title: Low major histocompatibility complex class I (MHC I) variation in the European bison (Bison bonasus).
abstract: Variation in the major histocompatibility complex (MHC) class I of the European bison was characterized in a sample of 99 individuals using both classical cloning/Sanger sequencing and 454 pyrosequencing. Three common (frequencies: 0.348, 0.328, and 0.283) haplotypes contain 1-3 classical class I loci. A variable and difficult to estimate precisely number of nonclassical transcribed loci, pseudogenes, and/or gene fragments were also found. The presence of additional 2 rare haplotypes (frequency of 0.020 each), observed only in heterozygotes, was inferred. The overall organization of MHC I appears similar to the cattle system, but genetic variation is much lower with only 7 classical class I alleles, approximately one-tenth of the number known in cattle and a quarter known in the American bison. An extensive transspecific polymorphism was found. MHC I is in a strong linkage disequilibrium with previously studied MHC II DRB3 gene. The most likely explanation for the low variation is a drastic bottleneck at the beginning of the 20th century. Genotype frequencies conformed to Hardy-Weinberg expectations, and no signatures of selection in contemporary populations but strong signatures of historical positive selection in sequences of classical alleles were found. A quick and reliable method of MHC I genotyping was developed.
authors.affiliation: Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland. wieslaw.babik@uj.edu.pl
authors.forename: Wieslaw
authors.initials: W
authors.lastname: Babik
authors.forename: Agata
authors.initials: A
authors.lastname: Kawalko
authors.forename: Jan M
authors.initials: JM
authors.lastname: Wójcik
authors.forename: Jacek
authors.initials: J
authors.lastname: Radwan
mesh_terms: D000818:Animals; D016164:Bison / Q000235:genetics*; D005060:Europe; D005091:Exons; D005805:Genes, MHC Class I; D014644:Genetic Variation; D006239:Haplotypes; D015810:Linkage Disequilibrium; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA