双棘黄姑鱼促性腺激素释放激素基因的克隆及系统进化分析

摘要

通过同源基因克隆方法得到双棘黄姑鱼促性腺激素释放激素（GnRH ）的3个基因：cGnRH、sGnRH、sbGnRH ，其开放阅读框为258、273 bp和261 bp ，分别编码85个、90个和86个氨基酸，3个基因的信号肽为23个氨基酸，核心十肽分别是QHWSHGWYPG、QHWSYGWLPG和QHWSYGLSPG ，这3种核心十肽经生物信息学分析均高度保守。氨基酸序列比对分析表明，双棘黄姑鱼与同科美国红鱼GnRHs基因亲缘性最近，它们的cGnRH和sGnRH的氨基酸同源性达100％，两种鱼sbGnRH 的同源性也高达92．2％。用MEGA 4．0构建GnRHs Neighbour‐joining系统进化树，结果显示双棘黄姑鱼cGnRH先于同科的美国红鱼聚类，再与星点东方鲀、斑马鱼和虹鳟等共同聚类；双棘黄姑鱼 sGnRH则先后与其他鱼类 sGnRH、cGnRH、sbGnRH 聚类；而双棘黄姑鱼 sbGnRH 先后与其他鱼类的sbGnRH、cGnRH和sGnRH聚类。%Three genes of gonadotrophin hormone releasing hormone (GnRHs) including cGnRH (chicken GnRH) ,(salmon GnRH) and sbGnRH(sea bream GnRH) were cloned from croaker nibea Protonibea di‐acanthus by a homology cloning method .It was found that the ORF was comprised of 258 bp coding 85 a‐mino acids in cGnRH ,273 bp coding 90 amino acids in sGnRH and 261 bp coding 86 amino acids in sbGn‐RH .T he three GnRH genes had signal peptide of 23 amino acids ,and the highly conservative core de‐capeptide of QHWSHGWYPG in cGnRH ,QHWSYGWLPG in sGnRH and QHWSYGLSPG in sbGnRH by bioinformatics analysis .Amino acid sequences alignment analysis proved that the amino acid sequences of cGnRH ,sGnRH and sbGnRH had the most affinity between croaker nibea and red drum Sciaenops ocel‐latus ,with the homology of up to 100% in the amino acid between cGnRH and sGnRH ,and the homology of 92 .2% in sGnRH .Phylogenetic unrooted trees constructed by neighbour‐joining method and the molec‐ular phylogenetic tree of GnRH established by NJ method using software MEGA 4 .0 showed that cGnRH of croaker nibea tended to cluster with red drum in the same family firstly ,then with puffer Taki f ugu ni‐phobles ,zebrafish Danio rerio ,and rainbow trout Oncorhynchus mykiss ;while that sGnRH tends to clus‐ter with sGnRH ,cGnRH and sbGnRH of other fish species step by step .The sbGnRH of croaker nibea was found to cluster with sbGnRH first ,followed by cGnRH ,and sGnRH successively .