关键词: 微卫星, SSR起源, 基因组分布, 功能, 进化

Abstract: Microsatellites, tandem Simple Sequence Repeats(SSR, 1~6 bp motif) are abundant across the genome and show high levels of polymorphism. This review discusses the association of SSR genesis with mobile elments as retroposons, suggests that most SSR genesis may be related to retroposons. This review also summarizes the evidence related to SSR functional importance in regulation of gene expression, chromatin organization, recombination, DNA replication, cell cycle, etc. These evidence indicates that SSRs are very important DNA fragments for organism's normal growth and keeping species-specific characteristics. SSR evolutionary mechanisms are also reviewed here:The internal mechanisms(replication slippage and recombination) create SSR variations, and the external forces, such as natural selection through different forms of natural selection, may shape SSR distribution across genome, and constrain repeated sizes at both the upper and lower thresholds, locus-specific variation and population differentiation.

Key words: MICROSATELLITE, SSR GENESIS, GENOMIC DIST IBUTION, FUNCTION, EVOLUTION