罗非鱼免疫球蛋白（IgM）重链基因全长cDNA序列分析

从已经构建的罗非鱼白细胞cDNA文库中测定获得罗非鱼免疫球蛋白（IgM）重链的eDNA序列，全长1885bp，有一个完整ORF阅读框长1770bp，5’UTR为29bp，3’-UTR为86bp，编码588个氨基酸。罗非鱼与大黄鱼、斜带石斑鱼、南极鳕鱼、乌鳢、鳜鱼、伯氏豚[鱼叚]虎鱼、牙鲆、花狼鱼、硬头鳟的IgM重链氨基酸序列有较高的同源性，最高达到69％，表明已经获得罗非鱼IgM重链基因；对所得氨基酸进行二级结构预测发现，罗非鱼IgM重链基因全长cDNA序列所编码的氨基酸分子量为41453．94Da。该试验结果为罗非鱼IgM重链基因功能的实验性鉴定工作奠定了基础。

cDNA sequence analysis of serum immunoglobulin M heavy chain gene ot Tilapia nilotica

The sequence of a clone （CM998） obtained from the cDNA library of Tilapia nilotica leucocytes was determined and the whole cDNA sequence of serum immunoglobulin（lg）M heavy chain of Tilapia nilotica were worked out. The overall length of immunoglobulin M heavy chain was found 1885bp, it had an open reading frame of 1770bp and coded 588 amino acids, flanked by a 29bp of 5＇-UTR and a 86bp of 3＇-UTR. The coded protein had a high homology to immunoglobulin M heavy chain of Larimichtbys crocea, Epinephelus coioides, Notothenia coriice, Channa argus, Siniperca chuatsi, Trematomus beruaechii, Paralichthys olivaceus, Anarhichas minor and Oncorhynchus mykiss, and the highest homology rate was 69%. The secondary structure of obtained amino acid was detected and it was found that the molecular weight of amino acid coded by cDNA sequence was 41453.94 Da, which provided a basis for further study on gene function.