太湖鲂鲌F2代GH基因结构、系统发育和表达特征

STRUCTURE,PHYLOGENY AND TISSUE DISTRIBUTION OF GH IN CULTER ALBURNUS♀×MEGALOBRAMA TERMINALIS♂

采用PCR及T-A克隆技术,从基因组DNA成功克隆三角鲂、太湖鲂鲌、太湖鲂鲌F2代含完整阅读框的生长激素基因全序列,经测序拼接获得序列全长分别为6009、6042和6058bp,转录单元长分别为2049、2014和2045bp。三种群体的GH基因序列均包括五个外显子、四个内含子及5′侧翼区和3′侧翼区;编码氨基酸序列均为633bp,编码210个氨基酸。对3个目14种鱼类进行同源性及系统发育分析发现,太湖鲂鲌F2代与其祖父母的遗传距离相比亲本较近。另取10尾太湖鲂鲌F2代,对其进行GH基因编码区SNPs筛选,共得到7处SNPs,其中有3处位点的突变导致其氨基酸序列发生了明显的变化;对其蛋白质结构分析发现,突变后的氨基酸残基导致蛋白质二级结构发生改变。我们将该10尾个体按体重分为小个体组和大个体组,经组织表达分析发现,大个体组中的个体具有较高的转录水平,进一步分析发现其氨基酸残基有所不同。

Using polymerase chain reaction(PCR)and T-A cloning technology,we successfully obtained complete sequences of growth hormone(GH)gene with complete open reading frames from complete genomic DNA from three fish populations Megalobrama terminalis,Culter alburnus♀×Megalobrama terminalis♂(Ca×Mt),and the F2 of Ca×Mt.The total length of the sequence was 6009,6042,and 6058bp,respectively,and the length of the transcription unit was 2049,2014,and 2045bp,respectively.The GH gene sequence of the three populations includes five exons,four introns,5′UTR(untranslated region)and 3′UTR.All of them encoded 633bp amino acid sequence and 210 amino acids.The homology and phylogeny analysis on 14 fish species from 3 orders showed that the genetic distance between the F2 and its grandparents was closer than that of their parents.Seven SNPs(single nucleotide polymorphism)were obtained from 10 individuals of the F2,from which three mutations were observed causing significant changes in amino acid sequence.The analysis of protein structure showed that the mutated amino acid residue resulted in the change of protein secondary structure.We divided the 10 individuals into small and large body groups according to their body weight.Through tissue expression analysis,we found that the individuals in the large group had higher transcription level,and further analysis found that their amino acid residues were different.