title: Extensive MHC class II B gene duplication in a passerine, the common Yellowthroat (Geothlypis trichas).
abstract: The major histocompatibility complex (MHC) is characterized by a birth and death model of evolution involving gene duplication, diversification, loss of function, and deletion. As a result, gene number varies across taxa. Birds have between one and 7 confirmed MHC class II B genes, and the greatest diversity appears to occur in passerines. We used multiple primer sets on both genomic DNA (gDNA) and complementary DNA (cDNA) to characterize the range of class II B genes present in a passerine, the common yellowthroat (Geothlypis trichas). We confirmed 39 exon 2 sequences from gDNA in a single individual, indicating the presence of at least 20 class II B loci. From a second individual, we recovered 16 cDNA sequences belonging to at least 8 transcribed loci. Phylogenetic analysis showed that common yellowthroat sequences fell into subgroups consisting of classical loci, as well as at least 4 different clusters of sequences with reduced sequence variability that may represent pseudogenes or nonclassical loci. Data from 2 additional common yellowthroats demonstrated high interindividual variability. Our results reveal that some passerines possess an extraordinary diversity of MHC gene duplications, including both classical and nonclassical loci.
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, WI 53201, USA. bollmer@uwm.edu
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Bollmer
authors.forename: Peter O
authors.initials: PO
authors.lastname: Dunn
authors.forename: Linda A
authors.initials: LA
authors.lastname: Whittingham
authors.forename: Charles
authors.initials: C
authors.lastname: Wimpee
mesh_terms: D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D005091:Exons; D020440:Gene Duplication; D005802:Genes, MHC Class II / Q000235:genetics*; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D008969:Molecular Sequence Data; D046109:Passeriformes / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D018076:DNA, Complementary; D000949:Histocompatibility Antigens Class II