title: Isolation and characterization of major histocompatibility complex class II B genes in cranes.
abstract: In this study, we isolated and characterized the major histocompatibility complex (MHC) class II B genes in cranes. Genomic sequences spanning exons 1 to 4 were amplified and determined in 13 crane species and three other species closely related to cranes. In all, 55 unique sequences were identified, and at least two polymorphic MHC class II B loci were found in most species. An analysis of sequence polymorphisms showed the signature of positive selection and recombination. A phylogenetic reconstruction based on exon 2 sequences indicated that trans-species polymorphism has persisted for at least 10 million years, whereas phylogenetic analyses of the sequences flanking exon 2 revealed a pattern of concerted evolution. These results suggest that both balancing selection and recombination play important roles in the crane MHC evolution.
authors.affiliation: Department of Natural History Sciences, Faculty of Science, Hokkaido University, N10W8, Kita-ku, Sapporo, Hokkaido, 060-0810, Japan.
authors.forename: Tetsuo I
authors.initials: TI
authors.lastname: Kohyama
authors.affiliation: Department of Natural History Sciences, Faculty of Science, Hokkaido University, N10W8, Kita-ku, Sapporo, Hokkaido, 060-0810, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Akiyama
authors.affiliation: Department of Natural History Sciences, Faculty of Science, Hokkaido University, N10W8, Kita-ku, Sapporo, Hokkaido, 060-0810, Japan.
authors.forename: Chizuko
authors.initials: C
authors.lastname: Nishida
authors.affiliation: Osaka Municipal Tennoji Zoological Gardens, 1-108, Chausuyama-cho, Tennoji-ku, Osaka, Osaka, 543-0063, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Takami
authors.affiliation: Ecological Genetics Analysis Section, Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Onuma
authors.affiliation: Red-crowned Crane Conservancy, Wakatake-cho, Kushiro, Hokkaido, 085-0036, Japan.
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Momose
authors.affiliation: Department of Natural History Sciences, Faculty of Science, Hokkaido University, N10W8, Kita-ku, Sapporo, Hokkaido, 060-0810, Japan. masudary@mail.sci.hokudai.ac.jp.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Masuda
mesh_terms: D000818:Animals; D001717:Birds / Q000235:genetics*; D019143:Evolution, Molecular; D005091:Exons / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics*; D012641:Selection, Genetic / Q000235:genetics*; D013045:Species Specificity
chemical_list: D000949:Histocompatibility Antigens Class II
keywords: Aves; Concerted evolution; Gruiformes; MHC; Trans-species polymorphism