Mechanisms of sex determination in South American silversides: from TSD to GSD

HATTORI, R.S.; ZHANG, Y.; SARIDA, M.; YAMAMOTO, Y.; STRÜSSMANN, C.A.; FERNANDINO, J.I.; SOMOZA, G.M.

Ottawa, ON

Conferencia; 3th North American Society of Comparative Endocrinology; 2015

North American Society of Comparative Endocrinology

Sex differentiation in silversides can be easily modulated by the water temperature experienced during embryogenesis or early larval development (TSD, temperature-dependent sex determination). In general, low temperatures produce female-biased whereas high temperatures produce male-biased populations, with proportions that vary according to species or populations. However, since the discovery of the sex-determining gene amhy (Y-chromosome-linked, antiMüllerianhormone) in Odontesthes hatcheri, it is becoming clearer that genotypic factors (GSD, genotypic sex determination) are also present in this group of fish. In this study we examined the presence of amhy gene in several Odontesthes species and analyzed its role in the process of sex determination of Odontesthes bonariensis.The homologue of amhy gene was found in 11 species of Odontesthes genus. A field screening analysis revealed the presence of sex reversal in about half of the species. Interestingly, species showing no sex reversal inhabit marine or estuarine environments whereas those with sex reversal inhabit inland waters. A more detailed analysis of amhy in Odontesthes bonariensis revealed that it is functional, especially at intermediate, mixed-sex producing temperatures.Furthermore, our expression analysis showed that the autosomal loci amha may also be crucial for testis differentiation in this species. Overall, this study showed that genotypic and environmental sex determinants can coexist in Odontesthes species.