Pioneering studies funded by the Agricultural Research Service (ARS) are helping explain how the foods that soon-to-be-moms eat in the days and weeks around the time of conception—what's known as periconceptional nutrition—may affect the way genes function in her children, and her children's health. In an early study, the scientists examined the gene function of 50 healthy children living in rural villages in the West African nation of The Gambia. The study helped shape the current research into the effects of nutrition on what geneticists refer to as epigenetic mechanisms. The epigenetic mechanisms can impact, for example, the levels at which an everyday biochemical process, DNA methylation, occurs at regions of certain genes. The researchers found that levels of DNA methylation were higher at regions of five genes in children conceived during the peak rainy season months of August and September, when food would typically have been less available to their mothers. Two of the five genes in which elevated DNA methylation occurred warrant further study because they are associated with risk of disease. Specifically, the SLITRK1 gene is associated with Tourette's syndrome, and the PAX8 gene is linked to hypothyroidism.
Weight-management studies led by Agricultural Research Service (ARS) scientists are helping determine why some dieters lose more weight than others, and are more successful in keeping it off. In one ARS investigation, 29 obese but otherwise healthy women aged 20 to 45 years participated in a 12-week weight-loss regimen. The researchers assessed several factors related to weight management, including the volunteers' patterns of decision making, and changes in their levels of cortisol, a stress-associated hormone. The amount of weight that volunteers lost varied greatly, from zero to 27 pounds, despite the fact that all were essentially eating the same foods in the calorie-controlled meals provided to them at the nutrition center. It was noted that the finding underscores the need for weight-management plans that are even more individualized than those available today.
Agricultural Research Service (ARS) scientists and their cooperators have published the chemical composition and potential bioavailability of some nutritious compounds in a representative group of five colorful rice varieties. Though often thought of only as white or brown, rice is categorized into seven color classes, based on bran color, and darker varieties are thought to have higher amounts of some phytochemical compounds than lighter varieties. The researchers found a wide variation in the concentrations of the two forms of vitamin E and of gamma-oryzanol. The team also analyzed other phytochemicals—specifically phenolics and flavonoids—in the same five color classes of bran. The study showed that the red and purple rice brans had higher phenolic and flavonoid concentrations than the lighter-colored rice brans measured. The researchers also identified one purple rice bran variety that was both high in phenolic compounds as well as vitamin E and oryzanols.
A team of Agricultural Research Service (ARS) scientists has developed and tested an improved method for measuring an indicator of the body's stores of vitamin B12 via a very small blood sample. That's an advantage in both medical and research situations. The test can be done with only 25 microliters of blood plasma or serum and, if the assay is performed using robotics, the sample could perhaps be as small as 5 microliters. The 25-microliter sample size needed for the new MMA (methylmalonic acid) assay represents a 4- to 10-fold reduction in the volume of specimen required for other MMA-based B12 tests. Samples take only about four minutes to process.
When the label on a bottle of olive oil misrepresents what's inside, shoppers may not be getting what they thought they paid for. Help may be on the way in the form of new laboratory assays developed by ARS researchers and their colleagues. One assay relies on PCR (polymerase chain reaction) technology to compare olive DNA to that of canola and sunflower plants. Oil from these plants is sometimes mixed with olive oil, but not disclosed on the label. The assay is not based just on DNA from a single olive tree or sunflower or canola plant. Instead, each barcode is a broadly representative composite, known as "consensus DNA." Another assay is based on ESI-MS (electrospray ionization-mass spectrometry) and enables scientists to glean details about variations in specific triglycerides of interest, referred to as regioisomers. From that, users can develop ratios of regioisomers that can be used to determine whether the sample contains undisclosed oils. The value of ESI-MS for analyzing plant fatty acids has been recognized since at least 1994. But this protocol helps make the application simpler.
For details, contact: Talwinder Kahlon, (510) 559-5777, Processed Foods Research Unit, and Jiann-Tsyh (Ken) Lin, (510) 559-5764, Crop Improvement and Utilization Research Unit, ARS Western Regional Research Center, Albany, Calif.
Farm-raised Atlantic salmon maintains its healthy levels of omega-3 fatty acids when baked, according to the results of Agricultural Research Service (ARS) studies. Two omega-3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are abundant in oily fish such as salmon, tuna, mackerel, and herring. Some data have shown that consuming 250 milligrams daily of EPA and DHA—the amount found in a 3-ounce salmon fillet—is associated with reduced risk of heart disease. But it had not been known previously whether baking caused loss of omega-3s in farm-raised Atlantic salmon. The extent to which baking Atlantic salmon alters healthful fatty acids through oxidation that leaves unhealthy compounds, such as toxic omega-3 oxidation byproducts, was also examined. The ARS researchers demonstrated that baking salmon to the proper temperature does not decrease its content of beneficial omega-3 fatty acids. They found that baking actually decreases the presence of fatty acid oxidation byproducts. Preparing the fish based on restaurant and safety guidelines—to a tender-but-safe 145 degrees Fahrenheit rather than overcooking—was a key factor.
Agricultural Research Service (ARS) scientists have identified sources of Escherichia coli bacteria that could help restore the reputation of local livestock. The studies suggest that in some parts of California, pathogens in local waterways are more often carried there via runoff from urban areas, not from animal production facilities. They also found the greatest variety of different types of E. coli in runoff discharged from areas dominated by urban development or human activities. It was also found that from 88 to 95 percent of the E. coli isolates were resistant to the antibiotic rifampicin, and that about 75 percent were resistant to tetracycline. Tetracycline resistance was by far the most common type of resistance observed in E. coli isolates collected near wastewater treatment plants. The scientists also found that 24 percent of E. coli collected in sediment samples associated with urban runoff—a total of 144 isolates—showed resistance to as many as seven antibiotics.
Small amounts of beta-glucan, a fiber-rich component of oats, can be added to low-fat yogurt without noticeably affecting the texture or other key characteristics of this increasingly popular dairy food, Agricultural Research Service (ARS) researchers have shown. They experimented with adding oat beta-glucan to what's known in the dairy industry as low-fat yogurt mix. The mix is made up of low-fat milk and a selection of common, safe-to-eat bacteria, such as Lactobacillus acidophilus, or various Bifidobacterium species, that ferment the milk. The scientists' intent was to see how much fiber they could add without altering the texture, viscosity, or other aspects of the microscopic structure of the yogurt, or its color, pH, or fermentation time, for example. The team determined that up to 0.3 percent highly purified (95 percent pure) oat beta-glucan, which translates to 0.3 grams of beta-glucan per 100 grams of yogurt mix, could be added without significantly altering key yogurt qualities. But adding 0.4 percent or higher changed the yogurt's color, contributed to unwanted hardening, and slowed fermentation.
For details, contact: Mukti Singh, (309) 681-6357, Functional Foods Research Unit, ARS National Center for Agricultural Utilization Research, Peoria, Ill.
Poultry producers can reduce bacterial cross-contamination in poultry cages by treating the cages with forced air that's been heated to 122 degrees Fahrenheit, according to a study by Agricultural Research Service (ARS) scientists. While being transported in coops on trucks, poultry that have bacteria such as Campylobacter can contaminate, through their feces, other poultry that are free of pathogens. Those disease-causing bacteria can then be passed on to the next group of birds during the next trip, and so forth, unless the cycle is broken. When the hot flowing air was applied to fecally soiled transport cage flooring samples for 15 minutes after a water-spray wash treatment, Campylobacter levels declined to an undetectable level. Static heat at similar temperatures was not nearly as effective, and unheated flowing air was moderately effective, but less so than hot flowing air.
Agricultural Research Service (ARS) scientists working as part of an international team have completed a "shotgun sequencing" of the wheat genome, which was published in the journal Nature. The achievement is expected to increase wheat yields, help feed the world and speed up development of wheat varieties with enhanced nutritional value. Grown on more land area than any other commercial crop, wheat is the world's most important staple food, and its improvement has vast implications for global food security. The work to complete the shotgun sequencing of the wheat genome will help to improve programs on breeding and adaptation in Asia and Sub-Saharan Africa for wheat crops that could be drought tolerant and resistant to weeds, pests and diseases. ARS is one of nine institutions with researchers who contributed to the study.
Agricultural Research Service (ARS) scientists and their university cooperators have developed a biodegradable plastic that could be used in disposable food containers. The plastic, called a thermoplastic, becomes soft when heated. To make the plastic, the scientists incorporated biodegradable sugar beet pulp, which is the leftover residue from sugar extraction, with a biodegradable polymer. The result is thermoplastic composites that retain mechanical properties similar to polystyrene and polypropylene, the compounds used to make white, spongy food packages.
Pacific Northwest wheat growers now have added insurance against outbreaks of yield-robbing fungi, thanks to "Cara," a new, white winter club wheat cultivar developed by Agricultural Research Service (ARS) scientists. "Cara" is the product of a cooperative wheat breeding effort to combine high grain yields and flour quality with resistance to multiple fungal diseases. It also scored high on standard industry evaluations for milling, baking and other end-use properties. For example, like other club wheats, flour milled from "Cara" has low viscosity and protein content, coupled with high "break flour" and "weak gluten," characteristics ideal for making air-leavened cakes, sugar snap cookies, biscuits, pastries and other soft, fluffy-textured baked goods.
For details, contact: Kimberly A. Garland-Campbell, (509) 335-0582, ARS Wheat Genetics, Quality Physiology and Disease Research Unit, Pullman, Wash.