6种重要经济鱼类生长激素完整cDNA的克隆和序列分析

通过RT-PCR、3′RACE、5′-RACE方法，从6种重要经济鱼类——大眼鳜(Siniperca kneri)、石斑鱼(Epinephelus coioides)、黄鳝(Monopterus albus)、鲶鱼(Silurus asotus)、泥鳅(Misgurnus anguillicaudatus)和方正银鲫(Carassius auratus gibelio Bloch，Fang Zheng crucian carp)中克隆了生长激素(Growth Hormone，GH)的完整cDNA序列(除石斑鱼序列外，其他生长激素序列均系第一次克隆)，并详细分析了其序列特征。测序结果显示，克隆的6种GH cDNA长度依次为953bp、1023bp、825bp、1082bp、1154bp和1180bp，它们均包含一个长度为600个左右核苷酸的完整阅读框，分别编码一个200个左右氨基酸的蛋白：大眼鳜、石斑鱼和黄鳝GH为204个氨基酸，鲶鱼GH为200个氨基酸，泥鳅和方正银鲫GH为210个氨基酸。这6种蛋白序列与其他已知的鱼类GH序列都有较高的同源性，特别是与相同目的鱼类序列相比。通过序列比对，在这些蛋白序列内鉴定了许多保守的氨基酸残基，其中的大多数聚集而成5个保守域。基于这6种鱼类序列的编码区和其他鱼类的GH编码序列进行分子系统学分析，结果(MP和NJ树)与根据形态特征构建的系统发育树基本一致，特别是在硬骨鱼类较大分类阶元(目间、目以上)的系统发育研究方面比较一致，尽管仍存在一定差异，说明生长激素基因的编码区应该在硬骨鱼类系统发育研究领域得到更多的重视。

Molecular Cloning and Sequence Analysis of Full-Length Growth Hormone cDNAs from Six Important Economic Fishes

In this study,the full-length cDNAs of GH (Growth Hormone) gene was isolated from six important economic fishes,Siniperca kneri,Epinephelus coioides,Monopterus albus,Silurus asotus,Misgurnus anguillicaudatus and Carassius auratus gibelio Bloch.It is the first time to clone these GH sequences except E.coioides GH.The lengths of the above cDNAs are as follows: 953 bp,1 023 bp,825 bp,1 082 bp,1 154 bp and 1 180 bp.Each sequence includes an ORF of about 600 bp which encodes a protein of about 200 amino acid: S.kneri,E.coioides and M.albus GHs of 204 amino acid,S.asotus GH of 200 amino acid,M.anguillicaudatus and C.auratus gibelio GHs of 210 amino acid.Then detailed sequence analysis of the six GHs with many other fish sequences was performed.The six sequences all showed high homology to other sequences,especially to sequences within the same order,and many conserved residues were identified,most localized in five domains.The phylogenetic trees (MP and NJ) of many fish GH ORF sequences (including the new six) with Amia calva as outgroup were generally resolved and largely congruent with the morphology-based tree though some incongruities were observed,suggesting GH ORF should be paid more attention to in teleostean phylogeny.