Chromosomal and temperature-dependent sex determination: the search for a conserved mechanism.

To test the hypothesis that the same (or similar) genes may be involved in chromosomal sex determination and temperature dependent sex determination we investigated the expression of the mammalian testis determining gene SRY in the American alligator (Alligator mississippiensis), a species with temperature dependent sex. We have cloned Alligator SRY-related genes (A-Srys) which constitute three major gene classes with high degrees of sequence homology (45-87%) to mammalian SRY and related genes. Expression analysis and cellular localisation studies using staged embryonic material from male and female incubation temperatures are underway to assess the role of A-Sry genes in temperature dependent sex determination.