海参纲线粒体基因组特征分析及分子标记探讨

Characteristics and Exploration of Molecular Markers in Holothuroidea Mitochondrial Genomes

通过常规PCR和长PCR扩增获得仿刺参的线粒体DNA,进而采用鸟枪法测序、序列拼接获得仿刺参的线粒体基因组全序列。结合瓜参、拟刺参、海参及另外一个仿刺参的线粒体基因组,初步揭示了海参纲线粒体基因组的基本特征。楯手目的3个物种(仿刺参、拟刺参和海参)线粒体基因组的基因排列完全一致,且与海胆纲物种线粒体基因组的基因排列相同。隶属于枝手目的瓜参线粒体基因组的基因排列与其他海参线粒体基因组相比,发生6个tRNA基因的易位。海参纲线粒体基因组主编码基因的变异特征分析揭示了在海参类线粒体基因组所有的主编码基因中,cox1基因多态位点的比例最低,仅为29.46%;nad2、nad4、nad5三个基因的多态位点不仅比例较高,而且基因的长度较长,从而拥有最多的多态位点。因此,nad2、nad4和nad5基因可以cox1基因辅助的分子标记。

The mitochondrial DNA was obtained in sea cucumber Apostichopus japonicus by conventional PCR and Long-PCR amplification,and the mitochondrial genome sequence was sequenced using shotgun sequencing and sequence assembly.The general features of the Holothuroidea mitochondrial genomes were evaluated by comparison of mitochondrial genomes in Cucumaria miniata,Parastichopus nigripunctatus,Holothuria forskali and another A.japonicus.The mitochondrial genomes of three species（A.japonicus,P.nigripunctatus and H.forskali in Order Aspidochirotida） had same gene arrangement and consistent with that observed in the studied sea urchins.Compared with the echinoderm ground pattern,the traslocation was observed in six tRNAs in mitochondrial genomes of C.miniata in Order Dendrochirotida.Gene variation analysis of Holothuroidea mitochondrial genes revealed that cox1 had the minimal proportion of polymorphic loci（29.46%）.There were higher proportion of polymorphic loci and longer length in nad2,nad4 and nad5 genes,resulting in largest number polymorphic sites in those genes.Therefore,nad2,nad4 and nad5 genes can be used as supplementary molecular markers to cox1 gene,providing a reference for the conservation of Holothuroidea biological diversity and rational use of the biological resources.