【作者】 李扬威；

【导师】 路纪琪； 王振龙；

【作者基本信息】 郑州大学 ， 动物学， 2013， 硕士

【摘要】 本文利用长PCR扩增与引物步移法,测定了分类地位存在一定争议的三种地下鼠——棕色田鼠(Lasiopodomys mandarinus)、东北鼢鼠(Myospalax psilurus)和高原鼢鼠(Myospalax baileyi)的线粒体DNA (mtDNA)全序列,并利用生物信息学软件对这三种地下鼠mtDNA的基因组结构和系统进化进行了分析。棕色田鼠、高原鼢鼠和东北鼢鼠的mtDNA全长分别为16367bp、16351bp、16360bp,三种鼠的mtDNA基因组均由2个rRNA编码基因、22个tRNA编码基因、13个蛋白编码基因和非编码区组成,除8个tRNA基因及1个蛋白编码基因由轻链编码外,其余均由重链编码。三种地下鼠mtDNA的基因组成和排列顺序与大多数啮齿动物的mtDNA相同,碱基比例也与其它啮齿动物mtDNA碱基A+T>C+G这一特点相同,棕色田鼠的碱基比例与田鼠属(Microtus)、沟牙田鼠属(Proedromys)和绒鼠属(Eothenomys)动物的(?)ntDNA碱基比例接近,而两种鼢鼠与小鼹形鼠属(Nannospalax)动物的碱基比例更为接近。三种地下鼠的蛋白编码基因密码子的使用、不完全终止密码子的出现、tRNA中tRNASer的二级结构缺失一臂、控制区D-loop和轻链复制起始区rep-origin的结构等特点都与其它啮齿动物mtDNA中的同类结构特点相似。基于对三种地下鼠mtDNA的13个蛋白编码基因、2个rRNA基因以及Cytb基因的系统进化分析结果,本文认为,棕色田鼠应隶属于仓鼠科(Cricetidae)毛足田鼠属(Lasiopodomys),与田鼠属(Microtus)、沟牙田鼠属(Proedromys)和绒鼠属(Eothenomys)亲缘关系较近,结合形态学特征和数据,毛足田鼠属应作为一个单独的属存在；东北鼢鼠和高原鼢鼠同属鼢鼠属(Myospalax),与小鼹形鼠属(Nannospalax)亲缘关系较近,与鼠科、仓鼠科物种距离较远,结合形态学数据,支持鼢鼠属单独成属并与小鼹形鼠属一起隶属于鼹形鼠科(Spalacidae);对Genbank中现有的啮齿动物mtDNA蛋白编码基因系统进化分析,结果支持啮齿目的单系假说。与非地下鼠类相比,三种地下鼠在mtDNA基因组长度、结构、碱基组成等方面并未出现过大的差异,在系统进化分析中也没有表现出较大的波动。因此,本研究认为,地下鼠的mtDNA在长期进化过程中并未因环境的不同而出现较大的变异。更多还原

【Abstract】 In this thesis, Long-PCR amplification and primer walking methods were used in sequencing the complete mitochondrial genome of three subterranean rodents, Lasiopodomys mandarinus, Myospalax psilurus and Myospalax baileyi. The taxonomic statuses of these rodents are still in dispute. Then bio informatics software was employed in analyzing the gene content, and organization of the mtDNA, phylogenetic position of three rodents was also analyzed.The length of the mtDNA of L. mandarinus, M. psilurus and M. baileyi were16367bp,16351bp,16360bp. The three mtDNA had a typical gene content of13protein coding genes,22tRNA genes and2rRNA genes, which were highly conserved among most rodents. Except for the eight tRNA and one ND6genes, all other mtDNA genes were encoded on the heavy strand. Like the other rodents mtDNA, the base usage of the three mtDNA also followed the A+T>C+G rule. The A+T content of L. mandarinus mtDNA was close to genus Microtus, Proedromys and Eothenomys, and two zokor’s mtDNA A+T content were close to genus Nannospalax. The codons usage, use of incomplete stop codons, tRNASer secondary structure lost its DHU arm, structures of D-loop and rep-origin were similar to other rodents’ mtDNA. The phylogenetic analysis based on13protein coding genes,2rRNA genes and Cytb genes were constructed. Phylogenetic analysis with the support of morphology data showed that L. mandarinus was one of the species of Lasiopodomys, which had a close relationship with rodents in genus Microtus, Proedromys. And the Lasiopodomys should be retained as a separated genus of Cricetidae. Two zokors were species of genus Myospalax, and the genus Myospalax and Nannospalax were two genus of Spalacidae. The phylogenetic analysis also gave further evidence for the notion of Rodentia monophyly. Compared with non-subterranean rodents, the mtDNA of three subterranean rodents didn’t show any differences in length, structures and base composition, and the phylogenetic analysis also didn’t have any fluctuations. So we suggest that the mtDNA of subterranean rodents didn’t obtain any mutations under the different environments during long-term evolution.更多还原