Meeting Abstract
Many species of turtles exhibit temperature dependent sex determination (TSD). In TSD species, the differentiation of gonads into ovaries or testes appears to depend on egg incubation temperature during a period of embryonic development known as the thermo-sensitive period (TSP). In response to key environmental variables, a network of differential genetic and cellular responses lead to the formation of ovaries or testes. In addition to temperature, experimental studies suggest that moisture may influence sex determination in a variety of turtle species. In this study, we used the freshwater turtle Trachemys scripta to test the effects of both temperature and moisture on expression patterns of genes that likely play an important role both in sex determination (CIRBP, WT1, DMRT1) and later in sex differentiation (sox9, aromatase). Eggs were incubated at male promoting temperatures and moderate moisture until the beginning of the TSP and were then split into four different temperature and moisture treatments. Half of the eggs in each treatment were sacrificed ~48h after the treatment shift to collect gonads and identify differences in gene expression early during sex determination. The remaining embryos were sacrificed after completion of the TSP for collection of differentiated gonads; one gonad from each embryo was preserved for gene expression analysis and the other was prepared for histological identification of sex. Here, we aimed to expand our understanding of the mechanisms underlying TSD, particularly the expression of the initial genes that respond to an environmental cue and signal the development of an ovary vs. a testis. Integrating the processes from the molecular mechanism to an organism’s sex and to a population’s sex ratios at ecologically relevant scales could help fill a long-standing gap in the understanding of how TSD species react to dynamic environments.
