title: Characterization, polymorphism and selection of major histocompatibility complex (MHC) DAB genes in vulnerable Chinese egret (Egretta eulophotes).
abstract: The major histocompatibility complex (MHC) is an excellent molecular marker for the studies of evolutionary ecology and conservation genetics because it is a family of highly polymorphic genes that play a key role in vertebrate immune response. In this study, the functional genes of MHC Class II B (DAB) were isolated for the first time in a vulnerable species, the Chinese egret (Egrettaeulophotes). Using a full length DNA and cDNA produced by PCR and RACE methods, four potential MHC DAB loci were characterized in the genome of this egret and all four were expressed in liver and blood. At least four copies of the MHC gene complex were similar to two copies of the minimal essential MHC complex of chicken, but are less complex than the multiple copies expressed in passerine species. In MHC polymorphism, 19 alleles of exon 2 were isolated from 48 individuals using PCR. No stop codons or frameshift mutations were found in any of the coding regions. The signatures of positive selection detected in potential peptide-binding regions by Bayesian analysis, suggesting that all of these genes were functional. These data will provide the fundamental basis for further studies to elucidate the mechanisms and significance of MHC molecular adaptation in vulnerable Chinese egret and other ardeids.
authors.affiliation: Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China.
authors.forename: Zeng
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhou
authors.forename: Qingxian
authors.initials: Q
authors.lastname: Lin
authors.forename: Wenzhen
authors.initials: W
authors.lastname: Fang
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001717:Birds / Q000145:classification / Q000235:genetics / Q000276:immunology*; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D005787:Gene Frequency; D016013:Likelihood Functions; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D004247:DNA
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