Evolution of duplicated IgH loci in Atlantic salmon, Salmo salar
Date
2010-09-02
Authors
Yasuike, Motoshige
De Boer, Johan
Von Schalburg, Kristian Robert
Cooper, Glenn A.
McKinnel, Linda
Messmer, Amber
So, Stacy
Davidson, William S.
Koop, Benjamin F.
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: The Atlantic salmon (Salmo salar) immunoglobulin heavy chain (IgH) locus possesses two parallel IgH
isoloci (IGH-A and IGH-B), that are related to the genomic duplication event in the family Salmonidae. These
duplicated IgH loci in Atlantic salmon provide a unique opportunity to examine the mechanisms of genome
diversity and genome evolution of the IgH loci in vertebrates. In this study, we defined the structure of these loci
in Atlantic salmon, and sequenced 24 bacterial artificial chromosome (BAC) clones that were assembled into the
IGH-A (1.1 Mb) and IGH-B (0.9 Mb) loci. In addition, over 7,000 cDNA clones from the IgH variable (VH) region have
been sequenced and analyzed.
Results: The present study shows that the genomic organization of the duplicated IgH loci in Atlantic salmon
differs from that in other teleosts and other vertebrates. The loci possess multiple Cτ genes upstream of the Cμ
region, with three of the Cτ genes being functional. Moreover, the duplicated loci possess over 300 VH segments
which could be classified into 18 families. This is the largest number of VH families currently defined in any
vertebrate. There were significant structural differences between the two loci, indicating that both IGH-A and -B loci
have evolved independently in the short time after the recent genome duplication approximately 60 mya.
Conclusions: Our results indicate that the duplication of the IgH loci in Atlantic salmon significantly contributes to
the increased diversity of the antibody repertoire, as compared with the single IgH locus in other vertebrates.
Description
BioMed Central
Keywords
Citation
Yasuike et al.: Evolution of duplicated IgH loci in Atlantic salmon, Salmo salar. BMC Genomics 2010 11:486.