Institute of Biological Sciences and Technology, Donghua University, Shanghai 201620, China.
Gene. 2012 May 1;498(2):288-95. doi: 10.1016/j.gene.2012.02.022. Epub 2012 Feb 24.
Microtus fortis is a special resource of rodent in China. It is a promising experimental animal model for the study on the mechanism of Schistosome japonicum resistance. The first complete mitochondrial genome sequence for Microtus fortis calamorum, a subspecies of M. fortis (Arvicolinae, Rodentia), was reported in this study. The mitochondrial genome sequence of M. f. calamorum (Genbank: JF261175) showed a typical vertebrate pattern with 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) and conserved sequence block 1 (CSB-1) were found in the CR region. The putative origin of replication for the light strand (O(L)) of M. f. calamorum was 35bp long and showed high conservation in stem and adjacent sequences, but the difference existed in the loop region among three species of genus Microtus. In order to investigate the phylogenetic position of M. f. calamorum, the phylogenetic trees (Maximum likelihood and Bayesian methods) were constructed based on 12 protein-coding genes (except for ND6 gene) on H strand from 16 rodent species. M. f. calamorum was classified into genus Microtus, Arvcicolinae for the highly phylogenetic relationship with Microtus kikuchii (Taiwan vole). Further phylogenetic analysis results based on the cytochrome b gene ranged from M. f. calamorum to one of the subspecies of M. fortis, which formed a sister group of Microtus middendorfii in the genus Microtus.
东方田鼠是中国特有的鼠类资源，是日本血吸虫抗性机制研究很有前途的实验动物模型。本研究首次报道了东方田鼠指名亚种（M. fortis calamorum）（田鼠科，啮齿目）的完整线粒体基因组序列。M. f. calamorum 的线粒体基因组序列（Genbank: JF261175）表现出典型的脊椎动物特征，包含 13 个蛋白质编码基因、2 个核糖体 RNA、22 个转移 RNA 和一个主要非编码区（CR 区）。在 CR 区发现了扩展终止相关序列（ETAS-1 和 ETAS-2）和保守序列块 1（CSB-1）。M. f. calamorum 轻链（O(L)）的假定复制起点长 35bp，在茎和相邻序列中高度保守，但在三个田鼠属物种的环区存在差异。为了研究 M. f. calamorum 的系统发育位置，基于 16 种啮齿动物 H 链上的 12 个蛋白质编码基因（除 ND6 基因外）构建了最大似然法和贝叶斯法的系统发育树。M. f. calamorum 被归入田鼠属，与台湾鼠（Microtus kikuchii）亲缘关系密切，属于田鼠亚科。基于细胞色素 b 基因的进一步系统发育分析结果，从 M. f. calamorum 到其中一个东方田鼠亚种，与田鼠属的 Microtus middendorfii 形成姐妹群。
