PNAS March 1, 2010, doi: 10.1073/pnas.0909519107
Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis)
Tyrone B. Hayesa,1, Vicky Khourya,2, Anne Narayana,2, Mariam Nazira,2, Andrew Parka,2, Travis Browna, Lillian Adamea, Elton Chana, Daniel Buchholzb, Theresa Stuevea, and Sherrie Gallipeaua
aLaboratory for Integrative Studies in Amphibian Biology, Department of Integrative Biology, Museum of Vertebrate Zoology, Energy and Resources Group, Group in Endocrinology, and Molecular Toxicology Group, University of California, Berkeley, CA 94720-3140; and
bDepartment of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221
The herbicide atrazine is one of the most commonly applied pesticides in the world. As a result, atrazine is the most commonly detected pesticide contaminant of ground, surface, and drinking water. Atrazine is also a potent endocrine disruptor that is active at low, ecologically relevant concentrations. Previous studies showed that atrazine adversely affects amphibian larval development. The present study demonstrates the reproductive consequences of atrazine exposure in adult amphibians. Atrazine-exposed males were both demasculinized (chemically castrated) and completely feminized as adults. Ten percent of the exposed genetic males developed into functional females that copulated with unexposed males and produced viable eggs. Atrazine-exposed males suffered from depressed testosterone, decreased breeding gland size, demasculinized/feminized laryngeal development, suppressed mating behavior, reduced spermatogenesis, and decreased fertility. These data are consistent with effects of atrazine observed in other vertebrate classes. The present findings exemplify the role that atrazine and other endocrine-disrupting pesticides likely play in global amphibian declines.