基于太平洋甲胁虱裂化线粒体基因组推测甲胁虱属祖先线粒体核型

Ancestral mitochondrial karyotype of Hoplopleura inferred based on fragmented mitochondrial genome of Hoplopleura pacifica(Anoplura:Hoplopleuridae)

【目的】动物典型的单一染色体线粒体基因组在甲胁虱属Hoplopleura已裂化成多个线粒体微环染色体。本研究旨在通过测定太平洋甲胁虱Hoplopleura pacifica的线粒体基因组来推测甲胁虱属祖先线粒体核型。【方法】利用Illumina HiSeq X Ten高通量测序技术对太平洋甲胁虱裂化线粒体基因组进行测定,分析其结构特征与变异情况;用最大似然法和邻接法构建7科7属15种吸虱的系统发育树;用简约法推测甲胁虱属祖先线粒体核型。【结果】太平洋甲胁虱线粒体基因组测序获得29个基因(11个蛋白质编码基因,16个tRNA基因以及2个rRNA基因),且不均匀地分布于10个线粒体微环染色体上,每个线粒体微环染色体的编码区包括1~5个基因,大小在690~1773 bp之间。甲胁虱属内物种线粒体微环染色体组成差异较小,与吸虱亚目(Anoplura)其他属相比,甲胁虱属线粒体微环染色体的基因组成和基因排列有差异,但这种差异仅限于tRNA基因。进化树强烈支持吸虱亚目分为两大进化支,一个大的进化支包括甲胁虱科(Hoplopleuridae)、多板虱科(Polyplacidae)、血虱科(Haematopinidae)和微胸虱科(Microthoraciidae),另一个大的进化支包括虱科(Pediculidae)、阴虱科(Pthiridae)和猴虱科(Pedicinidae)。甲胁虱属祖先线粒体核型由12个线粒体微环染色体组成,每个线粒体微环染色体由一个编码区和一个非编码区构成,编码区包含1~6个基因。【结论】本研究首次测定并分析了太平洋甲胁虱裂化线粒体基因组,并与迄今为止测序的另外2种甲胁虱的线粒体基因组进行了比较,推测出甲胁虱属祖先线粒体核型。

【Aim】The typical single-chromosome mitochondrial(mt)genome of animals has fragmented into multiple mt minichromosomes in Hoplopleura genus.To infer the ancestral mt karyotype for Hoplopleura genus,we sequenced the mt genome of Hoplopleura pacifica.【Methods】We sequenced the fragmented mt genome of H.pacifica by Illumina HiSeq X Ten platform,and analyzed the structure and variation.We constructed phylogenetic trees of 15 species of sucking lice in 7 genera and 7 families by using maximum likelihood method and neighbor-joining method,and inferred the ancestral mt karyotype of Hoplopleura by parsimony method.【Results】We identified 29 mt genes(11 protein-coding genes,16 tRNA genes and 2 rRNA genes)from mt genome of H.pacifica,which are unevenly distributed on 10 mt minichromosomes.The coding region of each mt minichromosome contains 1-5 genes with the length of 690-1773 bp.Species of Hoplopleura have a little difference in structure of mt minichromosomes.Compared with other genera in Anoplura,Hoplopleura have variation in the gene composition and gene arrangement of mt minichromosome,which,however are only limited to tRNA genes.The phylogenetic tree showed that Anoplura was divided into two major clades with strong supports,one major clade included the lice of Hoplopleuridae,Polyplacidae,Haematopinidae and Microthoraciidae,and the other major clade included the lice of Pediculidae,Pthiridae,and Pedicinidae.The ancestral mt karyotype of Hoplopleura comprises 12 mt minichromosomes,each having a single coding region with 1-6 genes and a single non-coding region.【Conclusion】We successfully sequenced and analyzed the fragmented mt genome of H.pacifica for the first time,compared it with the mt genome of the other two Hoplopleura species sequenced to date,and inferred the ancestral mt karyotype of Hoplopleura.