Molecular Cloning and Sequence Analysis of IGF- I from Triangular Bream （Mega／obrama terminalis）

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