Abstract Nile tilapia is a GSD + TE (genotypic sex determination plus temperature effect) fish species. However, the role of 17β-estradiol (E2) during high-temperature-induced masculinization is unknown in fish species exhibiting GSD + TE. Because letrozole can specifically downregulate E2, the differences of the E2 level and sex ratio between the high-temperature-treated groups and various doses of letrozole treated groups could help quantitatively analyze the role of E2 in Nile tilapia GSD + TE. The results indicated that high-temperature could also significantly downregulate E2, and the level of E2 in the XX + HT (9 days postfertilization (dpf) larvae cultured in 36 °C water for 12 days) group at 21 dpf was only approximately half that in the XX group. Comparison of E2 and the sex reversal ratio between the high-temperature treated group and various letrozole treated groups showed that the level of E2 in the XX + HT group at 21 dpf was almost the same as that in the XX + L1.5 (9 dpf XX larvae cultured in 28 °C water with1.5 μg/L letrozole for 12 days) group, but the 70.00% male ratio in the XX + HT group was significantly higher than that in the XX + L1.5 (58.33%) group and was similar to that in the XX + L4.5 groups (66.25%) and the XX + L13.5 group (77.08%). Comparison of E2 and the female ratio between the high-temperature treated group and the HT + E2 compensation groups further indicated that the E2 level in the XX + HT + E:4 (9 dpf fry cultured in 36 °C water containing 4 μg/L E2 for 12 days) group was similar to that in the XX group at 21 dpf, and the female ratio was close between the two groups. qRT-PCR and western blot analysis showed that the high-temperature treatment significantly downregulated the expression of ovary-type P450 aromatase (cyp19a1a) and upregulated the expression of the male sex differentiation genes doublesex and mab-3 related transcription factor 1 (Dmrt1) at 21 dpf. Additionally, the high-temperature treatment also down-regulated Nile tilapia gonad aromatase activity. Collectively, the present study uncovered the role of E2 during high-temperature–induced Nile tilapia female sex reversal into pseudomales (phenotypic males) and the regulatory effect of high-temperature on the E2 pathway, providing an important foundation for understanding the mechanisms of high-temperature-induced Nile tilapia female sex reversal.

中文翻译：

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定量比较分析揭示了 E2 在尼罗罗非鱼 GSD + TE 中的作用

摘要 尼罗罗非鱼是一种GSD+TE（基因型性别决定加温度效应）鱼类。然而，17β-雌二醇（E2）在高温诱导的雄性化过程中的作用在表现出 GSD + TE 的鱼类中是未知的。由于来曲唑可特异性下调E2，高温处理组与来曲唑处理组不同剂量E2水平和性别比的差异有助于定量分析E2在尼罗罗非鱼GSD+TE中的作用。结果表明，高温也可以显着下调E2，XX+HT（受精后9天（dpf）幼虫在36℃水中培养12天）组在21dpf时的E2水平仅为其一半左右。在XX组。高温处理组与来曲唑各处理组的E2和性别逆转比的比较表明，XX+HT组在21dpf时的E2水平与XX+L1.5几乎相同（9 dpf XX 幼虫在 28 ℃水和 1.5 μg/L 来曲唑培养 12 天）组，但 XX + HT 组雄性比例 70.00% 显着高于 XX + L1.5（58.33%） XX+L4.5组​​（66.25%）和XX+L13.5组（77.08%）相似。高温处理组与HT+E2补偿组E2和雌性比例的比较进一步表明，XX+HT+E：4（9dpf鱼苗在36℃水中培养，含4μg/ L E2 12 天）组与 XX 组在 21 dpf 相似，并且两组之间的女性比例接近。qRT-PCR和蛋白质印迹分析表明，高温处理显着下调卵巢型P450芳香化酶（cyp19a1a）的表达，上调雄性分化基因doublesex和mab-3相关转录因子1（Dmrt1）的表达。 21 dpf。此外，高温处理还下调了尼罗罗非鱼的性腺芳香酶活性。综上所述，本研究揭示了 E2 在高温诱导的尼罗罗非鱼雌性向假雄性（表型雄性）转变过程中的作用以及高温对 E2 通路的调节作用，为理解高-温度诱导的尼罗罗非鱼雌性性别逆转。qRT-PCR和蛋白质印迹分析表明，高温处理显着下调卵巢型P450芳香化酶（cyp19a1a）的表达，上调雄性分化基因doublesex和mab-3相关转录因子1（Dmrt1）的表达。 21 dpf。此外，高温处理还下调了尼罗罗非鱼的性腺芳香酶活性。综上所述，本研究揭示了 E2 在高温诱导的尼罗罗非鱼雌性向假雄性（表型雄性）转变过程中的作用以及高温对 E2 通路的调节作用，为理解高-温度诱导的尼罗罗非鱼雌性性别逆转。qRT-PCR和蛋白质印迹分析表明，高温处理显着下调卵巢型P450芳香化酶（cyp19a1a）的表达，上调雄性分化基因doublesex和mab-3相关转录因子1（Dmrt1）的表达。 21 dpf。此外，高温处理还下调了尼罗罗非鱼的性腺芳香酶活性。总的来说，本研究揭示了 E2 在高温诱导的尼罗罗非鱼雌性向假雄性（表型雄性）转变过程中的作用以及高温对 E2 通路的调节作用，为了解高温诱导的尼罗罗非鱼雌性变性机制提供了重要基础。 -温度诱导的尼罗罗非鱼雌性性别逆转。