凡纳滨对虾CTSL基因PCR-SSCP多态性与生长 性状的关联分析及其mRNA的差异表达

利用PCR-SSCP技术对379尾凡纳滨对虾组织蛋白酶Cathepsin L（CTSL）基因多态性进行检测，采用最小二乘法对多态性与生长性状的相关性进行分析；利用Real-time quantitative PCR检测CTSL基因mRNA的差异表达情况。结果表明:引物C6 （F/R）扩增片段具有多态性，其扩增产物具有CC、CT和TT 3种基因型，TT基因型与CC基因型相比在第6外显子92 bp处发生了C→T的突变，为沉默突变。最小二乘法分析结果表明，在体重、体长、第一腹节长和尾节长这4个指标上CC和CT基因型显著高于突变型TT（p<0.05），而在头胸甲长和头胸甲宽2个指标上，CC基因型显著高于CT和TT基因型（p<0.05）。CTSL基因mRNA在凡纳滨对虾各组织、不同性别个体肌肉组织、极端体重个体肌肉组织中相对表达量大小顺序分别为:肝胰脏>胃>眼柄>心脏>消化腺；雌虾>雄虾；极大个体>极小个体。结论:CTSL基因多态性对凡纳滨对虾生长性状有显著影响，可以作为影响该虾生长性状的候选基因，为该虾的选育提供分子遗传标记；CTSL基因mRNA的分布情况表明此基因可能正向调控对虾生长。

PCR-SSCP Polymorphism of CTSL gene and its correlation with growth traits of Litopenaeus vannamei and the different mRNA expressions of CTSL

The polymorphism of CTSL gene in 379 Litopenaeus vannamei was detected using PCR-SSCP technique and its correlations with growth traits of L.vannamei was analyzed by least square method in this study. In addition, differential mRNA expressions of CTSL were carried out by real-time quantitative PCR. The results showed that the product amplified by primer C6 (F/R) displayed polymorphisms containing three genotypes: CC, CT and TT. Compared with the CC genotype, a silence mutation (C→T) occurred in TT genotype in exon6(92 bp)of the CTSL gene. For body mass, body length, the first abdominal segment length, and the last abdominal segment length, shrimps of CC and CT genotypes were significantly higher than those of the TT genotype(p<0.05), while for carapace length and carapace width, shrimps of CC genotype were significantly higher than those of CT and TT(p<0.05). The expressions of CTSL mRNA in various tissues, muscle tissues of different sex, different body weight individuals were: hepatopancreas>stomach>eyestalk>heart>digestive gland, female>male and heavy>light, respectively. The results obtained in this study suggest CTSL gene may be one of the candidates which significantly affect the growth of Litopenaeus vannamei. It can be used as the molecular genetic marker applying for Litopenaeus vannamei breeding. The distribution of the CTSL mRNA may be related to its specific functions in different tissues and its positive roles in the regulation of the shrimp muscle growth.