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Directional fixation of mutations in vertebrate evolution.
1Institut d'Evolution Moléculaire, Université Claude Bernard--Lyon I, France.
Journal of Molecular Evolution
|January 1, 1987
Summary
Warm-blooded vertebrates show higher GC levels in gene coding sequences, especially at third codon positions, compared to cold-blooded ones. This suggests body temperature influences genome composition and evolutionary constraints.
Area of Science:
- Genomics
- Evolutionary Biology
- Molecular Biology
Background:
- Gene coding sequences exhibit variations in Guanine-Cytosine (GC) content across different vertebrate groups.
- Understanding GC content variations can provide insights into genome evolution and regulatory mechanisms.
Purpose of the Study:
- To investigate the differences in GC levels between coding sequences of genes in cold-blooded and warm-blooded vertebrates.
- To explore the potential influence of body temperature on GC content and its evolutionary implications.
Main Methods:
- Pairwise comparison of coding sequences from 21 cold-blooded and 41 warm-blooded vertebrate genes.
- Analysis of GC content at different codon positions.
- Correlation of gene GC levels with isochore composition.
Main Results:
- 12 genes showed higher GC levels in warm-blooded vertebrates, particularly at third codon positions.
- Six genes displayed no significant GC level difference.
- Three genes exhibited lower GC levels in warm-blooded vertebrates.
- Higher GC content in warm-blooded vertebrates correlated with GC-richer isochores.
- GC-rich isochore formation was observed in some cold-blooded vertebrates post-divergence.
Conclusions:
- Body temperature likely drives directional mutation fixation, increasing GC levels in warm-blooded vertebrates.
- Compositional constraints on the genome are supported by directional GC content changes and their evolutionary conservation.