Meeting Abstract

P1.85  Saturday, Jan. 4 15:30  Gonadal DNA methylation patterning is affected by incubation temperature in the American alligator, a species undergoing temperature-dependent sex determination PARROTT, B.B.*; KOHNO, S.; CLOY-MCCOY, J.A.; GUILLETTE, JR, L.J.; Department of Obstetrics and Gynecology, Medical University of South Carolina and Hollings Marine Laboratory, Charleston, SC benbparrott@gmail.com

Epigenetic mechanisms have been implicated as key mediators of interactions between the genome and the environment. DNA methylation is a well-characterized epigenetic modification and is generally thought to result in transcriptional repression in vertebrates. Sex determination in many taxa is dependent upon environmental cues, and in the American alligator incubation temperature of the egg determines sex. Here, we incorporate multiple approaches to examine the relationship between incubation temperature and DNA methylation patterns at critical loci in the sex determining genetic cascade. Aromatase (CYP19A1) is an enzyme that coverts androgens to estrogen and plays a pivotal role in specifying ovarian development in non-mammalian vertebrates. We find that incubations at male producing temperatures (MPT) result in increased gonadal DNA methylation in the CYP19A1 promoter region when compared to incubations at female promoting temperatures (FPT). Conversely, the promoter region of SOX9, a key gene involved in the initial specification of testis development, is hypermethylated in gonads from embryos incubated at FPT compared to those incubated at MPT. We also examine expression levels of CYP19A1 and SOX9 in these tissues and find that whereas methylation status at particular nucleotides is tightly associated with transcriptional activity, methylation at other nucleotides is non-informative. These data are consistent with a role for DNA methylation in the negative regulation of transcriptional activity and suggest epigenetic patterning plays a role in sex determination in the American alligator.