Berkeley -- A new study led by researchers at the University of California, Berkeley, identifies specific gene expression changes in a species of water flea in response to contaminants, lending new support for the role of toxicogenomics in environmental monitoring.

The study, published online today (Wednesday, Dec. 20) in the journal Environmental Science & Technology, focused on the water flea Daphnia magna, considered the lab rat of ecotoxicology because of its sensitivity to contaminants in its environment. The organism is commonly used by regulators to monitor freshwater toxicity, but the tests used typically look at levels of toxicity that will kill the water flea within 24 hours of exposure.

Those tests employ "a 'kill 'em and count 'em' technique that doesn't provide a great deal of insight into the mechanism of action," said Dr. Chris Vulpe, associate professor of nutritional sciences and toxicology at UC Berkeley's College of Natural Resources and principal investigator of the study.

There also is a chronic toxicity test that assesses the impact of lower levels of exposure on reproduction, but again, exactly how the toxicant is affecting the organism is unclear, the researchers said.

But with toxicogenomics, scientists are hoping to understand toxicants based upon characteristic changes in an organism's gene expression. "By looking at the pattern of genes turned on and off in response to toxicants, we can get an idea of what is causing the toxicity," said Vulpe, who is also a member of the Berkeley Institute for the Environment on campus, which brings together diverse programs and units focused on environmental research. Vulpe worked with Helen Poynton, UC Berkeley graduate student in nutritional sciences and toxicology and lead author of the study.

In an effort to test the viability of gene expression assays in environmental toxicity screening, the researchers exposed the water flea to copper, cadmium an
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Contact: Sarah Yang
scyang@berkeley.edu
510-643-7741
University of California - Berkeley
20-Dec-2006