Atherinopsid fishes as models for the study of temperature-dependent sex determination: Physiology of gonadal sex differentiation in pejerrey Odontesthes Bonariensis

The development of a functional gonad implies consequences not only for the phenotypic sex but also for the reproductive capacity during adulthood. In recent years, atherinopsid fish have been extensively studied because they present a variety of and sometimes contrasting mechanisms of sex determination/differentiation. In the present work we review the sex determining mechanisms in different species belonging to this family. As an example, Odontesthes bonariensis, commonly known as pejerrey, was singled out in order to discuss morphological aspects of the gonadal differentiation process in males and females and its relation to water temperature, the expression profile of some selected genes involved in this process, and the involvement of cortisol in the masculinizing process induced by warm temperature. The well described process of sex determination/differentiation in O. bonariensis and other atherinopsid species makes this family an emerging model to study the interactions between the environment and genotypic factors that ultimately lead to determination of the gonadal fate.