Defining the Turkey MHC: identification of expressed class I- and class IIB-like genes independent of the MHC-B

The MHC of the turkey ( Meleagris gallopavo ) is divided into two genetically unlinked regions; the MHC-B and MHC-Y . Although previous studies found the turkey MHC-B to be highly similar to that of the chicken, little is known of the gene content and extent of the MHC-Y . This study describes two p...

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Bibliographic Details
Published in:Immunogenetics (New York) 2011-11, Vol.63 (11), p.753-771
Main Authors: Reed, Kent M., Bauer, Miranda M., Monson, Melissa S., Benoit, Benjamin, Chaves, Lee D., O’Hare, Thomas H., Delany, Mary E.
Format: Article
Language:English
Subjects:
Allergology
Amino Acid Sequence
Animals
Antigens
Biomedical and Life Sciences
Biomedicine
Cell Biology
Centromere - genetics
Chickens - classification
Chickens - genetics
Chickens - immunology
Chromosome Mapping
Chromosomes
Cloning
Gene Expression
Gene Function
Genes
Genes, MHC Class I
Genes, MHC Class II
Genetic Linkage
Genetic Loci
Genomes
Haplotypes
Human Genetics
Immunology
Lymphocytes
Meleagris gallopavo
Molecular Sequence Data
Original Paper
Peptides
Phylogeny
Proteins
Turkeys - classification
Turkeys - genetics
Turkeys - immunology
Veterinary medicine
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Summary:The MHC of the turkey ( Meleagris gallopavo ) is divided into two genetically unlinked regions; the MHC-B and MHC-Y . Although previous studies found the turkey MHC-B to be highly similar to that of the chicken, little is known of the gene content and extent of the MHC-Y . This study describes two partially overlapping large-insert BAC clones that genetically and physically map to the turkey MHC chromosome (MGA18) but to a region that assorts independently of MHC-B . Within the sequence assembly, 14 genes were predicted including new class I- and class IIB-like loci. Additional unassembled sequences corresponded to multiple copies of the ribosomal RNA repeat unit (18S–5.8S–28S). Thus, this newly identified MHC region appears to represent a physical boundary of the turkey MHC-Y . High-resolution multi-color fluorescence in situ hybridization studies confirm rearrangement of MGA18 relative to the orthologous chicken chromosome (GGA16) in regard to chromosome architecture, but not gene order. The difference in centromere position between the species is indicative of multiple chromosome rearrangements or alternate events such as neocentromere formation/centromere inactivation in the evolution of the MHC chromosome. Comparative sequencing of commercial turkeys (six amplicons totaling 7.6 kb) identified 68 single nucleotide variants defining nine MHC-Y haplotypes. Sequences of the new class I- and class IIB-like genes are most similar to MHC-Y genes in the chicken. All three loci are expressed in the spleen. Differential transcription of the MHC-Y class IIB-like loci was evident as one class IIB-like locus was only expressed in some individuals.
ISSN:0093-7711
1432-1211
DOI:10.1007/s00251-011-0549-1