中文摘要：

为阐明松墨天牛肌肉收缩机理和相关基因表达模式,用构建c DNA文库方法,从松墨天牛c DNA中克隆到松墨天牛肌球蛋白轻链2基因,命名为Ma MLC-2（Gen Bank：KM371003）。该基因c DNA为882 bp,其中开放阅读框（ORF）为618 bp,编码205个氨基酸,推测的蛋白等电点为4.66,分子量为22.26 k Da。Ma MLC-2的氨基酸序列与赤拟谷盗同源性最高,为96%,与东方蝼蛄等8种昆虫同源性为85%-88%。松墨天牛与赤拟谷盗处在系统发育树的同一分支上。Ma MLC-2属于亲水性氨基酸,存在2个EF-hand结构域,长度均为29个氨基酸,其中第1个EF-hand结构域含有Ca2＋结合位点。SWISS-MODEL预测结果显示,Ma MLC-2有2个螺旋-环-螺旋结构。用RT-q PCR分析了Ma MLC-2基因的相对表达量,结果显示：蛹和幼虫的表达量高于成虫;成虫中足表达量最高,腹部表达量最低,各部位均有表达,且有显著差异（P〈0.05）。

英文摘要：

In order to elucidate the muscle contraction mechanism and related gene expression pattern of Monochamus alternatus,the myosin light chain 2 gene from Monochamus alternatus,called Ma MLC-2（ Gen Bank：KM371003） was cloned by using c DNA library construction. The cloned c DNA of Ma MLC-2 was 882 bp in length,which contains a 618 bp open reading frame（ ORF） encoding 205 amino acids with a calculated molecular mass of22. 26 k Da and an isoelectric point of 4. 66. Ma MLC-2 showed the highest homology with Tribolium castaneum（ 96%）,and has amino acid sequence homology with the myosin light chain 2 from 8 species of insects such as Gryllotalpa orientalis（ 85%-88%）. M. alternatus and T. castaneum on the same branch in the phylogenetic tree based on insect myosin light chain 2 amino acids. Ma MLC-2 was hydrophilic,which contains 2 EF-hand functional domains,and both of the domains are comprised of 29 amino acids. The first EF-hand functional domain can bind Ca2 ＋. There was a Ca2 ＋binding site in the first EF-hand domain. SWISS-MODEL prediction results showed that Ma MLC-2 has 2 helix-loop-helix structures. The relative expression levels of Ma MLC-2 detected by RT-q PCR indicated that the expression levels of Ma MLC-2 in pupae and larvae were higher than that in adults,and the expression level in head of adults was the highest,nevertheless,the expression level in abdomen of adults was the lowest. The Ma MLC-2 were prominently and differently expressed in all of the adult parts（ P〈0. 05）.