<i>Dmrt1</i> induces the male pathway in a turtle with temperature-dependent sex determination

Abstract

The molecular mechanism underlying temperature-dependent sex determination (TSD) has been a long-standing mystery; in particular, the thermosensitive genetic triggers for gonadal sex differentiation are largely unknown. Here, we have characterized a conserved DM domain gene, <i>Dmrt1</i>, in the red-eared slider turtle <i>Trachemys scripta</i> (<i>T. scripta</i>), which exhibits TSD. We found that <i>Dmrt1</i> has a temperature-dependent, sexually dimorphic expression pattern, preceding gonadal sex differentiation, and is capable of responding rapidly to temperature shifts and aromatase inhibitor treatment. Most importantly, loss- and gain-of-function analyses provide solid evidence that <i>Dmrt1</i> is both necessary and sufficient to initiate male development in <i>T. scripta</i> Furthermore, the DNA methylation dynamics of the <i>Dmrt1</i> promoter are tightly correlated with temperature and could mediate the impact of temperature on sex determination. Collectively, our findings demonstrate that <i>Dmrt1</i> is a candidate master male sex-determining gene in this TSD species, consistent with the idea that DM domain genes are conserved during the evolution of sex determination mechanisms.