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%0 Journal Article
%A MEYER-LUCHT, Y. & SOMMER, S.
%D 2005
%T MHC diversity and the association to nematode parasitism in the yellow-necked mouse (Apodemus flavicollis)
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%B Molecular Ecology
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%V 14
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%P 2233-2243
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%F meyerlucht05mhc
%K MHC feces mouse parasitism 
%X In vertebrates, the genes of the major histocompatibility complex (MHC) are among the most debated candidates accounting for co-evolutionary processes of host–parasite interaction at the molecular level. The exceptionally high allelic polymorphism found in MHC loci is believed to be maintained by pathogen-driven selection, mediated either through heterozygous advantage or rare allele advantage (= frequency dependent selection). While investigations under natural conditions are still very rare, studies on humans or mice under laboratory conditions revealed support for both hypotheses. We investigated nematode burden and allelic diversity of a functional important MHC class II gene (DRB exon2) in free-ranging yellow-necked mice (Apodemus flavicollis). Twenty-seven distinct Apfl-DRB alleles were detected in 146 individuals with high levels of amino acid sequence divergence, especially at the antigen binding sites (ABS), indicating selection processes acting on this locus. Heterozygosity had no influence on the infection status (being infected or not), the number of different nematode infections (NNI) or the intensity of infection, measured as the individual faecal egg count (FEC). However, significant associations of specific Apfl-DRB alleles to both nematode susceptibility and resistance were found, for all nematodes as well as in separate analyses of the two most common nematodes. Apodemus flavicollis individuals carrying the alleles Apfl-DRB*5 or Apfl-DRB*15 revealed significantly higher FEC than individuals with other alleles. In contrast, the allele Apfl-DRB*23 showed a significant association to low FEC of the most common nematode. Thus, our results provide evidence for pathogen-driven selection acting through rare allele advantage under natural conditions.
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%U http://www.blackwell-synergy.com/doi/full/10.1111/j.1365-294X.2005.02557.x
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%0 Journal Article
%A Smulders, G. Booy M.J.M. & Vosman, B.
%D 2003
%T Complete loss of MHC genetic diversity in the Common Hamster (Cricetus cricetus) population in The Netherlands. Consequences for conservation strategies 
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%B Conservation Genetics
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%V 4
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%P 441-451
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%F MCH_loss_in_Hamster
%K Common_Hamster MHC 
%X The Common Hamster (Cricetus cricetus L.)has suffered from changes in agriculturalpractices. In some Western European countriesthe populations have become so small andscattered that they are threatened withextinction. We studied the genetic diversity ofmitochondrial and major histoincompatibilitycomplex (MHC) loci in the few animals left inthe South of the Netherlands and in threeanimals from the Alsace region in France, andcompared it to the diversity in Dutch animalsin the past (samples taken from stuffed animalsin museum collections dating back to the period1924–1956) and in a large present-daypopulation from Czech Republic. For themitochondrial cytochrome b gene, SNP mappingdemonstrated a total of nine alleles among 14Czech samples, of which one (possibly two) waspresent in the Dutch museum samples, and onlyone in the current Dutch animals. For the MHCgenes, DQA exon 2 and 3 showed no variation,while 14 different alleles were found at DRBexon 2. The Czech population contained 13different alleles in 15 animals sampled, andmost animals were heterozygous (Ho = 0.80,He = 0.91). Therefore, the solitary livingHamster maintains, in nature, a large diversityat this MHC locus. The Dutch museum samplescontained eight different alleles in 20 samples, and they were slightly less heterozygous (Ho = 0.60, He = 0.75). All but one ofthese alleles were also found in the Czechsamples. In contrast, the present Dutch andFrench animals (a total of 16 samples)contained only one of these alleles, and allanimals were genetically identical andhomozygous. We conclude that the remaininganimals have lost all diversity at this MHClocus. This is probably the result of a severebottleneck, which may have been quite severe,reducing diversity in many loci. In addition,the remaining Dutch animals are partly derivedfrom one family. These animals are now part ofa breeding program. Options for restocking thegenetic diversity are discussed.

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%U http://www.springerlink.com/content/h026737vh0n372jv/
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