Natural selection and the evolutionary history of major histocompatibility complex loci

10.2741/a298 ◽  
1998 ◽  
Vol 3 (4) ◽  
pp. d509-516 ◽  
Author(s):  
Austin L Hughes
Keyword(s):  
Major Histocompatibility Complex ◽  
Natural Selection ◽  
Evolutionary History ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
History Of

scholarly journals Low major histocompatibility complex diversity in the Tasmanian devil predates European settlement and may explain susceptibility to disease epidemics

2013 ◽  
Vol 9 (1) ◽  
pp. 20120900 ◽  
Author(s):  
Katrina Morris ◽  
Jeremy J. Austin ◽  
Katherine Belov
Keyword(s):  
Major Histocompatibility Complex ◽  
Tasmanian Devil ◽  
Major Histocompatibility ◽  
European Settlement ◽  
Low Genetic Diversity ◽  
Histocompatibility Complex ◽  
Devil Facial Tumour Disease ◽  
History Of ◽  
Mhc Diversity ◽  
Disease Epidemics

The Tasmanian devil ( Sarcophilus harrisii ) is at risk of extinction owing to the emergence of a contagious cancer known as devil facial tumour disease (DFTD). The emergence and spread of DFTD has been linked to low genetic diversity in the major histocompatibility complex (MHC). We examined MHC diversity in historical and ancient devils to determine whether loss of diversity is recent or predates European settlement in Australia. Our results reveal no additional diversity in historical Tasmanian samples. Mainland devils had common modern variants plus six new variants that are highly similar to existing alleles. We conclude that low MHC diversity has been a feature of devil populations since at least the Mid-Holocene and could explain their tumultuous history of population crashes.

scholarly journals Different Evolutionary Histories in Two Subgenomic Regions of the Major Histocompatibility Complex

1999 ◽  
Vol 9 (6) ◽  
pp. 541-549 ◽  
Author(s):  
Silvana Gaudieri ◽  
Jerzy K. Kulski ◽  
Roger L. Dawkins ◽  
Takashi Gojobori
Keyword(s):  
Major Histocompatibility Complex ◽  
Homologous Recombination ◽  
Hla Class I ◽  
Gene Families ◽  
Class I ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Multicopy Gene ◽  
History Of ◽  
The Common

Two subgenomic regions within the major histocompatibility complex, the alpha and beta blocks, contain members of the multicopy gene families HLA class I, human endogenous retroviral sequence (HERV-16; previously known as P5 and PERB3), hemochromatosis candidate genes (HCG) (II, IV, VIII, IX), 3.8-1, and MIC (PERB11). In this study we show that the two blocks consist of imperfect duplicated segments, which contain linked members of the different gene families. The duplication and truncation sites of the segments are associated with retroelements. The retroelement sites appear to generate the imperfect duplications, insertions/deletions, and rearrangements, most likely via homologous recombination. Although the two blocks share several characteristics, they differ in the number and orientation of the duplicated segments. On the 62.1 haplotype, the alpha block consists of at least 10 duplicated segments that predominantly contain pseudogenes and gene fragments of the HLA class I and MIC (PERB11) gene families. In contrast, the beta block has two major duplications containing the genes HLA-B and HLA-C, and MICA(PERB11.1) and MICB(PERB11.2). Given the common origin between the blocks, we reconstructed the duplication history of the segments to understand the processes involved in producing the different organization in the two blocks. We then found that the beta block contains four distinct duplications from two separate events, whereas the alpha block is characterized by multisegment duplications. We will discuss these results in relation to the genetic content of the two blocks.

Natural selection at the class II major histocompatibility complex loci of mammals

1994 ◽  
Vol 346 (1317) ◽  
pp. 359-367 ◽  
Keyword(s):  
Major Histocompatibility Complex ◽  
Natural Selection ◽  
Balancing Selection ◽  
Synonymous Substitution ◽  
Class Ii ◽  
Class I ◽  
Major Histocompatibility ◽  
Class I Mhc ◽  
Histocompatibility Complex ◽  
Class Ii Mhc

The role of natural selection at major histocompatibility complex (MHC) loci was studied by analysis of molecular sequence data from mammalian class II MHC loci. As found previously for the class I MHC molecule and a hypothetical model of the class II molecule, the rate of non-synonymous nucleotide substitution exceeded that of synonymous substitution in the codons encoding the antigen recognition site of polymorphic class II molecules. This pattern is evidence that the polymorphism at these loci is maintained by a form of balancing selection, such as overdominant selection. By contrast, in the case of monomorphic class II loci, no such enhancement of the rate of non-synonymous substitution was observed. Phylogenetic analysis indicates that, in contrast to monomorphic (‘non-classical’) class I MHC loci, some monomorphic class II loci of mammals are quite ancient. The DMA and DMB loci, for example, diverged before all other known mammalian class II loci, possibly before the divergence of tetrapods from bony fishes. Analysis of the patterns of sharing of polymorphic residues at class II MHC loci by mammals of different species revealed that extensive convergent evolution has occurred at these loci; but no support was found for the hypothesis that MHC polymorphisms have been maintained since before the divergence of orders of eutherian mammals.

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