"Everything we put in this mixture died within a week, except for frogs that have adapted to that environment. "They're not doing too well, are they?" Hayes says, brushing a cricket off his neck with a practiced flick. In this quadruple-blind experiment, neither Hayes nor his assistants know exactly what they're testing. Strips of colored tape adorn each tank, each color denoting a particular mix of compounds. On another shelf, tadpoles swim in one set of deli cups while metamorphs, which have both tails and legs, swim in another. He deftly shakes crickets-frog breakfast-from a plastic bag into dozens of tanks. It's 7 a.m., but Hayes has been here since 4:30 this morning, when he came to "make water"-mix the chemical cocktails in which he's raising 3,000 leopard frogs in a crowded basement lab. ![]() The doors respond to a security card in his pocket and swing wide onto an empty corridor. Inside Berkeley's Valley Life Sciences building, Hayes approaches a set of double doors and lifts his thigh, doggy style, toward the wall. Workers at a Louisiana plant where atrazine is manufactured are now suing their employer, saying they were nine times as likely to get prostate cancer as the average Louisianan. Could the chemical also affect humans? The beginning of an answer may be emerging. Wild frogs collected from areas with atrazine showed the same number of abnormalities. The two studies showed equally dramatic results: 40 percent of male frogs were feminized 80 percent had diminished larynxes. Both times the media went a little crazy. He published the second set in October, in Nature. Hayes published his first set of findings last April, in the Proceedings of the National Academy of Sciences. To see if frogs were vulnerable as adults, and if the effects were reversible, he exposed them to atrazine at different stages of their development. To find out if frogs in the wild showed hermaphroditism, Hayes dissected juveniles from numerous sites. He thawed the frozen water, poured it into hundreds of individual tanks, and dropped in thousands of leopard-frog eggs collected en route. He parked near an Indiana farm, a Wyoming river, and a Utah pond, filled his buckets with 18,000 pounds of water, and headed back to Berkeley. The next summer Hayes loaded a refrigerated 18-wheel truck with 500 half-gallon buckets and headed east, followed by his students. The atrazine apparently created hermaphrodites at a concentration one-thirtieth the safe level set by the Environmental Protection Agency for drinking water. There were also males with shrunken larynxes, a crippling handicap for a frog intent on mating. Some male frogs had developed multiple sex organs, and some had both ovaries and testes. ![]() But when Hayes looked closer, he found problems. When the frogs were fully grown, they appeared normal. To test its safety, Hayes put trace amounts of the compound in the water tanks in which he raised African clawed frogs. Atrazine is the most widely used weed killer in the United States. Syngenta is the world's largest agribusiness company, with $6.3 billion in sales of crop-related chemicals and other products in 2001 alone. The controversy began five years ago, when a company called Syngenta asked Hayes to run safety tests on its product atrazine. That vulnerability has lately garnered Hayes more attention than his appearance ever has. With their permeable skin, frogs are especially vulnerable to environmental factors such as solar radiation or herbicides. Their transformation from egg to tadpole to adult is rapid, and it's visible to the naked eye. Frogs make convenient study subjects for anyone interested in how hormones affect physical development. His research centers on frogs, of which he keeps enormous colonies. Hayes, 35, is a professor at Berkeley, where he has taught human endocrinology since 1994. "Hey, wassup?" he'll say to anyone, from the president of the United States on down. He keeps his pocket money in a baby's sock. He drives a truck littered with detritus human, amphibian, and reptilian. ![]() Not counting his four inches of thick, upstanding hair, Hayes is just over five feet tall, with smooth features and warm eyes. At the University of California at Berkeley, he glides around his lab wearing nylon shorts and rubber flip-flops, with a gold hoop in one ear and his beard braided into two impish points. To use his own idiom, Hayes is several standard deviations from the norm. ![]() Tyrone Hayes stands out in the overwhelmingly white field of biology, and his skin color isn't the half of it.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |