title: Molecular cloning, characterization, and expression analysis of a gonadotropin-releasing hormone-like cDNA in the clam, Ruditapes philippinarum.
abstract: 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.
authors.affiliation: The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Song
authors.affiliation: The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China. Electronic address: jmiao@ouc.edu.cn.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Miao
authors.affiliation: The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China.
authors.forename: Yuefeng
authors.initials: Y
authors.lastname: Cai
authors.affiliation: The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China.
authors.forename: Luqing
authors.initials: L
authors.lastname: Pan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics* / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006458:Hemolymph / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D011374:Progesterone / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012098:Reproduction; D013696:Temperature; D013739:Testosterone / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol
keywords: Gene expression; GnRH; Molecular cloning; Ruditapes philippinarum