SEQUENCE AND EXPRESSION ANALYSIS OF WT1 AND SOX9 IN THE RED-EARED SLIDER TURTLE, TRACHEMYS-SCRIPTA

Temperature-dependent sex-determination (TSD) is a phenomenon that has been characterized at the ecological, morphological, and endocrinolog ical levels in some reptilian species. We have begun to investigate TS D at the level of molecular development by cloning, sequencing, and an alyzing the expression of two genes, WT1 and Sox9, in the red-eared sl ider turtle Trachemys scripta. We obtained almost full-length cDNA clo nes for WT1 and Sox9 that were greater than 73% identical to the human homologues at the nucleotide level. WT1 was expressed in urogenital t issue at all developmental stages examined (Yntema stages 12-20) at in cubation temperatures that produce males (26 degrees C) or females (32 degrees C). Sox9 was also expressed throughout these same stages, but some differences were observed. At both 26 degrees C and 32 degrees C Sox9 was expressed in the mesonephroi and the undifferentiated gonads until Yntema stage 20, when only the gonad from the 26 degrees C embr yos expressed a high level. In addition, there were two transcripts of Sox9 at all stages, but the relative proportion of the two transcript s differed at the two temperatures. Although the similarities in gene expression between a TSD species and other species with genotypically determined sex probably reflect the common features of organogenesis, differences may illustrate unique mechanisms for TSD. (C) 1998 Wiley-L iss, Inc.