大口黑鲈组织蛋白酶B基因SNP筛选及其与生长性状关联分析

SNP detection in cathepsin B gene and analysis of its correlations with growth traits in Micropterus salmoides

在动物体内组织蛋白酶B(cathepsin B,CTSB)是以酶原形式存在于溶酶体中,能水解多种蛋白,是调控动物生长发育的重要候选功能基因。为开发与大口黑鲈(Micropterus salmoides)生长性状相关的单核苷酸多态性(single nucleotide polymorphism,SNP)标记,本研究对大口黑鲈EST-SNP库中CTSB基因上的SNP位点进行筛选。经PCR扩增和测序分析,从该基因中筛选到1个SNP位点(命名为C+598G),该位点属于错义突变位点,编码的甘氨酸突变成为精氨酸。采用Sna Pshot方法对C+598G位点在165尾大口黑鲈养殖样本中的基因型进行检测,并分析其在群体中的遗传多样性。结果显示,C+598G位点在养殖群体中存在CC、GC和GG3种基因型,其频率分别是40.6%、47.3%和12.1%,C和G等位基因频率分别是64.2%和35.8%;该位点在群体中的观测杂合度(Ho)和多态信息含量(PIC)分别为0.473和0.354,符合哈代-温伯格平衡定律。进一步分析不同基因型与大口黑鲈生长性状相关性,结果表明,3种基因型个体的体质量、全长、体高、尾柄长和尾柄高性状平均值从小到大依次为GG型、GC型和CC型,其中GG型个体在体质量上显著小于CC型个体(P<0.05)。本研究获得的C+598G标记与大口黑鲈生长性状显著相关,可作为大口黑鲈分子标记辅助育种研究中的生长标记。

Cathepsin B(CTSB)exits in the lysosome as the form of zymogen,which can hydrolyze different proteins and be a novel candidate functional gene that regulates growth and development in animals.SNP site in CTSB gene obtained from Micropterus salmoides EST-SNP library was screened to exploit SNP markers associated with growth traits.One SNP site(C+598G)was gained by PCR amplification and direct sequencing from CTSB gene coding region.This site was a missense mutation that changed a codon for glycine to a codon for arginine.The genotype of C+598G site in 165 M.salmoides individuals was detected using SnaPshot method.The genetic diversity in the population was also analyzed.The results showed that C+598G site was constituted with CC,GC and GG genotype and their frequency in the population was 40.6%,47.3%and 12.1%,respectively.The frequency of C and G allele was 35.8%and 64.2%respectively.The observation heterozygosity(Ho)and polymorphic information content(PIC)of C+598G site was 0.473 and 0.354,respectively.This population was in the Hardy-Weinberg equilibrium for C+598G locus.Correlation analysis between different genotypes and M.salmoides growth traits showed that the order for the average body weight,total length,body depth,caudal peduncle length and caudal peduncle depth in different genotype was GG<GC<CC from small to large.The body weight of individuals with GG genotype was significantly lighter than that of CC genotype(P<0.05).The C+598G gained in this research was significantly related to growth traits,which can be useful in marker assisted breeding for M.salmoides.