Meeting Abstract

55-2  Friday, Jan. 5 10:30 - 10:45  Epigenetic dimorphism and predisposition to sex under temperature-dependent sex determination FLORES, DV*; JANZEN, FJ; Iowa State University; Iowa State University dvflores@iastate.edu

Vertebrates with temperature-dependent sex determination (TSD), a mechanism that relies on incubation temperature to determine irreversibly the sex of developing embryos, are especially threatened by the impending changes in climate. Though they have the same genome, males and females of species with TSD commonly have many dimorphic physical characteristics. Dimorphism may also extend to the molecular level, as regulation of genes involved in sex-specific characteristics may vary greatly. DNA methylation is an epigenetic modification well-known for its dynamic ability to silence genes in response to environmental triggers, including temperature. This study sought to characterize DNA methylation profiles between sexes across multiple life stages of a vertebrate with TSD, while also investigating its potential to predispose an embryo to develop into one sex over the other. We collected tissue from adults, hatchlings, and early-stage embryos of painted turtles, Chrysemys picta, to compare genome-wide DNA methylation of males and females at each stage. We followed this procedure by profiling candidate genes in the sex-determining cascade. Sexually dimorphic DNA methylation profiles were evident at all life stages. Additionally, embryos sampled from clutches that produced mostly one sex showed biased DNA methylation compared to embryos from clutches that produced mostly the opposite sex. Further epigenetic investigation of the TSD molecular mechanism will continue to unlock critical information previously cryptic in traditional genetic/genomic studies.