Project Overview

The focus of this research project is to determine the temperature-sensitive sex determination (TSD) factor in Chelydra serpentina, the snapping turtle. In most species of vertebrates the initial trigger for sex determination is genetic and, in a much smaller number of species, the sex determination relies on environmental factors. In the snapping turtle sex determination is temperature dependant; eggs incubated at 26 degrees (celsius) produce all male hatchlings, while eggs incubated at 31 degrees (celsius) produce only females. The exact mechanism that regulates sex determination is unknown, but it is believed to depend on the expression of a series of sex determining genes.

I am focusing my work on the protein-protein interactions of DAX1 and SF1. Evidence suggests that these genes may work together to regulate the downstream expression of SOX9 and AMH, eventually leading to testes differentiation. DAX1, is a promising candidate for the "master switch," because it appears to regulate the expression of both the male and female sex determining genes. That's why I'm trying to figure out if DAX1 has different binding capabilities to SF1 at 26 and 31 degrees. My hypothesis is that DAX1 binds to SF1 at 31 degrees and inhibits the downstream expression of male sex determining genes. Conversely, at 26 degrees, DAX1 may be incapable of binding to SF1, resulting in the expression of the female sex determining genes. I will be performing experiments this summer in an effort to test this hypothesis.