Group Title: Agricultural research (Washington, D.C.)
Title: Agricultural research
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Title: Agricultural research
Uniform Title: Agricultural research (Washington, D.C.)
Physical Description: v. : ill. ; 25-28 cm.
Language: English
Creator: United States -- Science and Education Administration
United States -- Agricultural Research Administration
United States -- Agricultural Research Service
Publisher: Science and Education Administration, U.S. Dept. of Agriculture :
Science and Education Administration, U.S. Dept. of Agriculture :
Supt. of Docs., U.S. G.P.O., distributor
Place of Publication: Washington D.C
Publication Date: March 2001
Frequency: monthly[1989-]
bimonthly[ former jan./feb.-may/june 1953]
monthly[ former july 1953-198]
Subject: Agriculture -- Periodicals   ( lcsh )
Agriculture -- Research -- Periodicals   ( lcsh )
Agriculture -- Periodicals -- United States   ( lcsh )
Agriculture -- Research -- Periodicals -- United States   ( lcsh )
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Statement of Responsibility: U.S. Department of Agriculture.
Dates or Sequential Designation: Began with vol. 1, no. 1 (Jan. 1953).
Issuing Body: Vols. for Jan./Feb.-Nov. 1953 issued by: Agricultural Research Administration; Dec. 1953-<Sept. 1976> by: Agricultural Research Service; <June 1979>-June 1981 by: the Science and Education Administration; July 1981- by: the Agricultural Research Service.
General Note: Description based on: Vol. 27, no. 7 (Jan. 1979).
General Note: Latest issue consulted: Vol. 46, no. 8 (Aug. 1998).
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Bibliographic ID: UF00074949
Volume ID: VID00040
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - ABP6986
oclc - 01478561
alephbibnum - 000271150
lccn - agr53000137
issn - 0002-161X

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Finding Foods That

Agree With Our Genes

Since the recent announcement of completion
of the rough draft of the sequence of the human
genome, there has been much speculation about
how this information will change our understanding of health
and disease. This gene-mapping accomplishment, which started
with the landmark discovery of DNA in 1953, raises many
questions about the value of sequence data. After all, know-
ing the sequence of the genes in the body is interesting,
but it doesn't tell us what the genes do.
DNA scientists are striving to relate the sequence data
to gene function. This includes not only what the genes
do, but also how they interact with each other and the
environment to control our body's responses to chang-
es in the environment and diet.
This knowledge will come about through function-
al genomics, the science of understanding the
organization of genetic pathways and the expression
of genes.
Genes produce mRNA, which directs synthesis of proteins.
Studying cell type and the conditions under which specific genes
are activated to produce a specific protein will lead to describ-
ing roles for genes in response to environmental and dietary
stimuli. The modem study of the cellular function of
proteins has been labeled "proteomics." Proteomics and
functional genomics will become a larger part of the
human nutrition program in ARS.
What does all of this have to do with foods we eat?
A lot.
Certain variants of genes predispose us to respond
to nutrients in a particular way. For example, some of
us are predisposed to cardiovascular disease (see
"Attacking Heart Disease at Its Genetic Base," Agricultural
Research, July 1999, pp. 20-21) or chronic diseases, like obesity,
certain cancers, cataracts, and diabetes.
Other people may have difficulty absorbing and using
nutrients. The story on page 12 in this issue of Agricultural
Research provides new evidence that given the exact same
amount of a nutrient, each of our bodies might use the nutrient
differently. In this study the nutrient administered
was beta-carotene, and some people absorbed

vitamin A.
In the first half of the 20th century, human
nutrition research focused on studying nutritional
deficiencies and inadequate diets. Later the
emphasis switched to the role of phytochemicals
and other nonclassical nutrients. Many of these phytochemicals


S are thought to prevent or reduce risk for certain chronic
diseases. For those diseases strongly linked to diet, the
costs for treatment and care exceed $200 billion per year.
One goal of future research will be to describe the role of
particular genes that predispose people to diseases as a result
of a specific food consumption pattern. Very little is
known about how nutrient intakes, genotypes, and
living environments interact to affect individual
health. There are, however, known genetic defects
that interfere with normal nutrient action, such as
in Menkes' disease or Wilson's disease in which one
has inadequate or excess copper absorption,
respectively. But more needs to be discovered about
other gene-nutrient interactions that play a key role
in our health.
Today we're trying to refine the recommended dietary
intakes (RDIs) for copper and other micronutrients to ensure
that Americans of all ages get enough of these nutrients (see
the article on page 8 of this issue). ARS scientists are among
the prominent experts nationally who have been selected to
help establish RDIs for these nutrients. Ideally, genetic factors
that affect an individual's uptake and use of essential nutrients
could be taken into account in RDIs of the future.
New and innovative genetic information will
advance the science of human nutrition. This
information will not only aid those who have known
genetic defects, but will just as importantly help those
with common variants of genes. One day, individuals
may be able to tailor their diet to their genetic
constitution to reduce the risk of chronic disease.
Our past and our future are in our genes. ARS
human nutrition research will help us to extend our life and be
healthier by identifying foods that agree with our genes.

Kathleen C. Ellwood
ARS National Program Leader
Human Nutrition
Beltsville, Maryland

Agricultural Research/March 2001

March 2001
Vol. 49, No. 3
ISSN 0002-161X

Agricultural Research is published monthly by the
Agricultural Research Service, U.S. Department
of Agriculture (USDA). The Secretary of
Agriculture has determined that this periodical is
necessary in the transaction of public business
required by law.
Ann Veneman, Secretary
U.S. Department of Agriculture
Floyd P. Horn, Administrator
Agricultural Research Service
Sandy Miller Hays, Director
Information Staff

Editor: Robert Sowers
Associate Editor: Sue Kendall
Art Director: William Johnson
Photo Editor: Anita Daniels
Staff Photographers: Scott Bauer
Peggy Greb

(301) 504-1651
(301) 504-1623
(301) 504-1659
(301) 504-1609
(301) 504-1607
(301) 504-1620

Information in this magazine is public property and
may be reprinted without permission. Non-
copyrighted photos are available to mass media in
color transparencies. Order by photo number and
date of magazine issue.
Agricultural Research magazine articles and
photographs are posted on the World Wide Web
monthly at
Paid subscriptions are available from the U.S.
Government Printing Office (Superintendent of
Documents). See back cover for ordering
information. Complimentary 1-year subscriptions
are available directly from ARS to public libraries,
schools, USDA employees, and the news media.
Call 301-504-1660 or e-mail
This magazine may report research involving pesti-
cides. It does not contain recommendations for
their use, nor does it imply that uses discussed
herein have been registered. All uses of pesticides
must be registered by appropriate state and/or fed-
eral agencies before they can be recommended.
Reference to any commercial product or service is
made with the understanding that no discrimination
is intended and no endorsement by USDA is
The U.S. Department of Agriculture (USDA)
prohibits discrimination in all its programs and
activities on the basis of race, color, national
origin, sex, religion, age, disability, political
beliefs, sexual orientation, or marital or family
status. (Not all prohibited bases apply to all
programs.) Persons with disabilities who require
alternative means for communication of program
information (Braille, large print, audiotape, etc.)
should contact USDA's TARGET Center at (202)
720-2600 (voice and TDD).
To file a complaint of discrimination, write
USDA, Office of Civil Rights, Room 326-W,
Whitten Building, 1400 Independence Avenue,
SW, Washington, DC 20250-9410, or call (202)
720-5964 (voice and TDD). USDA is an equal
opportunity provider and employer.

Agricultural Research

Was It a Slab, a Slice, or a Sliver? 4
Investigating Minor Nutrients of Major
Importance 8

Estimating Energy Expenditure 11
New Clues About Carotenes Revealed 12
New Technology Boosts Fiber in Foods 14
Folate and Choline Interplay Investigated 16
Kaolin Particle Film Knocks Out Citrus'
Evil Weevil 18

Feeding Sodium Chlorate to Livestock To Kill
Salmonella and E. coli 19

A Plant by Any Other Name 20
Looking for Genes To Protect Beans 21
Listening to Larvae 21
Honey Bees Mite Breathe Easier 22

Science Update 23

COVER: A meal as appetizing as this one may prove memorable indeed, especially if
your memory is jogged by the new food-survey techniques described in the cover story,
beginning on page 4. Photo by Peggy Greb. (K9315-1)

In the next issue!

** Next month, the magazine goes on tour-to Nepal, Brazil, and France,
to name just a few of the countries featured. Each year, ARS researchers
venture far and wide to seek new ways to fight exotic plants and insects
that could or do cause trouble here at home. Read about attempts to
eradicate screwworms in Panama, efforts to battle mosquito-borne
diseases in Brazil, and a perilous expedition to Nepal to hunt enemies of
Arundo donax, or giant reed.


Agricultural Research/March 2001

A according to the last USDA
nationwide food consumption survey,
conducted from 1994 to 1996, Americans
of all ages averaged about 2,000 calories
a day. So why are we overweight as a
Some Americans obviously eat more
than they report, say Linda E. Cleveland
and Linda A. Ingwersen, of ARS' Food
Surveys Research Group, which devel-
ops and oversees the periodic survey. So

often, we tend to forget that soda, bag of
chips, or candy bar we snatched yester-
day when our tummies rumbled. And we
may think we ate smaller portions than
actually passed our lips.
So Cleveland, a nutritionist, Ingwer-
sen, a home economist, and other survey
group members are working hard to catch
those forgotten and underestimated
calories in the next nationwide survey-
expected to begin in 2002 (see box).

It's Not So Much What You Ask,
As How
Staffers have improved the way the
interviewers will probe for all the foods
and beverages a respondent ate during
the previous 24 hours so that the ques-
tions don't seem repetitive. "It sounds
more conversational," says Cleveland,
"like you're chatting about the meal,
rather than questioning their memory."
And Cleveland and Ingwersen believe

Agricultural Research/March 2001


r.-. 'M

they have improved the accuracy with
which people estimate the size of the
portions they consume. The two scien-
tists have developed an easy-to-use Food
Model Booklet that incorporates high-
tech graphics and research on how people
perceive quantities and on what is and
isn't helpful.
In previous surveys, interviewers
were armed with measuring cups,
spoons, and rulers when they visited

Survey participants position
the movable arrow on this
model to resemble the size of
the pizza, cake, or other
wedge-shaped food they ate.

households. But during the next survey,
respondents will be able to turn to life-
size, two-dimensional pictures-each
marked by a numbered tab-as well as
the cups, spoons, and ruler.
"We're trying to provide a variety of
ways for people to estimate amounts in
order to make it as easy for them and as
accurate as possible," Ingwersen says.
Respondents may find it easier to re-
call the size of that slice of pizza by turn-
ing to one of the wedges pictured under
tab 7 and adjusting it to just the right
width than to estimate its length and
width with a ruler (see above diagram).
Under tab 6, the 5-inch-by-5-inch
grid for estimating that serving of lasa-
gna, meat loaf, brownies, or corn bread
may shake loose old memories of math
class, Ingwersen says, noting that focus
groups have helped them fine-tune the
For instance, on the opposite page are
blocks for estimating the thickness of
lasagna or meat loaf servings. "The
focus groups wanted to know the actual
measurements, so we added them,"
Ingwersen says. One focus group of
women wanted a smaller wedge for
estimating pie or cake servings. "And
they wanted it on a dessert plate," she
says. The researchers obliged.
To put the servings in perspective,
Ingwersen and Cleveland had the grid,
circles, and several amorphous mounds
printed on transparent pages that over-
lie a full-size dinner plate straddled by
a full-size knife. "The transparencies
give the quantity a three-dimensional
appearance," Ingwersen says.
And the different-sized mounds-for
estimating foods ranging from a dollop
of whipped cream to a heap of spaghet-
ti-have depth. A graphic designer used
a computer program to draw the mounds
and then rotate them to a 55-degree
angle-the perspective one would have
while sitting at a table, says Cleveland.
Developing the collection of glasses,
cups, mugs, and bowls under tabs 2 and
3-each marked at several different

USDA and HHS Surveys
To Be Wed

In an effort to increase efficiency in
government, the USDA food survey will be
integrated with the National Health and
Nutrition Examination Survey-better
known as NHANES. Directed by the U.S.
Department of Health and Human Services'
National Center for Health Statistics in
Hyattsville, Maryland, the NHANES collects
food-intake data from participants nation-
wide, along with biological samples taken
during a physical examination.
The merger will enhance food data
collection and analysis, says Alanna J.
Moshfegh, who oversees the USDA food
survey. "For the first time, we'll be able to
compare food intakes with measures of
health status," she says, because the same
people are being assessed for both diet and
health indicators.
Traditionally, the NHANES emphasized
nutrient intakes-such as fat or specific
vitamins or minerals-not the foods them-
selves. So researchers primarily looked for
associations between nutrients and health
"Now, we'll be able to look at both foods
and nutrients in relation to health," says
Moshfegh. "For example, do people who
eat more fruits and vegetables have more
favorable health outcomes?"
Moshfegh's group will oversee training
of the data collectors contracted to conduct
the food-intake interviews using the new
tools developed by her staff. Interviews
along with comprehensive physical exam-
inations will take place in the mobile exam
centers currently being used in the
NHANES. Plans call for a second day's in-
take to be collected by telephone interview
a few days after the first interview.
Moshfegh, Joseph Spence, director of
ARS' Beltsville [Maryland] Human Nutrition
Research Center, and their counterparts at
the National Center for Health Statistics are
working out details for the merger, which is
slated to begin sometime next year. Spence
says the integrated survey will continue to
collect data annually from 5,000 partici-
pants, who are selected to represent U.S.
demographics. And Moshfegh's group will
continue to process and compile the data,
which will be released annually.

Agricultural Research/March 2001

These two-dimensional drawings represent
foods that mound on a plate, such as
casseroles, vegetables, or rice. The plate and
knife provide a size reference.

volume amounts-took a lot of thought,
as well as some computer tricks.
"We filled a table with glasses and
bowls. We surveyed stores and looked
at what people had in their cabinets to
determine which shapes and sizes to in-
clude in the booklet," says Cleveland.
And, adds Ingwersen, "we included a
wine glass. That says, 'Yes, we do want
you to report any alcohol you drank,'"
because it contributes calories.
All their planning should produce
more accurate data, according to tests
conducted by the ARS researchers. The
tests involved 264 men and women from
age 20 to over 60, who estimated the
portion sizes of all types of foods and
beverages using the booklet or the cups,
spoons, and ruler.
"People estimated serving sizes
reasonably well with both types of
guides," says Cleveland. "But they did a
little better using the booklet, especially
the mounds." On average, estimates im-
proved by about one-third with the


mounds compared to the measuring

Asking Without Badgering
The booklet is only part of the effort
to improve the survey data, says Alanna
J. Moshfegh, who oversees the Food
Surveys Research Group. During the last
3 years, the group has expanded and

A new, computerized interview process, developed by the Food Surveys Research Group,
prompts nutritionist and group leader Alanna Moshfegh to ask survey respondents about
"forgotten foods." The mounds help the respondents estimate portion size.

improved the method of questioning to
help respondents remember the foods
they ate. They've also automated the
whole interview, computerizing the
questions, prompts, and details about
the food and how it was prepared.
"Since the first nationwide collection
of individual dietary intakes in 1965,"
Moshfegh explains, "the focus of re-
search in USDA's nutrition monitoring
program has been the question, What is
the most effective way to collect a com-
plete 24-hour dietary recall?"
In the 1994-96 survey, interviewers
used a triple-pass method, she explains,
because her group's research had shown
that asking people about their intakes
in different ways helped respondents
recall more of the foods they ate the day
before. Since then, Cleveland, Ingwer-
sen, and their colleagues have been
testing and refining a better instru-
ment-the new USDA Multiple-Pass
In addition to asking the respondent
to remember all they ate, interviewers
specifically ask about "forgotten foods,"
such as nonalcoholic and alcoholic bev-
erages, sweets, snacks, or breads.
"Our research showed that beverages
accounted for half of forgotten foods,"
says Moshfegh. "Sweets accounted for
The method has a number of built-in
cues to help jog the memory. One step,
for example, asks respondents what
time they ate the food and what they
would call the eating occasion-lunch,
snack, dinner, etc. The questions don't
seem repetitive, says Moshfegh. "The
respondents remain engaged because
they are still adding foods throughout
the interview."
Based on the results of pilot tests,
"we believe this method does a better
job of collecting more complete food
intakes," she contends. In the first test,
383 women recalled eating an average
16 foods instead of the 14 reported by
their counterparts in the last survey. And
they reported 300 more calories, on

Agricultural Research/March 2001

-111 1- -- o n.

average. In a larger study with nearly 800
men, women, and children, the trend of
more food and more calories continued.

No Easy Task
The fact that the questions and
prompts are computerized is one reason
for its success. "It's easier to administer
and more consistent," Moshfegh says.
"Participants said they liked the inter-
view. And the interviewers who pre-
viously collected data with paper and
pencil liked the automated version much
That's because the automated pro-
gram prompts the interviewers and leads
them through the details they must ask
about each food. For instance, the pro-
gram would prompt the interviewer to
ask, "Was that candy bar regular, king
size, or fun size? Was that apple small,
medium, or large?" explains Moshfegh.
Prepared foods require more details.
Take carrots, for instance. Were they
cooked, creamed, fried, pickled, or raw?
the program would prompt. If the answer
is "raw," you get to move on to the next
food. If it's "cooked," however, the in-
terviewer would ask if they started as
fresh, frozen, or canned. Were they
cooked with fat or oil? And so on.
If you had beef stew, the interviewer
might ask if it was home prepared,
canned, frozen, a restaurant entree, or
something else. If it was a home recipe,
what were the ingredients? If it was a
frozen brand name, what brand?
"There are 2,400 questions about
foods and 21,000 possible answers,"
says Nancy R. Raper, who oversaw the
automation. And the job is never end-
ing: "We have to keep up with the foods
on the market to assess whether the ques-
tions we ask are relevant," she notes.
Programming all these questions took
about 2 years, Raper says, with input
from several scientists in the survey
group. They used survey software devel-
oped in The Netherlands and used by the
U.S. Bureau of the Census and other
government agencies. So far, she says,

This grid is used to estimate the
length and width of square and
rectangular foods like meat loaf,
brownies, or lasagna.
. M : "'*.W


the program developed for the food sur-
vey is the largest and most complex ap-
plication of this software.

Finding the Trends
As the data is collected, another
program-Survey Net-will code each
reported food by number. "We have over
7,000 foods in the database, with
descriptions of their package sizes and
weights, types of preparation, and nu-
trient profiles," says
Ingwersen, who en-
sures that the data-
base is updated.
When all the sur-
vey data is translated
into numbers, it can be
analyzed for intake lev-
els of either nutrients or
foods, Ingwersen says.
"And it can be sorted by
any variable you want: Sui
age, gender, socioeconom- pai
ic group, geographic re- U d
gion, food or nutrient, Food gla
Guide Pyramid servings, esti
foods eaten on weekday ver- am
sus weekend, or outside the drt
home versus at home."
That versatility is what
makes the survey data so valu-
able to researchers and educa-
tors, says Moshfegh. And it's
critical to government agencies

in planning food assistance programs and
nutrition education programs.-By Judy
McBride, ARS.
This research is part of Human Nutri-
tion, an ARS National Program (#107)
described on the World Wide Web at
Alanna J. Moshfegh, Linda E. Cleve-
land, Linda A. Ingwersen, and Nancy R.
Raper are in the USDA-ARS Food Sur-
veys Research Group, Beltsville Human
Nutrition Research Center, 10300
Baltimore Ave., Bldg. 005, Beltsville, MD
20705-2350; phone (301) 504-0170, fax
(301) 504-0376, e-mail
amoshfegh @
lingwersen @ *


Agricultural Research/March 2001

Investigating Minor Nutrients of

Major Importance

bars and some kinds of beer
are-perhaps surprisingly-
rich in an essential nutrient,
copper. So, too, are the foods
that Mom may have told you to eat, like
liver and other organ meats; peas, beans,
and other legumes; and whole-grain
breads or other grain products.
Even though copper has been known
for a century to play a key role in our
health, much more remains to be discov-
ered about this vital mineral. Investiga-
tions led by Judith R. Turnlund at the
ARS Western Human Nutrition Research
Center in Davis, California, are helping
to fill in missing pieces of this puzzle.
Her studies are revealing new clues about
what our bodies do with the copper that
we get from everyday foods.
"We already know that we need cop-
per for strong bones, a well-functioning
nervous system, and a healthy heart,"
says Turnlund. "But we'd like to know
more, like where exactly does it go after
we eat? How fast does it get there? How
much do we store? How much do we
To help answer these questions,
Turnlund's group uses rare, trackable
forms of copper, called stable isotopes,
to follow copper's fate in the body.
Turnlund pioneered the use of isotopes
to study essential minerals in humans.
The information that her team uncovers
can be used-along with findings from
labs elsewhere-in setting the national
nutrition guidelines, or recommended
dietary intakes, which help ensure that
Americans of all ages get enough copper
to stay healthy. The recommended in-
takes for some nutrients show up in the
familiar lists printed on regular products,
like a box of breakfast cereal, can of fruit,
or bottle of vitamin/mineral tablets.
Among Turnlund's other research tar-
gets are molybdenum and magnesium.
Molybdenum is an essential component
of three enzymes needed to chemically
process-or metabolize-certain amino
acids that we get from protein. Magne-

sium, like copper, is important for our
bones, nervous system, and heart.
Turnlund's work with these trace ele-
ments, plus zinc and iron, has made her
an international authority on mineral
nutrition. Her copper studies include
unique investigations in which she has
scrutinized the effects of very low and
very high intakes to find out what's safe
for us-and what likely isn't.
"In our tests of healthy young men,"
she reports, "we found that 0.38 milli-
grams of copper a day is too low." Lev-
els of a copper-containing enzyme called
lysyl oxidase-needed in the skin, bones,
and heart-decreased in most of the vol-
unteers during the low-copper regimen.


In a study of magnesium absorption,
chemist Joseph Domek measures
magnesium content in water with an atomic
absorption spectrophotometer.

What's more, a trio of other indicators
of copper nutrition-serum copper, cer-
uloplasmin, and superoxide dismutase-
also declined.
Turnlund and collaborators in the
United Sates and abroad are currently
analyzing the data from their recent high-
copper study. "We want to know," she
says, "what might happen to people who
take two or three vitamin/mineral sup-
plements a day, meaning that they'd be
getting several extra milligrams of cop-
per. We think it's important to establish
whether that amount-if taken over a
long period of time-is too high."

Model Mimics Copper's Cycle
Discoveries from each of the copper
experiments help Turnlund refine a ma-
jor product of her research-a handy,
computer-driven model for filling in gaps
about how our bodies use copper. Says
Turnlund, "We started with a very so-
phisticated, highly versatile modeling
program that scientists at the National
Institutes of Health and the University
of Washington in Seattle developed for
simulating many different kinds of bio-
chemical processes. We use the program
in desktop computers to process-with
mathematical equations-our data as
well as data from other nutrition studies
of animals and humans.
"The result, in our case, is a best esti-
mate of how copper makes its way
through the body. For example, the mod-
el predicts how copper might move from
our digestive tract to the plasma in our
blood, then to our liver-where it is in-
corporated into enzymes-and, later, to
the cells of other tissues and out of our
"Each of these points along the path-
way," she notes, "is called a compart-
ment. Some, like plasma or urine, can
be easily sampled to get a better idea of
how much copper goes into each and for
how long, and how much remains."
But what about compartments like the
liver, where following copper's progress
would be difficult unless one sampled a
little chunk of liver from time to time?
"For those compartments," explains
Turnlund, "we start with animal data. The
mathematical equations can help us
extrapolate it to match-to the greatest
extent possible-what may happen in
"Our model," she says, "is only a pre-
diction, or estimate, of course. But it
allows us to apply the computer's

Chemist Judith Turnlund and physical
scientist William Keyes use thermal
ionization mass spectrometry to measure
trackable forms of copper, called stable
isotopes, in blood plasma.

Agricultural Research/March 2001




Agricultural Research/March 2001



is" .," M-"' 1

Chemist Joseph Domek prepares ion exchange chromatography columns for separation of
copper, iron, and zinc in samples from participants in a study of high dietary copper.

enormous speed and power to crunch
mountains of data into possible sce-
narios. Looking at the scenarios helps
reveal new possibilities. And it can help
us decide what needs to be studied next."
Turnlund's copper model, first pub-
lished in 1994, was based on studies of
healthy volunteers. It was the first-ever
computerized model of how copper is
metabolized in healthy people. The mod-
el has provided new support for what
some scientists had suspected earlier,
namely that copper most likely progress-
es though our bodies primarily in one-
way paths, with little recycling. Notes
Turnlund, "That's unlike molybdenum,
zinc, or a number of other nutrients that
tend to move back and forth from one
compartment to another."

Monitoring Molybdenum and Magne-
In their studies of molybdenum,
Turnlund and coinvestigators have
produced another computerized model

similar to the copper one. Data for the
model came from studies in which
Turnlund's team fed volunteers various
amounts of molybdenum, "ranging from
as low as we could get to as high as might
be conceivable," she says.
"We found that it's unlikely that
healthy people would develop a molyb-
denum deficiency at any of these levels,"
she reports. "We estimated that the min-
imum requirement for adults is about 25
micrograms a day. People usually eat
considerably more than that in a day's
worth of ordinary meals." The investi-
gation was the first to provide an esti-
mated minimum level for molybdenum
in healthy volunteers.
Seeds, such as those from sunflower
or pumpkin; legumes like peas, beans,
and peanuts; and grain-based products,
such as breakfast cereals or whole-grain
breads, are often good sources of molyb-
denum. The level varies, however, ac-
cording to the quantity of molybdenum
in the soil where the crop was grown.

In her magnesium research, Tumlund
is now tackling the daunting task of
determining an easy, reliable way to
measure how much of this mineral we
absorb from our food. Good sources of
magnesium include green, leafy vegeta-
bles; whole grains; and nuts.
In this venture, she's collaborating
with the producers of Perrier, a premi-
um bottled water. "Perrier researchers,"
says Turnlund, "want to know if bottled
water is a good source of magnesium.
To find out, they need a good way to
measure magnesium absorption. We
need that for our research, too. So we're
working together to find a test that is fast,
easy, accurate, reliable, reproducible,
and, of course, affordable."
So far, they've found that a urine test
appears to be as accurate as fecal anal-
yses-and is faster and easier. For the
urine test, researchers provide volunteers
with a food or beverage that's spiked
with a traceable form of magnesium.
They also inject a tiny quantity of the
tracer magnesium into the volunteers'
blood, then collect urine specimens
about 2 days later. To determine the
amount of tracer magnesium in the
sample, the researchers use a high-tech
instrument known as an inductively
coupled plasma mass spectrometer.
From this they can calculate how much
magnesium each volunteer absorbed and
Turnlund's team will also use data
from the magnesium study-hundreds
of specimens in all-to create a new
model of how our bodies cycle this im-
portant mineral.-By Marcia Wood,
This research is part of Human Nu-
trition, anARS National Program (#107)
described on the World Wide Web at
Judith R. Turnlund is with the USDA-
ARS Western Human Nutrition Research
Center, One Shields Ave., Davis, CA
95616; phone (530) 752-5249, fax (530)
752-5271, e-mailjturnlun @whnrc. usda.
gov. *

Agricultural Research/March 2001

, ,


JA~ "


Estimating Energy Expenditure

What types -
of activities did
you do yester-
day? When this
question is asked, people often don't
remember time spent vacuuming, rak-
ing leaves, climbing stairs, or even
watching television. This can be a
problem for scientists, health care prac-
titioners, and physicians as they try to
make health assessments and recom-
mendations for life-style changes. This
kind of information is important, since
physical activity is a vital part of preventing and managing
diseases like high blood pressure, diabetes, and obesity.
"Many things contribute to difficulty and inaccuracy in
measuring physical activity in people," says chemist Joan M.
Conway, with the ARS Diet and Human Performance
Laboratory in Beltsville, Maryland. A main problem is that
people may not report all of their physical activities on
questionnaires. This can lead to errors in estimating energy
expenditures. "Physical activity includes occupational activ-
ities, leisure activities, household tasks, social activities, and
physical fitness activities," Conway notes.
To help solve this problem, Conway, ARS colleague James
L. Seale, and university collaborators conducted a study to
test how well activity records and questionnaires estimate daily
energy expenditures.
They found that it's possible to use activity records to
estimate energy ex-
penditures in groups,
but they are not re-
liable for individ-
uals. Questionnaires
were less reliable
than activity rec-
ords. Poor ques-
tionnaire design,
time spent mov-
L ing and using up

a too-small
sample size
can cause
error e en in group estimates.
There !\ a more accurate method,
hut it', hih-iech. Scientists use latest
with double labeled water to deter-
mine energy\ e,.penditure in people.
The water c_,itlin l heavy forms of
Ih, dr.eni andl ,\_, en called isotopes,
which can be traced in the urine or
blood to determine how much of the
isotope is still present in the body. From this measurement,
scientists can determine how much energy a
person used during the study and
then calculate average daily
energy expenditure. But
this test is expensive, so
it's not practical to use ""
with large groups.
"Future studies
should address rede-
signing current meth-
ods, or developing new
techniques to assess
daily physical activity,"
says Conway. "These
types of studies are
important because obe-
sity in Americans is increasing, and nutrition and life-style
decisions are based on this information."-By Tara Weaver-
Missick, ARS.
This research is part of Human Nutrition, an ARS National
Program (#107) described on the World Wide Web at http://
www. nps.ars. usda. gov.
Joan M. Conway is with the USDA-ARS Diet and Human
Performance Laboratory, BARC-East, Building 308, Beltsville,
MD 20705; phone (301) 504-8977, fax (301) 504-9098, e-mail *

Agricultural Research/March 2001

New Clues About Carotenes Revealed

T he rich yellow of a mango or deep orange of a carrot
are the work of nutrients called carotenes. Our bodies
can convert some carotenes-namely, alpha-carotene,
beta-carotene, and beta-cryptoxanthin-into vitamin A,
a nutrient essential for proper growth and reproduction as well
as for good eyesight. What's more, new evidence further
supports the value of carotenes as antioxidants that may reduce
our risk of cancer, stroke, arteriosclerosis, and cataracts.
Dozens of familiar, brightly colored, yellow, orange, or dark-
green vegetables and fruits provide carotenes. Perhaps most
studied to date is beta-carotene. Scientists have long suspected
that individuals differ in their ability to absorb beta-carotene
and convert it to vitamin A. Early beta-carotene studies with
humans gave researchers a glimpse of this variability. But a
series of investigations over the past 5 years, led by ARS
chemist Betty J. Burri, offers new, more detailed proof of this
These findings are important for people who are cutting back
on the amount of meat and dairy products they eat. "Meat,
eggs, cheese, and whole milk are rich in vitamin A," says Burri,
"so people who eat little if any of these foods need to be sure
they are getting an adequate supply of this nutrient from other
Burri is with the ARS Western Human Nutrition Research
Center in Davis, California. She did the work with Terry J.
Neidlinger, also at the center; Andrew J. Clifford, Stephen R.
Dueker, Sabrina J. Hickenbottom, and Yumei Lin of the
University of California, Davis, Department of Nutrition; and
Jin-Young K. Park, formerly with ARS and now with the Food
and Drug Administration.

Special Compounds Used As Trackers
The researchers studied 45 male and female volunteers, aged
18 to 42. For some of the studies, volunteers were fed
supplements containing special forms of vitamin A and of beta-
carotene. These forms can be traced, or detected, because they
weigh more than naturally occurring vitamin A and beta-
carotene. The sophisticated laboratory instruments that the
researchers used-a gas-chromatograph mass spectrometer and
a high-performance liquid chromatograph-can differentiate
the tracer compounds from the naturally occurring forms.
Research done elsewhere has tracked the fate of one or
another of the compounds in human volunteers. But the
California studies were apparently the first to evaluate uptake
and use of both tracer beta-carotene and tracer vitamin A
concurrently. That gave Burri's team what is probably the best-
ever look at the interaction of these nutrients in healthy humans.

Surprising Variability
"We found new extremes in the amount of time it takes for
beta-carotene to be absorbed and converted-and in the amount

that is converted," Burri reports. "But most unexpected was
the statistically significant difference in beta-carotene uptake
and conversion by physically similar volunteers, including one
pair who were so alike that they could well have been twins.
"Both were females of nearly identical age, height, and
weight. They had a similar amount of body fat and about the
same amount of vitamin A in their blood at the start of the
study. Their uptake of our tracer vitamin A was similar. That
isn't unusual, because we already know that most well-fed
people absorb vitamin A in nearly the same way. But the first
volunteer used about 30 percent of the tracer beta-carotene
within only 12 hours of taking it. Of that amount, she convert-
ed about 30 percent to vitamin A.
"The second volunteer took up only about 15 percent of the
tracer beta-carotene and took about 3 days to do it. Then, she
converted only about 8 percent to vitamin A.
"Essentially," Burri summarized, "the first volunteer used
up about twice as much beta-carotene and converted it to about
8 times more vitamin A. We hadn't expected individuals who
were so similar in so many key variables to be so different in
their processing of beta-carotene."
With the exception of a volunteer who was very low in
vitamin A at the outset of one of the studies, most volunteers
handled vitamin A similarly, as had been shown in previous
research in the United States and abroad. But about half of all
Burri's volunteers-male and female-didn't take up much
beta-carotene at all. Uptake amounts ranged from undetectable
to about 50 percent. About half of the volunteers didn't form
much vitamin A from the beta-carotene they did absorb.

Basic Chemistry Doesn't Apply
Notes Burri, "None of our volunteers metabolized 100
percent of the beta-carotene, but that's what we expected to
happen. Even though beta-carotene-of all the carotenoids-
is the easiest for us to convert into vitamin A, we don't do it as
efficiently as the basic chemistry of beta-carotene might
"Beta-carotene is a large molecule. Its chemical structure
looks like two molecules of vitamin A joined end to end but
facing opposite directions. It would seem-on paper, at least-
that one molecule of beta-carotene should, logically, yield two
molecules of vitamin A. But the body isn't a perfect chemical
factory. We don't form two molecules of vitamin A for every
one molecule of beta-carotene that we consume."
Burri says the findings may help explain why giving beta-
carotene supplements to people who are deficient in vitamin A
may not be sufficient to prevent the blindness and death that
lack of vitamin A causes today in Southeast Asia, sub-Saharan
Africa, or South America, for instance. The procedure that her
team used for tracking vitamin A and beta-carotene simulta-
neously could be adapted to screen individuals in these regions

Agricultural Research/March 2001

for their ability to process beta-carotene. That could save vi-
sion and lives by identifying-earlier on-those who likely
won't respond to beta-carotene supplementation.
Vitamin A deficiency isn't prevalent in the United States.
Nevertheless, the procedure could be used here to help health-
care professionals identify individuals at risk of developing a
shortage of this nutrient. An example: people who don't pro-
cess fats efficiently. Fats, like those in whole milk, help our
bodies absorb and digest vitamin A.

Genes Likely Control Beta-Carotene Processing
"The variation in the way our bodies respond to beta-carotene
is likely gene-based," Burri points out. "Some genes that govern
our use of this compound have already been identified, and
more will likely be pinpointed as a result of the human genome
project. That might lead to new strategies for fighting vitamin

A deficiency. And it may reveal useful clues about how other
genes control processing of other compounds and nutrients.
"Ideally," adds Burri, "it may also help us produce custom-
ized dietary guidelines that take into account an individual's
ability to convert carotenes from fruits and vegetables into vi-
tamin A."
Burri and co-researchers published their findings in the
American Journal of Clinical Nutrition and in Mathematical
Modeling in Experimental Nutrition.-By Marcia Wood, ARS.
This research is part of Human Nutrition, an ARS National
Program (#107) described on the World Wide Web at http://
Betty J. Burri is with the USDA-ARS Western Human Nutri-
tion Research Center One Shields Ave., Davis, CA 95616; phone
and fax (530) 752-4748, e-mail *

Agricultural Research/March 2001






PEGGY GREB (K9309-1)

Charles Onwulata, a food technologist, prepares ingredients for
high-pressure homogenization, a process that can increase fiber
content in fluid foods.

A mericans fall short when it comes to eating enough
fiber each day. So what are scientists doing to help?
They have come up with a new technology that allows
them to add more fiber to foods without changing
their texture, says food technologist Charles I. Onwulata, who's
in the ARS Eastern Regional Research Center's (ERRC) Dairy
Products Research Unit, in Wyndmoor, Pennsylvania. "Until
now, adding fiber to foods was difficult because it changed the
qualities-particularly the texture and mouth feel-of the
food," Onwulata says.
Onwulata has filed for a patent on the new technology,
"invisible fiber," a process that uses milk protein to envelop
the fiber and keep it from soaking up water. "The protein barrier
makes the fiber 'invisible' to water. The fiber doesn't pull
moisture out of the rest of the food product," he notes. "But
the invisible fiber envelope will dissolve during digestion,
allowing the fiber to perform its normal function in the gut.
This new, encapsulated fiber can be incorporated into food
products without changing texture or moisture. Many foods
can be modified with the invisible fiber."
Traditionally, food manufacturers have increased fiber in
foods in small amounts to avoid negative effects such as chang-
es in texture, color, and mouth feel. In foods with high fiber
content, the fiber absorbs water from its surroundings, giving
the food a dry texture. Reducing the water-holding capacity of
the fiber improves food quality and allows more fiber to be
added without changing its texture, Onwulata says.
Onwulata and colleagues conducted baking studies to test
the moisture level, protein content, color, and hardness of foods
made with invisible fiber and compared them to recipes with
regular fiber. Fiber affects these properties, and these proper-
ties determine consumer acceptability.
The scientists-turned-chefs baked cookies and muffins
power-packed with invisible fiber. The invisible fiber improved
the goodies' qualities.
ARS researchers are also working with industry to increase
fiber in fluid foods. They had a cooperative research and
development agreement with Verion, Inc., of Exton,
Pennsylvania, to adapt a "dynamic pulse-pressure treatment"
process for the food industry. The technology, which is patented
by Verion, uses hydrostatic pressure-the force applied through
water-to change the moisture, density, and melting properties
of foods. The treatment was originally used for making
"Scientists have known for a hundred years that high pres-
sure can be used to process foods," says Onwulata. "Old meth-
ods take anywhere from 20 to 30 minutes to pressure-process
foods. With dynamic pulse-pressure treatment, pressure-
processed fluid foods like milk or slurries (pastelike fluid that
can pass through a nozzle) can be processed in 1 second-
faster than with anything else that's on the market," he says.

Agricultural Research/March 2001

Chemist Renee Wildermuth bakes muffins and cookies
containing "invisible fiber."

Foods react differently to pressure processing, since they
have varying densities and abilities to dissolve in water. In
studies at ERRC's dairy pilot plant, a small-scale processing
facility, scientists tested several food ingredients, including
whey proteins, corn starch, wheat bran fiber, and cellulose fiber.
They found that pressure treatment modified the molecular
structure of the starches. Pressure-treated fiber had about a 40
percent reduction in its water-holding capacity. Microscopic
images revealed that pressure treatment packed the fibers into
small balls that were impervious to moisture.
"Once these technologies are fully developed and
commercialized, the food industry will greatly benefit from
them," Onwulata says. Many companies are interested in
increasing the amount of fiber in their foods as a benefit to
consumers. The recommended fiber intake is 20 to 35 grams
per day. But on average, Americans get only about 15 grams
per day. Studies suggest that fiber decreases heart disease, some
cancers, high blood pressure, and diabetes.
Nutritionists still agree that eating a variety of grains, fruits,
vegetables, and legumes is the best way to get fiber. Mean-
while, ARS researchers will continue to look at ways to boost
fiber in other foods.-By Tara Weaver-Missick, ARS.
This research is part of New Uses, Quality, and Market-
ability of Plant and Animal Products, an ARS National Pro-
gram (#306) described on the World Wide Web at http://
Charles I Onwulata is at the USDA-ARS Eastern Regional
Research Center, Dairy Products Research Unit, 600 E. Mer-
maid Lane, Wyndmoor, PA; phone (215) 233-6497, fax (215)
233-6795, e-mail *

Foods With Fiber
Dietary fiber comes from plant cell walls. There are two
main types of dietary fiber, and \ e need a combination of both.
Soluble fiber (gums, mucilages. pectins) forms a gel and is
found in fruits, dry beans and peas. vegetables and some
cereals. Insoluble fiber (cellulose. hemicelllulose. lignini passe.
through your digestive tract basically intact and is primarily
found in whole-grain products, like wheat bread. Insoluble fiber
helps get rid of food your body can't use. It also gi\ e.s you that
full feeling. Soluble fiber lowers blood cholesterol and helps
regulate blood sugar. Here are just a few sources of fiber:

Po ;- -

Appled4aw,1wiflsldn tinediun y
Baby Hima bemta 60-";cx
BakeW potatoW iWsk ic p-otaw 4
SBanan... t. td

P Bcroch". ':-. C0414^ ^ ^l--. "- .i ;

SOleendam:.- I..i;.


Popcort ;a,-p edi. i-. .

G ours re:. L aLffdr Igdoj/itmj4,
I9M LEBDA MAWe deas.
K len a0,t i i
PeGaY49eatsMl-MI -

U _

Agricultural Research/March 2001

'1~LII crrs~F

Folate and Choline

Interplay Investigated

I inside our bodies, the B vitamins
folate and choline work in a deli-
cate balance. A team led by ARS
chemist Robert A. Jacob has now
shown-for the first time in
healthy people-that we can't synthesize
enough choline if we are low in both cho-
line and folate.
"That's in contrast to the assumption
that the body can make as much choline
as it needs," says Jacob. He is with the
ARS Western Human Nutrition Research
Center in Davis, California.
Jacob's studies with healthy men and
women volunteers agree with some of the
findings of animal studies conducted

Chemist Robert Jacob prepares blood
samples for analysis in a study of the B
vitamin folate.

earlier by ARS scientists at Tufts
University in Boston and by nutrition
researchers elsewhere. In all, these
investigations helped pave the way for
the recent announcement of a recom-
mended daily amount of choline.
"The choline recommendation," says
Jacob, "is the first ever made in the
United States for this nutrient." The Food
and Nutrition Board of the National
Academy of Sciences now suggests that
an adequate choline intake is 425
milligrams a day for women and 550
milligrams for men. "There are about 250
milligrams of choline in a 12-ounce beef
steak," he says.

Choline Carries Out Many Chores
Choline helps the body absorb and use
fats, including those that become part of
membranes that keep our cells intact.
"Choline deficiency," according to
Jacob, "can result in fat accumulating in
the liver and subsequent liver damage."
In addition, choline is required for
synthesizing acetylcholine, a neuro-
transmitter needed for memory storage
and muscle control, for example.
And choline-as well as folate-con-
tains what's known as a methyl group,
which the body uses to form genetic
material, or DNA. "The process by
which methyl groups, borrowed from
methyl donors such as choline and folate,
are added to DNA is known as DNA
methylation," explains Jacob. It can be
monitored in blood samples and is one
of several indicators of the integrity, or
condition, of DNA.
Our bodies also use methyl groups
from folate and choline to convert the
amino acid homocysteine-which can be
harmful at high amounts-into another
amino acid called methionine. In turn,

the body can convert methionine into S-
adenosylmethionine, a valuable methyl
donor. That same compound is currently
a popular supplement.
This choline- or folate-assisted con-
version of homocysteine prevents the
body from accumulating an overload of
homocysteine. High levels of homocys-
teine are associated with increased risk
of heart attack or stroke.
Choline, folate, and methionine are
the body's primary sources of methyl
groups. "If your supply of folate is low,"
says Jacob, "your body may compensate
by taking methyl groups from choline.
Our results indicate that under those con-
ditions, your body might not be able to
synthesize enough choline. You'll likely
need more choline to help meet the in-
creased demand."

High Protein Means High Choline
High-protein animal products like
meats and dairy foods are rich in choline.
So are soy foods. Folate is highest in
plant sources such as orange juice; green
leafy vegetables like spinach; grain
products fortified with this vitamin,
including bread flour, cornmeal, pasta,
and rice; dried beans and peas; and most
berries. Nuts and liver contain both
What's the best way to make sure you
are getting enough folate and choline?
"As you might expect," Jacob advises,
"for most healthy people, a varied,
balanced diet is probably the best bet.
That should include an assortment of
plant foods, which give you folate, and
animal foods, which provide choline."

Low-Folate Regimen Leads to Choline
Jacob and colleagues conducted the
folate and choline investigations in
separate studies with 11 men, aged 33 to
46, and 10 postmenopausal women, aged
49 to 63, as volunteers. All were healthy
and nonsmokers. The volunteers lived at
the research center, then located in San
Francisco, to ensure that they ate only

Agricultural Research/March 2001


Jacob places blood samples into a centrifuge.
affected by folate content in the diet.

foods meticulously measured and custom
prepared for them by the research
center's dietary staff. Women of
childbearing age weren't allowed into the
research because of evidence associating
birth defects, such as spina bifida, with
inadequate intake of folate before
Throughout the 13- to 15-week stud-
ies, the volunteers followed a basic reg-
imen that varied in the amount of folate
it provided. The low-folate, low-choline
portion of the study gave them as little
as 13 percent of today's recommended
daily allowance of folate, which is 400
Later, researchers added folate back
in the form of a supplement, boosting the
level to as much as 130 percent of the

The separated blood plasma and cells will be analyzed for substances that may be

recommended intake. In the men's study,
the supplement was mixed with a
soybean-based, high-energy shake that
the volunteers drank at lunchtime. The
women received their supplemental folate
in applesauce served at breakfast and
Tests of the volunteers' blood and liver
function indicated that no severe choline
or folate deficiencies occurred during the
study. Nevertheless, blood levels of cho-
line decreased an average of 25 to 28
percent in men and women during the
low-folate, low-choline stints. But those
levels returned to at least normal when
researchers provided more folate.
"We showed that the amount of folate
you get dictates how much choline you
need," Jacob says. He did the work with

Donald J. Jenden of the University of
California at Los Angeles School of
Medicine; Marian E. Swendseid of the
UCLA School of Public Health; and
Margaret A. Allman-Farinelli of the
University of Sydney Department of
The scientists published their findings
in the Journal of Nutrition.-By Marcia
Wood, ARS.
This research is part of Human Nutri-
tion, an ARS National Program (#107)
described on the World Wide Web at http:/
/www.nps. a rs.
Robert A. Jacob is at the USDA-ARS
Western Human Nutrition Research Cen-
ter One Shields Ave., Davis, CA 95616;
phone (530) 752-4726, fax (530) 752-
8502, e-mail *

Agricultural Research/March 2001

Kaolin Particle Film Knocks Out Citrus' Evil Weevil

innocuous shipment of
nursery plants from Puerto
Rico destined for Florida's
lush, subtropical gardens
contained a broad-nosed weevil-
Diaprepes abbreviatus. Since then,
that pest's appetite for the roots and
leaves of citrus trees has made it one
of the most damaging insects in the
state of Florida. Young (left) and older
ARS scientists, led by entomologist root weevil on cakes of
Stephen L. Lapointe of the U.S. developed by ARS.
Horticultural Research Laboratory in
Fort Pierce, Florida, have found a way to counter this pest.
They use kaolin particles not only to keep D. abbreviatus from
feeding on treated foliage, but also to dramatically reduce the
number of eggs it deposits on leaves. The commercial kaolin
formulation they use was developed by soil scientist Michael
Glenn and entomologist Gary J. Puterka, with ARS'
KEITH WELLER (K7456-1) Appalachian Fruit Research
Station in Kearneysville,
West Virginia.
The weevil was first de-
tected in Apopka, Florida, in
1964. In the 37 years since,
D. abbreviatus has spread
.c through 19 counties, infest-
a ing more than 150,000 acres
and endangering the state's
$8.5 billion citrus industry. In
the Caribbean, this pest exacts an estimated $75 to $100 mil-
lion worth of crop losses every year.
Several characteristics make the hardy D. abbreviatus par-
ticularly difficult to control. Both immature and adult stages
are polyphagous, meaning they feed on many different plants,
including sugarcane. Adults live for about 4 months, and fe-
males each produce several thousand eggs. Larvae are hard to
detect because they drop from leaves onto the soil surround-
ing the tree, where they burrow in and feed on the roots. A
relatively few larvae can kill a mature tree by chewing around,
or girdling, its structural roots. Their feeding also provides
infection sites through which disease-causing microorganisms
can enter. So it is the Diaprepes larvae that inflict most of the
"In addition, citrus rootstocks have a very low degree of
genetic diversity," says Lapointe. "Florida soils are also high-
ly permeable, making groundwater contamination with pesti-
cides a major limitation to chemical control. We really need
new alternatives to control this pest. Kaolin may be one such
alternative for citrus growers."

larvae of the Diaprepes
an artificial diet

Kaolin is a soft, white, clay mineral
that, when combined with water, can be
sprayed on citrus or other trees to form
a protective particle film. This film
prevents the eggs of Diaprepes root
weevils from sticking to the leaf.
Each female can produce up to 5,000
eggs. She creates a kind of egg sandwich,
nestling her eggs gently between two
leaves. If the eggs fail to stick to the leaf,
they fall to the ground and dry up or are
eaten. In preliminary tests, kaolin film
completely sup- PEGGY GREB (K9304-1)
pressed the de- LL

positing of eggs.
Kaolin also seems to prevent the
weevil from feeding on citrus leaves.
Puterka thinks that the particle film
could be keeping the weevil from sens-
ing-through its antennae or legs-the
physical or chemical cues it uses to The citrus leaf on the
identify host plants. Adult weevil feed- left was sprayed with a
ing was reduced 68 to 84 percent on kaolin-based particle
film as a deterrent to
treated foliage. Diaprepes root weevils.
"These results indicate a potential
for kaolin as a barrier to the weevil's
egg-laying in citrus groves," says
Lapointe. "It may prove to be an eco-
nomically viable and environmentally sound component of an
integrated approach to control D. abbreviatus and related root
weevils."-By Jesds Garcia, ARS.
This research is part of Crop Protection and Quarantine,
an ARS National Program (#304) described on the World Wide
Web at http://www.nps.ars.

PEGGY GREB (K9302-1)
0 _7a .*

- X . IY :0 .
r A-~j. r::!~'''~li: :~~r E_-~ :
Stephen L. Lapointe is
with the U.S. Horticultural
Research Laboratory, 2001
South Rock Rd., Fort Pierce,
FL 34945; phone (561) 462-
5914, fax (561) 462-5986, e-
mail slapointe@ushrl.ars. *

At the U.S. Horticultural
Research Laboratory farm
in Fort Pierce, Florida,
technician Anna Sara Hill
and entomologist Steve
Lapointe examine an
orange tree sprayed with a
kaolin film.

Agricultural Research/March 2001

Feeding Sodium Chlorate to Livestock To Kill Salmonella and E. col

hen fed in low doses,
sodium chlorate kills Sal-
monella typhimurium and
Escherichia coli 0157:H7
in pigs and cows. Agri-
cultural Research Service scientists in
College Station, Texas, have shown that
levels of these harmful bacteria can be
reduced in the intestinal tract of pigs and
cows if they're given sodium chlorate
before slaughter.
"Because the gut and lymph tissue of
meat animals and chickens are major
reservoirs for Salmonella and E. coli
0157:H7, this research offers a practical
approach for reducing on-farm concen-
trations of these pathogens," says David
J. Nisbet, an ARS microbiologist and
research leader for the Food and Feed
Safety Research Unit in College Station.
Fewer bacterial pathogens in the gut can
significantly reduce the chance of carcass
contamination during food processing.
These two bacteria-culprits in most
cases of human food poisoning-can live
both aerobically and anaerobically, that
is, with or without air. That makes them
different from most gut bacteria, which
are anaerobes.

Salmonella and E. coli 0157:H7
contain an enzyme known as a res-
piratory nitrate reductase. This enzyme
coincidentally converts the chlorate to
chlorite, which kills the harmful bacteria.
Beneficial bacteria in the intestinal tract
lack respiratory nitrate reductase, so they
are not affected by the addition of
chlorate. The cost of using sodium chlo-
rate at a meat processing facility could
be less than 10 cents per pig, estimates
ARS microbiologist Robin C. Anderson.
In laboratory studies, 45 weaned pigs
were fed up to 0.04 grams of sodium
chlorate per kilogram of body weight
after being infected with S. typhimuri-
um. Within 16 hours, the treatment pro-
duced a 150-fold reduction in the num-
ber of pathogenic cells in the intestines.
"The research is in the early stages,"
cautions Anderson. Before this approach
could be widely used in the United
States, the Food and Drug Administra-
tion would need to approve its use.
"But if results from large field trials
hold up, I can envision a marketing
system that includes feeding chlorate to
animals before they're transported to
slaughter. Another opportunity would be

to add chlorate to drinking water at the
slaughterhouse," Anderson adds.
The Centers for Disease Control and
Prevention estimate that about 1.4 mil-
lion cases of salmonellosis and 73,000
cases of diarrheal illness due to E. coli
0157:H7 occur in the United States each
Anderson, Nisbet, and ARS microbi-
ologist Larry H. Stanker have applied for
a patent. Results of the study conducted
with weaned piglets were published in
the February 2001 issue of The Journal
of Food Protection.-By Linda
McGraw, ARS.
This research is part of Food Safety
(Animal and Plant Products), an ARS
National Program (#108) described on
the World Wide Web at http://www.nps.
Robin C. Anderson and David J. Nis-
bet are in the USDA-ARS Food & Feed
Safety Research Unit, Southern Plains
Agricultural Research Center, 2881 F&B
Road, College Station, TX 77845; phone
(979) 260-9484 [Nisbet], (979) 260-9317
[Anderson], fax (979) 260-9332, e-mail
nisbet@ffsru. tamu. edu, anderson @ffsru. *

A Plant by Any Other Name

GRIN Web Site Updated and Enhanced

N eed to find up-to-date scientific
names for economically im-
portant vascular plants-with-
out spending a small fortune
for a current reference book?
Agricultural Research Service experts in
taxonomy, or the official naming of
living things, have the solution: a newly
improved, user-friendly, multilingual
web site.
"At the site, interested people can find
the correct common and scientific names
of plants as well as information about
their uses. The information was garnered
during more than 2 decades of nomen-
clatural research on economic plants by
ARS taxonomists," says ARS botanist
John H. Wiersema. He worked with
former ARS taxonomist Blanca Le6n at
the Systematic Botany and Mycology
Laboratory in Beltsville, Maryland, on
developing and upgrading the site. The
web address is
"The web site adds some important
improvements to the Germplasm Re-
sources Information Network (GRIN)
taxonomy area, including a new web
page devoted to enhancing and expand-
ing the World Economic Plants: A Stan-
dard Reference. The 749-page reference
was published in 1999," says Wiersema.
"So far, the web pages devoted to
economic plants and their uses-a subset
of GRIN taxonomy-comprise scientific
information on 9,356 of the most im-
portant plant species from 2,616 genera
and 290 families," he says. The economic
coverage includes plants or plant
products that are traded, regulated, or
otherwise used in international com-
merce. Many plants important to regional
commerce of larger countries are also
included as well as plants with recog-
nized potential for widespread economic
use or for negative economic impact, like
weeds and poisonous plants.
Several search engines allow users to
key in criteria like genus, common name,
or economic use-such as food, fiber,
forage, timber, fuel, spice, or genetic,

The revised web site for the Germplasm
Resources Information Network (GRIN)
now includes a new segment on noxious
weeds, such as (top to bottom) dyer's
woad, leafy spurge, and yellow starthistle.

medicinal, ornamental, and social uses.
Another advantage of the web site
over the book is the user's ability to
search for a plant by country, state, or
geographical distribution. Users can
produce a condensed report that's similar
to the book's format. Or they can click
on links to more detailed information on
each species, such as scientific and
common names, synonyms, native dis-
tribution, and botanical uses. Each name
has a unique identifying code number, a
reference to the original description, and
other pertinent taxonomic literature.

"Over 75,000 literature citations are
cross-referenced to our economic-plants
names alone and over 175,000 to all our
names," Wiersema says. "And we have
developed Spanish and Portuguese ver-
sions of many of our web pages,, with
French and German ones on the way."
Another new web page provides
access to a specialized segment of the
GRIN database: The noxious-weed site
lists the names of thousands of weeds and
has links to the USDA-ARS "Invaders"
database and other federal weed
"Links connect users to other avail-
able on-line state noxious-weed docu-
ments or regulatory agencies," says
Wiersema. "Several state sites have
drawings or pictures of the weeds and
other information of interest to scientists,
gardeners, and farmers." The new web
pages are part of the GRIN database,
which includes over 62,000 botanical
names of mainly economic plants.
Other linked taxonomy pages access
GRIN data on federally and inter-
nationally regulated, threatened, and
endangered plants and on vascular plant
family and generic names from through-
out the world.
The site is well used. "In October
2000, over 70,000 reports were provided
to users of GRIN taxonomy, so it is
obviously of great use to workers in
agriculture, commerce, regulation, and
other fields," Wiersema says. "By tap-
ping into our web site, they can all be
assured they are talking about the same
plant."-By Hank Becker, ARS.
This research is part of Plant, Micro-
bial, and Insect Genetic Resources, Ge-
nomics, and Genetic Improvement, an
ARS National Program (#301) described
on the World Wide Web at http://
www.nps. ars.
John H. Wiersema is with the USDA-
ARS Systematic Botany and Mycology
Laboratory, Bldg. 011A, BARC-West,
Beltsville, MD 20705-2350; phone (301)
504-9181, fax (301) 504-5810, e-mail *

Agricultural Research/March 2001

Looking for Genes To Protect Beans

Snap bean growers nationwide could benefit if ARS
geneticist Phillip N. Miklas succeeds at unlocking the genetic
secrets of resistance to white mold disease. Unlike dry beans,
snap beans are eaten as flavorful, fleshy green pods. They are
sold fresh, frozen, or canned.
Some breeding lines already have partial resistance to white
mold, the most costly disease of snap beans in the United States.
White mold lowers bean yield and pod quality and can kill the
plants. The fungus also infects many other crops, including
lettuce, soybean, alfalfa, potato, pea, canola, and sunflower.
Miklas works at the ARS Vegetable and Forage Crop
Research Unit in Prosser, Washington. He's
teaming up with researchers at
Novartis Seeds, Inc., of
Nampa, Idaho, under a co-
operative research and de-
velopment agreement. They
will each develop a separate
population of beans. Both sets of
beans will use a breeding line
developed at Cornell University as one of the parents. The line
demonstrates some resistance to the disease.
For the other parents, they'll use different commercial snap
bean varieties that are susceptible to white mold. One popula-
tion will be used to generate the genetic information and the
other to confirm the genetics.
"By crossing a resistant and a susceptible line of beans and
then comparing the offspring, we hope to narrow down the
location and number of genes responsible for the resistance,"
Miklas says. Then he plans to develop resistance-linked markers
that can be used to incorporate this resistance into commercial
snap bean cultivars.
Scientists estimate that 5 to 15 percent of the world's snap
bean crop is lost to white mold. The disease costs U.S. farmers
$18 million each year in lost yields and fungicide sprays. World-
wide, the crop is worth about $300 million annually. Because
the disease lives in the soil and infects a myriad of plants, grow-
ers have limited options for using other crop rotations to break
the fungus' life cycle.
While the resistance genes would probably apply only to
beans, it is possible that information obtained by Miklas may
help researchers working with other crops affected by the
disease.-By Kathryn Barry Stelljes, ARS.
Phillip N. Miklas is in the USDA-ARS Vegetable and Forage
Crop Research Unit, 24106 N. Bunn Rd., Prossel; WA 99350-
9687; phone (509) 786-9258, fax (509) 786-9277, e-mail +

Entomologist Richard W. Mankin has eavesdropping down
to an art. Using a self-developed computer program that can
tell the difference between the sounds made by termites, root
weevils, and many other insects, he's found a way to expose
hidden insects that infest and damage packaged goods,
ornamentals, and other valuable agricultural commodities, even
golf courses.
"Typically," says Mankin, "the only way to determine
whether there is an infestation of insect larvae is to wait for
adults to emerge or to dig or cut out a sample. By that time, it
can be too late. It's also not economical to dig up large parts of
a field or crop to check for infestations."
Mankin, who is with the ARS Center for Medical, Agri-
cultural, and Veterinary Entomology's Post-Harvest and
nation Research Unit in Gainesville, Florida, has
developed intrusive eavesdropping tool using a sensor
h --eas-sures vibr ns given off by insects as they move and
The sensor can be attached to a spike that is pushed into soil
or poked into a tree trunk, or it can be clamped to a plant stem.
By poking the specially rigged nail into a tree or a plank, Mankin
can tell whether it's infested with termites just from the sounds
he hears. A series of scrapes and clicks in particular rhythms at
particular frequencies reveal insects "on the take." Mankin can
also use the specially designed clamps to eavesdrop on larvae
in stored products or sawflies inside wheat stems.
Different insects give off different sounds, depending on their
feeding and movement patterns, their sizes, and what they are
eating. Mankin has developed a computer program to distin-
guish larval movement and feeding activity from background
noises, like wind or blowing leaves, and in many cases, the
program can distinguish different insects from each other. This
is done partly by matching new sounds with previously recorded
"Our long-term goal is to develop rapid, nondestructive
techniques for pinpointing hidden infestations, which should
reduce pesticide use and decrease treatment costs," Mankin
says. -By Tara Weaver-Missick, ARS.
Richard W. Mankin is at the USDA-ARS Center for Medi-
cal, Agricultural, and Veterinary Entomology, Postharvest and
Bioregulation Research Unit, 1700 S.W. 23rd Dr., Gainesville,
FL 32608; phone (352) 374-5774, fax (352) 374-5781, e-mail
rmankin @gainesville. usda. ufl. edu. *

Agricultural Research/March 2001

Listening to Larvae

Honey Bees Mite Breathe Easier
Mite-resistance testing service to be offered soon.

P ollinating crops keeps honey
bees busy. But some bees are
more vulnerable than others
when it comes to getting
"winded" because of tiny tra-
cheal mites that clog their airways.
Now, plans are in the works to create
a new service that breeders can use to
check their bees' mettle against the par-
asitic mite, Acarapis woodi. Scientists
behind the plan expect it to speed efforts
to pinpoint tracheal mite-resistance traits
worth breeding into the entire U.S. honey
bee population, whose crop-pollinating
duties are a $15-billion asset to the
nation's agriculture.
Under the plan, Agricultural Research
Service entomologists in Baton Rouge,
Louisiana, are providing a Shelbyville,
Tennessee, beekeeper with the scientific
expertise necessary to conduct mite-
resistance testing as a commercial
Through such a service, for example,
a client could decide to cull a suscepti-
ble queen breeder colony or further prop-
agate one that fares well against the
mites. A similar service operated in On-
tario, Canada, helped the industry there
reduce the mite-to-bee ratio from 13
mites per bee to 1.5.
"We believe the most effective way
to enhance resistance is to make certain
that breeding colonies can be tested for
resistance and encourage U.S. breeders
to test their colonies," says Robert G.
Danka, an entomologist with ARS' Hon-
ey Bee Breeding, Genetics and Physiol-
ogy Laboratory, in Baton Rouge.
There, he and ARS colleague ento-
mologist Jos6 D. Villa have used a pro-
tocol for testing and characterizing the
relative resistance levels of bee stocks
subjected to heavy mite infestations.
Through such research, for example,
they've discovered one resistant honey
bee strain that fends off the mites through
a behavioral trait called autogrooming.
Simply put, this refers to the bees' use
of their legs to comb crawling tracheal
mites out of the hairs on their bodies. In

trials, susceptible bees used as checks
weren't so limber and averaged more
mites than resistant bees had.
In the May 2000 issue of the Ameri-
can Bee Journal, the two researchers
published results of a survey in which
they characterized mite-resistance levels
in 83 breeder colonies managed by 8
commercial queen producers in Califor-
nia, Hawaii, Louisiana, Texas, and Vir-
ginia. Specifically, they tested young
worker bees from the breeder colonies
and compared them to bees from colo-
nies known to be resistant or suscepti-
ble. Of the surveyed colonies, two-thirds
proved resistant, while one-fourth were
clearly very susceptible. "It's remarkable
how variable resistance is in the breed-
ing pool," says Danka.
Eager to transfer what they learned to
the U.S. bee industry, the researchers
raised the idea for a commercial testing
service at a bee breeders' conference held
in January 2000 in Fort Worth, Texas.
Backwood Apiaries owner Edwin R.
Holcombe attended that meeting.
"I was listening and decided to par-
ticipate," says Holcombe, who has been
a commercial queen bee breeder since
1973, and owns 80 hives. Tracheal mites
"are still a serious problem to bee-
keeping," he adds, "though the Varroa
mite has been getting the attention."
In April, Holcombe spent a week at
the ARS scientists' Baton Rouge
laboratory to learn
their mite-testing
protocol firsthand. It
includes managing
colonies of resistant
and susceptible bee
stock for use as ref-
erence points, main-
taining "inoculation
colonies" that are
infested with mites,
and tending combs
with developing ..,
young bees in incu- .
bators. Young adult
bees that emerge Microscopic view of

-- -

Scanning electron micrograph of an
Acarapis woodi tracheal mite.

from the combs are carefully marked and
placed in the mite-infested colonies.
After a week, the test bees are retrieved,
dissected, and checked under a micro-
scope for mites.
Once Holcombe feels he's honed
these skills, Danka and Villa will put
them to the test before certifying Hol-
combe's proficiency-and for good rea-
son: The testing service envisioned calls
for handling at least 15 colonies from as
many as 10 queen-breeder clientele, on
a first-come, first-served basis.
"I plan one more practice run," says
Holcombe, who is eyeing a summer 2001
debut. Then it'll be time to get down to
beesness.-By Jan Suszkiw, ARS.
This research is part of Crop Produc-
tion, Product Value, and Safety, an ARS
National Program (#305) described on
the World Wide Web at http://www.nps.
ars. usda. gov.
Robert G. Danka and Jose D. Villa
are with the USDA-ARS Honey Bee
Breeding, Genetics and Physiology Lab-
oratory, 1157 Ben Hur Road, Baton
Rouge, LA 70820; phone (225) 767-
9294, fax (225) 766-9212, e-mail
rdanka @

a bee trachea infested with tracheal mites.

Agricultural Research/March 2001


Corn Extract for Waxing
Zein is a corn protein making up about
half of the protein found in the corn ker-
nel. Unlike other corn proteins, which are
water soluble, zein repels water, making
it an ideal coating material. It was dis-
covered when researchers, at work on
reducing the cost of distilling ethanol
from corn, isolated it as a zein-lipid mix-
ture. They found it had good grease re-
sistance and water barrier properties.
Extracting such mixtures from ground
corn should cost about $1 to $2 per
pound. The zein coating would be
suitable for most packaging material
requiring waterproofing, such as boxes
for perishable fruits, vegetables, or fish.
Nicholas Parris, USDA-ARS Engineer-
ing Science Research Unit, Wyndmoor,
Pennsylvania; phone (215) 233-6453, e-

What Do You Get When You
Cross a Plum With an
Why, a plumcot, of course. And this
one, named "Spring Satin," is the first
such fruit well adapted to the medium-
high chill areas of the Southeast. It pro-
duces beautiful white blooms in mid-
March that mature into large,
high-quality, reddish-black fruit in late
May. The yellow flesh takes on a red-
dish hue as it ripens and develops very
good flavor when soft.
This unique cross is tolerant of major
plum diseases-like bacterial spot,
bacterial canker, and plum leaf scald-
that limit an orchard's life-span in the
Though the Spring Satin plumcot is
now available to commercial growers,
consumers won't be seeing the fruit in
grocery stores for about 3 years. It will
take that long for the trees to mature for
large-scale harvest. William R. Okie,
USDA-ARS Southeastern Fruit and Tree
Nut Research Laboratory, Byron,
Georgia; phone (478) 956-6405, e-mail
dokie @saa. ars. usda. gov.

Speedier Fat Analysis in
Certain kinds of fats, called tri-
glycerides, play a key role in the flavor
and texture of food formulations. Seed
oils-canola, corn, soybean, and sun-
flower-are a complex mixture of
triglycerides, and predicting how they
will change during food processing and
storage is a complicated and time-
consuming task.
Now the chore has been simplified by
a new analytical technique that can show
how triglycerides change under different
circumstances. The technique is called
reverse-phase high-performance liquid
chromatography (HPLC)/atmospheric
pressure chemical ionization (APCI)
with mass spectrometry (MS)-or
The researchers can see intact trigylc-
erides before they break down to form
negative byproducts during storage or
high-temperature frying. They've been
able to identify from 35 to over 100
trigylcerides in just 2 hours and to
correlate their composition with the
physical properties of food, such as
melting range, mouth feel, and reaction
to refrigeration. Eventually, the new
technique could lead to margarines,
shortenings, and cooking oils with good
taste and longer shelf life. Gary R. List,
USDA-ARS Food Quality and Safety
Research Unit, Peoria, Illinois; phone
(301) 681-6388, e-mail listgr@mail.

Multiplying Macrophages
the Easy Way-in Cell
In humans and livestock, such as pigs,
these amoebalike white blood cells help
eliminate dead cells, used proteins, and
other refuse. They also attack bacteria,
viruses, fungi, or other disease-causing,
or pathogenic, organisms at infection
sites. And by "wearing" a dead patho-
gen's proteins, macrophages also mobi-
lize the immune system's T-cells and
antibody-producing B-cells.

The standard way of obtaining
macrophages has been to flush them
from fluids pumped into an animal's
lungs or peritoneal cavity. The new
method begins with culturing precursor
cells called monocytes from just 10 drops
of blood on a special layer of "feeder
After several weeks, a bumper crop
of hundreds of millions of mature
macrophages is ready for storage or
immediate research use. It doesn't harm
animal donors and yields cells similar to
those found in the animals' bodies.
Researchers are using cultured
macrophages to study the virus that
causes porcine reproductive and res-
piratory syndrome, which leads to late-
term abortions, stillbirths, and other
costly problems in pigs. Neil Talbot,
USDA-ARS Gene Evaluation and
Mapping Laboratory, Beltsville, Mary-
land; phone (301) 504-8216, e-mail

Shedding New Light on
Deadly Bacteria
A prototype of a newly patented
device tested at a large midwestern beef
packing plant can successfully detect
small amounts of fecal matter on meat
animal carcasses. Invented cooperatively
by ARS and Iowa State University (ISU)
researchers, the instrument uses specific
wavelengths of light to illuminate each
carcass and then electronically analyzes
the light that is reflected.
Work to commercialize the tech-
nology is being done under a cooperative
research and development agreement
with ISU and eMerge Interactive, Inc.,
of Sebastian, Florida. Optical and elec-
tronic engineers are working with
scientists to develop both large-cut and
whole-carcass detection systems. Mark
A. Rasmussen, Thomas A. Casey, USDA-
ARS National Animal Disease Center,
Ames, Iowa; phone (515) 663-7350,
tcasey @nadc.ars.

Agricultural Research/March 2001

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