Tyrone B. Hayes - Case Study of Atrazine and Environmental Health

The Hayes Laboratory is examining the effects of exogenous steroids on gonadal differentiation and the potential role of endogenous steroids. The main goal is to synthesize ecological/evolutionary, organismal/physiological, and biochemical/molecular studies to learn how an animal translates changes in its external environment to internal changes, how these internal changes are coordinated, what molecular mechanisms are involved, and in turn, how changes at the molecular level affect an animal's ability to adapt to the changes in its external environment. Professor Hayes' two main research areas of interest are metamorphosis and sex differentiation, but also growth (larval and adult) and hormonal regulation of aggressive behavior. The work addresses problems on several levels including ecological, organismal, and molecular questions. Studies examine the effects of temperature on developmental rates, interactions between the thyroid hormones and steroids, and hormonal regulation of skin gland development. He is also examining the effects of tadpole density on developmental rates and measuring metamorphic rates and hormone levels of tadpoles in the field and in the laboratory. The work on sex differentiation involves the African clawed frog (Xenopus laevis), the Japanese kajika (Buegeria buegeri), and the Pine Barrens treefrog (Hyla femoralis). While Xenopus serves as a good model because of its availability, the latter two species have genetically distinguishable sexes. He can therefore examine early events in gonad differentiation, steroid enzyme activities, steroid receptors, etc., knowing the genetic sex of the individual larvae.