title: MHC class II A genes in the channel catfish (Ictalurus punctatus).
abstract: In order to characterize the Major histocompatibility complex (MHC) class II A genes of the channel catfish (Ictalurus punctatus) a cDNA library was screened and PCR was performed. Four different full-length cDNA sequences for MHC class II A genes were obtained from a clonal B cell line derived from an outbred fish. Two different genomic sequences and corresponding cDNAs were obtained from a presumably homozygous gynogenetic catfish. The A genes have five exons and four phase one introns. The first exon encodes the 5' untranslated region (UTR) and leader peptide; the second and third exons encode the alpha1 and alpha2 domains, respectively. The connecting peptide, transmembrane and cytoplasmic domains, as well as part of the 3' UTR, are encoded by the fourth exon and the rest of the 3' UTR is encoded by the fifth exon. Southern blot analyses using an exon three probe revealed two to four hybridizing fragments with considerable restriction fragment length polymorphisms evident among randomly selected outbred channel catfish. These findings are consistent with the presence of at least two functional polymorphic MHC class II A gene loci. An unusual aspect of the channel catfish MHC class II alpha chain is its lack of N-linked glycosylation sites.
authors.affiliation: N108 Howell Science Complex, Department of Biology, East Carolina University, Greenville, NC 27858-4353, USA.
authors.forename: U B
authors.initials: UB
authors.lastname: Godwin
authors.forename: M
authors.initials: M
authors.lastname: Flores
authors.forename: S
authors.initials: S
authors.lastname: Quiniou
authors.forename: M R
authors.initials: MR
authors.lastname: Wilson
authors.forename: N W
authors.initials: NW
authors.lastname: Miller
authors.forename: L W
authors.initials: LW
authors.lastname: Clem
authors.forename: T J
authors.initials: TJ
authors.lastname: McConnell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002460:Cell Line; D018076:DNA, Complementary / Q000302:isolation & purification; D015723:Gene Library; D005802:Genes, MHC Class II / Q000235:genetics*; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000235:genetics*; D007059:Ictaluridae / Q000235:genetics* / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012098:Reproduction / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment
chemical_list: D018076:DNA, Complementary; D000949:Histocompatibility Antigens Class II