Zhang Ruidong, Yin Yanan, Sun Long, Yan Peng, Zhou Yongkang, Wu Rong, Wu Xiaobing
Key Laboratory for Conservation and Use of Important Biological Resources of Anhui Province, College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China.
Alligator Research Center of Anhui Province, Xuanzhou 242000, China.
Gene. 2017 Aug 5;623:15-23. doi: 10.1016/j.gene.2017.04.028. Epub 2017 Apr 19.
Estrogens play critical roles in reproductive physiology via estrogen receptors (ESRs) in vertebrates, including reptiles. Chinese alligator (Alligator sinensis) is an endemic and endangered reptile species in China. In the present study, we cloned ESR2 gene from the ovary using rapid amplification of cDNA ends (RACE), investigated the spatial expression of ESRs in various tissues and temporal expression of ESRs in the pituitary glands during the reproductive cycle in Chinese alligators by quantitative real-time PCR (qPCR). Bioinformatics and phylogenetic analysis of deduced ESR2 protein were also performed. The full-length cDNA of the ESR2 is 1647bp in length, with an open-reading frame encoding 548 amino acids. The bioinformatics analysis indicated that the deduced amino acid sequence of alligator ESR2 was highly conserved with that of other vertebrate species. In addition, compared to human ESR2, the 14 amino acids in the alligator ESR2 that are essential for specific recognition of estradiol are entirely conserved. The phylogenetic analysis showed that alligators were more closely related to birds than to other reptiles. The results of qPCR showed that the tissue distribution patterns of both ESR subtype mRNAs appeared to be different. In male tissues, the highest mRNA level of both ESRs is in the liver. While in female tissues, ESR1 and ESR2 showed the highest mRNA level in the hypothalamus and pituitary gland, respectively. During the female reproductive cycle, the expression level of ESR1 mRNA increased from the initial post-hibernation period to the reproductive period, reached its peak in the reproductive period, and then decreased in the autumn active period and hibernation period. Conversely, the highest transcription level of ESR2 was observed in the hibernation period.
雌激素通过雌激素受体（ESRs）在包括爬行动物在内的脊椎动物的生殖生理过程中发挥关键作用。扬子鳄（Alligator sinensis）是中国特有的濒危爬行动物物种。在本研究中，我们利用cDNA末端快速扩增（RACE）技术从卵巢中克隆了ESR2基因，通过定量实时PCR（qPCR）研究了扬子鳄生殖周期中ESRs在各种组织中的空间表达以及在垂体中的时间表达。还对推导的ESR2蛋白进行了生物信息学和系统发育分析。ESR2的全长cDNA长度为1647bp，具有一个编码548个氨基酸的开放阅读框。生物信息学分析表明，扬子鳄ESR2推导的氨基酸序列与其他脊椎动物物种的高度保守。此外，与人类ESR2相比，扬子鳄ESR2中对雌二醇特异性识别至关重要的14个氨基酸完全保守。系统发育分析表明，扬子鳄与鸟类的关系比与其他爬行动物更密切。qPCR结果表明，两种ESR亚型mRNA的组织分布模式似乎不同。在雄性组织中，两种ESRs的最高mRNA水平都在肝脏中。而在雌性组织中，ESR1和ESR2分别在下丘脑和垂体中显示出最高的mRNA水平。在雌性生殖周期中，ESR1 mRNA的表达水平从冬眠后初期到生殖期升高，在生殖期达到峰值，然后在秋季活跃期和冬眠期下降。相反，ESR2的最高转录水平在冬眠期观察到。
