Tempo and mode of evolution of the Rh blood group genes before and after gene duplication
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The Rh blood group genes became duplicated in a common ancestor of human–chimpanzee–gorilla. We compared the evolutionary rates of the Rh blood group genes for each exon for branches connecting to humans, having duplicated Rh loci, and to orangutan, gibbon, and Old World monkeys, species having a single Rh locus. Our results show that evolutionary rates of nonsynonymous substitutions at exon 7 became accelerated in the human lineage. Furthermore, we surveyed the sequence variation in the region surrounding exon 7 of gibbons to clarify whether the diversity of the human exon 7 was introduced after the duplication or had been maintained before it. Two amino acid polymorphisms in white-handed gibbons were observed in the immediate vicinity of the D-specific motif in the human exon 7. Although the evolutionary rate of exon 7 was accelerated after the gene duplication, our results suggest that exon 7 had the potential for change even before the gene duplication.
KeywordsRh Blood Gibbon Primate Nucleotide diversity Evolutionary rate
We are grateful to the Great Ape Information Network (GAIN) for providing us an orangutan DNA sample and to Dr. Osamu Takenaka (now deceased) for providing us gibbon DNA samples. This study was supported by a grant-in-aid for scientific studies from the Ministry of Education, Science, Sports, and Culture of Japan to TK.
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