鳞翅目三种不同科的昆虫线粒体基因组学分析

发布时间：2018-08-26 11:34

【摘要】：线粒体DNA由于具有母系遗传、进化速率快和较少发生基因重组的特点,被作为进化的分子标记,并被广泛的应用于分子进化、系统发育、群体遗传学、比较和进化基因组学等研究。鳞翅目昆虫种类众多,总数有超过14000种之多,但是目前只有约700种完整的或不完整的线粒体基因组能从GenBank上获得。为了丰富鳞翅目昆虫线粒体基因组数据,进一步深入开展鳞翅目昆虫线粒体基因组的结构与进化特征的研究,本论文选取三种不同科属的鳞翅目昆虫柳二尾舟蛾(Cerura menciana)、甘薯天蛾(Agrius convolvuli)和臭椿皮蛾(Eligma narcissus),扩增并测定了其线粒体基因组全序列,并对编码基因进行了注释,再结合GenBank中其他己测序的鳞翅目昆虫的线粒体基因组数据,从线粒体基因组序列长度、四种碱基的含量、线粒体蛋白质编码基因、tRNA基因、密码子使用偏好性以及控制区等六个方面对鳞翅目昆虫的线粒体基因组进行了较为详细的比较及分析。并基于鳞翅目的全线粒体基因组数据对鳞翅目部分类群的系统发育关系进行了重建。本研究结果主要包括以下七个方面:1.三种鳞翅目昆虫分别为柳二尾舟蛾、甘薯天蛾和臭椿皮蛾。线粒体基因组全序列总长度分别为15,369,15,349和15,376 bp。各个线粒体基因组都由37个基因构成,包含有13个蛋白质编码基因,22个tRNA基因和2个rRNA基因,还有1个A+T富集区构成。2.通过对三种鳞翅目昆虫线粒体基因组碱基组成进行比较,发现AT含量明显高于GC含量,且GC偏斜均为负值。其中柳二尾舟蛾AT含量为80.06%,甘薯天蛾AT含量为81.49%,臭椿皮蛾AT含量为80.99%。3.本研究中三种鳞翅目昆虫线粒体基因组的蛋白编码基因除cox1的起始密码子CAG以外,其他12个蛋白编码基因都使用了ATN作为起始密码子。此外,大多数蛋白编码基因以TAA、TAG作为终止密码子,少数以不完整的T作为终止密码子。4.三种鳞翅目昆虫线粒体基因组22个tRNA基因的大小与其他鳞翅目昆虫较为相同,都介于64-73 bp之间。此外,柳二尾舟蛾和甘薯天蛾中除trns1(AGN)外,其余21个tRNA二级结构为典型的三叶草结构。但在臭椿皮蛾中,22个tRNA的二级结构均为典型的三叶草型。5.三种鳞翅目昆虫线粒体基因组中蛋白编码基因密码子的使用和氨基酸使用都具有一定的偏好性,G和C含量较高的密码子都较多的被舍弃,氨基酸中天冬酰胺(Asn)、异亮氨酸(Ile)、亮氨酸(Leu2)和苯丙氨酸(Phe)的使用频率最高。半胱氨酸(Cys)的使用频率最低。6.三种鳞翅目昆虫线粒体基因组的A+T富集区均位于rrnS和trnM之间,长度和A+T含量分别为:柳二尾舟蛾为372 bp和94.35%,甘薯天蛾为331 bp和93.35%,臭椿皮蛾为434 bp和96.54%。相对于tRNA,PCG和rRNA,A+T富集区中所含AT的含量最高。7.基于线粒体基因组13个蛋白质编码基因的核苷酸序列重新构建了鳞翅目昆虫系统发育进化树。采用ML(Maximum Likelihood method)分析方法建树,所得结果都显示,夜蛾总科,蚕蛾总科和麦蛾总科关系较近。这与前人的研究有所不同。因此,对鳞翅目系统发育关系的精准分析需要进行更多样本的线粒体基因组的测序。本研究首次对鳞翅目三种昆虫柳二尾舟蛾、甘薯天蛾和臭椿皮蛾线粒体基因组进行了测定、注释和分析,丰富了鳞翅目昆虫线粒体基因组数据库。为以后的研究提供了一定的理论基础。
[Abstract]:Mitochondrial DNA (mtDNA) is a molecular marker of evolution because of its maternal inheritance, rapid evolution and less recombination. It has been widely used in molecular evolution, phylogeny, population genetics, comparative and evolutionary genomics. About 700 complete or incomplete mitochondrial genomes can be obtained from GenBank. In order to enrich the mitochondrial genomic data of Lepidoptera insects and further study the mitochondrial genome structure and evolutionary characteristics of Lepidoptera insects, three different families and genera of Lepidoptera, Cerura menciana, were selected in this paper. The mitochondrial genome of Agrius convolvuli and Eligma Narcissus was amplified and sequenced, and the coding genes were annotated. The mitochondrial genome data of other Lepidopteran insects in GenBank were combined with the mitochondrial genome data, including the length of the mitochondrial genome sequence, the content of four bases, and the mitochondrial proteins. The mitochondrial genomes of Lepidoptera insects were compared and analyzed in detail from six aspects: plasmid coding gene, tRNA gene, codon usage preference and control region. The phylogenetic relationships of some Lepidoptera groups were reconstructed based on the whole mitochondrial genome data of Lepidoptera. The total length of mitochondrial genome was 15,369,15,349 and 15,376 bp, respectively. Each mitochondrial genome consisted of 37 genes, including 13 protein coding genes, 22 tRNA genes and 2 rRNA genes, and one A+T enrichment. By comparing the mitochondrial genomic base composition of three Lepidoptera insects, it was found that AT content was significantly higher than GC content, and GC skewness was negative. Among them, AT content was 80.06%, AT content of Sweet Potato Spodoptera was 81.49%, and AT content of Helicoverpa altissima was 80.99%. Apart from the cox1 initiation codon CAG, the other 12 protein-coding genes use ATN as the initiation codon. In addition, most protein-coding genes use TAA and TAG as the termination codon, and a few use incomplete T as the termination codon. 4. The size and size of 22 tRNA genes in the mitochondrial genome of three Lepidopteran insects In addition, except for trns1 (AGN), the other 21 tRNA secondary structures were typical clover structures. However, the secondary structures of 22 tRNA in the mitochondrial genomes of the three Lepidoptera species were typical clover type. 5. Both codon usage and amino acid usage of codon genes were preferred. Codons with higher G and C contents were abandoned more frequently. Amino acids used asparagine (Asn), isoleucine (Ile), leucine (Leu 2) and phenylalanine (Phe) were the most frequently. Cys was the least frequently used in mitochondria of three Lepidopteran insects. The A+T enrichment regions of the body genome were located between rrnS and trnM, and the length and A+T content were 372 BP and 94.35%, 331 BP and 93.35% and 434 BP and 96.54% respectively. Compared with tRNA, PCG and rRNA, the A+T enrichment regions contained the highest AT content. The phylogenetic tree of Lepidoptera was reconstructed by nucleotide sequence analysis. ML (Maximum Likelihood method) method was used to analyze the phylogenetic tree of Lepidoptera. The results showed that the phylogenetic relationships among noctuidae, silkworm moth and wheat moth were close. This was different from previous studies. In this study, the mitochondrial genomes of three Lepidopteran insects, Sagittaria willow, Sweet potato moth and Ailanthus altissima, were determined, annotated and analyzed for the first time, which enriched the mitochondrial genome database of Lepidoptera insects and provided a theoretical basis for future research.
【学位授予单位】：安徽农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q963

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