Gene duplication and evidence for balancing selection acting on MHC class II DAA gene of the half-smooth tongue sole ( Cynoglossus semilaevis)

Allelic polymorphism and evolution mechanism of major histocompatibility complex (MHC) genes has been investigated in many mammals, however, much less is known in teleost. In order to investigate the mechanisms creating and maintaining variability at the MHC class II DAA locus, we examined the polym...

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Bibliographic Details
Published in:Marine genomics 2010-06, Vol.3 (2), p.117-123
Main Authors: Xu, Tian-jun, Sun, Yue-na, Wang, Ri-xin
Format: Article
Language:English
Subjects:
Allelic polymorphism
Animals
Balancing selection
Base Sequence
Cloning, Molecular
Cluster Analysis
Cynoglossus
Cynoglossus semilaevis
DNA Primers - genetics
Evolution, Molecular
Flatfishes - genetics
Gene Duplication - genetics
Genes, MHC Class II - genetics
Major histocompatibility complex
Marine
Molecular Sequence Data
Phylogeny
Polymorphism, Genetic
Selection, Genetic
Sequence Analysis, DNA
Teleostei
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Summary:Allelic polymorphism and evolution mechanism of major histocompatibility complex (MHC) genes has been investigated in many mammals, however, much less is known in teleost. In order to investigate the mechanisms creating and maintaining variability at the MHC class II DAA locus, we examined the polymorphism, gene duplication and balancing selection of MHC class II DAA gene of the half-smooth tongue sole ( Cynoglossus semilaevis). We described 33 alleles in the C. semilaevis, recombination and gene duplication seems to play more important roles in the origin of new alleles. The rate of non-synonymous substitutions ( d N ) occurred at a significantly higher frequency than that of synonymous substitutions ( d S ) in peptide-binding region (PBR) and non-PBR, suggesting balancing selection for maintaining polymorphisms at the MHC II DAA locus. Many positive selection sites were found to act very intensively on antigen-binding sites. Our founding suggests a snapshot in an evolutionary process of MHC- DAA gene evolution of the C. semilaevis.
ISSN:1874-7787
1876-7478
DOI:10.1016/j.margen.2010.08.004