AGROCHEMICAL IMPACTS ON HUMAN AND ENVIRONMENTAL HEALTH: MECHANISMS AND MITIGATION

Research proposed in the current project involves an integrated analysis of physiological, behavioral, and ecological effects of steroid hormones and steroid-mimetic compounds, including endocrine disruptors, in native species of amphibians and lizards.In the case of amphibians, effects of environmental exposure to atrazine, a widely-used endocrine-disrupting herbicide, will be investigated with regard to behavioral development, growth and metamorphosis, and gonadal differentiation, building on previous research involving the non-native model species Xenopus laevis (African Clawed Frog). Experiments will involve amphibian development from egg through gonadal differentiation exposed in captivity to the range of atrazine measured in agricultural run-off water. These experiments are expected to contribute important new knowledge on unintended biological impacts of atrazine on non-target species in the environment, with the potential to change societal concern for and tolerance of the agricultural use of atrazine.In the case of lizards, evolutionary lability in steroid hormonal effects on growth-regulatory gene networks will be investigated in model species of native lizards characterized by male-larger or female-larger sex differences in body size (sexual size dimorphism; SSD). Research will focus on how steroids, especially androgenic steroids, contribute to the development of SSD. This research is important in the context of W-3045 because of the prevalence of synthetic steroids and steroid-mimetic compounds in the environment, with potential exposure and anomalous growth responses in non-target species. Our previous research has revealed fence and spiny lizards (genus Sceloporus) to be particulalry useful as model organisms in this research because of the occurrence of both patterns of SSD within the genus. Further, we have found that androgenic steroids hold the bipotentiality of operating as to stimulate or inhibit growth, depending on natural sex differences in growth contributing to SSD. The present project holds unprecedented potential to add to our knowledge of evolutionary lability in growth regulatory gene networks and thus in possible interference from steroidogenic compounds in the environment.