Temperature-dependent expression of turtle Dmrt1 prior to sexual differentiation

Vertebrates employ varied strategies, both chromosomal and nonchromosomal, to determine the sex of the developing embryo. Among reptiles, temperature-dependent sex determination (TSD) is common. The temperature of incubation during a critical period preceding sexual differentiation determines the future sex of the embryo, presumably by altering the activity or expression of a temperature-dependent regulatory factor(s). Here we examine the expression of the Dmrt1 gene, a candidate regulator of mammalian and avian sexual development, in the turtle. During the sex-determining period, Dmrt1 mRNA is more abundant in genital ridge/mesonephros complexes at male-promoting than at female-promoting temperatures. Dmrt1 is the first gene found to show temperature-dependent expression prior to sexual differentiation, and may play a key role in sexual development in reptiles.