title: A genome-wide survey of Major Histocompatibility Complex (MHC) genes and their paralogues in zebrafish.
abstract: BACKGROUND
  The genomic organisation of the Major Histocompatibility Complex (MHC) varies greatly between different vertebrates. In mammals, the classical MHC consists of a large number of linked genes (e.g. greater than 200 in humans) with predominantly immune function. In some birds, it consists of only a small number of linked MHC core genes (e.g. smaller than 20 in chickens) forming a minimal essential MHC and, in fish, the MHC consists of a so far unknown number of genes including non-linked MHC core genes. Here we report a survey of MHC genes and their paralogues in the zebrafish genome.
  
  
  RESULTS
  Using sequence similarity searches against the zebrafish draft genome assembly (Zv4, September 2004), 149 putative MHC gene loci and their paralogues have been identified. Of these, 41 map to chromosome 19 while the remaining loci are spread across essentially all chromosomes. Despite the fragmentation, a set of MHC core genes involved in peptide transport, loading and presentation are still found in a single linkage group.
  
  
  CONCLUSIONS
  The results extend the linkage information of MHC core genes on zebrafish chromosome 19 and show the distribution of the remaining MHC genes and their paralogues to be genome-wide. Although based on a draft genome assembly, this survey demonstrates an essentially fragmented MHC in zebrafish.
authors.affiliation: Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge CB10 ISA, UK. js8@sanger.ac.uk
authors.forename: Jennifer G
authors.initials: JG
authors.lastname: Sambrook
authors.forename: Felipe
authors.initials: F
authors.lastname: Figueroa
authors.forename: Stephan
authors.initials: S
authors.lastname: Beck
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D016000:Cluster Analysis; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D020440:Gene Duplication; D008040:Genetic Linkage; D016678:Genome; D015894:Genome, Human; D023281:Genomics; D006239:Haplotypes; D006801:Humans; D008285:Major Histocompatibility Complex / Q000235:genetics*; D015233:Models, Statistical; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D012984:Software; D015027:Zebrafish
chemical_list: D018076:DNA, Complementary; D004247:DNA