; Latr, atI

min after adding the solution. This glucose could hav; cvnli friom the

extracellular inversion of sucrose cr from glucose difiuilrng cut of

the tissue following Intracellular inversion of sucrose. TbeIso-

the data from which the upper two curves in Figure 1 were calcull us.li

The rol;d lirr in FiguLre 1 repf858Dts datj cjlcu~latedd (froni- clui~nr.~,
















/ O'

r, O




o b~
:Ti rise red n

Figur L urs pceV i\e. Oego lcsntue
inf eah la n T lice ee icb td frIb

in a-arergiven I rin e, an then 10 mi f m g r



th as 0 min ha er eue o 80n















~I_~ __ __
~I~


Klett units


Table

Method of Calculating Data"
(0.00750M sucrose)


1 2


Decrease
in sucrose
due to
uptake


Due to
suc rose
(3-2)


Decrease
in column
3


Concentration
of sucrose
M


Time Without With
mi n invertase invertase


0 0

30 1

60 3

90 4

120 4


88 88

84 83

76 73

66 62

55 St


0.00660

0.00623

0.00547

0.00463

0.00383


Values shown in Figure I were derived by multiplying the figures in
column 5 (dottedj line) and column 6 (solid line) by the appropriate
conversion factor.







Tab le II 'a; i gnor ing, th.e non- iniert.1-.e -It reted complei hic.

i t i s asumrd rhjt glucose i s comin.) frm~ exrale li11lar ire.ir:ion Jnd

thel ~Lu:rose` inverUtFP but notI taken.T up i i notL counteI as i5urtiak~. The~

dotrzed line repres*:.-nt. the actual acreasej in :ucrose of rhe =olurio~n

(ca~~ljculJe froml column ',, Tjble 1.. Th~e two Is thods J0 no: result in

large J;iffrences in calculated uprake. Table I is presented~ to deI--

unstrzte t~cime method of m.eaiuring jucrose uptae. he..1.3n-r

'uLroSe uptak.e data p~risented~a ..a alculated t., thi .nethoJ r:Cr~:esened

bi rhe solid lines,

'Ihen thie rinet- ursrr unsc rrichd~rjaun bi' ucrior, i.Tun~edi-sal b.3fore

.adding rlhe sucrose, an uinme-surra s~nou.e o~f .rater adheircd to :he slice:

andl EG :he sides o~f the F lass and caused a dilation ofi trl; Ijdded jugar

solution.. There Is probabit also j r'ree npjce .coluT.. in t~e slice

which causes di Hlrion Co rhjt jnal,*Sis of the r'irst sanples i ndiclted

3 sucrose concenirtratin cornsirc~rjbl lo--aer than that vbi~ch .-,a in:Elalls

a3ddd. Thiis decrcr.s-- ;in con~centlratin can be Jccounted for by dilucinn.

In Ihe i-rfpejriment Of Figure 1, rle iconc~tientrno I mirs after adding rhr:

sucrjse <.asr 0.00fa.0,I whe-n 0.00j':O00 iucroce was jddedj s.]n 0.0132--#.1 Hhen

0.lr)150M1 S..acTros was5 adae.. These c<..rn~rentration canr be accesi~ired sor



case of 0.002500; :..**ro~se. The E p~ro fojr 0.0050%SJC sucrose :would be Imr

ai~l, f l eif frt wis in~de ro ~e~ter~rnine thet amount: o~F vlatr ,nd Eree

space. Thet problems was gnored byl r..e~asuring upr.--'tl *"rr~m melc time [he

fisrs ssample rwas r.ake. Thie ij.[3 Fare prasanted to Ihr.r that !ther is

Iict a large, rapid: pooJr Jf uptal-e -men :uCro.e i. FirSI added t, rth

EIS Sue.

The~ rat1e oiir u tal..e ;ocrease= iifter C:Ie firTC 3 niiri. 6.t hellr Lhe




33

rate gradually increases over the first 30 min or there is a delay be-

fore uptake begins. In subsequent experiments the First sample was

taken 15 min after adding the solution.

Notice that the rate of uptake was constant with time in spite of

the fact that the concentration of the external solution was continually

reduced. In the upper curve the concentration at the beginning of the

last 30-min period was 70%/ of that at the beginning of the first 30-min

period. In this same series of experiments a constant rate of uptake

was obtained with 0.001M sucrose (data not presented) in spite of the

fact that the concentration of the external solution was reduced to

40% of that added.

More experiments were run to determine the rate of sucrose uptake

with time and the erffct of sugar concentration on uptakte rate. The

rate of sucrose uptak~e with time is shown in Figur~es 2 and 3. The

curves are more unifcrm at the lower concentrations and as the concen-

trations increase the curves become more erratic owing to the difficult,

of detecting small changes in concentrated sugar solutions. A water

control showed that the leakage of sucrose amounted to no more than

0.2 umoles per g fr wt over the period of time during which uptake was



Thi. betl app~rOii.ne~tic-r. C\f .ll GIj [hL cur~i; 3 ;-earn to: bet j trlraighr



F; 'ur 4 sho**C (ht ffe;,[ .:.t iucri*(.F i~cC~=ntrjtion Or,n iarote UpI-



perijd j rr rrich uptake~ <..az re:asur ed. Ais seen t, the twior ctical

CUrse,~ the djja~.: cTI r, <...II ll;h the tyIp;Cjl rliihis*-li and~ herntcin

h*pertsolic subotrjte concentrats.-n cur.<- foir which h thF iOnItants werTe

deri.ed r'rcurs j L~ncij..co r .an Burk, pl.:t of the data,
































F i ure 2. Sacrros? Uprtake Vs Tarne. In thtse emptiiirianen I -4 of r I ce-,
vwjs incusjted ;n water for hr. This r1as I:licIEed b;
2-13 c.! rinsr; and then the~ upralke rDlution v*LL add~d to rh-
lis.Tcn mi or' uptak~e C0'uian~ wasj idded sild th: arriot~nt
of sucrose remo3 0.0 in tii 5olvpling was taksn intou jaccoune
<*hen r:. 1 cu la t ;nr the~ du e Th i e e r.p : >= '.'.n
Ii~n jF ter jdd; tion oF th-e upta's solurion I.ir..s _. rr- on r1.<
?I jph).Sml;0"05n wr e !r S.i. Each
L.u..E rieprscnts .jr.a f roJ.1 1 d:*,' cx.


































0.005M


T i mie mi n








r---'--

P


lii3 0. IIt




60 r.3




20. ~r

L. ..*

5 0 351





45 mO 1n .


0)











I~-ll-l---'UII1----------111-1-111


CO


OE
L.

a- G)
X (
Q 0 9



E- m
me t



ERc
OO C

L e-

G)






m -- a







oom~





*0



oa




L- 3C



CCC

1 GI



Tc


\ m
d 1
c


L'S





Jud jon.1 .].]d. O...r._.-







The erp-rim~ent or' F;igur 5 ShlorS Sucrose5 uptaker; wh~an the btjhing

solution is rmain:oined at a constant sucrose concentration. In thi:

ezper ir..ant th .olumae of the t~athing Folution was reduced to II ml fo.~

greajter accuracy. At the end of i.ach 15-m~in upt:4l.; periodj th- solution

\as rzinoved snd fresh 0.0018I sucrose wras a~dded to, the slices. Th~e rate

of uptake cai be seen to increase v,;th time c.er a period of hr.

Figures 6 and i shot** the rate of rjlucose uptake \th ti ime. As

w~ith suirose, the glccosr uptak~e ca~r.es roughly, represent straight l~ine

rwith possibi, a little miore tenden, for the rjtes to iecre~asL a~ r;t

tIme. In thet case of 0.005ti glucose thc concentrratin of the sugar

solution <*as reduced b, about half during th-? course of th~E erocriienen,

,ct the A~te olf uptae c.rr the lajst three: periods Was about thie rjise~

Vler; simil~ ar data uere collutedd usin3 fructose but~ rher-.. are nlor pre-

senterd.

Figure 8 -hou~s the iptalke .5 concentration datj for glucoji and

fr uc tose. n trne iase of gluiose and fructose thle data do not fi t jt

all urhen an attempts ;s ma-de '.0 find the constants Vr..a, and 1:rui bi clort-

ting the data according to a Linewcaserr an~ Burk plort, fleither di the

data agree Ilith whatr would be expirCte if difiusiOn wepre the drivings

force for glu~cose uptt.lli-

Uranyl ion has been jhown to inhibi;t sugar uptalke 1,67) jnd to~ act

at the cell surface (5.5). Uranyl ion caused a partial inl-ibition of

glucose anld fructoSe uptak~e. This was true both e-henn uran,I ion ass

added 10 the uptake solution and wvhen the .lices werre rr-alted r:;th

uran;1l ion prior ri. the uptak~e period. Th. dotted lIn;:s inl Figure 4

show tht uptakLe vi concentrrtior data for glucose and fructose a-.hen

uptak~e -;at Ireasured fo~l loving a pre-treate~ren rri th urar,l ion. Tat..e 2

































Figure 5. Sucrose Uptake at Constant Sucrose Concentration. One g of
slices was incubated in water for I hr followed by 2-10 ml
rinses, 4,2 ml of 0.001M sucrose was then added and 1 min
later a 0.2 ml sample was taken. A second sample was taken
15 min after the first. Then the entire solution was removed
and 4.2 nl of a fresh 0.001M sucrose solution added. This
procedure wars continued throughout the experiment,






16 -





12











30 6090 F2


T remi






28 1


15 30656
Time, min

Fiue6 lcs ptk sTm. Tedaafo hc hs

cuvswr rpae oefo tesm yeo
exprimntsas hon i Fiure 2and: v thth
exepio thtguoewsth ua o r

















200

/ 0. In n

I F.


120o .05n









1 -1









Ti mir .1-



Figure 7. Glucose Uptake Vs Time. The data from -thich these
cur:cs werie p~reparedJ comrie f'rom the senser r.*pe of
periments"[ ac sh~or-an in Figures: 2 and 3 \-si th the
BKCeptican th5t glucrOSC \*JBS thi sugar Lak~en up.





43













Om
LO
VCI


C-LC
(OV

ro




fGL
OX


C -,


OE


ro



oa
OC





OU
o














r.



IJI


a,
ul
O
U


B


, I ~.. I..L. ... .c _


.s t,': 0 n d :o H






















I~ I


I a d





o v


II V
|~ s

t_ O








































It ,


ItI




o~ 3

IT~~ j


lit C
G rar

sc c.





.- a .

r OOC 00
cau a. . .-

C LI o ~
a .-- ai




L-C
L U i O L 5
E P u- >C
n A- ~ .- C




Cr a-c .,

10 -


.I T








-t L. C -
O~ - 130



I-C II
c j .-

o r le OE-r.




4.L3- .C
4.- i D *
I -' C~ G. L E
<[ *** d d






rO JC

(1~ c-- -- O


. 00 O

La O 1 T I
d~ 1. 3~

-- C D

C ~ ii .0 -
















Glucose
concentration Uptake period Inhibition
M hr %


.001 1 58

.005 1 54

.005 2 53

.01 2 44

.01 3 45

.1 3 34


Table 2

Glucose Uptake as Affected by Uranyl
lon in the Bathing Solution






46

jhumsj the effect or' urjin,l ;ion on gluccst uptake'r when urinl;, ion ,.aj

adde~l to ther ulptal e solution, Ilocuce that in tooth pretrreatmorst anid

crearrentr during upcjlke, th-e inhib;ition ras greater at low-.
[;ons3 of Ilucase. The in~hititioni vas5 nreSte when the slices <-.ere pre-

created it urAnI,I ioni. Th is ii perhip5 .I result or' j long~ trm cr'fect

or LranI ion iinic in rhe prelrtreament apesrimentsit uran.l ;oni waj first

applied to~ the jii.:es 105 iil.. prior to the uptjlke per;od.

The glucose uptakle rs concentrjtion cur=.e sitir uranyl ion prc-

trejtmenti rcjsembled, at least at lo- concensrurioni,, a diffusion curse

(Figur~e i). Since glucose is niot dccumulatred b; th.e ..issuc bL ;s

rapidl, used for sucrose J rrlhesiis or ;s (frmanted (60. 65) thi question

arises as towehrtekntc rsne re tose of uptake i.c.

th-ar .glu~osa is. limliTed 'u, diiFUsionl or thojd 01 [h2 hb.-okinese: res~:CiOn.

Jone.. 1,83 studied r1.0 propertiesj of he:
and .rports che Kr. for glucose as 6.5 .s 10-61'.At. o hsmantd

indlcarcs rhat difr'usion and not rhe hiok~inaser reactionr i. linic~ng,

I~f dFfuionl ij rhs. dr;.*ng rorce for uptake and ;f :t ;r s Mr~uwl thje

[Ihe inte~rnal FlucileC cr.cencratio.-, remdins constant anI .er,* 10.? Ehecn

the~ u ata.e should be j srra;ight lIne function ofi thr 3lucate con;'rn~raj-

tion, ** straight line rai, ;1 fact, obtained jt cojn:cntralioior: of 0.OiMi

Und belour. The de.*i~atin frcal lIn:.;rit, at nigi- e* Oncentrat~on mTayi

be due1 to hiviedr intri'ral conclent."3Eijan s 1 i-i jIos- adl: EO- a Si~Uration

of the ?lucose ucilize don procejj .at thet '-iiger concentrations.

To cli=:R this hlpo~lchS;S furhthr CRe rjte of u,.ca~l.e ;nto urran,l

treated ard untreated -lices' *;os follou~ed ith [inic (F;~luit 10),. ).1

the care at glucost alont the uptake Proiced~ J a alm~asr ;1 .:.~rstent

rate u~nt I the 9;oc31e in t",u ''Ctake- 'olutio~i had ec~ 1 depil-!c.! co a





























Figure 10. Uranyl lon Pretreatment and Glucose Uptake. The pretreatment
consisted of I hr in either water or 0.003M uranyl nitrate.
The slices were then given 2 rinses, 30 min in water, .ure
rinses, and then the 0.01M glucose solution was added.Th
first sample was taken 8 min after the solution was ;dded
and samples were taken every 30 min thereafter for a Ftri;d
of 210 min. The curves are an average of 2 determinations.
The volume of the uptake solution was 6 ml so that lbarne
differences in Klett readings were noted over short thi-e
periods.
















/L tr pre tr a r -a t















12 r J0



P ~~rPi U~rlln ior re lr t.nin









60 120 I80
T i c..e mi;n






level below that of the detection system used for glucose analysis.

This curve cannot be explained on the basis of diffusion alone. It

might be argued that the rate of utilization of glucose by the tissue

is constant and that the curve simply represents the glucose utiliza-

tion rate. HowEever, as shown elsewhere by both uptakce and accumulation

data (Figure 7, Table 9), the uptake mechanisms of the tissue are not

saturated even at mnuch higher hexose concentrations. In contrast the

curve after uranyl nitrate pretreatment is typical of a diffusion curve.

If an arbitrary constant is multiplied by the concentration at the

beginning of each period of uptake, the curve represented by the dotted

line is obtained (Figure 10).

It is postulated that glucose uptake is the total of two processes,

one consisting of simple diffusion soon after uranyl ion treatment and

one an active process which is subject to inhibition by uranyl ion

binding.

If' this is true it means that the active component as represented

by the difference in the two curves in Figure 10 is increasing with

time (1.e., since the external concentration ii d creasing, diffus ;or

is decreasing and the active component must b~ inireaijing in ordirr [G;

maintain a steady rate). With this in mind jn cxpiriment -a run ;n

which thle concentration of glucose was kept c.rnety~t b, inreneir~3 the

solution after each sample as was done with fucr;se (Foure 5). The

results of this experiment failed to support the b..othts isFigene II).

Glucose uptake remained constant with time ir. sFit ofc~ the fact t h jt

the concentration was kept Ecentur.. The up tale C.r aj per~iod iof 2 b

was very close to the value obtained with~ delinlr., ?lucose ianicntrh-

tion. When uranyl nitrate was added to the uptale ;;lut~ar. ir. thiE




50?

r~C.




Uran, .o, ded ,-








121







~ ~ ~ ~ ~ ~ s~ ..iad~- rnlin d iezr






Tier ,i ot minl
Fiul I. C uc se U tal a C n ta E(o ce tato is u \/

sub cte to I h nw tr inc ,ad te h
0.0Er upJ:slto s. Te fr tCopew s rle
I i ftr ad ng te sl/o Te.L 'ue ae
a ecndsapl ws akn.. n h ptk outo -/





use~Ilrn,I nitra jte. The uptke o lm a mi







experiment the rate of uptake declined with time. This may be due Ic.

a long term effect of uranyl ion. The amount of inhibition caused by

uranyl ion was the same whether it was added at the beginning of the

uptake sampl ing or added after the tissue had been taking up glucose

for 80 min.

An experiment was run to determine whether or not the inhibition

of glucose uptake by uranyl ion was parallelled by an inhibition in

the amount of sucrose gained by the tissue. The slices were placed in

water or 0.0038 uranyl nitrate for I hr, rinsed, placed in water for




0~r~dr. rin rd, and JLIaCedI ir. .hIl fructose or 9lucse forJ ?O bri star


whi.::1 ~ ~ ~ ~ ~ ~ ~ F~b th sne:vreritd n klldfo .r5 i lj 01 Einu ;nucrose





i [Cd j'. .3~.-.d 4L.: .


tucr~...=c Ugrai

le. Order toj 5Fud sucrc.:e: ult=Le ir should ter urlatbl;; hed !hj

iuicrose :s .uch if thC iulphr b9;nll !Bakeni Up 6.rl ie f .dj

v~ill be preiSenced FO ih~ru thaE suirose ; rla tnkr upF witho:ut in.trsio:n t,



rugar uptake- willI alo be promoted- in thii scioLCTi n.

The Sii.LIutI of ;r..ersio of suerC.:el in [I.6 .-r erma~l zo~luiusl i j

Jiinal jI n.:.32ured t., the spearancer 01 riluco'se ;n the So~lutior~.,

ir.itarli c it .. I.ucIro: e cors.:eat~ji ion l i. 0.0011 [hl r.6,,irlurel .j,.:OUnL 01

gluc;.e noted in the iolut~ion 0.1 0.000i')l. The amount .Bried~ o C-r the

upI3Ce Ieriodl frossI Ehli ..alue LO .30 Samun t [.10 th 1 G~it 01 dtEDrrso








folr [lle daunt oF wlr~plee used, Thi; ..ould mean a endsamliumil I-evote con-

cenrration of (3.U!Jlll Jnd an uiptake scordi, eg o F;gur- .: cl' appro .-



rought~ one~-r~-nth of the rate o~f sucr~ojs uptake o~bsei.rved (njule 41.

This jrigumernt jip3it S :IheL jSSUmptiion,. justifitd by Figure i, thit chrt

t*-so heroses ;Ire t il.-n uIp .t jboutI thJ iameI rtj* hi rutC.l a

beenr piaison ced fore b i Humpnre ys jnd Garr ard (6~4). The possijbili t?

- ..;-.s that In.ersion [jlkis plac: in J posi rion iuch Lhai he:-oses mJe a

prefertnri-all/ toward the point of uptake,.

Ki;ntilc djta on tlF: uproae oi sucrosi glucose and fructose rwere

pr1jnted in che first rition, TheJ on.erjll s~hapes of thr, upl.JI race

. j .ncent ration curies~ is co~ns i drab ig different. \lnesreas herose

uptal..e iicrt as es ..irh co~ne..lrrttrati ove.r the ranger sh.:.L.n. 3uslojse uptake

a~pproaches a ma.ximumi. The conrsiderable dirfferenc in !he ef'iett -of ion-

ccntrationn on up~Ale if an ;ndi-ation that. rv) different pro~cesses ire



B, concering the data in Figures 4 and E. it can; De sen thjt the

total amou~nr. cf carbt~n rjlkn up fr.1,i 0,1 11 solution i 3 highe r when her.-

oser .re suppl ieJ. In e.per;i.Tsent iiearuring c'jssue s*.crnse It <,as

notred tlhar rih amounllt of sucrose ga~ined b,' rhe rissue was thi janme or

highel.r hcn th lices j U.:5I.-eF Inrcubased T.~ :Utrose as iJompare]J to ;rcuFba-

r i on in hthXose. ir. Ordr Eoi shrrk this effec: Onl ?he sarre grculp oF

lI;cesj an I..pel'rine~! r-t wa run in; .hichi uptake wa~s alloued~ to proceed



Dual;cact flasks ..;ere rur, UpF~a!..o waS5 mejSuu c o.er i hr of :hi .Jpcjle

proThe amount ofr caJrbon taken up fr'rn. giis-acese sltir on~~ was 1 O

of rhat taken up from sucr'ose solution although th-e snount of ucrose




53

gained by the slices was the same in both cases, The slices were in-

cubated in water following the uptake period and then rinsed, killed

and analyzed for sucrose content.

When gas exchange studies were carried out using 300 mg of tissue

in the Warburg flasks it was found t'nat the addition of sucrose, glucose,

or fructose to the solution caused high rates of fermentation to occur.

It was assumed that the amount of 02 consumption represented sugars be-

ing completely r-espired wrhereas the amount of C02 evolved in excess

of the amount of 02 consumption represented sugars being fermented,

It has been demonstrated previously that under similar conditions

ethanol is produced in amounts equal to the excess CO2 (65).

The data in Table 3 show the amount of fermentation over a 2 hr

period caused by the various sugar solutions. In the fermentation

experiments the slices were incubated in water for I hr in the water

bath, blotted, and weighed into Warburg flasks which contained the

sugar solutions. The flasks were then attached to the manomneters,

equlil brated for 15 min and t:he readings begun. No effort was made to



the begin.1ir.) of the readil~ing

Th-- r.Ee of resp;rtitoo~~.i :: rc.3:crabi cor..irrntr regar3J1. of the



h o fa combelnricn rri r. Th r i i '-.jz ;n .uicro~.-- n t r so ..o e u l



pe.r bl;C ..:omp.re;~j [o -~ j; rate of 5 u...elesf for tHlc:re.- Up~t-li- of1 3lucos

a.j-..i ;.u TC-se~ fr~oli 0.010 Iiolutionl b, th.C jjir;.06 :i~iices. ga he

followr i lg ri. ults; uro~t 17 uml es/hi~h r (c~r j4I ,,,,c-lc: h; o. -}c, ?lucose

21uale/H.Il' the jToun[ oI' termecnrjtion is a ful'.:rior. I:r the coc.-
















RespFi ratei in Fri Tnen ta ron
clmo les u~nle: I No r. ofi
Eol ut i on li.oe/rher~se,' nr prmn


(Djta j.erjgzd frolll se.evrrl dai'i preparjtio~n;)

W.'aer F.8 (0.4): 4.j (0.E) 5

0.01M suc roe 4.5 (0.41 1 Lt (1 .9) 5

0. 11 fo.to e4. g (0. ) 120 (17

0. 00511 fr uctore
r. 0.000M gllucos 53 0.1 13.8 ( i.2)

0. Irr Jucroje 5, 2.5

0. I1 fructase 5.0 (0. 1) 36.F (LIE.) 2

0.0 Ir lucose 4.6 40.5I



''Nor..ber s in parentheses'r indicate the j.l.erjag draiation. See 10/[, read
materialr and Int~atod;, for er.rprilrental detl I,.


lat~ie 3

Fcrmentraticn ir. Water ar~d Cusjr folul~non





55

centration of hexose in the fermentation compartment and if sucrose is

being inverted, even in the process of uptake, the rate of fermenta-

tion in sucrose should be higher than it is. The sane argument can be

made in the case of 0.1M sugar, since the amount of fermentation in

hexose solution is proportionately greater than the amount of hexose up-

take.

Further evidence that sucrose is taken up wi thout inversion comes

from the effects of uranyl ion on sugar uptake. The effect of uraniyl

nitrate pretreatment on the uptake of hexoses has already been giveni.

Table 4 shows the effect of uranyl ion on sucrose uptake. Uranyl ion

more completely inhibits the uptake of sucrose. UHith hexvose the effect

is to cut the uptake roughly in half. If sucrose were being inverted

prior to uptake, the expected effect of uranyl ion on the basis of

the hexose uptake after uranyl treatment curves would be to cut the

uptake of sucrose in half. It might be argued that uranyl ion is in-

hi biting the inversion of sucrose but the inversion of sucrose as

measured by the amount of glucose found in solution is higher after

uran~yl ion pretreatmer~t than it is after water pretreatment. In mea-

suring sucrose, It was consistently noted that the non-invertase-treated

sample gave slightly higher Klett readings in :he cases where the slices

had been pretreated with uranyl ion.

The effects of anerobic conditions on the uptake of sucrose glo-

cose and f-ructose were determined by incubating slices in waei~r fo.r

Ihr and then transferring the slices to sugar solutions and ir.iutnling

in air or under nitrogen. Nitrogen was continuously bubbled clhrcshh

the solution. ;LucroJ Il ..pacE in Ng2 was only 33% of that in olr r.

wi th gl IcoF 3ndJ frucae roi .r. rates cl u'~ptak~e In 11, were 65% of~ U.l:ez























0.001 4.1 0.i


Table $

The Effecr of U~ron I rritrjte Fretreatmen.. sr. Sucrose Uptak~e


Ulptale uiinnle: hr ~


Colcncetintrtin


Uran,l I ntrate
prc rreatment


\later protrbillaint


C. 005


14.3

11.0



4a1 O)


Slices- (1,0 3 Tr ut) ~ere pla~ced ir. iither us[Er or liran,l
n~itrate for I br. The sli~ice were J;:rn T' 0 ter r;n5Ss p~~lace ;[
rater for 30 Irlin, gi'en r more rwater r~rirnse oind f;nall, .laed Ir. the
batLhi ni 50i utlon. T.*j sampilrs we~re tsken. rlhe firal 15 Pin sc rrr the
bathinglr so;utionT \las addedJ jri thj SecOnd .11 the end of the uIptl.F
pe~riod. Uptakel~ was measured c..er a piriod of ii0 mTn .ri tr. I.00111~ eirtd
0.00)511 scrosc 90! min .-al th 0.001l iucrose .-nd IIO min url h 0.05 ;nd
0.iM CuiTcee. PeteS of Upts~.e in the first thrte are o.:\rajse of the
rcsults 01 two~ e.periments, [hC las~t t1o are Iro~m o~ne rgriment.~n





57

Table 5 shows the inhibition of7 sugar uptake by phlorldzin. At

lx 10-3M this inhibitor caused aboui twice the amount of inhibition

of sucrose uptake as i t did wi th glucose uptake. Witeh nei the~r sugar

was uptake inhibited strongly by the low concentrations used with

animal systems.

Dinitrophenal (DN`P) also inhibited sugar uptake (Table 6). The

inhibition was considerably greater with sucrose than with glucose;

the sucrose inhibition approached 100% whereas the inhibition of glucose

uptake approached 50%/. sucrose uptake in the presence of lx~ 10-4M1

DNP was l inear with time for at least hr.

The uptake of sucrose was measured in the presence of several di-

saccharides to determine if the uptake process was subject to inhibition

by molecules of similar structure. Several of the disaccharides caused

an increase inl thle non-invertase-treated samples. This caused confusion

in interpreting the results since it was not known wh-ether the increased

amount of glucose in solution was coming from hydrolysis of the disac-

charide or from an increased hydrolysis of sucrose caused by the pres-

ence of the disacchalride. Unless otherwise stated these experiments were

run by incubating first for I hr in water and then placing the slices in

0.01M sucrose plus the various disaccharides in concentrations of 0.005,

0.01, and 0.05M. The uptake period' was- Ir.

Lactose was not taken up by the tissue as determined by measuring

the lactose concentration before and after I br incubations by the

reducing sugar method. When solutions were tested for glace-se the

amount was found to be insignificant. When sucrose uptakl.r- ,, menure.1

in thie presence of lactose there wras an inhibition of 33% i. rh c;:e

of 0.0EM lactosee ir i t is assumed that the higher glucose cone~F: ir.?m
















Concntrto Inh it i [ i o

phlo~rid-in
ti Clucose Su. rose







I. 10 1 I 25



2 10 -47







twrice, and placed in a solution of 0.0l1M rugar an~d phlorld.Tin as in-
dicated. F-esulis jre based on a non-inhlbited conrro~l, UpcJake as~
ns:-asured c~ar j L br period.


1shle 4


Inhib; itin of Sug~ar Uptak.e t., Phl;oridzln







Table 6

The Inhibition by DNP of Uptake from 0.01M Sugar Solution



Inhibition
~_~ ~%
Concentration
of DNP Glucose Sucrose


1x 10-51 2 31

3 x 10-58 14 51

1x 10-4MI 35 89

3 x10-4 M 43 94



The schedule was the same as wi th phloridzin. The uptake per iod
was 90 mi n,







the increased h,dial islr of ucrose in the iresence of lac rvte. Ir.

O~thJI woirds. ther rame~ jGrwunt of SucTrofe \iaS iou.10 it thi endC of Lthe

uptaike period vrith or rrithoIut lac toSC. There was mOre qluCOLE in SO u-

tion at thi colo of the vp[ake period w~hen using sucro~Se and lacrose

than ~there unas in the cas6 oi lacrk*Le or sucrose ljnS. If this glucoSC

came from h,drolesis of sucr'ose then u~ptake wars in~hibitedi. This is a

reasonablL assu~,ption s inlce no h,droly iis was i ound i n the cjre ofi

lactose obere asr ar iFLcrease in sacroseS hldrol'.Cis in the pI.E:CnCe of

\ar;ous inhibtlor5 tas commonJrlJ found,

50croji u~ptake Iva; not irnhlblted br m?Iib;ose. rehjrose or cm 1-



When rnaltose wasj suppliied to the ti'sue- there hlas con~siderablt

h~drolysis. As sho.rn in Tible 7 the glucose iconcentrationr incireased

fromi the beginning of the uptake. periodj to the end, w~hilr the co~nccntrs-

ricn of maltorEe declined. The daount of uptake~ is explressed ,-, t,.rn,

of umnOles of 91ucome. The con~centration of oluose i..nsufficient to

account for the uptake (Flgure b) indicating t~hat som~e maltose \rjs taken

up ri t hou t hi droly s ri This experiment jhows firstl*," [h.7 th" discjcha-

ride is being hydrol,red and second, that iGilowr~ina hrrolsis the

roonortc~hande0 cn to detiectej in th~e e.-:rernal so~lut~ion. It miight be

pointed out that maltose would be an expected product of the rreakdo:.-n

of starch in the endojperm.

The app~aranic of gl ease in solution coming from both maltons jnd

sucrose maks i t di fficul t to dcetemine th~e effect of maltosr on jiucrose



:he r. urajnOSe was added to the slices na glucGse appeared in solu-

tiorn. Whin turanose and ucrrose toglether w-erii added to the slices thec
















Concentration Change in Change in Uptake
of added glucose mal1tose umoles
mal1tose umoless/flask umoles/flask qlucose/hr


0.005M 6 to 24 39 to 23 14

0.011 10 to 40 80 to 52 26

0.05M 22 to 78 346 to 274 88



Slices (1.0 g fr wt) were incubated in water for 1 hr, rinsed
twice, and then placed in the various concentrations of maltose, 15
min after adding the maltose the first 2 ml sample was teken. The
second sample was taken Ihr after the first, Glucose was measured by
using glucostat, Reducing sugars were run on the same solutions and
maltose determined by difference. Reducing sugar standard curves were
obtained for bothi sugars. The results are averages of 3 determinations
on 2 days' slices.


Table 7

Maltose Uptake





F. 2

alu..oi 1 a redings ncars littll or nu higher [han uhien 5ruccose ras .dd~dc

alne uran~or = jt j.0511 ijurd jppro ;ijlcatel, a jU01 irhibi t on of;

ucroe ut..,.e(Tale ). he uptale of Eurannse alone was rhecked t.,

using t~E reduicin? sugar rnalr[ed and was found not to~ be :uken up LI., [he

slices.. That the- iel'ect of tbraraoit ;Is not a.ji ur;~ntic iffacr wras derlr-~in

strat-1 t., nleasurinig the ulptakE Oi suifo58 jl00, rucrose In thA pre.-

ence' of ruranost jnd ucrosei in rni piresence of Irlann; tol,

S*:.eral *::per;brants wrei disigrned to ihot-. the effect of tissur

sllcroser le.*l onr the rate- of jucrose~ upt.j:sk*. The c...periinr~nts jre

sual-i~arizied in Tabic 4. Generall, t.er~e is jn ice~irse: correljtionn be-

rr,.*een thE a~llroviL OI SaICrOfS in rre ririui and the- lc'tE of uprE~.ake Thel

tissue ..as subjected ro:~r~l.. rrious trec,ar. -Lquue~Cr- ce SO jn \ntr,' the

amo~unt of ruirose in theF [iSsuei prior to brjeauringl uptake;. I r.hosi

thra.. case~ narkid 6, ar. azterisk the equncrres were th: sjrne C>r.iept

fo-r the cinoncentrato oa' rugjr during !he firit I hr and in t:=.:h casei

;ucriJse uprake u3r IreaSUred during the fif h hr f rarri, th.- ime the irper; -

me1nt rarted. In thise ijses there ;is jn true-llent ;!ir.*;r*. correlation

t..-twEen [h= aBolount ofi Lissue~ SUCcroe C.'tored jnd rthe rjri ofi uptal.e.

Th~ir is tor t~e e-~pected since- thcre umust be~ somer limr~i to the: jlr~ount ofi

sucrose that cjr. t~e accuuilatedi b; the, slices and one would c.>.pect thi

rare- of uprake to to r-educed js thij liln; t is Tejihid.


G;Is E.iBgL

11h1n yas5 t)change exprCTmnts[ areT carried our usi-ng 3.00 nap of

tiiSFu ir, the \~U~atJur FjLarSk the aliounL Of O, rjiten up tt the clssue

was limritd b, thr rate jt which 1? difluses into3 uner. Thsi h l

by thr: fo~llo\sing: (a) 7).@ rat-s or' 02 co~nsuti~ption noted in thiese experi-

mentrs we~ri cqurl rO the 11rinits of the rate at sshich 32 di fuser into
















Uptake umoles/q br

0.01M1 sucrose 0.01M sucrose

Experi ment 0.01Ml sucrose 0.05M turanose 0. 05M manni tol


1 15.2 10.1

2 15.5 11.7

16.0 12.2

16.5 12.7

3 16.1 11.4 15.6

17.1 14.6 16.6



Slices (1.0 g fr wt) were incubated for I br in water, rinsed
twice, and the indicated solutions were added. The first sample was
taken 15 min after addition of the uptake solution. Uptake was


Table 8

The Effects of Turanose and Mannitol on Sucrose Uptake

















TIssue SiicroSe
le,el up~rjak
Trretnen: sequence umOlFIS.g umoleS'J hr


\lAter 3 Fr, rinse, waerIT br,
ricscoeIhr 50 25::

\ljrcr I r, rini:0, sucrose I hr 68g 17

0.020i Iru~ct:Le 7 hr, rlnje, water~
I br rir.Ee. S crose I r 81 Il

0.III fract;se 3hl. rinse, ueter
3 hr, rinSC, suciJte I hr 914 i

0,lIn fructoje ; he, rinrce, raterT
Ihr. rin:e. scrose I he 125 15;

0.111; fructose : hr. rinse ,
cuirjse I br 133 11



The results. from 3 cropsC of seedling s re riported hire. In each
case the uptakle period ejas I bir, the sucrose fronll r-st..c*, up:3l-e vas
nriasuiied ~as 0.0!11 and~ there was a 15 miir, delal L.etueen ocdainq hth upF-
tjLe scilution ond! taking ther first sanple. Dupl Icat rs amp les ,;re
5ubjiated to the requen~ce as listed and at the beginn~ing of the uiptake
Period onez group rjs k~illed for sucros~e anal,sis rrhile rne other .*.ai
usedto- rmeas~ure c_gar uptale.r


Tjble- 9

Sucro;e Ticsue leverl ilrnd Sucrose Ulptake




65

water (74). (b) W~hen DNP was added under these conditions the amount

of CO2 evolution was increased; however, the amount of 02 consumption

was not. (c) When experiments were run using 100 mg of tissue in water

the 02 consumption increased on a per weight basis and the RQ decreased.

The figures from two typical experiments were: wi th 300 mg tissue, 33

umoles 02/g br, RQ 1.3; with 100 mg tissue, 53 umoles 02/g hr, RQ 0.8.

Since when using 100 mg of tissue, the rate of 02 consumption is well

below the limit and since the RQ is quite low it was assumed that 02

was not limiting under these conditions.

It was not known whether or not 02 consumption was limited under

conditions which prevailed in the water bathi. An experiment in which

sucrose uptake from 0.005M sucrose was measured as a function of the

surface area of the liquid per weight of tissue showed that uptakte was

not l limited by the amount of surf ace area. In this experiment uptake

by 0.2, 0.4, and 1.0 g of tissue was measured. The volume to tissue

ratio was kept the same by starting with 2, 4, and 10 ml of sucrose

solution, respectively, and removing relatively the same amount of

sample for sucrose analysis. The rates of uptake were 11.9, 11.4, and

11..3 .arreiles/9C br t, ?.2, I?.1 4, an 1.0 J oF t;ue. Theic. differences



.uirrj; upt.3|e ase r.or I1I~r..rd L. 0 i b li .








where I fl3Cd, a Luj Seid ..nd 13:i umoles/31 alhlre 4 rwer: used~. !Th so~

t'igures 3re not ns! sucrocse .iccumulated jince thi amountnt Of: tijsu8

suCroSe at Ih: beginning o r ne upraki- period nas not been iiubtracred.)

\Jork byi Hus..phreys arid florrird (701) jnj by thi author hj.e shon,,

that rhe sulcrore content of rcu~telluslr. SliCes is Treducd rher,~ jliiCe

are inrubated in war-r ;ndicating? that rEugar is the jiubscrjite for rre-

pi ratio:n. his; waJ jlso rioted ..hen 0, 25 g of t i 3;ui per f l iSk: ras u~ed.

Hlowvesr, gas eYchdnge StudieS using 100 mg ofi Lis:u+ h e e~l idcjted jr.

P..) ir. water subjstntiall, less than I.0 indicatinq a subjtr. to other

than sugar. This 5 nconj s t ency weiight be a~r la I ned L,< the Con.irsion

of ilcrosee to olrganic 3i;ds.

Figure 12 shows: the anoun[ of Fernientation in \Iater snd in twoo

conccntrrtions oi iucrojsl when j.00 myg O ri.isue u15 used. It i, acjsumed

in present;ng thes fiiures rIha, for tachi uno's af CO2 e .ol\ed in ex~cs~s

of' 0) take..I up orle-h.11f uiinole) of Choxas .-sa; tbeir fe.-,i:nted, Figure 178

repiesents tht 33rs.* e~Perinent laut rhe aiouint of Forilentaririo in the

rwater control haJs been sbtcracted fromn that caus:d b, surose,

fnh the b-si2 Of 0: ptake iexperiments it r -,as clculated that thr

solurions in rheie rI asks w would be dEpleted of surcrose after j b~r in

the~ case of 0.001J:I an~d 4 ;rr ;n the: casei of 0).)035r slucroii.. In the~ case

of 0.0010r >Icro~ r th suga3r-csu jed feri-antation tr .e rh ar

is j dded, incr;ehie in rare, A~id then decrease1 at Frnc (10.9r then the

Jugrl" should all Lakes been tj!.en uo, T.;i sinountr of iiearment t ica caused

b,' 0.0051 juirore. ij about thrE e i~ t r'?j (MC cus:J br ;j.001ft iucrose

andJ as rhow.n eairlierT in Fi3url: 4 the~ raCL of upta're ;s about tlTree

time as rea.' WIh 0;.000.1 juirote thep agreemenr ;n timing bc ..:een

uptakec and ferl-enit.&tn i; not aj c lose, ho..-eST .,lrco care do-.5 begln

ro dzcline at a time~ where1 uptakCe ihouldJ. be coFplem.































Figure 12. Fermentation in later and Sucrose. Each flask contained
300 mg of tissue. The sucrose was placed in the side arm
and added at 30 min to give the concentration indicated on
the gr-aph. Three sets of flasks wrere used, one each for
the 2 concentrations of sucrose and one containing water.
The values were obtained from; CO2 -02/2 (in umoles), in
B the values found with water have been subtracted from the
values found wi th sucrose.







A
60








so oarose;






3 urs jOdddedrs~or





10/





30l



0.00""511 soross


Sucrese odr'd edC

/oO
1 0O -q-q-twM-~

a r~S~:;% ?C~0. 00111 SuCroS C
r $r
.d2 e-I Ir C

Time, hr




69

Figure 13 shows the gas exchange in 0.1M sucrose as compared to

that in water. These experiments were run under conditions in which 02

was not limiting. With water the RQ is less than 1.0 and both 02 uptake

and CO2 evolution proceed at constant rates throughout the experiment.

When sucrose is added there is some depression in the rate of 02 con-

sumption. The rate of evolution of CO2 on the other hand continues to

increase throughout the experiment. Over the period of this experiment

the uptake of: sucrose would proceed at a constant r-ate (Figures 2 and

3). When 0.01M sucrose was added in the same type of experiment (data

not presented) the patter-n of gas exchange was the same; howJever: the

02 consumptioni was not depressed as much and the rate of CO2 evolution

was not as high.

Figure is shr.:si the~ sjare ie pa f U~Ita fo'r 0.1[1 glu~cos. r.ar



resolution of~ C0-. ; grtsll, nrcreased t., [Ihe adds F.(an 0i 1Urj glc li to

sincei. Ibe. F.I during Ith l ear. pr ..d mat-urcd ..jr z7; 115 .,,,.0?. acr..

0. lr.01/1 glu cs !data nres ireset ed)j caused ro:uJh.1, I'te rsame p L~ir r, -,



If Ith .assUmIPLtio is need tha thel d~;liffrtence ir. C02 t\olution ir.

vetrj E It r..u5 thol in sugar ii lui Er.11-I t r e tai;(.S' r r t

is ol~ib~lC to CalCUlateC Ihe reek.-:*r ofi umle!'~C i hCrSid tbeir.9 Fer.T:nited.

Figuret IF shar~~ ~-e thC.- J res lt of uh a icalcula tin. Th sr.lt. r

frir, thC sar~e e~p rir-nts .a Itpo~rted ;rn rigure: 1.. and IL*,

Rate: of~ IIIrrilireatio~ ~U suggested bt [lithe .-.t. d31 t.- ar-conl..ustrar



As ioir-tedJ out crl~ie, 1:F.6 rjte of ftri.,ntation~ ;r higher under icndi-











V00 ;


.p iO. -" arose


1 O, ae



<, 0 ,. i cr'





Sl ,-o~ O,,, water


15 ll


100 L_


,/


C.. ..... .... -L 1.. IJ _1..1. ..L_ .
30 60 90 I20 I50 180 210

Ti rne~, ai n


\:ere run rri lhi 100 cl] L 5ue per i last.
olC'uri.Ior (LOM() was- ajdde f ruin thE Side
of ter re-dilngsr were tregun~.


The sucrose
jrmr 30 rainr









0 C2, glucose 1
300 CO2,water


O 02, gl ucose

y 02, we te r
250




200
















-- .. . L e .

Tij no r
Figu e 1 L 1.ch ~ g. iri'a e a,< 0 11C' ...e cn iE o e
tr e It : i .. F a u e i













C, .0i r1 gluccose

ri* 0. I t avc ros5e















140 //





20 .*








Sugar adde~




L L --. ...
i0 60 90 120 1',0 1 0 210
Timie, min

Figure IS. FcrTer~!a tior, in 5u3ar .elation. odio. n
Figures 13 and IN, F'e ull: \*ere ;alcu;lct d s LO,






73

accumulated is lower under conditions of limited 02 in the water bath.

The rate of glucose uptake from 0.1M glucose was about 87 umnoles/g hr.

The rate of fermentation as indicated in Figure, 15 was 28 umoles hexose/

g hr. This would leave about 60 umoles of hexose available for accumu-

lation, or enough to accumulate sucrose at a rate of 30 umoles/g br.

An experiment was run in which slices were incubated in 0.IM glucose

for 3 hr. Each flask contained 250 mg of slices in 2.5 ml glucose

solution. Sucrose accumulated at a rate of 35 umoles sucrose/g br.


Metal Binding

Experiments were designed to determine the amount of uranyl ion

that would bind to the slices, the effect of other cations on sugar

uptake, and the relationship between the binding of some other cations

and the binding of uraniyl ion.

Table 10 shows the results of two experiments on the effect of

cations on sucrose uptake. In the first experiment the cations were

added to the uptake solutions. In the second experiment the slices

were first treated wi th 0.01N HC! to remove cations attached to the

slices, then treated with metal cations, rinsed, and placed in su-rose.

Uranyl ion reduces sucros~e uptake when it is used as a pretreat-

ment or when it is present in the uptake solution. Cations other than

uranyl ion have little effect on uptake. Notice that the acre~rol,

third column of Table 10, was treated with acid showing tnue rth acidl

treatment does niot ser-iously impair uptake.

The next series of experiments were designed to determine: _Th? quani-

ti ties of the various ions that would bind to the surface- of .nec laces.

Figure 16 shows the amounts of the various Ions that cjn to reno.ed~

..im rhr.01t ~i HI after p~re real~nirr witrh the various metalIs. ea
















Upte..ce in urooles 'q br

Treatment Ul; th upt~l:e Siolution Pr~ e r lle et L


Table 10

Suc-rrose Ilpraic as k.ifcceed b,' Variojus, (io~ns


Coll 2


lInLI2


11.0


li).O


UO2 3 ?


The d)(a~ ill trd riCond Co~lumn sf6 ffrnm ,n experilifnt ir nhi ch
slices were incu!,..ted ;rn warter for I br, rinsed. llith \tearC.r adTI: pl.=sCii
inr 30o1lclons containling 0.005M sucrose anj ii.i0311 cation solution.
Th~e t h Ird iCo lilr., repFrese n 1 a 1 5 -min i ncuta tion in 0].011 H C.I fo lkI..,e.1
by 2 rinses, 50 min in 0.003tt :ar.;or, solution, another rinre jnd i,-
nally the (>.00*,11 suirosE sojlution from r-th~ih uptak~e wass i~eneasred. In
btlUh e~.*periai~nlnt :he uptal:- period wa~s 2' hr b. ig 0 f slices. per flail:







--.I--I-------------- ----- ---- --I----------~-----l"r


I


a


(0.010M)













(0.02MI)

0 M 2


2+
(7 ] 022

W Ca 2+

0 Co2+


SMn24
aa 3+
!:[ Al



Salt solution, N x 103

Figure 16. Metal Finding. The schedule for these e-peria-ncnr
involvedl the following: 1 br in the car~~ .: llr. olud
(or water control), 3 rinses, I hr in !*,<, 3 r~orar
r:i-. ---.' I.r analysiss of th~e respective c nores, tail
i1.0 c..com...ed 1 9 of slices.







points .;an be made. ,iTein..r on ftiecyr eit

searij' rinces and a I-br .r~cubation in eY->rer. (b) A- concentrjttion of

0.0020 .:ation rolution r,:ided enoujh ions5 Eo saturjte the rltes ;rn

all Cases. \c) ApPrCTiiabe quantities o~f the ;oni at 10.-, concentrJ--

rtoi rcr- ur boundl to the slice. In the case ofi ;Jbal: (0.000)11), 1.6

un~clers or the 3 umeles ;I.ji lble wrere bo~und b: rne jlices. (d) fljgne-

jium jppersr to be th-: ;on rhat, normally occupie; the sites. The data

from Fiqure e 1 hou thlE the slici-; incubjtedj in \-d~ear insread oi

mea~l iarion solurionj released3 6.5 umolej ofl 1122'+ aInd 0.?S uni~ls of

Cs- i. (I) G;-earer quait~itiesj of uran,*I ;c7, jrE boul~nd the. ,an OF the

O~lher ions [GE L.d evcept[ r1ig'

In theI caset oi I~renyl ion, twro T.-pZrimenri~ :,rTT de-~;i. d to see- i

rh: cffect in sugjr uotrake paralle~l !he deglre- of catio~n bin~in3 to

the ti res. i re i h a- h re u o h s p ri nt .nd t

can bt: seen that maximum ilhibtr ion i; reached jC concentratacni of

urinel ion tha~t jecrur.te the binding ;irej. TI-e inhibirlor. of glucoC'e

uptcake in this expcrinent was.s greater th~an ruju' !c'.g.s ce Flgu e 9).

IF the- slI;er we~rc first treated --with lICI uni thien incubear~il in

melitpl iolu~~Tions, thF jmouLn*, oir coacTn bihJndin \1as Consideraldl riduced.l.

This is shot-*n in Fi lur- e !2 fo." ursn,*, ;on, 11nl and (C'f. a.1n i

[he jcid treatmcnl I'endered i.oLE of !h's sitri und.alajlblz ror C3Eion

bind ing. M~e..avr, thi EliC; L oo'* up sucroje as ;hanr in Tabls 13 .i Ih

or rithojur replacing th; catinsh. Of TCoorCe the por::bilit C.:.its

thjt the~ sites in.crl ed if. sugarI 'JJ~rj e werre fear-TCapied~ b.' TJa;r; on rom~ri

.cin he 51maliZr I~auanic i. n Urlnyl( "on [I at bind5 after acid

[Ltrel:tmnt vas surficien[ 10 irhibit uitake s jS s sho.an ir. Took 10.

Wlork ,r;th~ 'ICast In..icvtsLda* ll et nll le i ir displaced f..On the binri-


















80






40/


SSucrose

20 .~ 9 Glucose





S2 3 4

Pretreatment uranyl ion concentration, M x 103

Figure 17. Effect of Urany) lon Pretreatment Concentration
on Sugar Uptake. In the two experiments reported
here the schedules were as follows: 1hr in the
designated concentration of uranyl nitrate, 2
rinses, 30 min in later, 2 more riioses, thE- ..pcIIe
solution. The uptakte solution was 10 ml or Ul.0111
sugar in both cases. With sucrose the ayrj;. pi'ned
was 90 min; with glucose the uptake period j; I br.
(Whereas the uptake period mnay affect the Jag~ree Ji
inhibition, in this case the experiment wa; ~sl i 5cja
to emphasize inhibition as a function of J on,I .00
binding and not the amount of inhibition.

























I~ j r- f -n



SI
u 2+
L O
qJ

U j ] ji ~' '
.1 so u io 111 1
ure I.T fla Bi~ ig r le na cd P
'ue:Le rr Tre sl cs'. r st
.:rc ?uj ce o th o lwn
!,r u.: nce s mn i.002 ~ ,I
ir ih 7 .5 l to. ".e o
to- PI h 2 a e r n r is ..0 0
HO re I3 slu,2 '-e c-. eoe

..or ar:1 ,* i .1 c e c t o





79

ing sites during sugar uptake and are again bound after the sugar has

been taken up (53). Sever-a; experiments which involved pre treatment

with Co2+ or M92+ fai led to detect this phenomena ri th slices of the

corn scutellum,

As described in the methods section, corn was normally grown in

tap wa ter, In one experiment corn was grown in distilled water, Su-

crose uptake by slices from this group of seedlings was about the same

as with slices from tap-water-grown seedlings (i.e.,17 umoles/g hr
from 0.01M su~crose). Prtetetwt at fC2+, Mg2+, or KC had

little effect on sucrose uptake into slices from seedlings grown in

distilled water.















From thie ri-rults of this 'tudy the follorinj conclusion jlre

drjwn. (5) SucroseC ;S telken up jcti\ ely~ without in\erdion. (b) Hezasej

3rt tak~en u~P byi tlvo prTO'LCe.Ss operating S;imulter.eo-iUtI,, dillu5;5r 5:rd

3Ct;ic Ironsport. (c) The acLi~ LCu [31 .511( 1801810$ fn $UjrorLe 8"r( 10

hc.srs ari locjted at the plj51male~i m~ma (d) The actise uc;:.i:L mechaj-

r~i ms for b~oth jucross and the hr:..G.5rcEre dlriken toi .0,iol,siia. ()

The charjiracr i st ic o m rE [al b~ndinj 35 relate [d to sugar uptle areCd

quLi re d~i ffrent in thei corln jcur-l lumT .-then ~cmji lre 1 EO (ho~re i*1 ,cjs t



Several line- of evidence hose- IJllCdHunhreis >..3 Garrard (115) to

thr -::niclus~ion tIat jaCrCote iC. taknC~ up vithoUt i I~crsior. b,. th3 Corn

9CUrtlyl. r;SU: 1' cut btained ir. this c-Jork. sul'po t that co~nclusion.

(j) The amount ofi ..xtracellular inversion <*: insufiident~ t, sLpport

u~ptak' it ;he ob C; -ed rate. (b) The tircat~ics of hC:.r~os uptakei d.e

different fr-om the~ ~inedeis ol sucrose uptake (ci. Figure 4 and Ficiure

8). (c) The rate cr ferarranjtition in sucro;F was less than would reo

expcted (Tiable 1) i f inve~rsioi occurred ci ther pr;or- to or during urp-

talke. (d) if inter;on prcu;lsd uprjke, thie attee.: o uranil ;on on

sucrose should I..G simllar to the rFfect on herose rvbich is nrio the

case (ofi. Tablel 4 .and Figure Y). (e) Tjhr rat;O ofr jcCL~Ul3[- d Su~ClO5C

LOr Suga~Tr ken up it ; g. hir Irhenl Cu;Troe iS iUppliced thaln obetn 3lucuse

is cuPplisd (p. 51).

The mj tor.: draa (Table 7) showJ thj; malic.Le is alsor trJ-i-n upF b,

thF LISSue w~itho1~ut hydrob)li .


DISCUS5101J





81

That sucrose uptake is an active process is indicated by the fact

that it is taken up against concentration gradients. Slices that con-

tained 133 umoles sucrose/g (0.13M~ sucrose) will take up sucrose from

0.01M solution (Table 9). Slices incubated in water for I hr contained

68 ucoles sucrose/g (0.068M sucrose) and will take up sucrose from

0.001M sucrose (Figuire 2), The tissue sucrose concentrations given

above are minimum values since an equal distribution of sucrose through-

out the tissue water is assumed; compartmentation of sucrose would in-

crease the ratios. Ihe scutellum is composed of mesophyll parenchyma,

an epithelial layer and vascular tissue. It is assumed that most up-

take occurs in the parenchyma cells since these cells appear to make

up about 80-90%~ of the scutellum.

'The inhibition of sucrose uptake by DNP is consistent ,i th the

idea of an active, metabolic energy-requiring process.

The inhibition of sucrose uptake by turanose (and probably by

lactose) fulfills one of the criteria given for a facilitated diffusion

or an active transport process (I).

The data in Table :0 clearly show that a 15-m~In rinse in 0.01N

HCI does not disrupt the normal functioning of the cells insofar as

uptak~e is concerned. Since this treatment removes uranyl ion from the

cells anid restores the ab iity of the cells to take up sugar (67) it

appears that the effect of uranyl ion is at the cell surfjce. I: ii

concluded that the mechanism for sucrose uptake is located ji the plat-

malemulal and the same argument can be applied to the: activI j.-r."al jr:

glucose uptake (see below). :n contrast to :has..c results, ~is:M-r :ik)

found that uraniyl ion had no effect on sugar uptake. Hum h r: ; I pt, o 1l







suCiroe. i n con tra t prE t,-ca rirtet of i 5ic:1 ; a 1.0.4 aucrosei cauSed

the: slices to 3Cppearj il-cc;d and ienderedi IhemT IsocapillleS ~r :ath~esz-

ingJ sue Isse = hen pi ;_ed i n I!. 1. I Fruc re,L TheSe obse at~t io .5:~ :'uPF:rt

the~ col~tntentio [l,<. the~ .warm~ral R.'mbrjrnc is pFcret~eur. c cc herose. t..a

not [.' ruirose.




ilso0 has an acri.: i ose' transport miechanistll.. The constur nt rtei IJF

?luaSi uptake until ;'u bathi.ng solution h.15 been .Jeacre.)o- (Fi |13)

;;annor be- izploin.1.1 :. .lirfurion alone and ,cr ,i..an darj had bien

aCcumullated to ShlOu rhat Ihi- Cl!Oprl35m is .'ric SFpice U.j C00.~.~. Thi.

combinati o~ CI' diffusion and .in 3cti.C ICr.isport[ m-...aniser ce., i .plaIinr

rthese resulrs. Th: h:t.-use- uptjke j cancincrrcioron cur-:0s mighte ;'so






Is ar~p~aldiffs cuse.It i; ctruc that this curse co:ul.:1 jlro

h the result ofi i ..r;ocss -h~ic follor-0 enz,.r~e hirleic-: prOviGed that

rE.: I'ni is hign in iconsp~rljo n to the concenl rraton.Hss*er hesb

strteL c..ncnttrrration ia,a O.0111 glucoser which -souldJ require quit.-. 3 Yigh






blocking ~.he2 4ctivl porT[; on of gluoseJ Irptake. iht upat.E rtte s Con-

ce~n;..Mrir *:-.cj 'Or thd becoses~ (Figh~ F) jlnd ') do no7. t re-emble




paic-ISS r:-.xpr JFter LT.tret--irt ri te vlrar.,I ;inn in which :;:1 -s losr J

g Ilucc:O ;caus, Irlcai.~L :n I :3. dif ;'? i n 5e al.- re plr f5Cnt rf 0. .3




83

form sucrose or is catabolized. It is assumed that the glucose which

diffuses into the tissue is phosphorylated via hexokinase whi le that

glucose taken up actively is phosphorylated at the plasmalemma. This

is active transport in the sense that uptake is being energetically

driven at thle membrane but it is not active transport in the sense that

glucose is being accumulated against a gradient. The active process

described h~ere would be called group translocation by Roseman (57).

A combination of active transport and facilitated diffusion is

thought to be i involved i n the uptake of glucose by yeast (55). Rei nhold

and Ellam (2.6), working with sunflower hypocotyl, suggested that active

transport operated in the a'osence of DNP but that in i ts presence

sugars diffused into the cells.

The idea that all of sucrose uptake is active whereas half of

glucose uptake is active and half passive is supported by the following

results. (a) At concentrations of 0.01M sugar and 1 x 10~3M phloridzin

the inhibition of sucrose uptake was twice that of glucose uptake

(Table 5), (b) Sucrose uptake wlas inhibited twice as much by DNP as

was glucose uptake. (c) The effect of anerobic conditions (p. 'fl was

10~ irnhib~l ea'ur.:.' e parate [,.ICr i. iiuch "us ?luccee uptall._- h:.-Tae,



_uc.s, inh Ibi io jr; ri ecrose u.rsI; a rt. co l t .









Th: lac: tr t icrmorstjltion ie d-sected c.;i~r. hen 0, ii not lir..iring is

ar. ind ; c'io i on !h-at bL.jn lr[ rati o .Jri.,i; uptke iregrdicr s of' :h~e a jll-










o~F CO-. !o 5 ji!Luration of the le3;pirjtor*, C71 risT. sno h

case rirh J1:te~llum~ 5lic5 inci "hie cojnsumnption ,f On ra; relducId ;n

rlhB pr7eseceii o1: 0.It Sugar.

E.ide~nc;- hjs ben presented to show* thjr ierimenl.Jion dr;t.< suear

upjltae, t: c.-jinr~e hjs beein et~tjirn:J to 3hoes thJt i iPecific. 9l;roI l; i.

Cst'F is responsble, howet~er, !he data ar cjnsist~entr ..ri II- j,: r,.n

5uch as th: phof phot -jnorjes e Ie 5,seiT i n b3,reria w he-:re TE i s thr

enerjv sOurCe for up two Ga3rrard ;rnd Huimphrc,*s (.LS) U~.u-i,ingl iontrol

of gl*,colysse in the minjzi liurcllum foundl no diffriirnces ,n th? r\TP

leittr1 if the pr'eSenic jrid jbienii of fructOse, TIhe ~ir.ount of frucrore-

Pwih:riianslates prsphoffrTuar.lki nrte doubled i n the~ jlresicac of

fruiroie bJt [h.5 rrt; cOnsjiderd iniadequale to, aiccount fiir a ior-fc IJ

in~crea-,2 in th-e rjte of .,liCol,-sis The usr of PEP .0? the suar/~ uprC!;

proces ar ~;ii h tr i gge.r t rm n tajt ion.

Th: .fate ;n Figure & whiic h)\ shu TucO:G upE~he j+ 9 function jF

the concentrrat!Goi in chu bathing silutiorn ilojc!, fit flhes d

;enren cuirse. Tis j .pe of dataJ i of ten pr..:-r crt i,. su!;orr of j



iur-.t.: th:., rhC, J lInes* upiakle ri; h '.ice in .5 bjth of dlecrea~sing icar.-

centrj lion (Fip. 1, i, and 3) are nioc j ..II r,p~ical of rnz,m.. !:;..ic>.

Peg.3rdians of the n~cchainn~ir~a o uptjl:e, La it dififusion or .3 carricr-

ac.0 sted 3c :I.C p'rocu, the rate would~ 'Je pa ~tted rr ~...crejse js the

jug.- cojnirntri atn in th': ,jluti n waj rCduC' 2.5 3 result of upsti-c.

Ait a ;.2n c.)nce~r[ Trade. the ;on4tanL Uptak.e rTeI r.]ht be 61-~

plainrd. js 2. Saturi tion ,f th :Iptae sic..hdn;ism for sucrevez Zut this

tIr`c'lborlio is japparnT~LI na.! Cjaturad unti[l .1a5n--antration o~f aboar







0,4M (64) which does not explain the constant rate at 0.005M (Fi;. :1.

It appears that whereas the substr'ate is not the limiting factor

(Fig. 2) the substrate concentration has something to do wi th the rate

of uptake (Fig. 14). When the sugar concentration is maintained at a

constant level sucrose uptake increases with time~ whereas glucose up-

take does not (c-f. Figs. 5 and 11), A possible explanation for these

phenomena follow. The rate of sucrose uptake is governed by at least

two factors. the external concentration of sucrose and the internal con-

centration of the phosphate donor. When sucrose uptake begins, the








w~hir bi si-Z.:-. .s i.-.ci-:::ir ei rare orf r02 0 .it, H e .c e






Lei r..3 coure.l:; :J t, .r. I;~r..3:re ir ;n[r-t r..1 .isj .. Icl? :s aIC I:;rn`; 1 su



;U..rC;c upro;l e.






L-r.relir s .i., ~.i.por jr .1:nt d jlerine: 1-.e rate: oF CrJ:tr r:p r i r








Th~us :s: the C;co--st.itio dec~linE; inS Sci e proie~s. .: I~j j ijlal.. ..



car..:-c.rr aro ica of L.Y.:.:Phale~ doreT .r : rer~i~l UKl prC e::.; Tne r jIi







re~ul[ ; isi I.0 up..rla- CCate rJij i; almostJ 3 r.ornstinll uniil Ilh' Bla~ocs In




thec 3nmoun: Of e~xt:rnest gliro.,r ; i ConStant t murofd ui

;.COnSrant andl thusl rhe O.srall r.ite GIi uptal.. Irenlj;.5 cons .-.nt.

.4; comisinlar tion of sct;is are) paSrs: e jlutoi C~~~.: uptake netchani e. (ir

<
conc: ntrati[on .*,jljh bic rto i.he i ulllu r: lj 10, the 5rst..m is capable

oi' rL1soIn.)~l~ all of cihe j.J;I-ble glu.cose~ quickly; h3~e..cr w~hcn thi

--ndu',pern l IjllCUm: Is blig'1 the 'cultellun cji.. (;1;C up !lucorei ur. exceI

of the cjp~ci, of th:r ;J=rtl, procrss.

.i; juga- ul tal e~ i5-st~rldr. eri :.,- giJ,col, .;s .lgso fIts Che 1ole 3.

the Lo r~ ur.. Ther x,.lli, to d~i. .- uprjl.*= undEri I~jnited i, 5uPpl .

:lould be of ob..iau. ;.1.tintag toj j s CJ under 3oil canii~r.Jin. sr.r

and- riump;irc rj I.; ')as me..asun-d aj iQ of i wi ch ..holel .calleIcle ;n Air

indij cacingr t1\3 LhE sCu C. 11ucr.~ itseli meight ;imp.'i e conder5n on S o Ilsi r red




I' is ot;iouis 1..1t [hM mu l;l t..iiders. Chara4 cLer St.(. ofl Ir:utL ur..

sli :-sJifer rer, o e of ea=v. TheC tindinj s uran,*l I sn to ;er st

cills -.esonsr to e :u: r. spc~ir'ic to the uprjlid sit. r.53'. ;rt h sc i-

rillUil ;ICi.. noC li.. .,ct of' Ih' Ma~n.' urs.. ion is Csu if lVOL.~1 .3

thei sp[Ske i.r~re~SS aS sh7'~ran 'i! 'he sectucedl bur rill effecc:; .. as.,Irul

J:u ndJ .jfter acidi EreC reent-I (ci. F17r. 16 anld I I, sold T~t.Il: lIC). I




chdl ..randl ion ..a. t~ilun :I L, onr root~ ..issue, -t ....n i o b r s

thei m-~.mbraini surf ac-= If' the 'e~lTaJ F Oi bound icanOn; OiCcurs dancyi

segor uptak.e to sCU[Cll,' n Slice. th-1 as-sun =. 1- Eco,3 Cmil II~ 0. L aleC[':

rith th*- mci;J1 d;S53. pl'O.CJ1ri* uis ...














LITERATURE CITED


1. Ll. D. Stein, The Monvement _lof Molecue Across Cell Membaranes
Academic Press, New York (1967).

2. R. K. Crane, in Comprehepsive Biochemist~ry, ed. by Ri. D. Stotz.
Elsevier Publishiniy Company, Amsterdam, Vol. 17 (1969).

3. A. L. Kursanov, in Advances in Botanical Research ed, by R. D.
Preston, Academic Press, NewJ York, Vol. I (15163).

4. C. E. Hartt, HI. P. Kortschak, A. J. Forbes and G. 0. Burr, Plant
Phvsiol., 33, 305 (1963).

5. R. L. Bleleski, Plant ?111121., 41 Li47 (1966).

6. P. c:, \feathe~rley, New Phetol.i, 52, 76 (!953).

7. Libi., 53, 20:1 (locL}

8. Ibid.. Sk, 13 (19551.








12. lbid. 2.0, 565 (19< 1

13. P.' J, Hardy and C. .!:.rtc~r 'I i. ? .:.1. .. 1 I .6








17, P. Krie~demann, Pl r _:. . I

I G r r h . r n i .I








L, F.-int..:.id and 1. E-ht..r, Phon Ph,001,, 0,, 1021 (1). ).

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BIOGRAPHICAL SKETCH


Joseph Henry Whitesell was born August 11, 1936, at Clearwater,

Florida. In June, 1954, he was graduated from Large High School at

Largo, Florida. In June, 1958, ne received the degree of Bachelor

of Science writh a major in Ornamental Horticultulre from Auburn Univer-

sity, Auburn, Alabama. From 1958 until 1960 he served in the Uniited

States Nlavy and was stationied aboard thec USS Cutternut at Long Beach,

Ca lifornia. Following his active duty with~ the Nasvy, he w~orkedi for a

yea"r for the Countiy' of Los Ange-les as a1 marke-t inspector. In 1961

he returned to Florida wh~ere he w~orked as an Assistant County Agent in

Collier County, anld during that time he resided in N~aples, Florida.

In 196j he 2nro~lle in the Graduate School of the University of Florida,

Hea woirkedl as a graduate assistant in the Department of Botany and as

a r~ebeach 5Ssistant at the Pesticid~e Research Labor jor a .l e.

ber, :968, when he received the degren of Mlaster- cai "..:.n- e t ..r~ a1

m~aj or in Botdany. Fromt December, 1968, until the pre star nhna

puirsued his wrork toward the degree of: Occtor of Phi~... -il

Joseph Henry h'h~i teseli is malrried to the former !:.e.n-: 11, ..

Stens-on~ and is the father: of three children.














al..u i.ses n. ...sit .s c ~la di s r ia i r or te de r e 0




Profe i or o~f 150tin,


i c.rti., IhjI I h~a.i rE."d this itudrr and that ;ir rt, 1.pinQon .1
onf?-m r r.: acces EDLI~i srandarrdi Ofi shoi jrl prest~ni ot or, ari is f ul l,












i crCif; .r. L E l hs;.:- r:0CS Lhis stu d-, ur. thjt ir, n, opinion ;t
ior f:.i....r.5 to .:p.-ep tlc r.:ji.J-,d~ rds of h y :. pr snI o id fu
adrl' c quite -in* C e jnj q~ujl :v,, ar .; dlsctl Lijnn For r'.* de rs 01


DoctorL'Z C. f~leoh, -



P ychard C, mirn /h


ssiiit .t n. l fes -r f Bc a



:l. .I atJn.:. ..- Src.*e end .uolit,, as 2. dis oraI on[C for~ !Ie JEg:C-a of


Doctor ui *r'd:0(.h,.



Pc.L~ci H-. 8.ggs / /
Frofe nori l of F-rui~ r rr,









Thiis .J;~cirtaion ars sub~mirred to th~e Dejll of the L.ollege of Agricullalne
AIIJ to thei Gradve-ll: Council, andl was- acctepte ;I partial l ulfillmentr of
the requ~iem~in:i for the degree 01' i'c~ctr of Ph losoh,.

Juni, I 1;






Deac., College of Agr icul ture






ean IGraduatre ;ichoo




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