Two clear and present environmental impacts are affecting all life forms: climate change and anthropogenic chemical contamination. The red-eared slider turtle embryo has proven to be an exceptional model system to evaluate the role of each of these environmental factors and how they may interact. This species has temperature-dependent sex determination; that is, temperature (and hormones) acting during a narrow window of development, determine the sex of the individual. This research will reveal how the temperature signal is transduced into a molecular switch that results in an ovary or a testis. It will also evaluate the susceptibility of the embryo to anthropogenic environmental compounds, collectively known as endocrine disrupting chemicals (EDCs), which can cause disruptions in the normal steroid microenvironment causing developmental and reproductive abnormalities. This research integrates both areas of research and focuses on how the physical and chemical environments modify the molecular and cellular developmental pathways underlying gonad determination and sexual differentiation. Prior NSF-supported research established that two different "cassettes" of genes are involved in both processes. These cassettes are groups of functionally related genes that interact in a particular manner to cause an outcome at the cellular or tissue level. In this instance the first cassette is composed of a conserved core of gonad-determining genes that regulate gonadal differentiation in all vertebrates. The second cassette consists of the genes that code for the molecules that produce (steroidogenic enzymes) and sense (hormone receptors) steroid hormones. Understanding how these cassettes are engaged, how they interact with one another both temporally and spatially, and how the genes within each cassette interact under normal conditions as well as after exposure to EDCs are the long-term goals of this project.
The research program will provide interdisciplinary research opportunities for training graduate and undergraduate students. Regional mentoring activities will focus on undergraduate students from underrepresented groups. Sequence data generated will be deposited in GenBank.
