中文摘要：

目前关于螽斯科昆虫的线粒体基因组全序列及其分子进化的研究报道很少。本研究利用L-PCR技术结合嵌套步移PCR扩增获得纺织娘Mecopoda elongata和日本纺织娘M. niponensis的线粒体基因组全序列， 同时对二者之间的碱基组成和结构特点进行了比较分析。结果显示： 纺织娘线粒体基因组（GenBank登录号JQ917910）序列全长15 284 bp， A＋T含量71.8%； 日本纺织娘线粒体基因组（GenBank登录号 JQ917909）序列全长15 364 bp， A＋T含量72.4%； 2种纺织娘序列长度差异主要是控制区长度不同引起（纺织娘控制区长294 bp， 日本纺织娘控制区长393 bp）。2种纺织娘基因组基因含量、 相对位置及转录方向均与其他已报道的螽斯科昆虫一致， 未发现基因重排现象； 基因组中均存在较长的间隔序列， 在trnA/trnR之间的间隔序列长度分别为63 bp与68 bp， 在trnQ/trnM之间的分别为55 bp和26 bp， 在trnSUCN/nad1之间的均为21 bp。而最长的基因重叠区域在2种纺织娘trnC/trnW之间均为8 bp， 在atp8/atp6和nad4L/nad4L之间均为7 bp。蛋白质编码基因的碱基组成和密码子使用均具有明显的偏倚性； 除nad1和nad2以特殊的TTG作为起始密码子， cox1使用特殊的起始密码子ATGA外， 其余的10种蛋白质编码基因均使用典型的ATN作为起始密码子。在tRNA基因中， 除trnSAGN外， 均能折叠形成典型的三叶草形二级结构。在这些tRNA基因中均存在一定数目的以G-U错配为主的碱基错配， 类似现象同样存在于其他已测定的六足动物线粒体基因组中， 表明G-U配对在线粒体基因组中很可能是一种完全正常的碱基配对方式。基因组中控制区的A＋T含量略低于线粒体基因组的其他区域， 表明高A＋T含量并不是该区域的必要特征。本研究结果为螽斯科系统发生关系重建积累了有价值的数据资料。

英文摘要：

Up to now, the reports about the complete mitochondrial genome of katydids and their corresponding molecular evolution are still limited. In this study, the mitochondrial genomes （mitogenome） of two longlegged katydids, i.e., Mecopoda elongata and M. niponensis, were sequenced using the LPCR combined with the sub-PCR technology. The results showed that the mitogenome sequence of M. elongata is 15 284 bp in length, haboring the A＋T content of 71.8% （GenBank accession no.： JQ917910）, while M. niponensis is 15 364 bp in length with the A＋T content of 72.4% （GenBank accession no.： JQ917909）. The differences in their mitogenome sizes can account for the size variations in their control regions （294 bp for M. elongata and 393 bp for M. niponensis）. The organization and gene content of both two Mecopoda mitogenomes are identical with those of other studied Tettigoniidae species. A few of noteworthy larger non-coding regions are shared by both species： the first is between trnA and trnR （63 bp in M. elongata, and 68 bp in M. niponensis）, the second between trnQ and trnM （55 bp in M. elongata, and 26 bp in M. niponensis）, and the third between trnSUCN and nad1 （21 bp in both species）. In both Mecopoda species, there are overlaps between trnC/trnW （8 bp）, atp8/atp6 （7 bp） and nad4L/nad4L （7 bp）. AT nucleotide composition bias of both Mecopoda mitogenomes is also reflected in the codon usage of NNU or NNA bias. In both Mecopoda mitogenomes, all protein-coding genes （PCGs） start with the typical ATN initiator codon expcept for nad1 and nad2 with TTG and cox1 with ATGA. All tRNAs in both Mecopoda species have the typical clover leaf structure except for trnSAGN. Some unmatched base pairs occur in both Mecopoda species, and overwhelming majority of them are G-U pairs, indicating that G-U is a normal base-pairing model in insect mitogenomes. Another unusual feature is the relatively lower A＋T content of control region （CR） compared with other regions of the mitog