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Waters near croplands impair frogs' immunity

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6:38pm, October 17, 2006

From Virginia Beach, Va., at a meeting of the American Physiological Society

Pesticide-containing waters leave frogs more susceptible to fungal infections than pristine environments do, new field data suggest.

Tyrone Hayes and his collaborators at the University of California, Berkeley located tadpoles of Rana aurora, a protected frog species, at three sites in California. One site was upstream of any farm and had a comfortable water depth for tadpoles, about 2 feet. Another site, also upstream of agriculture, was so shallow that some frogs were exposed to air, causing some dryness-related distress. The third site was in Salinas Valley, a major area for lettuce and spinach cultivation. Waters there, about 2 feet deep, contain various pesticides that drain from the croplands.

The researchers confined some tadpoles in cages at each site and gave the animals injections of either an inert solution or a dose of bread yeast, a frog pathogen.

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