EFFECTS OF ENVIRONMENTAL FACTORS ON SEX DETERMINATION IN FISH

1)温度敏感期金鱼和比目鱼表现出一个临界温度敏感期。温度敏感期的结束正好发生在形态性别分化之前。此外，为了繁殖雄性化的XX金鱼，需要在整个温度敏感期保持高温。而为了产生基因型和表型性别一致的种群，需要在敏感期将鱼饲养在23℃以下，而不需要精确控制恒温。2)不同饲养温度下性别分化的组织学变化：低温处理下金鱼遗传雌性未发生雄性化。卵巢分化在低温下完全延迟。3)各种环境因素对性别决定的影响在金鱼中，密度和光周期对性别决定没有影响，尽管低pH处理产生雄性偏向性比，高pH处理对雄性化没有影响。相反，高pH处理导致了鲽鱼的雄性化。此外，皮质醇处理在金鱼中产生了较高的雄性种群，表明环境因素通过应激反应产生雄性化的可能性。

1) Temperature-sensitive periodGoldfish and barfin flounder exhibited a critical temperature-sensitive period. The end of the temperature-sensitive period was just before morphological sex differentiation. Moreover, to produce masculinized XX goldfish, it was needed to be kept in high temperatures throughout the temperature-sensitive period. While in order to produce a population where the genotypic and phenotypic sex coincide, it needed that fish are reared below 23℃ during the sensitive period without exact control of constant temperature.2) Histological changes in sex differentiation under the different rearing temperatureMasculinization of genetic female did not occur by low temperature treatment in goldfish. Ovarian differentiation was completely delayed at low temperature.3) Effects of various environmental factors on sex determinationIn goldfish, density and photoperiod have no effect on sex determination, although low pH treatment produced male-biased sex ratio while high pH treatment has no effect on masculinization. In contrast, high pH treatment led to masculinization in barfin flounder. In addition, cortisol treatment produced high male populations in goldfish, indicating a possibility of masculinization by environmental factors through stress responses.