Polymorphism Of MHC-DQB1gene Exon2in Macaca Thibetana And Macaca Mulatta From Sichuan

39randomly Macaca thibetana individuals and194indivalduals from7Sichuan Macaca mulatta wild groups indivalduals have been selected to study the polymorphism of MHC-DQB1exon2by PCR amplitication, cloning and sequencing, SSCP. Analysis their gene frequency, phylogenetic tree, alignment of the amino acid sequences and natural selection. Meanwhile, trans-species polymorphism of Macaca thibetana and the distance between groups of Macaca Mullata was also analysed. Results obtained listed as follows.1)Alignment of the sequences of the22Math-DQB1alleles and28Mamu-DQB1indicated48amino acid variable sites and105nucleotide variable sites. If analyzed separately, tibetan macaques has42amino acid variable sites,43nucleotide variable sites, while Macaca thibetana has48amino acid variable sites and99nucleotide variable sites. Alleles with the highest frequency among Macaca thibetana was Math-DQB1*18:01and among Macaca Mullata was Mamu-DQB1*0614.2)For all the site and PBR of Macaca thibetana, nonsynonymous substitutions(dn) was higher than synonymous substitutions(ds), indicating that Math-DQB1is subject to positive diversifying selection. While For non-PBR, synonymous substitutions(ds) was higher than nonsynonymous substitutions(dn), revealing purifying selection acting over Math-DQB1non-PBR domain.The analysis demonstrated that amino acids at the PBR showed higher polymorphism than at the non-PBR. For the16amino acids corresponding to the PBR, variation was detected at14sites. One codon sites (18th) wsa inferred to be subject to positive selection with high ω values under the Bayes empirical Bayes (BEB) analysis.For the16amino acids corresponding to the PBR, variation was detected at14sites in Macaca Mullata(87.5%). Of the69amino acid sites within non-PBR,34sites varied. For all the site, PBR and non-PBR of Macaca thibetana, nonsynonymous substitutions(dn) was higher than synonymous substitutions(ds), especially PBR domain, dn was significantlly higher than ds, indicating positive selection plays an important role towards DQB1locus. 3)DQB lineages of macaque have*06,*15,*16,*17,*18,*24.22Math-DQB1alleles grouped into DQB1*06(8),*18(8),*17(3),*15(3) lineages.28Mamu-DQB1alleles grouped into DQB1*06(12),*15(1),*16(1),*17(5),*18(9)lineages.4)Macaca thibetana shared12alleles with other macaca species which revealed that balancing selection maintains ancient alleles across speciation. They are: Math-DQB1*06:01vs Mamu-DQB1*0601, Math-DQB1*15:02:01vs Mafa-DQB1*15:03, Math-DQB1*17:02vs Maar-DQB*1702, Math-DQB1*15:01vs Mamu-DQB1*1501, Math-DQB1*06:08vs Mamu-DQB1*0609, Math-DQB1*15vs Mamu-DQB1*1801, Mart-DQB1*06:06vs Mamu-QDB1*06:14, Math-DQB1*06:07vs Mafa-DQB1*06:1101, Math-DQB1*06:04vs Mamu-DQB1*06:06, Math-DQB1*18:04vs Mamu-DQB1*18:04, Math-DQB1*18:05vs Mamu-DQB1*18:36, Math-DQB1*18:06vs Mamu-DQB1*18:30.5)Result of the the distance between groups of Macaca Mullata fluctuation from0.112to0.131where is not a very big difference. Distance between danba and bazhong is the highest(0.131). Secondly, distance between jiulong and hanyuan is0.13. Distance between heishui and xiaojin is the lowest(0.112).