Kim Tae Ha, Kim Mi Ae, Kim Kyeong Seop, Kim Jae Won, Lim Han Kyu, Lee Jung Sick, Sohn Young Chang
Department of Marine Molecular Biosciences, Gangneung-Wonju National University, 7 Jukheon-gil, Gangneung, Gangwon 25457, Republic of Korea.
East Coast Life Sciences Institute, Gangneung-Wonju National University, 7 Jukheon-gil, Gangneung, Gangwon 25457, Republic of Korea.
Comp Biochem Physiol A Mol Integr Physiol. 2017 Jul;209:1-9. doi: 10.1016/j.cbpa.2017.04.001. Epub 2017 Apr 11.
Gonadotropin-releasing hormone (GnRH) is a key neuropeptide regulating reproduction in humans and other vertebrates. Recently, GnRH-like cDNAs and peptides were reported in marine mollusks, implying that GnRH-mediated reproduction is an ancient neuroendocrine system that arose prior to the divergence of protostomes and deuterostomes. Here, we evaluated the reproductive control system mediated by GnRH in the Pacific abalone Haliotis discus hannai. We cloned a prepro-GnRH cDNA (Hdh-GnRH) from the pleural-pedal ganglion (PPG) in H. discus hannai, and analyzed its spatiotemporal gene expression pattern. The open reading frame of Hdh-GnRH encodes a protein of 101 amino acids, consisting of a signal peptide, a GnRH dodecapeptide, a cleavage site, and a GnRH-associated peptide. This structure and sequence are highly similar to GnRH-like peptides reported for mollusks and other invertebrates. Quantitative polymerase chain reaction demonstrated that Hdh-GnRH mRNA was more strongly expressed in the ganglions (PPG and cerebral ganglion [CG]) than in other tissues (gonads, gills, intestine, hemocytes, muscle, and mantle) in both sexes. In females, the expression levels of Hdh-GnRH mRNA in the PPG and branchial ganglion (BG) were significantly higher at the ripe and partial spent stages than at the early and late active stages. In males, Hdh-GnRH mRNA levels in the BG showed a significant increase in the partial spent stage. Unexpectedly, Hdh-GnRH levels in the CG were not significantly different among the examined stages in both sexes. These results suggest that Hdh-GnRH mRNA expression profiles in the BG and possibly the PPG are tightly correlated with abalone reproductive activities.
促性腺激素释放激素（GnRH）是调节人类和其他脊椎动物生殖的关键神经肽。最近，在海洋软体动物中报道了GnRH样cDNA和肽，这意味着GnRH介导的生殖是一种古老的神经内分泌系统，它在原口动物和后口动物分化之前就已出现。在此，我们评估了太平洋鲍鱼（皱纹盘鲍）中由GnRH介导的生殖控制系统。我们从皱纹盘鲍的胸膜-足神经节（PPG）中克隆了一个前体促性腺激素释放激素cDNA（Hdh-GnRH），并分析了其时空基因表达模式。Hdh-GnRH的开放阅读框编码一个由101个氨基酸组成的蛋白质，包括一个信号肽、一个GnRH十二肽、一个切割位点和一个GnRH相关肽。这种结构和序列与报道的软体动物和其他无脊椎动物的GnRH样肽高度相似。定量聚合酶链反应表明，在两性中，Hdh-GnRH mRNA在神经节（PPG和脑神经节[CG]）中的表达均强于其他组织（性腺、鳃、肠、血细胞、肌肉和外套膜）。在雌性中，PPG和鳃神经节（BG）中Hdh-GnRH mRNA的表达水平在成熟和部分排精阶段显著高于早期和晚期活跃阶段。在雄性中，BG中Hdh-GnRH mRNA水平在部分排精阶段显著增加。出乎意料的是，两性中CG中Hdh-GnRH水平在各检测阶段之间没有显著差异。这些结果表明，BG以及可能还有PPG中Hdh-GnRH mRNA的表达谱与鲍鱼的生殖活动密切相关。
