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.

Genetic diversity at the Major Histocompatibility Complex class II DZB gene, and geographical distribution of alleles, in platypuses in a Tasmanian river catchment.

2019 ◽  
Vol 40 (2) ◽  
pp. 241-250
Author(s):  
J.W. Macgregor ◽  
C. Holyoake ◽  
S. Munks ◽  
J.H. Connolly ◽  
I.D. Robertson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Major Histocompatibility ◽  
Island Populations ◽  
Low Genetic Diversity ◽  
Histocompatibility Complex ◽  
Wildlife Populations ◽  
River Catchments

Genetic diversity at loci concerned with fitness is an important part of the ability of a wild population to adapt to changes in its environment, including climatic events, disease and pollution. Research into the effects of genetic diversity on the impacts of disease on wildlife populations has focussed on genes of the major histocompatibility complex (MHC). This study investigated the genetic diversity at the MHC class II DZB gene, as well as the distribution of alleles of the same gene, for platypuses Ornithorhynchus anatinus in the Seabrook Creek Catchment in northwest Tasmania. This study detected 10 previously identified alleles and two previously unreported alleles at the MHC Class II DZB locus in 18 platypuses from the Seabrook Creek Catchment. An additional sequence isolated from two individuals was consistent with a pseudogene. Alleles were reasonably well distributed geographically through the catchment, but there was evidence of a degree of isolation at one site. Consistent with evidence that smaller wildlife populations have relatively low genetic diversity, and that there is relatively slow gene flow between river catchments, the observed genetic diversity at the MHC Class II locus was lower than those in larger previously studied river catchments but higher than those in two island populations. Consequently, this population of platypuses may have a limited capacity to respond to new infectious challenges, such as the fungal disease mucormycosis.

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.

Major Histocompatibility Complex Class II in the red-tailed phascogale (Phascogale calura)

2017 ◽  
Vol 39 (1) ◽  
pp. 28 ◽  
Author(s):  
Eden M. Hermsen ◽  
Lauren J. Young ◽  
Julie M. Old
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Genomic Dna ◽  
Class Ii ◽  
Brushtail Possum ◽  
Tasmanian Devil ◽  
Major Histocompatibility ◽  
Multiple Sequence ◽  
Phascolarctos Cinereus ◽  
Histocompatibility Complex

Diversity in major histocompatibility complex (MHC) genes can be correlated with the level of immunological fitness of an individual or group of individuals. This study tested published primer sets designed to amplify fragments of the MHC Class II DAB and DBB genes to amplify the equivalent gene fragments in red-tailed phascogales (Phascogale calura). Seventeen genomic DNA samples extracted from phascogale muscle tissue were used to amplify the initial DAB and DBB fragments; however, only DAB PCR proved successful. The fragments were 172 bp in length between the primers and had a high level of identity to other known marsupial MHC Class II DAB gene sequences (89–98%), including those of the koala (Phascolarctos cinereus), Tasmanian devil (Sarcophilus harrisii), common brushtail possum (Trichosurus vulpecula) and several wallaby species. Multiple sequence alignment revealed limited variability of MHC Class II genes between the individuals, but eight individual sequences in total. Genomic DNA was subsequently extracted from three fresh red-tailed phascogale scat samples and DAB fragments successfully amplified. The technique will allow for red-tailed phascogales to be sampled non-invasively in the wild and to determine the level of MHC diversity among individuals in the population.

scholarly journals Does intra-individual major histocompatibility complex diversity keep a golden mean?

2008 ◽  
Vol 364 (1513) ◽  
pp. 117-128 ◽  
Author(s):  
Benno Woelfing ◽  
Arne Traulsen ◽  
Manfred Milinski ◽  
Thomas Boehm
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
Adaptive Immune Response ◽  
Population Level ◽  
Current Data ◽  
Small Subset ◽  
Major Histocompatibility ◽  
Mhc Molecules ◽  
Histocompatibility Complex ◽  
Mhc Diversity

An adaptive immune response is usually initiated only if a major histocompatibility complex (MHC) molecule presents pathogen-derived peptides to T-cells. Every MHC molecule can present only peptides that match its peptide-binding groove. Thus, it seems advantageous for an individual to express many different MHC molecules to be able to resist many different pathogens. However, although MHC genes are the most polymorphic genes of vertebrates, each individual has only a very small subset of the diversity at the population level. This is an evolutionary paradox. We provide an overview of the current data on infection studies and mate-choice experiments and conclude that overall evidence suggests that intermediate intra-individual MHC diversity is optimal. Selective forces that may set an upper limit to intra-individual MHC diversity are discussed. An updated mathematical model based on recent findings on T-cell selection can predict the natural range of intra-individual MHC diversity. Thus, the aim of our review is to evaluate whether the number of MHC alleles usually present in individuals may be optimal to balance the advantages of presenting an increased range of peptides versus the disadvantages of an increased loss of T-cells.

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