Synergism Between Temperature and Estradiol: A Common Pathway in Turtle Sex Determination?

Wibbels, Thane; Bull, JJ; Crews, David

In many reptiles, the temperature at which the eggs are incubated determines the sex of the hatchlings. Administration of estradiol will counteract the masculinizing effects of a male-producing temperature, resulting in female hatchlings. To address whether temperature and estrogen are biologically equivalent, two experiments were conducted with the red-eared slider turtle, Trachemys scripta. In the first experiment, varying dosages of estrogen were administered at Stage 17 (the middle ofthe temperature-sensitive window) to eggs maintained at two temperatures, 26°C (which normally produces all males) and 28.2°C (which produces mostly males but lies at the threshold of the transition from male- to female-producing temperatures). Results indicate that estrogen and temperature exert a synergistic effect on sex determination. In the second experiment, estrogen was administered at different stages of embryonic development. The results indicate an estrogen-sensitive period ranging from Stage 14 through Stage 21, a period similar to the temperature-sensitive period for this species. The results of these experiments are consistent with the hypothesis that temperature and estradiol act in a common pathway in temperature-dependent sex determination.

Synergism Between Temperature and Estradiol: A Common Pathway in Turtle Sex Determination?

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