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By Rick Weiss
Washington Post Staff Writer
Federal oversight of crops genetically engineered to produce medications in their seeds and leaves is inadequate to prevent unwanted contamination of food crops, according to an analysis released yesterday by a scientific advocacy group. As a result, the report concludes, consumers are at risk of inadvertently dosing themselves with prescription drugs while eating a morning bowl of cereal.
The report, which biotech executives and regulators denounced as overwrought, is the latest to look at the small but rapidly growing "pharma" sector of agriculture, in which corn, soybeans and other plants are being designed to produce high-tech drugs or industrial compounds in their tissues.
The approach has many advantages over traditional systems for manufacturing those products, including potential cost savings, the report concludes. But it also raises the specter of accidental contamination of the food supply with blood thinners, hormones or any of the scores of biologically active compounds being made experimentally in plants.
"No one -- not consumers, not food companies, not biotech companies -- wants to discover drugs in our cornflakes," said Margaret Mellon of the Union of Concerned Scientists (UCS), a group long critical of the federal regulatory scheme for agricultural biotechnology.
The group commissioned six independent experts in the fields of agronomy, entomology and ecology to conduct an analysis of the fledgling industry, which makes a few chemicals for industrial uses and an array of drugs, none of which is yet approved for marketing. The analysis concluded that significant changes are needed in the way the Agriculture Department oversees the cultivation of such plants if the risk of contamination is to be brought close to zero.
"Genes can move in pollen by wind or insects. Seeds can get stuck in machinery or mixed in storage and transportation systems. There are very many routes of vulnerability," panel chairman David Andow of the University of Minnesota said yesterday in a telephone news conference timed to coincide with release of the report, "A Growing Concern: Protecting the Food Supply in an Era of Pharmaceutical and Industrial Crops."
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Biologists at the University of California, San Diego have identified a gene that appears to have been a critical trait in allowing the earliest plant breeders 7,000 years ago to transform teosinte, a wild grass that grows in the Mexican Sierra Madre, into maize, the world’s third most planted crop after rice and wheat.
In a paper that appears in the December 2 issue of the journal Nature, the scientists report their discovery of a gene that regulates the development of secondary branching in plants, presumably permitting the highly branched, bushy teosinte plant to be transformed into the stalk-like modern maize.
The researchers say the presence of numerous variants of this gene in teosinte, but only one variant of the gene in all inbred varieties of modern maize, provides tantalizing evidence that Mesoamerican crop breeders most likely used this trait in combination with a small number of other traits to selectively transform teosinte to maize, one of the landmark events in the development of modern agriculture.
“What we know is that this gene is critical for branching to take place in maize, including the branches that give rise to the ears of corn,” says Robert J. Schmidt, a professor of biology at UCSD who headed the research team. “And we presume that there was something unusual in the morphology that these early farmers selected from the wild teosinte that made it easier for them to plant, grow or harvest their crops. This gene will give us some important new clues to what genetic traits these plant breeders focused on when they transformed teosinte to maize. In a broader context, it is quite possible that the same gene in other plant species is equally essential to the overall architecture that a particular plant assumes by programming the very cells that produce new branches.”
The gene cloned by the scientists is called barren stalk1 because when the gene product is absent a relatively barren stalk results—one with leaves, but without secondary branches. In maize, these secondary branches include the female reproductive parts of the plant—or ears of corn—and the male reproductive organ, or tassel, the multiple branched crown at the top of the plant.
Teosinte has numerous tassels and tiny ears in its highly branched architecture, while maize has only one tassel and much fewer, but much larger, ears. This suggests that the limitations to branching imposed by some combination of the barren stalk1 and other genes that were selected for by the early plant breeders allowed the early genetic mutants of teosinte to concentrate more of the plant’s resources into producing bigger ears that could be harvested.
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Helen Pearson
The infectious proteins called prions that cause the human form of mad cow disease may hitch into the body on the back of another meat protein, US researchers have shown. The finding may help to explain how the rogue prions jump between species.
Disease-causing prions are thought to have passed into people when they ate beef from infected cattle, triggering the brain wasting condition called new-variant Creutzfeldt-Jakob disease, or vCJD. But researchers have not been sure exactly how prions enter the body.
To find out, Neena Singh and her team at Case Western Reserve University in Cleveland, Ohio, mimicked the process of eating and digesting infected meat.
They mashed up brain tissue that contained prions from patients who had a form of Creutzfeldt-Jakob disease. They then exposed it to a range of harsh digestive enzymes from the mouth, stomach and intestine, which normally break proteins into pieces.
Prions, which are known to be enormously tough, escape this attack almost unscathed, they showed, as does a second type of protein called ferritin, which stores iron and is abundant in meat. The two proteins seem to stick together, they report in the Journal of Neuroscience1.
The researchers next added the digested slurry to a lab model of the human gut: a growing sheet of cells from the intestinal lining. By attaching fluorescent tags to the two proteins, they showed that they are transported through the cells hand-in-hand. "Prions probably ride piggyback" through the gut wall into the body, Singh says.
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By JOHN FRIEDLEIN
For the past decade, tobacco farmers have seen profits go up in smoke.
Many have given up on the crop, especially after the quota buyout that was recently passed by Congress.
A new market could open up for local growers — one that could line pocketbooks and save lives.
It's called pharming. Growers produce crops after scientists tinker with the plants' genes to turn them into mini-production facilities that crank out pharmaceutical proteins.
And here's something tobacco farmers haven't heard in a while: If this happens, there could be an increasing demand for tobacco.
So far, however, there are no tobacco "pharmers" in Hardin County, but White Mills grower Steve Meredith is optimistic. He said the state has a "great potential" to raise tobacco for medicine because growers already know a lot about the crop and the University of Kentucky has strong college of agriculture and pharmacy.
Newer technology and mapping of the human genome have "really advanced those possibilities forward," Meredith said.
He doesn't think the average tobacco farmer is aware of these developments. Before the buyout, they were hopeful of new market opportunities, but, they are now interested in reinvesting buyout funds into operations that aren't tobacco-related.
Meredith sees the possibility of pharming replacing or exceeding past tobacco revenue.
Local farmers must wait, though. The pharming business is currently small and localized, but it will grow, said Dr. Orlando Chambers, biotechnology relations director of UK's Kentucky Tobacco Research and Development Center.
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Menno Schilthuizen
SINGAPORE--Fears that escapee zebrafish, genetically engineered to glow in fluorescent color, would interbreed with their drab brethren in the wild, may be unfounded. A study presented at the Biology in Asia conference here last week suggests that the mutant fish don't shine with sex appeal.
The zebrafish Danio rerio, native to streams in southern Asia, is normally silvery-grey with dark stripes. But in the 1990s, scientists in Taiwan and Singapore genetically modified strains with genes from jellyfish and anemones, giving the fish a green or red "glow" under UV or even visible light. Originally developed to aid in the detection of water pollutants (with a switch gene added, the fish would glow whenever the target pollutant was in the water), these and similar fish have been popular in the aquarium trade in the U.S. since late last year, with the red variety marketed under the name GloFishTM. But environmentalists have expressed concern that the modified fish will escape and interbreed with wild zebrafish, particularly in their native tropical Asia.
Wee-Khee Seah, Zhiyuan Gong, and Daiqin Li of the National University of Singapore made aquariums where a normal or green fluorescent zebrafish female would be confronted with the choice between a normal and a glowing green male behind glass. They found that both types of female spent more than 80% of their time with their noses glued to the glass of the unaltered males' compartments, with the green males jealously courting in vain.
Suspecting that the green-glowing fish might have subdued courtship behavior, they then showed the females videos of courting males after digitally doctoring the images of some of the wild males' courtships to make them look fluorescent green. Sure enough, the females always preferred wild males' courtships, whether cloaked in green or not. Finally, when forced to mate with green males, females would show their dissatisfaction by laying only half as many eggs as when paired with a wild male, the researchers found. Seah thinks the genetically-engineered fishes' lethargic courtship behavior may be the result of having too much energy drained by the glowing jellyfish protein in their muscles.
Fish ethologist Adam Shohet of the University of Sussex in Brighton, U.K., agrees that the insertion of a foreign fluorescent protein may upset the fishes' finely-balanced energy budget. He's convinced that the new results show that there is "little threat posed by the popular proliferation of these fish."
Related sites
Yorktown Technologies' GloFishTM site
The National University of Singapore's site on research into genetically-modified zebra fish
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