斑马鱼cGnRH-Ⅱ的基因克隆与序列分析

Cloning and sequence analysis of cGnRH-Ⅱ cDNA in Danio rerio

从斑马鱼脑组织提取总RNA,应用RT-PCR方法克隆cGnRH cDNA,其长度为646 bp,包括一个258bp开放阅读框;编码的cGnRH-Ⅱ前体为86个氨基酸残基,由一个信号肽、GnRH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(GAP)组成;其中信号肽和联接肽的长度分别为24和49个氨基酸.该cDNA编码的cGnRH-Ⅱ的前体氨基酸序列与其他物种的cGnRH-Ⅱ前体一致.表明物种间cGnRH-ⅡcDNA的蛋白编码区高度保守,而非编码区的保守性程度很低.进化分析表明,斑马鱼与鲤鱼、鲫鱼、拟鲤、黑头软口鲦等淡水的鲤科鱼类的同源性较高.

The total RNA was extracted from brain of zeabro fish. The GnRH cDNA was amplified by RT--PCR method using isolated total RNA as template. The cGnRH-- Ⅱ cDNA is 646bp in length that contain an open reading fram （ORF） of 258bp, which encode the 86 amino acids residues that including a signal peptide （SP）, a GnRH decapeptide and a GnRH- associated peptide （GAP） which is linked by the processing site Gly--Lys--Arg sequence. The cGnRH cDNA encode SP of 24 amino acids residues and GAP of 49 amino acid residues. The sequence structure of amino acids precursor encoded by cGnRH -- Ⅱ cDNA is identical to all others species reported to date. The result showed that the coding region of cGnRH-- Ⅱ eDNA are highly conserved and the untranslated regions are markely divergent in nucleotide sequence in the listed species. Phyligenetic tree indicated that Danio rerio was highly homologous with fresh water fish of Cyprinidae such as C. carpio, C. auratus,R. rutilus, P. prornelas.