Characterization of 40 full-length MHC class IIA functional alleles in miiuy croaker: Polymorphism and positive selection
The major histocompatibility complex is a highly polymorphic gene superfamily in vertebrates that plays an important role in adaptive immune response. In the present study, we identified 40 full-length miiuy croaker MHC class IIA (Mimi-DAA) functional alleles from 26 miiuy croaker individuals and fo...
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Veröffentlicht in: | Developmental and comparative immunology 2016-02, Vol.55, p.138-143 |
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Sprache: | eng |
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Zusammenfassung: | The major histocompatibility complex is a highly polymorphic gene superfamily in vertebrates that plays an important role in adaptive immune response. In the present study, we identified 40 full-length miiuy croaker MHC class IIA (Mimi-DAA) functional alleles from 26 miiuy croaker individuals and found that the alleles encode 30 amino acid sequences. A high level of polymorphism in Mimi-DAA was detected in miiuy croaker. The rate of non-synonymous substitutions (dN) occurred at a significantly higher frequency than that of synonymous substitutions (dS) in the peptide-binding region (PBR) and non-PBR. This result suggests that balancing selection maintains polymorphisms at the Mimi-DAA locus. Phylogenetic analysis based on the full-length sequences showed that the Mimi-DAA alleles clustered into three groups. However, the phylogenetic tree constructed using the exon 2 sequences indicated that the Mimi-DAA alleles clustered into two groups. A total of 22 positively selected sites were identified on the Mimi-DAA alleles after testing for positive selection, and five sites were predicted to be associated with the binding of peptide antigen, suggesting that a few selected residues may play a significant role in immune function.
•Forty full-length Mimi-DAA functional alleles were firstly identified.•High level of polymorphism in Mimi-DAA functional alleles was discovered.•Twenty-two positively selected sites were located on the Mimi-DAA alleles.•More DAA alleles detected in miiuy croaker than other teleost studied to date. |
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ISSN: | 0145-305X 1879-0089 |
DOI: | 10.1016/j.dci.2015.10.019 |