INVESTIGADORES
SOMOZA Gustavo Manuel
artículos
Título:
Are Stress-related Hormones Involved in the Temperature-dependent Sex Determination (TSD) of Broad-Snouted Caiman?
Autor/es:
JOSEFINA L. IUNGMAN; GUSTAVO M. SOMOZA; CARLOS I. PIÑA
Revista:
The South American Journal of Herpetology
Editorial:
Brazilian Society of Herpetolog
Referencias:
Año: 2015 vol. 10 p. 41 - 49
ISSN:
1808-9798
Resumen:
In some reptiles, the gonadal outcome is regulated by temperature 20 during a critical period of the embryonic development. Gonadal steroid hormones are seen as effectors of the gonadal differentiation process. Recently, stress and glucocorticoids (GCs), stress-related hormones in vertebrates, have been considered as potential modulators of the sex determination process in some TSD vertebrates. In reptiles, corticosterone is the main GC produced, and its administration on eggs causes a bias in sex ratio in some lizards. In this context, we aim at assessing whether dexamethasone (Dex), a potent synthetic glucocorticoid, can modify the sex ratio in Caiman latirostris Daudin 1802, a species with strong TSD. As a first step, we incubated embryos at masculinizing temperatures (33°C; 100% males). Different doses of Dex were topically applied to the eggshell at stage 20, previously to gonadal differentiation. We monitored the embryonic development at stage 22 and 25, and evaluated some physiological and morphological hatchling traits. Embryonic mortality was not affected by dexamethasone manipulation. No effects of Dex on sex ratio were found, and all histologically analyzed animals evidenced testis. However, older embryos and hatchlings from Dex treated eggs were heavier and larger than control ones, and hatched earlier. Our results do not account for Dex involvement in the process of ovarian differentiation. Nevertheless, they suggest that Dex might accelerate embryo development by enhancing intermediate metabolism, and/or by stimulating growth hormone secretion.