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Pesticide that turns male frogs into females | Atrazine, one of the world's most widely used pesticides, can turn male frogs into females, according to a new study by University of California, Berkeley, biologists. According to researchers, atrazine wreaks havoc with the sex lives
of adult male frogs, emasculating three-quarters of them and turning one in 10
into females. The 75 percent that are chemically castrated are essentially "dead"
because of their inability to reproduce in the wild, reports UC Berkeley 's Tyrone
B. Hayes , professor of integrative biology. "These male frogs are missing testosterone
and all the things that testosterone controls, including sperm. So their fertility
is as low as 10 percent in some cases, and that is only if we isolate those animals
and pair them with females," he said. "In an environment where they are competing
with unexposed animals, they have zero chance of reproducing." The 10 percent
or more that turn from males into females - something not known to occur under
natural conditions in amphibians - can successfully mate with male frogs but,
because they are genetically male, all their offspring are male. "When we grow
these guys up, depending on the family, we will get anywhere from 10 to 50 percent
females," Hayes said. "In a population, the genetically male females can decrease
or wipe out a population just because they skew sex ratios so badly." Though the
experiments were performed on a common laboratory frog, the African clawed frog
(Xenopus laevis), field studies indicate that atrazine, a potent endocrine disruptor,
similarly affects frogs in the wild, and could possibly be one of the causes of
amphibian declines around the globe, Hayes said. Hayes and his UC Berkeley colleagues
report their results in this week's online early edition ofoceedings
of the National Academy of Sciences. |
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