摘要
采用RACE方法 ,从鲤鱼脑组织克隆了两个差异的sGnRH(salmonGnRH ,[Trp7Leu8]GnRH)cDNAs ,即cDNA1和cDNA2 ,其长度分别为 393和 4 78bp。两个cDNAs都包括一个 2 85bp开放阅读框 ,编码的sGnRH前体为 94个氨基酸残基 ,由一个信号肽、sGnRH十肽和一个由蛋白水解位点 (Gly Lys Arg)连接的促性腺激素释放激素相关肽共 3部分组成。用内含子捕获得到相应的两个差异sGnRH基因 ,即sGnRHgene1和 gene2 ,其基本结构都包括 4个外显子和 3个内含子 ,3个内含子的核苷酸相似性分别为 71 1%、76 1%和 88.0 %。鲤鱼sGnRHcD NAs及基因的基本结构和编码特点与已报道的不同形式GnRHcDNAs和GnRH基因相似 ,由此推测所有类型的GnRH可能来自一个共同的祖分子。Southern杂交进一步证实鲤鱼基因组存在两个不同的sGnRH基因座位。相对定量RT PCR检测发现 ,两个sGnRH基因除在精巢的表达存在差异外 ,在脑区、垂体和成熟卵巢共表达。其中两个sGnRH基因在端脑和下丘脑的表达水平明显高于后脑区。根据sGnRHmRNAs在多个脑区、性腺和垂体的共存推测 ,sGnRH可能对鲤鱼下丘脑 垂体 性腺轴的调节有至关重要作用 。
Two types of complementary DNAs (cDNA) encoding the precursor of salmon gonadotropin-releasing hormone (sGnRH,[Trp^7,Leu^8]GnRH) are cloned and sequenced from common carp brain using rapid amplification of cDNA ends (RACE).The two cDNAs are referred to sGnRH cDNA1 and cDNA2,and the full-length fragment of cDNA1 and cDNA2 were 393 and 478 bp,respectively.Two sGnRH cDNAs contain an open reading frame of 285 bp,which encodes the sGnRH precursor including 94 amino acid residues.The sGnRH precursors consist of a signal peptide,sGnRH decapeptide and a GnRH-associated peptide (GAP) which is linked by the processing site (Gly-Lys-Arg).Two different sGnRH genes are characterized by intron trapping,and they share a similar structure composed of four exons and three introns.The nucleotide sequences identity of intron 1,intron 2 and intron 3 in sGnRH gene1 and gene2 are 71.1,76.1 and 88.0%,respectively.The basic structure and encoding architecture of sGnRH cDNAs and genes are similar with the reported GnRH.It is presumed that all the GnRH variants may evolve from a common ancestral molecular.Southern blot results confirm further the conclusion that there are two differential sGnRH genes in common carp genome.The results of reverse transcription-polymerase chain reaction (RT-PCR) assaying show that the two sGnRH genes co-express in the dissected brain regions,pituitary and ovary with the exception of expression of sGnRH genes in testis.According to the co-existence of two sGnRH genes in distinct brain regions,pituitary and ovary,it is presumed that sGnRH plays an important role in the regulation of hypothalamic-pituitary-gonadal (HPG) axis,and that sGnRH also operates as the neuromodulator,autocrine and/or paracrine regulator.
基金
国家高技术研究发展计划 ( 863计划 ) (编号 :2 0 0 1AA2 13 10 1
2 0 0 4AA2 13 12 1)
国家自然科学基金重点基金 (编号 :2 0 0 10 2 0 0 6)
国家重点基础研究发展规划 ( 973计划 ) (编号 :2 0 0 1CB10 90 0 6)资助项目~~
关键词
促性腺激素释放激素
表达分析
鲤鱼
gonadotropin-releasing hormone (GnRH)
expression analysis
common carp (Cyprinus carpio L.)
