Characterization of DNA Methylation and Transcript Abundance of Sex-related Genes during Temperature-dependent Sex Determination in Mauremys reevesii.

A number of genes relevant for sex determination have been found in species with temperature-dependent sex determination (TSD). Epigenetics play a key role in sex determination, but characterization of DNA methylation of sex-related genes on TSD remains unclear. Mauremys reevesii is a typical species with TSD. In this study, we analyzed the CpG methylation status of the proximal promoters, the mRNA expression patterns and the correlation between methylation and expression levels of CYP19A1, FOXL2, DMRT1, SOX9, and AMH, which are key genes in sex determination in other species. We also analyzed the expression level of genes that encode enzymes involved in methylation and demethylation. The expression levels of CYP19A1 and FOXL2 at the female producing temperature (FPT) were higher than those at the male producing temperature (MPT); the expression levels of DMRT1, SOX9, and AMH were higher at MPT. The expression of some genes involved in methylation and demethylation is significantly different between MPT and FPT. The expression of mRNA of genes involved in DNA methylation and demethylation affected by temperature, together with other factors, may change the methylation level of the regulatory regions of sex-related genes, which may further lead to temperature-specific expression of sex-related genes, and eventually affect the differentiation of the gonads.