Insights of sex determination and differentiation from medaka as a teleost model

The mechanisms of sex determination and differentiation in fish are highly divergent with a broad range of gonadal differentiation types from hermaphroditism to gonochorism. Multiple triggers regulate the process of sexual differentiation including genetic or environmental factors (temperature, light, hormones and/or pH value, etc.). In recent years, with the advances of molecular technologies and genetic engineering approaches, there are significant breakthroughs in identifying the master genes of vertebrate sex determination and differentiation. In this review, we explore the fundamental and molecular mechanisms underlying the sexual differentiation in teleost fish, using medaka (Oryzias latipes) as a model. We focus on the male pathways and factors, particularly on dmrt1, gsdf and amh genes involved in testicular differentiation, sexual reversal and plasticity. It is anticipated that new techniques will likely be developed in the field of sex manipulations and monosex breeding for fish aquaculture in the future.