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The major compositional transitions in the vertebrate genome
G Bernardi1, S Hughes, D Mouchiroud
1Laboratoire de Genetique Moleculaire, Institut Jacques Monod, Paris, France.
Journal of Molecular Evolution
|January 1, 1997
Summary
Vertebrate genomes experienced significant GC-level increases during transitions to mammals and birds. These changes impacted gene-rich genomic regions, affecting both coding and noncoding DNA sequences.
Area of Science:
- Genomics
- Evolutionary Biology
- Molecular Biology
Background:
- The vertebrate genome has undergone significant compositional shifts.
- Two major transitions occurred between therapsids and mammals, and between dinosaurs and birds.
- These transitions involved substantial portions of the genome, particularly gene-rich areas.
Purpose of the Study:
- To investigate the GC compositional changes in vertebrate genomes.
- To compare GC3 levels in orthologous genes across different vertebrate lineages.
Main Methods:
- Comparative analysis of GC3 levels.
- Focus on orthologous genes from Xenopus, chicken, calf, and man.
- Examination of both coding and noncoding sequences.
Main Results:
- A notable increase in GC levels was observed during the therapsid-mammal and dinosaur-bird transitions.
- This GC increase affected approximately one-third of the genome.
- The GC enrichment impacted coding sequences (especially third codon positions) and noncoding regions.
Conclusions:
- The GC compositional transitions represent major evolutionary events in vertebrate genomes.
- These findings shed light on the dynamics of genome evolution and composition.
- Understanding these transitions is crucial for studying gene function and regulation across species.