Recombination and mammalian genome evolution.
Several lines of evidence are presented which suggest that sequence G + C content and recombination frequency are related in mammals: (i) chromosome G + C content is positively correlated to chiasmata density; (ii) the non-pairing region of the Y chromosome has one of the lowest G + C contents of any chromosomal segment; (iii) a reduction in the rate of recombination at several loci is mirrored by a decrease in G + C content; and (iv) when compared with humans, mice have a lower variance in chiasmata density which is reflected in a lower variance in G + C content. The observed relation between recombination frequency and sequence G + C content provides an elegant explanation of why gene density is higher in G + C rich isochores than in other parts of the genome, and why long interspersed elements (LINES) are exclusive to G + C poor isochores. However, the cause of the relation is as yet unknown. Several possibilities are considered, including gene conversion.
Eyre-Walker
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Institute of Cell Animal and Population Biology, University of Edinburgh, U.K.
D000818:Animals; D001482:Base Composition; D005075:Biological Evolution; D003434:Crossing Over, Genetic; D004260:DNA Repair; D005260:Female; D005785:Gene Conversion; D005787:Gene Frequency; D016678:Genome; D008297:Male; D008322:Mammals / Q000235:genetics*; D051379:Mice / Q000235:genetics; D008957:Models, Genetic; D011323:Primates / Q000235:genetics; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014998:Y Chromosome