TEMPERATURE-DEPENDENT SEX DETERMINATION IN THE RED-FARED SLIDER TURTLE, TRACHEMYS-SCRIPTA

Temperature-dependent sex determination (TSD) in the red-eared slider turtle, Trachemys scripta, has been the subject of a variety of past s tudies. Incubation temperature appears to affect sex determination in a dose-dependent fashion. This suggests that temperature could be affe cting a dosage-sensitive element in the sex-determination cascade. Sex determination in T. scripta is sensitive to estrogen, and data from m any studies support the hypothesis that endogenous estrogen production may be involved in female sex determination. However, this hypothesis has not yet been evaluated through aromatase expression studies in th is species. Several recent studies have cloned cDNAs for genes that co uld be involved in sex determination and/or sex differentiation. The c DNAs for SF-1 and MIS have been cloned in T. scripta, indicating that these may represent conserved elements in the sex-determination/sex-di fferentiation cascade of reptiles. The SOX9 cDNA also has been cloned in T scripta (Spotila et al.,'98), and it shows a sex-specific express ion pattern. Future studies targeted at aromatase expression as well a s the expression of factors such as SOX9, SF-1, and MIS will begin to provide a more comprehensive picture of the events involved in TSD in T. scripta. Further, such studies could help pinpoint the temperature- sensitive element(s). (C) 1998 Wiley-Liss, Inc.