title: Characterisation of major histocompatibility complex class I genes in Japanese Ranidae frogs.
abstract: The major histocompatibility complex (MHC) is a key component of adaptive immunity in all jawed vertebrates, and understanding the evolutionary mechanisms that have shaped these genes in amphibians, one of the earliest terrestrial tetrapods, is important. We characterised MHC class I variation in three common Japanese Rana species (Rana japonica, Rana ornativentris and Rana tagoi tagoi) and identified a total of 60 variants from 21 individuals. We also found evolutionary signatures of gene duplication, recombination and balancing selection (including trans-species polymorphism), all of which drive increased MHC diversity. A unique feature of MHC class I from these three Ranidae species includes low synonymous differences per site (dS) within species, which we attribute to a more recent diversification of these sequences or recent gene duplication. The resulting higher dN/dSratio relative to other anurans studied could be related to stronger selection pressure at peptide binding sites. This is one of the first studies to investigate MHC in Japanese amphibians and permits further exploration of the polygenetic factors associated with resistance to infectious diseases.
authors.affiliation: Department of Evolutionary Studies of Biosystems, Sokendai (The Graduate University for Advanced Studies), Kamiyamaguchi 1560-35, Hayama, Kanagawa, 240-0193, Japan. quintin@soken.ac.jp.
authors.forename: Quintin
authors.initials: Q
authors.lastname: Lau
authors.affiliation: Global Career Design Center, Hiroshima University, 1-7-1, Higashi-Hiroshima, Hiroshima, 739-8514, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Igawa
authors.affiliation: Division of Developmental Science, Graduate School for International Development and Cooperation, Hiroshima University, 1-5-1, Higashi-Hiroshima, Hiroshima, 739-8529, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Komaki
authors.affiliation: Department of Evolutionary Studies of Biosystems, Sokendai (The Graduate University for Advanced Studies), Kamiyamaguchi 1560-35, Hayama, Kanagawa, 240-0193, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Satta
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D010802:Phylogeny; D011898:Ranidae / Q000145:classification / Q000235:genetics*; D012641:Selection, Genetic / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D015395:Histocompatibility Antigens Class I
keywords: Anura; Major histocompatibility complex; Rana; Selection