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Spring 2000

Research Magazine > ARCHIVE > Spring 00 > Article

Fishing for Answers
by Seth Coleman

The notion of scientific laboratories populated mostly by generations of research mice may soon be challenged by a new model: the lab stocked with fish.

With the help of his technicians, UGA environmental toxicologist Richard Winn is using specially bred fish to study the genetic health risks of chemicals in the environment.

"Transgenic fish offer nearly every kind of exposure route as mice," Winn said. "And in tests, they can be exposed at low-dose, realistic levels" of suspected contaminants, making them in some ways a better choice for research than some traditional animal models, like mice.

The fish are also much cheaper to use - costing just "pennies a year" compared to about 20 cents a day to maintain lab mice - and are less likely than mammals to be controversial as biomedical research subjects, he said.

The fish Winn uses in his research - the Japanese medaka, a tiny freshwater fish, and the mummichog, a saltwater fish - carry specific DNA sequences that serve as targets for DNA damage or mutations. The fish initially are exposed to a potential contaminant, and then their tissues are analyzed for mutations.

Since the same detection system is used in lab mice, Winn said comparative studies are now possible using two different species, yielding more accurate results. The fish can be used for screening organic materials, heavy metals, radiation, herbicides and pesticides. They are especially useful, he said, in toxicity screening for the more than 2,000 new chemical compounds into in the market each year.

The Georgia Research Alliance Biotechnology Center awarded Winn's team, which includes Michelle Norris, Charlie Brayer, Cecilia Torres and Stacy Muller, funding for a $1.4 million facility to be built later this year in the Whitehall Forest at the Warnell School of Forest Resources. It will include an aquatic laboratory, which will house the fish, and molecular biology laboratories, where Winn's team can continue research in such areas as water contaminants - an increasingly important field as the world's population increases.

"In the next century, people will go to war over clean water," Winn said. "In the United States, we've used chlorine to clean our water, but we've found that it can have certain negative effects."

Consequently, there has been a push to find other ways of cleaning drinking water. One of the methods is ozonation - bubbling ozone through the water to break up bacteria. However, a by-product of such a process is potassium bromide, which has been known to cause cancer in rodents.

Winn's team has studied the effects of this process by adding potassium bromide to water and analyzing the fish from that water after 28 days. They found a two-fold increase in the number of mutations in the exposed group compared with a group that had not been similarly exposed.

"With the fish, we are able to see the mutations when they plateau earlier [than with other animal models], which is want you want," Winn said. "Once that happens, [mutations] stay at that level and become fixed."

This type of research is useful because scientists are able to see the effects of a gene mutation much sooner. That is especially helpful in evaluating situations where people are being exposed to hazardous materials.

"You want an early warning of the effects that could come 20 years down the line," Winn said. "Will you see the development of cancer in 20 or 50 years, or will you see the mutations reproduced in offspring? By using transgenic fish, we are able to see these changes much sooner."

E-mail rwinn@smokey.forestry.uga.edu for more information.


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Transgenic fish