绿环缘蝽(昆虫纲,半翅目,缘蝽科)线粒体基因组分析(英文)

THE ANALYSIS OF MITOCHONDRIAL GENOME OF STICTOPLEURUS SUBVIRIDIS HSIAO (INSECTA,HEMIPTERA-HETEROPTERA,RHOPALIDAE)

本研究测定了昆虫纲半翅目姬缘蝽科Rhopalidae绿环缘蝽Stictopleurus subviridis Hsiao的完整线粒体基因组,为异翅亚目蝽次目Pentatomomorpha中的首例研究。该线粒体基因组为全长15139bp的双链环状DNA分子,含有后生动物线粒体基因组中典型的37个基因,AT含量为75.7%。各基因的排列方式与六足动物假想祖先相同。该线粒体基因组结构紧凑,有基因重叠现象。在tRNA-Ile与tRNA-Gln间发现一个罕见的79bp的非编码序列。tRNA-Ser的二级结构中DHU臂缺失,无法折叠成典型的三叶草结构。CO2和CO3终止密码子为T,其下游为同链编码的tRNA基因。基因组AT含量为75.7%,密码子使用频率也反映出AT偏好。两条链上蛋白质编码基因的CG-skew趋势相反,密码子使用频率也反映出两链不同的CG偏好。蛋白编码序列并不总是使用与tRNA的反密码子相对应的密码子,密码子的使用并不随机。使用频率最高密码子为NNA,使用频率最低的密码子为NNG。与臭虫次目Cimicomomorpha中的锥猎蝽Triatoma dimidiata线粒体基因组比较分析表明,ATP8为进化最快的蛋白质,CO1最慢,但tRNA和rRNA基因的进化速率比蛋白质基因低。

The first complete mitochondrial genome of pentatomomorphan bug,Stictopleurus subviridis Hsiao,1977（Insecta,Hemiptera-Heteroptera,Rhopalidae）was sequenced in this study.The genome was a circular molecule of 15319 bp containing the typical 37 genes that arranged in the same order as that of the putative ancestor of hexapods.Sequences overlaps were observed between several neighbor genes,which made the genome relatively compact.An unusual non-coding spacer was found between tRNA-Ile and tRNA-Gln.The tRNA-Ser（GCT）could not be folded into typical secondary structure because its DHU arm was replaced with a simple loop.CO2 and CO3 were terminated with a single T adjacent to a downstream tRNA gene in the same strand.The genome was AT-biased with a total A＋T content of 75.7% which was also demonstrated by the codon usage.Protein genes of two strands presented opposite CG-skew trends which was also reflected by the codon usage.For most of the amino acids,the protein coding sequences did not prefer to use the cognate codons of corresponding tRNAs and the codon usage of the protein genes was not random.The most frequently used codons were NNA and the most infrequently were NNG.Compared with another complete mitochondrial genome of Heteroptera,Triatoma dimidiata,ATP8 was the fastest evolving protein and CO1 was the slowest,while tRNAs and rRNAs were slower than all the proteins.