Fish sex determination: the interaction among genes and environment

GUSTAVO M. SOMOZA; LEANDRO A. MIRANDA

Mar del Plata

Congreso; Reunión Annual de Sociedades de Biociencas; 2023

SAIC SAB AAFE AACyTAL

Even though in most vertebrates gonadal sex is determined genetically (a phenomenon known as Genotic Sex Determination, GSD), the gene that determines sex is not always the same. However, in some ectothermic animals gonadal differentiation can be modulated by the environment, being the influence of temperature the best known, although not the only one. This phenomenon is calledTemperature Sex Determination (TSD). In this sense, Atheriniformes have become interesting vertebrate models to study. In two native species of Argentina, Odontesthes hatcheri (Patagonian pejerrey) and Odontesthes bonariensis (pejerrey), a Y-linked gene, amhy, has been identified, which is the determinant of testicular morphogenesis. It has also been seen that the expression of this gene is differentially regulated by water temperature, demonstrating that there is an interaction between both mechanisms of sexual determination (GSD-TSD). This fact makes possible to evaluate the relationship between gentotypic sex (evidenced by PCR). Our studies with pejerrey show that, even though the presence of the amhy gene is important for the differentiation of males,we found sexual inversions (both in the environment, as well as in experimental conditions in the laboratory or in semi-controlled conditions in the field) that can be explained by the influence of the environment, not only by effects of natural environmental factors but also by anthropic influence. In the present work we will not only present a theoretical introduction of the phenomena of determination and sexual differentiation in pejerrey but also the comparison between experiments carried out in laboratory conditions and experiments carried out in the field.