Low major histocompatibility complex class II DQA diversity in the Giant Panda (Ailuropoda melanoleuca)

Zhu, Liang; Xue-yu, Ruan; Ge, Yaming; Wan, Qiu‐Hong; Fang, Sheng‐Guo

doi:10.1186/1471-2156-8-29

Cited by 22 publications

(24 citation statements)

References 35 publications

(27 reference statements)

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“…In this study and previous studies (Wan et al, 2006;Zhu et al, 2007), a relatively low number of MHC class II alleles were observed in giant pandas. However, the sequences of alleles were divergent, especially at the ABS.…”

Section: Parasite Infection In Wild Pandassupporting

confidence: 78%

“…DRB and DQA sequences (AY895155-AY895161; EF554075-EF4080; GQ496165-GQ496181) from previous papers (Wan et al, 2006;Zhu et al, 2007;Chen et al, 2010) were included in phylogenetic analyses.…”

Section: Data Analysesmentioning

confidence: 99%

“…Nevertheless, direct information on contemporary selection processes involving the interaction of individuals with their environment can only be provided by genes under selection (Sommer, 2005). Though previous studies have shown evidence of low diversity but positive selection at MHC DRB and DQA genes in the giant pandas (Wan et al, 2006;Zhu et al, 2007;Chen et al, 2010), possible associations of these MHC variations with parasite infection were not explored to date.…”

Section: Introductionmentioning

confidence: 99%

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Major histocompatibility complex alleles associated with parasite susceptibility in wild giant pandas

Zhang

et al. 2014

Heredity

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Major histocompatibility complex (MHC) polymorphism is thought to be driven by antagonistic coevolution between pathogens and hosts, mediated through either overdominance or frequency-dependent selection. However, investigations under natural conditions are still rare for endangered mammals which often exhibit depleted variation, and the mechanism of selection underlying the maintenance of characteristics remains a considerable debate. In this study, 87 wild giant pandas were used to investigate MHC variation associated with parasite load. With the knowledge of the MHC profile provided by the genomic data of the giant panda, seven DRB1, seven DQA1 and eight DQA2 alleles were identified at each single locus. Positive selection evidenced by a significantly higher number of non-synonymous substitutions per non-synonymous codon site relative to synonymous substitutions per synonymous codon site could only be detected at the DRB1 locus, which leads to the speculation that DRB1 may have a more important role in dealing with parasite infection for pandas. Coprological analyses revealed that 55.17% of individuals exhibited infection with 1-2 helminthes and 95.3% of infected pandas carried Baylisascaris shroederi. Using a generalized linear model, we found that Aime-DRB1*10 was significantly associated with parasite infection, but no resistant alleles could be detected. MHC heterozygosity of the pandas was found to be uncorrelated with the infection status or the infection intensity. These results suggested that the possible selection mechanisms in extant wild pandas may be frequency dependent rather than being determined by overdominance selection. Our findings could guide the candidate selection for the ongoing reintroduction or translocation of pandas.

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Section: Parasite Infection In Wild Pandassupporting

confidence: 78%

Section: Data Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Major histocompatibility complex alleles associated with parasite susceptibility in wild giant pandas

Zhang

et al. 2014

Heredity

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“…Our results suggest that a common observation of reduced MHC variation in populations subject to recent population bottlenecks (e.g. Babik et al 2005;Hansson and Richardson 2005;Bollmer et al 2007;Mainguy et al 2007;Radwan et al 2007;Zhu et al 2007;Biedrzycka and Radwan 2008, but see Aguilar et al 2004 for an exception) does not need to imply that selection on MHC variation in these populations is weak or non-existent. Indeed, our results suggest a resolution of the apparent discrepancy between the widespread evidence for historical positive selection acting on MHC and inability of the same selection to maintain MHC diversity during population bottlenecks (reviewed in Radwan et al 2009).…”

Section: Discussionmentioning

confidence: 71%

MHC diversity in bottlenecked populations: a simulation model

2009

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The depletion of variation at MHC loci, which play a crucial role in pathogen recognition, has been postulated to be one of important extinction risk factors for endangered populations. Thus, it is important to understand how selection affects the level of polymorphism in these genes when populations undergo a reduction in size. We followed MHC diversity in computer simulations of population bottlenecks. The fates of MHC alleles in the simulations were determined either by drift, or by balancing selection resulting from host-parasite coevolution. We found that the impact of selection on MHC polymorphism in bottlenecked populations was dependent upon the timescales involved. Initially, selection maintained lower number of alleles than drift, but after *40 generations of hosts selection maintained higher MHC diversity, as compared to drift. The adverse effects of decreased MHC polymorphism on population viability may be, to some extent, compensated for if selection helps to retain MHC alleles which show high functional diversity, which should allow protection against a broader range of pathogens. Our simulation shows, however, that the mean divergence of alleles retained under selection in bottlenecked populations is not, on average, significantly higher than the divergence due to drift.

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“…E-mail: hyasukou@proof.ocn.ne.jp MHC studies of the giant panda, Ailuropoda melanoleuca, have been relatively extensive and results have played an important role in determining the optimum conditions for captive management (Zeng et al, 2005;Wan et al, 2006;Zhu et al, 2007;Zeng et al, 2007;Pan et al, 2008). Sequences of the DRB locus in the polar bear, Ursus maritimus, have also been submitted to Genbank (Wei and Happ, unpublished).…”

Section: Introductionmentioning

confidence: 99%

Identification of the expressed MHC class II DQB gene of the Asiatic black bear, Ursus thibetanus, in Japan

et al. 2010

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Genetic diversity estimation of the major histocompatibility complex (MHC) gene may be an important tool in the assessment of immune response ability against infectious disease. We were able to identify a near full-length expressed DQB sequence by RACE-PCR method from the Asiatic black bear, Ursus thibetanus in Japan. This is the first such full length expression in the Ursidae. The bear had at least one functional DQB locus. In phylogenetic tree analysis its DQB amino acid sequence formed a monophyletic group with DQB sequences from members of the order Carnivora and had a 90% nucleotide sequence similarity with the DQB allele of the California sea lion, Zalophus californianus. We compared the DQB amino acid composition of U. thibetanus with those of several other mammalian species including Homo sapiens. Amino acid residues known to be functionally important for human MHC genes, tended to be also conserved among other mammalian species while PBRs in the β1 domain were heterogeneous among mammalian species. The DQB sequence obtained from the bear had not only no putative frameshifts or deletions but also no abnormal amino acid mutations such as had been observed in human DQB molecules. This suggests that the bear DQB sequence was an apparently functional DQB allele. As a preliminary study, we sequenced the exon 2 region of DQB alleles from genomic DNA, and succeeded to amplify the exon 2 of DQB loci. Our study will provide useful information for conservation genetics of the U. thibetanus as well as more generally regarding the mammalian MHC region.

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Low major histocompatibility complex class II DQA diversity in the Giant Panda (Ailuropoda melanoleuca)

Cited by 22 publications

References 35 publications

Major histocompatibility complex alleles associated with parasite susceptibility in wild giant pandas

Major histocompatibility complex alleles associated with parasite susceptibility in wild giant pandas

MHC diversity in bottlenecked populations: a simulation model

Identification of the expressed MHC class II DQB gene of the Asiatic black bear, Ursus thibetanus, in Japan

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