Temperature-dependent sex determination in the red-eared slider turtle, Trachemys scripta

Area of Science:

• * Reproductive Biology
• * Developmental Biology
• * Molecular Genetics

Background:

• * Temperature-dependent sex determination (TSD) in the red-eared slider turtle (Trachemys scripta) is influenced by incubation temperature in a dose-dependent manner.
• * Estrogen is implicated in female sex determination, but its role via aromatase expression in T. scripta remains unevaluated.
• * Conserved genes like SF-1 and MIS, and sex-specifically expressed SOX9, have been identified in T. scripta.

Purpose of the Study:

• * To investigate the molecular mechanisms underlying temperature-dependent sex determination (TSD) in Trachemys scripta.
• * To evaluate the hypothesis that endogenous estrogen production, mediated by aromatase, is involved in female sex determination.
• * To identify temperature-sensitive elements within the sex-determination cascade.

Main Methods:

• * Review of existing studies on TSD in Trachemys scripta.
• * Analysis of cloned cDNAs for genes potentially involved in sex determination and differentiation (SF-1, MIS, SOX9).
• * Proposal for future studies focusing on aromatase expression and other key gene expressions.

Main Results:

• * Incubation temperature affects sex determination in a dose-dependent manner, suggesting a dosage-sensitive element.
• * Evidence supports estrogen's role in female sex determination, though direct evaluation via aromatase expression is pending.
• * SF-1, MIS, and SOX9 cDNAs have been cloned, with SOX9 showing sex-specific expression.

Conclusions:

• * Further research into aromatase, SOX9, SF-1, and MIS expression is crucial for a comprehensive understanding of TSD in T. scripta.
• * These studies could elucidate the specific temperature-sensitive mechanisms controlling sex determination.
• * Identifying these factors will advance knowledge of reptile reproductive biology and evolutionary genetics.