title: Assembly and characterization of the MHC class I region of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis).
abstract: The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis; YFP) is the sole freshwater subspecies of N. asiaeorientalis and is now critically endangered. Major histocompatibility complex (MHC) is a family of highly polymorphic genes that play an important immunological role in antigen presentation in the vertebrates. Currently, however, little is known about MHC region in the genome of the YFP, which hampers conservation genetics and evolutionary ecology study using MHC genes. In this work, a nucleotide sequence of 774,811 bp covering the YFP MHC class I region was obtained by screening a YFP bacterial artificial chromosome (BAC) library, followed by sequencing and assembly of positive BAC clones. A total of 45 genes were successfully annotated, of which four were MHC class I genes. There are high similarities among the four YFP MHC class I genes (>94%). Divergence in the coding region of the four YFP MHC class I genes is mainly localized to exons 2 and 3, which encode the antigen-binding sites of MHC class I genes. Additionally, comparison of the MHC structure in YFP to those of cattle, sheep, and pig showed that MHC class I genes are located in genome regions with regard to the conserved genes, and the YFP contains the fewest MHC class I genes among these species. This is the first report characterizing a cetacean MHC class I region and describing its organization, which would be valuable for further investigation of adaptation in natural populations of the YFP and other cetaceans.
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Ruan
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Xiao-Ling
authors.initials: XL
authors.lastname: Wan
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China. zhengjinsong@ihb.ac.cn.
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China. wangd@ihb.ac.cn.
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle / Q000235:genetics; D022202:Chromosomes, Artificial, Bacterial; D003001:Cloning, Molecular; D005091:Exons; D005805:Genes, MHC Class I / Q000235:genetics*; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D010802:Phylogeny; D019576:Porpoises / Q000235:genetics*; D012756:Sheep / Q000235:genetics; D013552:Swine / Q000235:genetics
keywords: Characterization; High similarities; MHC class I; Yangtze finless porpoise