Major histocompatibility complex variation in the endangered Przewalski's horse

The major histocompatibility complex (MHC) is a fundamental part of the vertebrate immune system, and the high variability in many MHC genes is thought to play an essential role in recognition of parasites. The Przewalski's horse is extinct in the wild and all the living individuals descend fro...

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Bibliographic Details
Published in:Genetics (Austin) 1999-08, Vol.152 (4), p.1701-1710
Main Authors: Hedrick, P.W, Parker, K.M, Miller, E.L, Miller, P.S
Format: Article
Language:English
Subjects:
amino acid sequences
Animals
Equus przewalskii
Evolution, Molecular
genbank/af084187
genbank/af084188
genbank/af084189
genbank/af084190
genbank/af084191
genbank/af084192
Gene Frequency
genes
Genes, MHC Class II
genetic markers
genetic polymorphism
Genetic Variation
genotype
horses
Horses - genetics
Horses - immunology
major histocompatibility complex
Major Histocompatibility Complex - genetics
molecular sequence data
nucleotide sequences
Pedigree
Phylogeny
Polymorphism, Single-Stranded Conformational
segregation
single stranded confrontation polymorhism
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Summary:The major histocompatibility complex (MHC) is a fundamental part of the vertebrate immune system, and the high variability in many MHC genes is thought to play an essential role in recognition of parasites. The Przewalski's horse is extinct in the wild and all the living individuals descend from 13 founders, most of whom were captured around the turn of the century. One of the primary genetic concerns in endangered species is whether they have ample adaptive variation to respond to novel selective factors. In examining 14 Przewalski's horses that are broadly representative of the living animals, we found six different class II DRB major histocompatibility sequences. The sequences showed extensive nonsynonymous variation, concentrated in the putative antigen-binding sites, and little synonymous variation. Individuals had from two to four sequences as determined by single-stranded conformation polymorphism (SSCP) analysis. On the basis of the SSCP data, phylogenetic analysis of the nucleotide sequences, and segregation in a family group, we conclude that four of these sequences are from one gene (although one sequence codes for a nonfunctional allele because it contains a stop codon) and two other sequences are from another gene. The position of the stop codon is at the same amino-acid position as in a closely related sequence from the domestic horse. Because other organisms have extensive variation at homologous loci, the Przewalski's horse may have quite low variation in this important adaptive region.
ISSN:0016-6731
1943-2631
1943-2631
DOI:10.1093/genetics/152.4.1701