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Tea for Tuna

by Carole VanSickle



Richard Winn’s “white mice” boast fins and gills and are healthiest when swimming in green tea.

Winn’s lab critters are genetically altered versions of a fish species called medaka, and they have helped verify what scientists have suspected and herbalists have insisted for years: Green tea is not only good for the soul, it’s also good for the cell.

“Inserting a piece of DNA called a reporter gene into the fish DNA results in every single cell in the fish having a copy of this gene,” said Winn, professor of biology and director of the University of Georgia Aquatic Biotechnology and Environmental Laboratory. “After we expose the fish to a carcinogen, we can not only see what kind of mutations resulted but also pinpoint where it caused them.”

The additional DNA does not adversely affect the fish; it just enables scientists to analyze mutation frequency by counting the times the target gene changed following exposure.

Medaka that are exposed to a carcinogen and then placed in an environment permeated with green tea compounds have 84 percent fewer cancer-causing mutations than fish exposed to the cancer-causing chemical alone, according to a paper Winn and his colleagues published in the May 2005 issue of Environmental and Molecular Mutagenesis.

Cancer cells differ from normal cells in that they have a mutation in their DNA that makes them endlessly divide, so an 84 percent reduction in mutations is important if translated to human beings, Winn said. “It would significantly decrease a person’s odds of developing cancer because it would significantly decrease the number of cells that might have this reproductive mutation.

“In short,” he said, “drink your green tea.”

These results also enabled Winn to “ride the tail of the mouse,” as he put it, by developing medaka that, like mice, can be used as models for human disease. Fish are much less costly than mice to grow and maintain, and medaka embryos in particular are very sensitive to many waterborne contaminants — such as the chemicals that flooded New Orleans following Hurricane Katrina. By exposing these embryos to samples from the city’s mounds of tainted mud, Winn and his colleagues hope to determine the risks incurred by people who move back and rebuild.

“We had to verify that medaka, like mice, could be models for human systems,” he said. “Now that we know that, we can use them to more effectively study vital aquatic issues.”

For more information, contact Richard Winn at


Research Communications, Office of the VP for Research, UGA
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