Among the vertebrates, the fish present mechanisms of determination and sexual differentiation, both as a genetic and environmental factor, such as temperature variations. These variations may influence the endocrine control of various hormones, such as thyroid hormones and cortisol, which are important modulators of the sex determination and differentiation process in fish. Thus, our objective is to test whether the increase in temperature could modulate endocrine mechanisms dependent on glucocorticoids and thyroid hormones, influencing the expression of genes involved in sexual differentiation in Medaka. For this, we will induce sexual reversion in medaka embryos and larvae in order to generate reversed males (XX) by increasing the temperature. To test whether heat-induced sexual reversal is mediated by cortisol and thyroid hormones specific inhibitors will be used for these hormones. In addition, the expression pattern of gsdf and differentially expressed genes during the period of male and female sexual differentiation in the different experimental groups (temperature, cortisol and THs) will be evaluated. Animals that overexpress gsdf will also be generated to evaluate the phenotype of these. These results will provide support for a better understanding between factors in the genetic - environmental - endocrine axis during sexual differentiation in this important biological model, expanding our knowledge about the regulatory genes of the sex determination/differentiation cascade in vertebrates.
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