Wang Yi Ya, Sun Li Xue, Zhu Jia Jie, Zhao Yan, Wang Hui, Liu Hong Jun, Ji Xiang Shan
College of Animal Science and Technology, Shandong Agricultural University, Taian 271000, China.
Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Institute of Fisheries, Nanning 530021, China.
J Therm Biol. 2017 Oct;69:76-84. doi: 10.1016/j.jtherbio.2017.06.006. Epub 2017 Jun 21.
In fish species with temperature-dependent sex determination (TSD) or genotypic sex determination plus temperature effects (GSD + TE), temperature can either affect sex differentiation or determine the sex. However, it is unknown if epigenetic control of cyp19a1a expression is critical for high temperature induced masculinization in the freshwater fish Nile tilapia. We analyzed the cyp19a1a DNA methylation levels in three age groups and found that they were lower in females than in males. At 8 months of age, males had DNA methylation levels of the cyp19a1a promoter that were almost twice as high as those of females. Exposure to high temperatures increased the cyp19a1a promoter DNA methylation levels from 30.87 ± 4.56% to 48.34 ± 0.92% (P = 0.035) in females and from 50.33 ± 7.38% to 51.66 ± 4.75% in males (P = 0.867). The increases in the cyp19a1a promoter DNA methylation levels were associated with the mRNA expression levels and might play a role in promoting gonadal differentiation in high temperature induced group females toward the male pathway. Western blot analysis revealed that the cyp19a1a protein expression levels in females significantly declined after high temperature treatment; only a slight decline was recorded in male fish. These results reveal that epigenetic control of cyp19a1a mRNA and protein expression is related to the environmental temperature and sex ratios in fish with TSD or GSD + TE.
在具有温度依赖型性别决定（TSD）或基因型性别决定加温度效应（GSD + TE）的鱼类物种中，温度既可以影响性别分化，也可以决定性别。然而，尚不清楚cyp19a1a表达的表观遗传调控对于淡水鱼尼罗罗非鱼高温诱导的雄性化是否至关重要。我们分析了三个年龄组中cyp19a1a的DNA甲基化水平，发现雌性的水平低于雄性。在8个月大时，雄性cyp19a1a启动子的DNA甲基化水平几乎是雌性的两倍。高温暴露使雌性cyp19a1a启动子DNA甲基化水平从30.87±4.56%增加到48.34±0.92%（P = 0.035），雄性从50.33±7.38%增加到51.66±4.75%（P = 0.867）。cypA1a启动子DNA甲基化水平的增加与mRNA表达水平相关，可能在促进高温诱导组雌性性腺向雄性途径分化中发挥作用。蛋白质免疫印迹分析显示，高温处理后雌性cyp19a1a蛋白表达水平显著下降；雄性鱼中仅记录到轻微下降。这些结果表明，cyp19a1a mRNA和蛋白表达的表观遗传调控与具有TSD或GSD + TE的鱼类的环境温度和性别比例有关。
