Song Ying, Miao Jingjing, Cai Yuefeng, Pan Luqing
The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China.
The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China.
Comp Biochem Physiol B Biochem Mol Biol. 2015 Nov;189:47-54. doi: 10.1016/j.cbpb.2015.07.005. Epub 2015 Jul 26.
Gonadotropin-releasing hormone (GnRH) is a key neuropeptide regulating reproduction in vertebrates. In the present study, we have cloned and identified the cDNA sequence of the prepro-GnRH (rp-GnRH) in the Manila clam Ruditapes philippinarum. The open reading frame encodes a protein of 94 amino acids, which consists of a signal peptide, a GnRH dodecapeptide, a cleavage site, and a GnRH-associated peptide. These deduced peptides were highly homologous to that reported for other molluscs. We used temperature control to promote gonadal development of the clams. The mRNA expression of rp-GnRH in the visceral ganglia from clams at different reproductive stages was determined by quantitative RT-PCR. The levels of steroids progesterone (P), testosterone (T), and estradiol-17β (E2) in the hemolymph of the corresponding clam were measured by ELISA. The rp-GnRH mRNA was highly expressed at the gonadal early development stage. Concentrations of P, T, and E2 also increased at the early development stage in both sexes. Positive significant correlations between rp-GnRH expression and P content as well as between rp-GnRH expression and T content were observed throughout the gonadal maturation. The results from this study may help to better understand the physiological functions of the native forms of GnRH-like peptides and the actions of GnRH on sex steroids release in bivalve molluscs.
促性腺激素释放激素（GnRH）是调节脊椎动物生殖的关键神经肽。在本研究中，我们克隆并鉴定了菲律宾蛤仔（Ruditapes philippinarum）中前体促性腺激素释放激素（rp-GnRH）的cDNA序列。开放阅读框编码一个由94个氨基酸组成的蛋白质，该蛋白质由一个信号肽、一个GnRH十二肽、一个切割位点和一个GnRH相关肽组成。这些推导的肽与其他软体动物报道的肽高度同源。我们利用温度控制来促进蛤仔性腺发育。通过定量RT-PCR测定不同生殖阶段蛤仔内脏神经节中rp-GnRH的mRNA表达。通过ELISA测定相应蛤仔血淋巴中类固醇孕酮（P）、睾酮（T）和雌二醇-17β（E2）的水平。rp-GnRH mRNA在性腺早期发育阶段高表达。两性在早期发育阶段P、T和E2的浓度也增加。在性腺成熟过程中，观察到rp-GnRH表达与P含量以及rp-GnRH表达与T含量之间存在显著正相关。本研究结果可能有助于更好地理解GnRH样肽天然形式的生理功能以及GnRH对双壳类软体动物性类固醇释放的作用。
