黄脸油葫芦线粒体基因组:一种新的基因排列方式

采用长距PCR扩增及保守引物步移法测定并注释了黄脸油葫芦（Teleogryllus emma）线粒体基因组全序列。结果表明，黄脸油葫芦的线粒体基因组全长15 660 bp，A+T含量为73.1%。谷氨酸、色氨酸及天冬酰胺的转运RNA基因由N链编码，形成了直翅目中的第三种基因排列顺序，其余结构与其它螽亚目昆虫的线粒体结构一致。基因间隔序列共计73 bp，间隔长度从1—24 bp不等；有14对基因间存在共54 bp重叠，重叠碱基数在1—11 bp之间。13个蛋白质编码基因中12个基因（除COⅠ基因外）的起始密码为标准的ATN组成，COI基因的起始密码子为TTA。有10个基因在基因3＇端能找到完全的TAA或TAG终止密码子，而有三个基因（COII，ND5和ND4）终止密码子为不完整的T。除tRNASer（AGN）外，其余21个tRNA基因的二级结构均属典型的三叶草结构。黄脸油葫芦940bp的A+T富集区中存在一个被认为与复制起始有关的保守的二级结构，该结构不仅存在于直翅目昆虫中，而且也存在于双翅目、鳞翅目和膜翅目中，但是未见于昆虫纲的早期分化类群——弹尾目中。

Complete Mitochondrial Genome of Teleogryllus emma (Orthoptera: Gryllidae) with a New Gene Order in Orthoptera

The complete sequence of Teleogryllus emma mitochondrial genome was determined using long PCR and conserved primer walking approaches. The results showed that the entire mitochondrial genome of T. emma was 15 660 bp in length, with an A T content of 74.3%. The most distinct feature of this mtDNA is that the tRNA genes of Glutamic acid, Serine and Asparagine are located in the minor strand, and thus constitutes the third type of gene order of mitochondria in Orthoptera. The intergenic spacers range from 1 to 24 bp in size, totaling 73 bp. A total of 54 overlapping nucleotides exist among 14 genes, ranging from 1 to 11 bp in size. The TAA and TAG codons are used as stop codons in all the protein coding genes (PCGs) except COII, ND5 and ND4. The COI gene has an unusual start codon, TTA, instead of ATN or NTG. Most of the tRNA genes, except tRNASer (AGN), form typical secondary structures. An A T rich region of T. emma mitochondrial genome with 940 bp in length exists as an ubiquitous secondary structure found in the Orthoptera and other orders of Insecta, such as Diptera, Lepidoptera, Hymenoptera, but not in Collembola, which is considered the basal group of Insecta.