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The contribution of slippage-like processes to genome evolution
1MRC Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Journal of Molecular Evolution
|December 1, 1995
Summary
Simple sequences in genomes correlate with genome size, with higher densities in noncoding regions of eukaryotes. Selection likely shapes these simple sequences, especially in coding regions.
Area of Science:
- Genomics
- Bioinformatics
- Evolutionary Biology
Background:
- Simple sequences, or repeats, are common in genomes.
- Their distribution and evolution across species are not fully understood.
Purpose of the Study:
- To analyze simple sequence distribution in five diverse species' genomes.
- To investigate the relationship between genome size, simple sequences, and evolutionary processes.
Main Methods:
- Analysis of long (> 30 kb) single-copy genomic sequences from Homo sapiens, Caenorhabditis elegans, Saccharomyces cerevisiae, E. coli, and Mycobacterium leprae.
- Statistical analysis including ANOVA to examine frequency distributions of simple sequence motifs.
Main Results:
- A positive correlation was found between genome size and overall sequence repetition.
- Simple sequence densities were higher in eukaryotic noncoding regions than coding regions.
- Eukaryotic genomes exhibited biased simple sequence motif frequencies (e.g., AAA, TTT).
- Noncoding sequences showed similar motif distributions across eukaryotic species, unlike coding sequences.
Conclusions:
- Simple sequence incorporation appears linked to genome size expansion during evolution.
- Both inherent sequence biases and selection influence simple sequence composition.
- Strong selection may act on coding regions to remove undesirable simple sequences, particularly in humans.