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Home / Equine Research Bank / Genetics / Major histocompatibility complex variation in the endangered...
Genetics1999; 152(4); 1701-1710; doi: 10.1093/genetics/152.4.1701

Major histocompatibility complex variation in the endangered Przewalski’s horse.

Abstract: 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.
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Publication Date: 1999-08-03 PubMed ID: 10430594PubMed Central: PMC1460696DOI: 10.1093/genetics/152.4.1701Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The researchers conducted a study on the variation in the major histocompatibility complex (MHC) in the endangered Przewalski’s horse. The study detected a surprisingly low level of genetic diversity in the immune system of these horses, likely a result of the species’ descent from few original survivors.

Study Background

  • The major histocompatibility complex (MHC) is a crucial component of the vertebrate immune system, playing an essential role in the recognition of parasites.
  • The Przewalski’s horse is a species extinct in the wild, with all living individuals descended from just 13 founders, most of whom were captured around a century ago.
  • One of the primary genetic concerns for endangered species is whether they have enough adaptive variation to respond to novel selective pressures.

Research Findings

  • The study found six different class II DRB major histocompatibility sequences in the 14 Przewalski’s horses that were sampled.
  • There was extensive nonsynonymous variation (changes that alter a gene sequence and the resulting protein function) in the antigen-binding sites with little synonymous variation (changes that do not affect the resulting protein).
  • Individual horses had between two to four sequences as determined by single-stranded conformation polymorphism (SSCP) analysis— a method used to detect differences in DNA sequences.

Conclusion and Inferences

  • Based on SSCP data, phylogenetic analysis of nucleotide sequences, and segregation patterns in a family group, the researchers concluded that four of the sequences stemmed from one gene and two others were from a different gene.
  • One of the sequences is believed to be nonfunctional because it contains a stop codon, a sequence of nucleotides within a gene that signals the end of protein synthesis.
  • The position of the stop codon is the same as in a closely related sequence from the domestic horse.
  • The researchers remarked that the Przewalski’s horse shows quite low variation in this indispensable adaptive region, particularly considering that other species display extensive variation at homologous loci, which points to compromised genetic diversity in the immune system.

Cite This Article

APA
Hedrick PW, Parker KM, Miller EL, Miller PS. (1999). Major histocompatibility complex variation in the endangered Przewalski’s horse. Genetics, 152(4), 1701-1710. https://doi.org/10.1093/genetics/152.4.1701

Publication

Genetics
ISSN: 0016-6731
NlmUniqueID: 0374636
Country: United States
Language: English
Volume: 152
Issue: 4
Pages: 1701-1710

Researcher Affiliations

Hedrick, P W
  • Department of Biology, Arizona State University, Tempe, Arizona 85287, USA. philip.hendrick@asu.edu
Parker, K M
    Miller, E L
      Miller, P S

        MeSH Terms

        • Animals
        • Evolution, Molecular
        • Gene Frequency
        • Genes, MHC Class II
        • Genetic Variation
        • Horses / genetics
        • Horses / immunology
        • Major Histocompatibility Complex / genetics
        • Pedigree
        • Phylogeny
        • Polymorphism, Single-Stranded Conformational

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