A NAHEIM , C ALIFORNIA - Many toxicologists can remember of be stubborn at some point by people opposed to chemical testing on animals, particularly mammals. Now, a researcher has taken another step to facilitate the disapproval that he and his colleagues often feel. At the annual meeting of the American Association for the Advancement of Science, which publishes Science NOW, aquatic toxicologist Richard Winn, University of Georgia, Athens, describes a promising new line of fish that can help replace the rats for screening toxic chemicals.
to improve their ability to detect chemical changes could result in the mid 1980s, toxicologists have begun using laboratory mice with bacterial genes that can be folded out and screened for damage. This is much easier than, for example, the screening of the whole mouse genome or waiting for the tumors to develop. Hoping to find an alternative to rodents, Winn and his colleagues turned to Medaka fish, which are already used for toxicology tests. They brought in the animals two bacterial genes, called Lad and eyelash , used in the lines of transgenic rodents to detect mutations caused by chemicals.
In the first tests, they spilled the mutagenic widely used N -ethyl- N -nitrosourea (ENU) in their fish tanks, and after waiting 1 to 16 hours, ground fish and bacterial DNA recovered for analysis. The researchers found they could detect even slight genetic changes, mapping of two to threefold increase in mutations at low exposure to ENU. Winn also describes a transgenic medaka with a third gene called LacZ said it works well to detect radiation damage. Radiation tends to knock out or rearrange chunks of DNA, and this gene is large enough - and its support, a circular piece of DNA called a plasmid, is strong enough - there is enough DNA for left analysis after radiation shot.
If the research pans, it could not only save the lives of many mammals, but also do toxicology tests cheaper and easier. Keep a cost of fish "a few cents a year," compared to 20 cents per day per mouse, Winn said. "I'm really happy" to hear about the progress of Winn says toxicologist Shane Barbara of Louisiana State University in Baton Rouge, who studies cancer in mice. She and others are eager to start tests on transgenic medaka .
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