The mitochondrial genome of Protohermes concolorus Yang et Yang 1988 (Insecta: Megaloptera: Corydalidae)
The mitochondrial genome of Protohermes concolorus Yang et Yang 1988 (Insecta: Megaloptera: Corydalidae)
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DOI：
10.1007/s11033-008-9379-0
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发表时间：
2009-09-01
影响因子：
2.8
通讯作者：
Bu, Wenjun
中科院分区：
文献类型：
--
作者：
Hua, Jimeng;Li, Ming;Bu, Wenjun
本研究首次测序了大翅目：斑蛉Protohermes concolorus Yang et Yang， 1988（大翅目：斑蛉科）的线粒体全基因组。该基因组是一个15,851 bp的圆形分子，包含典型的37个基因，与假定的六足动物祖先的基因排列顺序相同。在几个相邻基因之间观察到序列重叠，这使得基因组相对紧凑。tRNA-Ser （GCT）不能折叠成典型的二级结构，因为它的东华大学臂被一个简单的环取代。13个蛋白基因中的6个在同一条链上以一个与下游tRNA基因相邻的单个T终止。GC含量的变化导致蛋白质基因核苷酸取代模式的不同。该基因组具有at偏倚性，总a + T含量为75.83%，密码子的使用也证明了这一点。对照区是at含量最高的区域，a + T含量更高的子区域。两条链的蛋白质基因呈现相反的cg偏态趋势，这也反映在密码子的使用上。对于大多数氨基酸，蛋白质编码序列并不倾向于使用相应trna的同源密码子，蛋白质基因密码子的使用也不是随机的。蛋白质基因核苷酸取代模式的变化与GC含量显著相关。基于13个蛋白基因的系统发育分析表明，大翅目是除鞘翅目外其他全变态昆虫的姐妹类群。
The first complete mitochondrial genome of dobsonfly Protohermes concolorus Yang et Yang, 1988 (Megaloptera: Corydalidae) was sequenced in this study. The genome was a circular molecule of 15,851 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. The tRNA-Ser (GCT) could not be folded into typical secondary structure because its DHU arm was replaced with a simple loop. Six of the 13 protein genes were terminated with a single T adjacent to a downstream tRNA gene in the same strand. The variation of GC content caused the different nucleotide substitution patterns of the protein genes. The genome was AT-biased with a total A + T content of 75.83% which was also demonstrated by the codon usage. The control region was the most AT-rich region with a sub-region of even higher A + T content. 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 variation of nucleotide substitution patterns of protein genes was significantly correlated with the GC content. The phylogenetic analyses based on all the 13 protein genes showed that Megaloptera was the sister group of other holometabolous insects except Coleoptera.