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MHC evolution in three salmonid species: a comparison between class II alpha and beta genes.
- Source :
-
Immunogenetics [Immunogenetics] 2010 Aug; Vol. 62 (8), pp. 531-42. Date of Electronic Publication: 2010 Jun 03. - Publication Year :
- 2010
-
Abstract
- The genes of the major histocompatibility complex (MHC) are amongst the most variable in vertebrates and represent some of the best candidates to study processes of adaptive evolution. However, despite the number of studies available, most of the information on the structure and function of these genes come from studies in mammals and birds in which the MHC class I and II genes are tightly linked and class II alpha exhibits low variability in many cases. Teleost fishes are among the most primitive vertebrates with MHC and represent good organisms for the study of MHC evolution because their class I and class II loci are not physically linked, allowing for independent evolution of both classes of genes. We have compared the diversity and molecular mechanisms of evolution of classical MH class II alpha and class II beta loci in farm populations of three salmonid species: Oncorhynchus kisutch, Oncorhynchus mykiss and Salmo salar. We found single classical class II loci and high polymorphism at both class II alpha and beta genes in the three species. Mechanisms of evolution were common for both class II genes, with recombination and point mutation involved in generating diversity and positive selection acting on the peptide-binding residues. These results suggest that the maintenance of variability at the class IIalpha gene could be a mechanism to increase diversity in the MHC class II in salmonids in order to compensate for the expression of one single classical locus and to respond to a wider array of parasites.
- Subjects :
- Alleles
Amino Acid Sequence
Animals
Base Sequence
DNA genetics
DNA Primers genetics
Fish Proteins genetics
Fish Proteins immunology
Genetic Variation
Histocompatibility Antigens Class II genetics
Models, Genetic
Molecular Sequence Data
Oncorhynchus kisutch genetics
Oncorhynchus kisutch immunology
Oncorhynchus mykiss genetics
Oncorhynchus mykiss immunology
Recombination, Genetic
Salmo salar genetics
Salmo salar immunology
Salmonidae classification
Selection, Genetic
Sequence Homology, Amino Acid
Species Specificity
Evolution, Molecular
Genes, MHC Class II
Salmonidae genetics
Salmonidae immunology
Subjects
Details
- Language :
- English
- ISSN :
- 1432-1211
- Volume :
- 62
- Issue :
- 8
- Database :
- MEDLINE
- Journal :
- Immunogenetics
- Publication Type :
- Academic Journal
- Accession number :
- 20521040
- Full Text :
- https://doi.org/10.1007/s00251-010-0456-x