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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(sin-gle 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SnaPshot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 indi-viduals 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 pedun-cle length and caudal peduncle depth in different genotype was GG＜GC＜CC from small to large.The body weight of indi-viduals with GG genotype was significantly lighter than that of CC genotype(P＜0.05).The C+598G gained in this re-search was significantly related to growth traits, which can be useful in marker assisted breeding for M.salmoides.