Shakyawar Sushil Kumar, Joshi Balwindar Kumar, Kumar Dinesh
Department of Biotechnology, Indian Institute of Technology, Guwahati-781 039, Assam, India.
Bioinformation. 2009 Oct 15;4(4):158-63. doi: 10.6026/97320630004158.
SSR (simple sequence repeats) are ubiquitously abundant in genomes. In organellar mitochondrial genome of animals, its distribution, size dynamics and effectiveness for phylogenetic relationship have not been understood. Present investigation reveals organisation of SSR in genic and intergenic region, its length and repeat motif dynamics, extent of conservation of flanking regions, appropriateness of these SSR data in establishing phylogenetic relationship. Contrary to eukaryotic nuclear abundance of SSR in non-coding region, we found abundance in coding region. Like nuclear SSR, most hyper mutable repeats were found in non coding region having di nucleotide motifs of mitochondrial genome but contrary to human having high mutable tetra repeats in case of mitochondrial genomes this was found to be with tri-motif repeats. SSR of mitochondrial genomes also show cyclical expansion and shrinkage in pattern of SHM (simple harmonic motion) with respect to time its non- linear thus not appropriate for phylogenetic analysis though the flanking regions of these SSR also conserved like nuclear SSR.
简单序列重复（SSR）在基因组中普遍大量存在。在动物的细胞器线粒体基因组中，其分布、大小动态以及对系统发育关系的有效性尚未明确。目前的研究揭示了SSR在基因区域和基因间区域的组织情况、其长度和重复基序动态、侧翼区域的保守程度，以及这些SSR数据在建立系统发育关系中的适用性。与真核细胞核中SSR在非编码区域大量存在相反，我们发现在编码区域也有大量SSR。与核SSR一样，大多数高度可变的重复序列存在于具有线粒体基因组二核苷酸基序的非编码区域，但与人类线粒体基因组中具有高变四核苷酸重复序列不同，这里发现的是三基序重复序列。线粒体基因组的SSR在简单谐振动模式下也呈现出周期性的扩张和收缩，其随时间呈非线性变化，因此尽管这些SSR的侧翼区域与核SSR一样保守，但不适用于系统发育分析。
