小鼠基因组中的微卫星重复序列的数量、分布和密度

摘要

The mouse is a pivotal model organism in animal genomics. The availability of complete mouse chromosome sequences now makes possible the determination of frequencies of SSRs at the whole-genome level. In the study, the author analyzed the abundance and density of various microsatellite types (mono- to hexa-nucleotide repeats) in the exonic, intronic and intergenic regions of different chromosomes in the mouse genome. About 2.85 % of the mouse genome was occupied by SSRs, of which 46.2% were detected in the intergenic regions, 4.75% in the exons, and 49.05% in the introns. Microsatellites occurred predominantly in the noncoding DNA. The abundance of microsatellites was positively correlated with the size of the chromosome or the genomic region. However, their overall density was not closely related to the size of the chromosome or the genomic region. The abundance of all the six repeat types was relatively low in the exonic region of Chromosome 4 as compared with other regions. In the mouse genome, A, T, AC, AG, AT, AAC, AAG,AGG, AAAC, AAAG, AAAT, AACC, AAAAC, AAAAG, AAAAT, AAACC, AAAGG, AAGAG, AAAAAC,AAAAAG, AAAAAT, AAAGAG, ACACAT, ACAGAG, ACAGGC, ACATAT were the predominant repeat types while certain pentanucleotide repeats were absent in a certain chromosome or even in several chromosomes [ Acta Zoologica Sinica 52 (1): 138-152, 2006].%作者分析了老鼠基因组中各染色体及其内含子、外显子和基因间区上各种类型的微卫星(1-6个碱基的重复序列)的数量及其密度.SSR约占老鼠基因组的2.85%,其中46.2%存在于基因间区,4.75%存在于外显子,49.05%在内含子区域,即非编码区富含微卫星.微卫星的数量与染色体或基因区域的大小有关,但密度与染色体或基因区域的大小的关系并不十分密切.第4染色体的外显子区域中6种类型的SSR含量都比其它区域少.A,T,AC,AG,AT,AAC,AAG ,AGG,AAAC,AAAG,AAAT,AACC,AAAAC,AAAAG,AAAAT,AAACC, AAAGG,AAGAG,AAAAAC,AAAAAG,AAAAAT ,AAAGAG,ACACAT,ACAGAG,ACAGGC,ACATAT是老鼠基因组中主要的SSR类型,而一些5碱基重复单元的SSR在老鼠基因组的某一条甚至某几条染色体都不存在[动物学报52(1):138-152,2006].