哲罗鲑胰岛素样生长因子－I（IGF－I）cDNA 分子克隆、序列分析及组织表达

摘要

Total RNA was isolated from Hucho taimen liver tissue.The cDNA encoding insulin-like growth factor I (IGF-I) peptide was amplified by reverse transcription polymerase chain reaction (RT-PCR) strategy using isolated total RNA as template.The IGF-I mRNA level was detected in different tissues using real -time quantitative PCR technique.The results displayed that the IGF-I contained an open reading frame (ORF) of 573 bp, and encoded a polypeptide with length of 190 amino acids.The polypeptide was composed of signal peptide , B, C, A, D domain and E peptide and the isoelectric point was 9.21.The amino acid sequence of H.taimen IGF-I was high homologus to that of other Salmonidae.H.taimen shared the highest identity with Salvelinus alpinus and the homology at nucleotide level of the IGF -I gene was 99.2%.The expression analysis of IGF-I gene with real-time quantitative RT-PCR showed that the highest level of IGF -I mRNA was ob-served in liver, followed by in gill and anterior intestine .There was no obvious expression in brain , pronephros, spleen, heart, stomach and muscle.%采用逆转录聚合酶链式反应（RT－PCR）方法，从哲罗鲑（Hucho taimen）肝脏的总 RNA 中扩增出胰岛素样生长因子－I（IGF－I）的 cDNA 开放阅读框（Open reading frame， ORF）序列，运用软件对其进行生物信息学分析，并利用荧光实时定量 PCR 技术检测了哲罗鲑成鱼不同组织中 IGF－I mRNA 的表达情况。结果显示， IGF－I 基因的 cD－NA 开放阅读框为573 bp，编码190个氨基酸，蛋白质等电点为9．21，氨基酸结构由信号肽、 B、 C、 A、 D 结构域及 E 肽组成；氨基酸序列与其他鲑科鱼类具有较高的同源性，其中与北极红点鲑的 IGF－I 同源性最高（99．2％）；组织表达分析显示，哲罗鲑 IGF－I mRNA 在肝脏中表达量最高，在鳃、前肠中次之，在脑、头肾、脾、心、胃和肌肉等组织中的表达量较低。