February 15, 2004
10-Year Head Start Helps ARS Play Vital Role in Nutrition Program
Agricultural Research Service expertise in an emerging technique for naturally fortifying food crops will be a central part of a program recently launched to tackle malnutrition in developing countries.
The program, HarvestPlus, will emphasize the innovative method called biofortification, which makes staple foods inherently more nutritious. Researchers will identify and develop crops with increased levels of key nutrients and make these crop varieties widely available throughout entire regions.
HarvestPlus is managed by the Consultative Group on International Agricultural Research (CGIAR), a Washington, D.C.-based consortium of donors devoted to agricultural advancements in the developing world.
Through the program, ARS and CGIAR will develop varieties of six major staple foods -- rice, maize, wheat, beans, sweet potato and cassava -- containing increased levels of nutrients such as iron, zinc and pro-vitamin A carotenoids.
ARS' role in HarvestPlus will, in many ways, be a continuation of work that was started a decade ago and will focus on ascertaining the content and bioavailability of micronutrients in the staple food crops. It will involve lab studies, animal nutrition and human trials, as well as molecular biology.
Studies will be conducted at ARS Plant, Soil and Nutrition Laboratory in Ithaca, N.Y., by plant physiologist Ross Welch and human nutritionist Ray Glahn. They will implement an in vitro laboratory model developed by Glahn that couples simulated food digestion with a human intestinal cell line called Caco-2.
Welch will coordinate ARS activities in the HarvestPlus program.
Findings will be verified in research at ARS Grand Forks Human Nutrition Research Center in Grand Forks, N.D., led by center director Gerald F. Combs, Jr. Further enhancement of micronutrients in staples through molecular techniques will be coordinated by plant physiologist Michael Grusak at the ARS Children?s Human Nutrition Research Center in Houston, Texas.
CGIAR will focus mainly on the breeding and distribution of the fortified crop varieties, targeting resource-poor people in the developing world.
Boosting Vitamin E in Corn and Other Crops
An Agricultural Research Service scientist and cooperators are developing new varieties of corn and other food crops that have higher levels of vitamin E.
Twenty-five percent of Americans do not get enough vitamin E. It is particularly important for pregnant women, and some researchers have shown that it can decrease the risk of heart disease.
The research was done by molecular biologist Edgar B. Cahoon of the ARS Plant Genetics Research Unit at the Donald Danforth Plant Science Center in St. Louis, along with his former colleagues at DuPont Crop Genetics, Wilmington, Del. The scientists used genes found in rice, barley and wheat, each of which contains high levels of vitamin E.
Now that their three years of research have led to a safe, healthful variety of corn, Cahoon and his colleagues are working on similar studies with soybeans. He believes many other crops would benefit from the new approach.
Vitamin E is a generic name for naturally occurring compounds called tocotrienols and tocopherols. Cahoon looked at the pathway that leads to tocotrienols, something that had not been studied much. The scientists were able to isolate a gene for the enzyme homogentisic acid geranylgeranyl transferase. This enzyme is responsible for producing a tocotrienol form of vitamin E in cereal grains. When the gene was added to corn plants, the kernels' vitamin E content increased sixfold.
In addition to making the crop more nutritious, boosting vitamin E levels is likely to increase the crop's shelf life. Vitamin E occurs naturally in vegetable oils, nuts and green leafy vegetables.
Old Soil Study Uncovers Value of Long-term Nitrate Research
An Agricultural Research Service experiment finished nearly 30 years ago -- and uncovered recently during new study preparations -- shows that it's best to be patient when measuring the movement of nitrates through soil and groundwater.
Mark Tomer and Michael Burkart, both soil scientists and hydrologists at the ARS National Soil Tilth Laboratory in Ames, Iowa, found that nitrate applied during the experiment -- conducted between 1969 and 1974 -- apparently took nearly 30 years to move through soils and reach a 70-foot-deep water table.
This shows that water carrying nitrate can take decades to flow through a watershed's soil subsurface to a stream and should be studied for longer periods, according to the scientists, who work in the lab's Agricultural Land and Watershed Management Research Unit.
In the original study, conducted on a 74-acre field in western Iowa, fertilizer was applied to soil at three times the normal rate. The resulting soil nitrate concentration was tracked for the next decade.
In 1996, Tomer and Burkart were preparing to monitor groundwater for a new experiment when they detected the nitrate 60 feet deep in the soil. They confirmed that the nitrate originated from the old experiment by examining groundwater flow rates and ages, and by comparing the concentration's depth with stream flow records.
Leaching of nitrate from agricultural fertilizers has been linked to concerns such as drinking-water quality and hypoxia, a condition in which water bodies contain low oxygen amounts.
Farmers are being encouraged to use nitrogen more efficiently, but resulting environmental improvements have been difficult to document using studies lasting just two to four years, according to Tomer. In summary, he adds, application of a conservation practice within a watershed may take several decades to fully effect improvements in groundwater quality.
New, Quicker Tests Identify E. Coli Strains
New tests that more quickly identify dangerous strains of Escherichia coli bacteria are being developed by Agricultural Research Service scientists in Wyndmoor, Pa.
ARS microbiologist Pina M. Fratamico, at the agency's Eastern Regional Research Center (ERRC) in Wyndmoor, is working with Pennsylvania State University to develop tests that quickly identify E. coli strains.
Certain E. coli strains, such as O157:H7, causes serious
diseases, including bloody diarrhea and hemorrhagic colitis. Infections may result in serious health complications, including kidney failure. Other E. coli serogroups, including E. coli O26, O111 and O121, also cause gastrointestinal illnesses in humans.
Currently, scientists commonly use a procedure called serotyping to distinguish between different types of E. coli -- some harmful, others harmless. However, this procedure is time-consuming and labor-intensive.
Fratamico, with ERRC's Microbial Food Safety Research Unit, and her team are developing both conventional and real-time polymerase chain reaction (PCR) tests. These chemical procedures generate enough of a bacterium's genetic material so that it can be studied and identified. With one real-time PCR reaction, four products can be amplified simultaneously and detected in "real time" as they multiply.
Scientists have little information about some individual E. coli serogroups; therefore, the number of diseases these organisms cause is likely underestimated. Fratamico is targeting genes in the E. coli O-antigen gene clusters so researchers can detect and identify specific serogroups and increase knowledge about each one's potency.
In one study, a real-time PCR assay was more sensitive than other detection methods. According to Fratamico, the U.S. Department of Agriculture's Food Safety and Inspection Service has expressed interest in the new PCR tests for detection and confirmation of not only E. coli O157:H7, but of other E. coli strains as well.
Absorbent Polymer Has ?Thirst for Knowledge?
Cupped in the palm of one's hand, Super Slurper is a nondescript powder -- until you add water. Then, starch-based polymers in Super Slurper "drink" the water right up, transforming the powder into a gel capable of retaining nearly 2,000 times its weight in moisture.
Now, this same thirsty disposition could make Super Slurper worth its weight in gold to librarians and archivists. The Agricultural Research Service and Artifex Equipment, Inc., of Penngrove, Calif., are collaborating on tests of the polymer's ability to dry books, papers, photographs and other materials soaked by water from flooding, leaks and other disasters.
Kathleen Hayes, coordinator for the Technology Transfer Information Center at ARS' National Agricultural Library (NAL), Beltsville, Md., thought of the idea while attending a March 2002 workshop hosted by the National Archives and Records Administration. She envisioned using Super Slurper as a fast, new way to salvage water-damaged materials, rather than air drying them -- which is laborious and expensive -- and as an alternative to vacuum freeze-drying, a recovery process that can take months and cause collateral damage.
Artifex President Nicholas Yeager was intrigued, and conducted preliminary tests in which Super Slurper dried several wet books in about 10 minutes. Air-drying methods, by comparison, take weeks -- and mold growth can begin in just 48 hours.
In August, Yeager signed a cooperative agreement with the NAL to continue testing. Besides checking for mold inhibition, his tests aim to gauge Super Slurper's ability to minimize other types of water damage, including wrinkled pages and swollen book bindings that take up 20 percent more shelf space.
Super Slurper, for its part, must not produce any stains of its own nor mar an item's inks and pigments. J.L. Willett, a chemical engineer at the ARS National Center for Agricultural Utilization Research in Peoria, Ill. -- Super Slurper's "birthplace" -- is on hand to technically advise Yeager, who may opt to market the polymer commercially.
ARS is the U.S. Department of Agriculture?s chief scientific research agency.