MURDOCK, C.A.*; WIBBELS, T.; University of Alabama, Birmingham; University of Alabama, Birmingham: Dmrt1 mRNA levels during development in a turtle with temperature-dependent sex determination

Vertebrates exhibit a variety of sex determination systems, which include both genotypic and temperature-dependent sex determination (TSD). A number of genes have been identified in these sex determination systems, and some of these genes appear to be conserved among vertebrates. The Dmrt1 gene, which appears to be highly conserved between reptiles, birds, and mammals, has been identified as a potential regulator of vertebrate sexual development. Dmrt1 expression is thought to be a male-specific event during gonadogenesis in both mammals and birds. In the current study, Dmrt1 expression was examined in a turtle, Trachemys scripta. A quantitative competitive RT-PCR assay was developed for measuring Dmrt1 mRNA levels in adrenal-kidney-gonad complexes. These quantitative competitive RT PCRs were performed on total RNA isolated from six different stages of embryonic development (i.e., stages 15, 17, 19, 21, 23, and 26), at both male- and female-producing temperatures, which included stages from the approximate beginning of the temperature-sensitive period (i.e., the developmental period where incubation temperatures influence the sex of the embryo) until hatching. Dmrt1 mRNA levels were quantified as a result of these assays and the relative expression of Trachemys scripta Dmrt1 was compared between the stages of development at both male- and female-producing temperatures. The results indicate a sex-specific expression pattern similar to those patterns seen in birds and mammals.