Chronology, magnitude and duration of expression of putative sex-determining/differentiation genes in a turtle with temperature-dependent sex determination

Academic Article

Abstract

  • © 2014 S. Karger AG, Basel. The red-eared slider turtle (Trachemys scripta) possesses temperature-dependent sex determination (TSD) in which the incubation temperature determines gonadal sex. Although a number of mammalian gene homologues have been identified in reptiles with TSD, the exact sex-determining trigger(s) is not known. To date, the current study represents the most comprehensive simultaneous evaluation of the chronology of mRNA expression profiles of putative sex-determining/differentiation genes (Dmrt1, Sox9, Amh, Lhx9, and Foxl2) from gonads incubated at male- and female-producing temperatures in T. scripta. Additionally, sex-reversing treatments with 17β-estradiol and letrozole were examined. At a male-producing temperature, Dmrt1 expression was sexually dimorphic by stage 17, Sox9 by 19 and Amh by 21. In contrast, Foxl2 did not significantly increase until after the thermosensitive period at a female-producing temperature. Treatment with 17β-estradiol resulted in reduced gonad size and/or inhibited gonadal development and differentiation. Gene expression was subsequently low in this group. Sex reversal utilizing letrozole failed to produce testes at a female-producing temperature and as such, gene expression was comparable to ovary. These results indicate that Dmrt1 and Sox9 are potential triggers for testis differentiation and Amh, Lhx9 and Foxl2 represent a conserved core set of genes in the sex-determining/differentiation pathway of TSD species.
  • Authors

    Published In

  • Sexual Development  Journal
  • Digital Object Identifier (doi)

    Author List

  • Bieser KL; Wibbels T
  • Start Page

  • 364
  • End Page

  • 375
  • Volume

  • 8
  • Issue

  • 6