Toward a 60-Minute Diagnosis
Portable, DNA-based devices are being designed that will identify naturally
occurring or deliberately released disease organisms in under an hourinstead
of taking days or weeks, as today's methods require. Their adoption
would allow extension agents or consultants to make on-site, real-time
recommendations on how best to curtail a crop disease outbreak before
it spreads. The devices would also be useful in checking imported perishable
plant materials for hidden plant disease organisms that could imperil
Expertise in bacterial, fungal, and viral genetics enables scientists
to design primers and probes to target the specific DNA sequences of
several major plant pathogens. A primer binds with a pathogen's DNA
and prepares it for polymerase chain reaction amplification on the testing
unit. The amplified DNA then binds with the probe and emits a fluorescent
signal that can be measured and displayed on a computer.
The researchers are collaborating with Cepheid of Sunnyvale, California, to test this innovative technique for detecting bacterial wilt (brown rot) and ring rot of potato, citrus canker, Karnal bunt, Pierce's disease, citrus variegated chlorosis, plum pox, soybean rust, watermelon fruit blotch, and other emerging plant diseases.
Everything You Want To Know About Bees
A new Internet service is providing answers to wide-ranging questions
about honey beesfree of charge. Called the Expert Forum on Honey
Bees, it lists a wide range of frequently asked questions, along with
answers from scientists. It also provides information about beekeeping
as a hobby or profession, crop pollination, honey bee biology, and related
research. And the site maintains a Student Forum on Honey Bees, with
questions and answers for students in grades K through 12.
Users will play a key role in expanding this state-of-the-art, electronic question-and-answer service. As new questions are received and answered, the staff will update the forum, which can be accessed 24 hours a day, 7 days a week, by going to http://gears.tucson.ars.ag.gov.
Iron and Zinc Keep Brains in the Pink
Mental performance tests may be a simple way to detect shortages in
dietary iron or zincwell before other signs of deficiency might
show up in blood or urine.
A study of 27- to 47-year-old men found that a low attention span corresponded with a subsequent decline in iron levels in the body. A similar change in ability to focus occurred in a study with obese but otherwise healthy women. These were the first studies in healthy adults to link decreased body iron levels with lowered attention span. And when the male volunteers followed a low-zinc regimen, their ability to recall simple words slowed. Those with the greatest decrease in blood levels of zinc slowed the most.
Beyond Bread and BeerAnother Use for Baker's Yeast
Though a mainstay ingredient in bakeries and breweries, common baker's
yeast has potential uses far beyond these familiar products. Scientists
have learned to change the metabolism of Saccharomyces cerevisiae
by adding certain plant enzymes so that it can convert vegetable oils
into more valuable byproducts.
Baker's yeast depends on sugars and other carbohydrates for most of
the fermentative activity that produces the carbon dioxide and alcohol
that bakers and brewers need. It mainly uses lipids to reinforce cell
walls and store energy.
But the modified yeast can store up to seven times the normal amount of lipids. And by adding different enzymes under different conditions, researchers have enabled the yeast to convert oilseed crops such as soybeans, cotton, and linseed into products such as alpha eleostearic acidthe main ingredient of tung oiland alpha linolenic acid, which contains an omega 3 fatty acid shown to protect against heart disease and cancer. Further refinement of the procedures should allow for larger scale production of these and other valuable lipids.
"Science Update" was published in the May 2002 issue of Agricultural Research magazine.