吸虫类线粒体基因组的特征及系统发生分析

Characterization and Phylogenetic Analysis of Mitochondrial Genome of Trematoda

本研究分析了吸虫纲下单殖亚纲的13个物种和复殖亚纲的37个物种,共50个物种的线粒体全基因组序列,旨在揭示吸虫类线粒体基因组的主要基本特征,探究吸虫纲物种的系统发生关系。吸虫类的线粒体基因组具有明显的A+T含量偏向性。吸虫类的12个蛋白质编码基因和两个核糖体RNA基因的变异程度很大,其变异比例在48.8%到92.0%之间。根据线粒体基因组的12个蛋白质编码基因和两个核糖体RNA基因的差异位点分析,建议采用ND5、CYTB和ND4基因作为16S、12S和COⅠ基因的辅助分子标记。吸虫类各物种的线粒体基因组出现了大量的基因重排现象,除鸮形目裂体科和多后盘目外,其余物种均遵循类似的基因排列顺序。线粒体基因组的系统发育结果强烈支持将单殖亚纲提升到单殖纲,并支持将目前分类地位未定的腹盘科野牛平腹吸虫归入斜睾目同盘总科。本研究将为吸虫类线粒体基因组的研究、分子进化和分子诊断等方面提供诸多信息,并在今后的实践应用中起到一定的指导作用。

In this paper, the mitochondrial genome sequences of 50 species of 13 Monogenea species and 37 Digenea species of trematoda were analyzed, aiming at revealing the basic characteristics of trematoda mitochondrial genome sequences, and exploring the phylogenetic relationship of the trematoda species. The trematodes’ mitochondrialgenome had obvious A+T content bias. The 12 protein coding genes and 2 ribosomal RNA genes of trematodes varied a lot, the proportion of variance was between 48.8% and 92.0%. According to the differential site analysis of 12 protein coding genes and 2 ribosomal RNA genes in mitochondrial genome, ND5, CYTB and ND4 genes were suggested as auxiliary molecular markers for 16 S, 12 S and COI genes. Mitochondrial genomes of trematode species showed a large number of gene rearrangements sequences, and except for the Strigiformes Schistosomatidae and Polyopisthocotylea, the rest of the species followed a similar gene sequence. Phylogenetic results of mitochondrial genomes strongly supported that Monogenea should be promoted to Monogenoidea, and suggested that the Gastrodiscidae Homalogaster paloniae, which has not been classified at present, should be categorized into Plagiorchiida, Paramphistomidae. This paper would provide a lot of information for the research of trematoda mitochondrial genomes, molecular evolution and molecular diagnosis and would play a guiding role in the future practice of application as well.