The nematodes were grown on a culture medium coated with a soybean-based oil that is harmless to the worms but which can dissolve naphthalene and PDCBs, said Xue. When the chemicals were added to the culture, they deactivated the caspases, resulting in the survival of "extra" cells in the tiny worms that normally would have been eliminated by apoptosis, said Xue.

Apoptosis is an essential process in animal development and occurs in many tissues, said Xue. In amphibians it rids frogs of tails as they develop from larvae to adults, and in humans it removes cells that make up "webbing" tissue between the fingers and toes of embryos during development, he said.

"Apoptosis serves as a checking mechanism to ensure that the right amount of cells are generated in the body," Xue said. In Alzheimer's disease and Parkinson's disease, too much apoptosis is occurring, while in cancer and autoimmune disorders, too little apoptosis is occurring, he said.

Popular with scientists in research labs around the world, C. elegans worms have essentially the same basic biological processes as humans even though their average lifespan is less than three days, he said. Xue's team currently is using C. elegans as an animal model "bioassay" to test common industrial chemicals like biphenyl, toluene and benzene that are suspected to be carcinogens.

"The power of C. elegans' molecular genetics, in combination with the possibility of carrying out large-scale chemical screens in this organism, makes C. elegans an attractive and economical animal model for both toxicological studies and drug screens," the researchers wrote in Nature Chemical Biology.

"Bioassays involving lab rats can
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Contact: Ding Xue
ding.xue@colorado.edu
303-492-0271
University of Colorado at Boulder
20-Jun-2006