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鳜鱼(S.Keneri)以优良肉质性状成为极具商品价值和大力推广人工养殖名贵鱼类之一.为掌握控制优良肉质性状的遗传基础,采用同源克隆RT-PCR方法,克隆出该鱼肌球蛋白重链(MYH)cDNA序列.该基因cDNA序列全长5938bp,编码区长度为5814bp,含有poly(A)信号,3’非翻译区长124bp,其开放阅读框共编码1938个氨基酸,推算蛋白质分子质量为221.6Ku.鳜MYH基因由3个结构域组成,即MYSc-type-Ⅱ,SMC-N和Myosintail 1,其中MYSc-type-Ⅱ头部结构与鲤、斑马鱼同源性达90%,具高度保守性.通过DNAstar软件MegAlign构建进化树显示不同物种间该基因核苷酸编码序列同源性为77%—86%,氨基酸编码序列同源性达80%—92%.采用RT-PCR方法研究MYH在不同发育阶段差异表达结果表明,MYH在肌肉效应期开始有低量表达,成鱼期和鱼苗期表达量高,而囊胚期与神经胚均未表达.由此推测MYH基因于肌肉效应期开始表达.研究结果揭示鳜鱼肌球蛋白重链基因在进化上保持与其他脊椎动物相似性和差异性,为决定名贵鱼类肉质结构基因的研究提供了分子生物学基础.
S. Keneri became one of the most valuable commercially valuable fish with excellent meat quality traits.In order to understand the genetic basis of controlling excellent meat quality traits, homologous cloning RT-PCR was used to clone the fish The MYH cDNA sequence of MYH was 5938bp in length and 5814bp in length with a poly (A) signal. The 3 ’untranslated region was 124bp in length and contained an open reading frame (ORF) encoding 1938 amino acids. The deduced protein molecular weight was 221.6Ku. 鳜 MYH gene consists of three domains, MYSc-type-Ⅱ, SMC-N and Myosintail 1, in which the homology of MYSc-type-Ⅱ head structure to carp and zebrafish 90%, highly conserved.The construction of phylogenetic tree using DNAstar software MegAlign showed that the homology of the nucleotide sequence of this gene was 77% -86% and that of the amino acid sequence was 80% -92% The results of RT-PCR analysis of the differential expression of MYH in different developmental stages showed that MYH expression was low at the beginning of muscular-effect stage, high in fish-forming stage and fry stage, but not in blastula stage and neuroblast. The MYH gene begins to express during the muscular effect, revealing the results of the study Myosin heavy chain gene retaining the similarities and differences with other vertebrate evolution, a molecular basis for the study of the structural gene valuable fish meat determined.