Abstract：
The non-coding regions of the mitochondrial DNAs (mtDNAs) of hares, rabbits, and pikas (Lagomorpha) contain short (∼20 bp) and long (130-160 bp) tandem repeats, absent in related mammalian orders. In the presented study, we provide in-depth analysis for mountain hare (Lepus timidus) and brown hare (L. europaeus) mtDNA non-coding regions, together with a species- and population-level analysis of tandem repeat variation. Mountain hare short tandem repeats (SRs) as well as other analyzed hare species consist of two conserved 10 bp motifs, with only brown hares exhibiting a single, more variable motif. Long tandem repeats (LRs) also differ in sequence and copy number between species. Mountain hares have four to seven LRs, median value five, while brown hares exhibit five to nine LRs, median value six. Interestingly, introgressed mountain hare mtDNA in brown hares obtained an intermediate LR length distribution, with median copy number being the same as with conspecific brown hare mtDNA. In contrast, transfer of brown hare mtDNA into cultured mtDNA-less mountain hare cells maintained the original LR number, whereas the reciprocal transfer caused copy number instability, suggesting that cellular environment rather than the nuclear genomic background plays a role in the LR maintenance. Due to their dynamic nature and separation from other known conserved sequence elements on the non-coding region of hare mitochondrial genomes, the tandem repeat elements likely to represent signatures of ancient genetic rearrangements. clarifying the nature and dynamics of these rearrangements may shed light on the possible role of NCR repeated elements in mitochondria and in species evolution.
摘要：
野兔线粒体DNA（mtDNA）的非编码区，兔子,和pikas(Lagomorpha)包含短(~20bp)和长(130-160bp)串联重复，在相关的哺乳动物订单中不存在。在提出的研究中，我们对山地野兔（Lepustimidus）和棕色野兔（L.europaeus)mtDNA非编码区，以及串联重复变异的物种和种群水平分析。山野兔短串联重复序列（SRs）以及其他分析的野兔物种由两个保守的10bp基序组成，只有棕色的野兔表现出一种，更多可变的主题。长串联重复(LR)在物种之间的序列和拷贝数也不同。山兔有四到七个理数,中值五，棕色野兔展示5到9个LRs，中值六。有趣的是,棕色野兔中渗入的山兔mtDNA获得了中间LR长度分布，中值拷贝数与同种褐兔mtDNA相同。相比之下,将棕色野兔mtDNA转移到培养的无mtDNA的山地野兔细胞中，保持了原始的LR数，而相互转移导致拷贝数不稳定，表明细胞环境而不是核基因组背景在LR维持中起作用。由于其动态性质和分离的其他已知的保守序列元件上的非编码区的野兔线粒体基因组，串联重复元素可能代表古代基因重排的特征。阐明这些重排的性质和动力学可能会阐明NCR重复元素在线粒体和物种进化中的可能作用。
