Objective To obtain the nucleotide sequence of complete mitochondrial genome sequence of Microtus fortis fortis to provide molecular data for the genetic structure and phylogeny research of Microtus.Fortis.Methods By means of conventional and long distance PCR and sequence with the "primer walking" strategy to obtain the complete mitochondrial genome of M.ffortis (Genbank:JF261174).The phylogenetic tree was constructed based on Cyt b gene to investigate the phylogenetic position of M.f.fortis.Results The length of mitochondrial genome of M.f.fortis is 16312bp,include 13 protein coding genes,2 ribosomal RNAs,22 transfer RNAs and one major noncoding region (CR region).The extended termination associated sequences (ETAS-1 and ETAS-2),conserved sequence block 1 (CSB-1) and a Poly(C)10 section were found in the CR region.The putative origin of replication for the light strand (OL)of M.ffortis showed high conservation in stem and adjacent sequences,but the difference existed in the loop region among different species and subspecies.Phylogenetic analysis results based on the cytochrome b gene showed the closest phylogenetic relationship with Microtus middendorffi in the genus Microtus.Conclusion The mitochondrial genome sequence of M.f.fortis showed a typical vertebrate pattern.This study can provide useful molecular data for the further study about phylogenic relationships and subspecies taxonomy of M.fortis in the future%目的 获得东方田鼠指名亚种的线粒体基因组序列,为东方田鼠的遗传结构和系统进化研究提供分子数据.方法 照近缘的台湾田鼠的线粒体基因组序列(Microtus kikuchii,NC_003041.1)设计9对引物,利用传统和长距离PCR结合引物步移的策略,首次完成了东方田鼠指名亚种的线粒体基因组测序(Genbank:JF261174),并对该物种的线粒体基因组序列进行了分析,并利用线粒体基因组上的细胞色素b(Cytb)基因序列构建系统进化树,探讨中国东方田鼠的系统进化关系.结果 东方田鼠指名亚种的线粒体基因组全长16 312 bp,含有13个蛋白质编码基因、2个rRNA基因、22个tRNA基因和一个非编码控制区.同时,在其控制区,分别发现了终止序列区(EATS1、EATS2)、中央保守区1(CSB1)的相关保守序列和一个保守的Poly(C)10区段.在比较了东方田鼠指名亚种和长江亚种以及近缘物种的线粒体轻链复制起点(OL)序列的二级结果,发现茎环结构在茎和邻近序列处表现出高度保守性,而在环上的序列却存在着一定差异.通过Cyt b基因构建的系统进化树表明中国的东方田鼠与分布于俄罗斯的Microtus middendoffi田鼠,表现出最亲缘的系统进化关系.结论 中国东方田鼠指名亚种线粒体基因组各编码基因的长度、位置符合典型的脊椎动物特征,本研究的结果将为中国东方田鼠的系统进化、亚种分类研究提供重要的数据参考.
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