Gonadal development and gene expression in the leopard gecko during temperature-dependent sex determination

Area of Science:

• Reproductive Biology
• Developmental Biology
• Genetics

Background:

• Temperature-dependent sex determination (TSD) is common in reptiles, but its molecular basis in squamates is unclear.
• Understanding TSD mechanisms is crucial for reptile conservation and evolutionary studies.

Purpose of the Study:

• To investigate the molecular mechanisms of gonadal development and TSD in the leopard gecko (Eublepharis macularius).
• To identify key genes and regulatory pathways involved in temperature-sensitive sex determination in a squamate reptile.

Main Methods:

• Histological and transcriptomic analyses of leopard gecko gonadal development.
• Temperature-shift experiments to determine the temperature-sensitive period (TSP).
• Gene expression profiling to identify differentially regulated genes between sexes and temperatures.

Main Results:

• The TSP ended at embryonic stage 36; male and female pathways diverged at stage 34, before histological differentiation.
• Upregulation of male-associated genes (AMH, DMRT1, SOX9) preceded female markers (FOXL2, CYP19A1).
• Leopard geckos exhibit unique KDM6B regulation compared to turtles, with early activation by warm temperatures, and identified RNA splicing genes as early temperature-responsive factors.

Conclusions:

• The core gene network for gonadal differentiation is conserved, but upstream thermosensitive regulation varies across TSD reptiles.
• The leopard gecko is a valuable model for studying the environmental influence on gonadal fate and TSD evolution.
• Post-transcriptional regulation may play a role in the TSD cascade.