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Microsatellites: genomic distribution, putative functions and mutational mechanisms: a review
You-Chun Li1, Abraham B Korol, Tzion Fahima
1Institute of Evolution, University of Haifa, Haifa 31905, Israel.
Molecular Ecology
|November 28, 2002
Summary
Microsatellites (SSRs) are abundant DNA sequences with high polymorphism. Their non-random genomic distribution suggests selection against random changes due to functional importance in gene regulation and genome stability.
Area of Science:
- Genomics
- Molecular Biology
- Evolutionary Biology
Background:
- Microsatellites, also known as tandem simple sequence repeats (SSRs), are widespread in genomes and exhibit significant polymorphism.
- The precise genetic and evolutionary mechanisms governing SSRs are still debated within the scientific community.
Purpose of the Study:
- To synthesize current data on the distribution of SSRs within both coding and noncoding genomic regions.
- To explore the functional significance and evolutionary importance of SSRs.
Main Methods:
- Literature review and data synthesis.
- Analysis of existing evidence on SSR distribution patterns.
- Examination of proposed mutational mechanisms and their impact on SSR variation.
Main Results:
- SSR genomic distribution is demonstrably nonrandom, indicating selective pressures.
- Random expansions or contractions at SSR loci are often selected against, likely due to their influence on chromatin organization and gene regulation.
- SSRs impact various cellular processes, including recombination, DNA replication, cell cycle, and DNA mismatch repair.
Conclusions:
- SSRs play crucial roles beyond simple sequence variation, influencing fundamental genomic functions.
- Replication slippage and recombination are key mutational mechanisms driving SSR variation, often acting in concert.