三角鲂IGF-I基因的分子克隆及其序列分析

 采用RT-PCR技术首次从钱塘江三角鲂肝脏组织克隆了IGF-Ⅰ基因(GenBank No.AY247412)，序列分析表明钱塘江三角鲂IGF-ⅠcDNA序列由486个核苷酸组成，编码包括B、C、A、D和E 5个区域的161个氨基酸，为Ea-2亚型。同源性分析发现，钱塘江三角鲂IGF-ⅠcDNA与团头鲂、草鱼和鲤鱼的同源性分别为99.8%、88.8%和85.8%，钱塘江三角鲂IGF-Ⅰ前蛋白氨基酸序列与团头鲂、草鱼和鲤鱼的同源性分别为99.4%、88.8%和85.4%。在鲤科鱼类中，亲缘性越近鱼种，IGF-Ⅰ及其基因的同源性越高。试验结果为三角鲂种质研究和开发高效生物饲料添加剂提供基础资料。

Molecular Cloning and Sequence Analysis of IGF-I from Triangular Bream (Megalobrama terminalis)

The insulin-like growth factor Ⅰ(IGF-Ⅰ) gene of triangular bream (Megalobrama terminalis) (GenBank No.AY247412) was cloned for the first time from liver by RT-PCR .The nucleotide Sequence analysis showed that the triangular bream IGF-Ⅰ cDNA was consisted of 486 nucleotides and encoded 117 amino acids including B,C,A,D and E five domains. Analysis of E domain indicated that cloned triangular bream IGF-Ⅰbelonged to IGF-ⅠEa-2 subtype. Identity analysis showed that the IGF-Ⅰnucleotide sequence shared 99.8% homology with that of bluntnose bream, 88.8% homology with that of grass carp, 85.8% homology with that of common carp. The pre-IGF-Ⅰamine acid sequence shared 99.4% homology with that of bluntnose bream, 88.8% homology with that of grass carp, 85.4% homology with that of common carp. In the Cyprinus Carpio, the more high homology of nucleotide sequence and amino acid sequence in IGF-Ⅰshowed that the fishes have a closer relationship. These results could provide basic data for the research on triangular bream germplasm and the development and utilization of biological feed additives.