Saitou / Oral

Evolution of ABO and Rh blood group genes in primates

Naruya Saitou, Laboratory of Evolutionary Genetics, National Institute of Genetics, Mishima, Japan

     We have been studying evolution of the ABO blood group gene of primates. We recently determined intron 6 sequences for 10 alleles of common chimpanzee and for 3 alleles of bonobo to estimate nucleotide diversities among them. Sequence length polymorphisms are observed in this region due to differences of repeat numbers from 1 to 5. From a phylogenetic network of intron 6 sequences of ABO blood group genes for human, common chimpanzee, and bonobo, effects of parallel substitutions and/or some kinds of convergent events are predicted in the chimpanzee lineage. We also estimated nucleotide diversities for common chimpanzee and bonobo ABO blood group genes, and these values were 0.219 and 0.208, respectively. This study is in press in Kitano and others (1999). We also studied the Rh blood group gene. There are two tightly linked loci (D and CE) for the human Rh blood group. Their gene products are membrane proteins having 12 trans-membrane domains and form a complex with 50 kD glycoprotein on erythrocytes. We constructed phylogenetic networks of human and nonhuman primate Rh genes, and they seemed to have experienced gene conversions. We therefore used the site by site reconstruction method and found seven converted regions. After eliminating the effect of gene conversion, we reconstructed the phylogenetic tree for primate Rh blood group genes, and estimated rates of nonsynonymous and synonymous substitutions for each branch of the tree. Many branches showed higher rates of nonsynonymous substitutions than synonymous ones, and this suggests that the Rh genes have experienced some kind of positive selection, probably through interactions with other organisms. This study is in press in Kitano and Saitou (1999). However, we did not find such evidence in rodent Rh genes (Kitano and others, 1998).

Kitano T., Sumiyama K., Noda R., Ferrell R., and Saitou N. (1999) Gene diversity of chimpanzee ABO blood group genes elucidated from intron 6 sequences. Journal of Heredity (in press).
Kitano T. and Saitou N. (1999) Evolution of Rh blood group genes has experienced gene conversions and positive selection. Journal of Molecular Evolution (in press).
Kitano T., Sumiyama T., Shiroishi T., and Saitou N. (1998) Conserved evolution of the Rh50 gene compared to its homologous Rh blood group gene. Biochemical and Biophysical Research Communications, vol. 249, No. 1, pp. 78