海湾扇贝促性腺激素释放激素基因克隆及表达分析

Cloning and Expression analysis of Gonadotropin-Releasing Hormone Gene in the Bay Scallop

促性腺激素释放激素(Gonadotropin Releasing Hormone,GnRH)是脊椎动物下丘脑-垂体-性腺轴的关键信号分子。近年来的研究显示,GnRH也存在于贝类等无脊椎动物,且在雌雄异体性别分化与繁殖中起重要作用,然而雌雄同体贝类GnRH的研究仍处于空白。本文以海湾扇贝为研究对象,利用RACE技术克隆获得GnRH的cDNA全长序列,该基因长1335 bp,编码101个氨基酸,前体包含1个由24个氨基酸组成的信号肽以及1个具有酰胺化修饰的活性肽(QNFHYSNGWQP-amide)。GnRH在脑足神经节和脏神经节中均有表达,且在2015年10月-2016年1月,GnRH在脑足神经节中的表达量显著高于脏神经节(P<0.05);GnRH在两个神经节中的表达均呈现先上升后下降的趋势,峰值出现在11月份,推测可能与性腺发育启动有关。本研究为深入理解GnRH在贝类繁殖调控中的作用奠定了基础。

Gonadotropin Releasing Hormone(GnRH) is a key molecule in the hypothalamic-pituitary-gonadal axis of vertebrates. Recent research shows that GnRH also present in molluscs, and it plays a vital role in the sex differentiation and reproduction of dioecism.But its role in hermaphrodites remains unclear. In this study, we cloned the full-length cDNA sequence of GnRH from the bay scallop Argopecten irradians. The full-length cDNA of GnRH is 1 335 bp,encoding 101 amino acids. The predicted protein contains a 24-residue signal peptide, as well as anamidated bioactive peptide(QNFHYSNGWQP-amide). Quantitative real-time PCR was applied to investigate the dynamic expression of GnRH in the parietovisceral ganglion(PVG)and pedal and cerebral ganglia(PGCG) from August 2015 to March 2016. Results showed that GnRH is mainly expressed in the PGCG, and the expression patterns are similar between the two ganglia, with a peak in November, which is possibly related with the initiation of gonadal development. This research will assist in better understanding the role of GnRH in theregulation of mollusc reproduction.