title: Organization and characteristics of the major histocompatibility complex class II region in the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis).
abstract: Little is known about the major histocompatibility complex (MHC) in the genome of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) (YFP) or other cetaceans. In this study, a high-quality YFP bacterial artificial chromosome (BAC) library was constructed. We then determined the organization and characterization of YFP MHC class II region by screening the BAC library, followed by sequencing and assembly of positive BAC clones. The YFP MHC class II region consists of two segregated contigs (218,725 bp and 328,435 bp respectively) that include only eight expressed MHC class II genes, three pseudo MHC genes and twelve non-MHC genes. The YFP has fewer MHC class II genes than ruminants, showing locus reduction in DRB, DQA, DQB, and loss of DY. In addition, phylogenic and evolutionary analyses indicated that the DRB, DQA and DQB genes might have undergone birth-and-death evolution, whereas the DQB gene might have evolved under positive selection in cetaceans. These findings provide an essential foundation for future work, such as estimating MHC genetic variation in the YFP or other cetaceans. This work is the first report on the MHC class II region in cetaceans and offers valuable information for understanding the evolution of MHC genome in 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.|The University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Ruan
authors.affiliation: Agricultural Genomes Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Guangdong 518120, China.
authors.forename: Jue
authors.initials: J
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.|The 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.|The 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.
authors.forename: Min-Min
authors.initials: MM
authors.lastname: Chen
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: 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.
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
mesh_terms: D000818:Animals; D022202:Chromosomes, Artificial, Bacterial; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D019576:Porpoises / Q000235:genetics* / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II