Five amphibian mortality events associated with ranavirus infection in south central Ontario, Canada.

Using field, molecular and histological methods, an epizootic, systemic disease causing death within wood frog Rana sylvatica tadpoles and leopard frog Rana pipiens metamorphs at 3 different locations within Southern Ontario, Canada, has been investigated. Our results demonstrated that the probable cause of this disease was a ranavirus. Affected amphibians were found to exhibit necrosis within the hematopoietic cells.

Toxicity of glyphosate-based pesticides to four North American frog species.

Glyphosate-based herbicides are among the most widely used pesticides in the world. We compared the acute toxicity of the glyphosate end-use formulation Roundup Original to four North American amphibian species (Rana clamitans, R. pipiens, R.

Gonadal differentiation in frogs exposed to estrogenic and antiestrogenic compounds.

Exposure of amphibians to endocrine disrupting compounds (EDCs) may alter differentiation of gonads, especially when exposures begin during early life stages. Gonadal differentiation was observed in leopard frogs (Rana pipiens) and wood frogs (Rana sylvatica) exposed as tadpoles to estrogenic (estradiol, ethinylestradiol, nonylphenol) and antiestrogenic compounds (an aromatase inhibitor, flavone, and an antiestrogen, ICI 182780). Exposure to all compounds at micrograms/L concentrations altered gonadal differentiation in some animals by inducing either complete feminization or an intersex condition, and altered testicular tubule morphology, increased germ cell maturation (vitellogenesis), and oocyte atresia.