Defining the Turkey MHC: identification of expressed class I- and class IIB-like genes independent of the MHC-B

Reed, Kent M.; Bauer, Miranda M.; Monson, Melissa S.; Benoit, Benjamin; Chaves, Lee; O'Hare, Thomas H.; Delany, Mary E.

doi:10.1007/s00251-011-0549-1

Cited by 29 publications

(20 citation statements)

References 77 publications

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“…This shows that orthologous gene copies of classical and non-classical genes have persisted in sparrows over several speciation events in a time frame of at least 7 million years. Classical (MHC-B) and non-classical (MHC-Y) genes have also been reported among a wide range of birds in the order Galliformes, including chicken, turkey and golden pheasant, species that split 28–40 million years ago, and non-classical alleles in chicken and turkey form a gene specific cluster [4, 20, 21, 50–52]. It is possible that these different sets of paralogous genes are even older and evolved in an ancient common ancestor of galliforms more than 65 million years ago [53].…”

Section: Discussionmentioning

confidence: 99%

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

et al. 2017

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BackgroundThe Major Histocompatibility Complex (MHC) plays a central role in immunity and has been given considerable attention by evolutionary ecologists due to its associations with fitness-related traits. Songbirds have unusually high numbers of MHC class I (MHC-I) genes, but it is not known whether all are expressed and equally important for immune function. Classical MHC-I genes are highly expressed, polymorphic and present peptides to T-cells whereas non-classical MHC-I genes have lower expression, are more monomorphic and do not present peptides to T-cells. To get a better understanding of the highly duplicated MHC genes in songbirds, we studied gene expression in a phylogenetic framework in three species of sparrows (house sparrow, tree sparrow and Spanish sparrow), using high-throughput sequencing. We hypothesize that sparrows could have classical and non-classical genes, as previously indicated though never tested using gene expression.ResultsThe phylogenetic analyses reveal two distinct types of MHC-I alleles among the three sparrow species, one with high and one with low level of polymorphism, thus resembling classical and non-classical genes, respectively. All individuals had both types of alleles, but there was copy number variation both within and among the sparrow species. However, the number of highly polymorphic alleles that were expressed did not vary between species, suggesting that the structural genomic variation is counterbalanced by conserved gene expression. Overall, 50% of the MHC-I alleles were expressed in sparrows. Expression of the highly polymorphic alleles was very variable, whereas the alleles with low polymorphism had uniformly low expression. Interestingly, within an individual only one or two alleles from the polymorphic genes were highly expressed, indicating that only a single copy of these is highly expressed.ConclusionsTaken together, the phylogenetic reconstruction and the analyses of expression suggest that sparrows have both classical and non-classical MHC-I genes, and that the evolutionary origin of these genes predate the split of the three investigated sparrow species 7 million years ago. Because only the classical MHC-I genes are involved in antigen presentation, the function of different MHC-I genes should be considered in future ecological and evolutionary studies of MHC-I in sparrows and other songbirds.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0970-7) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

et al. 2017

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“…A feature typical for the structure of chicken MHC and some other closely related species is the presence of a second, unlinked cluster of MHC genes, the Y locus [27], [32], [81], [82] (Table 4). This cluster consists of genes with yet unclear functional significance [32], [81], but some of the MHC genes situated in the Y region have been shown to be expressed [31], [82], [83].…”

Section: Discussionmentioning

confidence: 99%

MHC Class IIB Exon 2 Polymorphism in the Grey Partridge (Perdix perdix) Is Shaped by Selection, Recombination and Gene Conversion

et al. 2013

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Among bird species, the most studied major histocompatibility complex (MHC) is the chicken MHC. Although the number of studies on MHC in free-ranging species is increasing, the knowledge on MHC variation in species closely related to chicken is required to understand the peculiarities of bird MHC evolution. Here we describe the variation of MHC class IIB (MHCIIB) exon 2 in a population of the Grey partridge (Perdix perdix), a species of high conservation concern throughout Europe and an emerging galliform model in studies of sexual selection. We found 12 alleles in 108 individuals, but in comparison to other birds surprisingly many sites show signatures of historical positive selection. Individuals displayed between two to four alleles both on genomic and complementary DNA, suggesting the presence of two functional MHCIIB loci. Recombination and gene conversion appear to be involved in generating MHCIIB diversity in the Grey partridge; two recombination breakpoints and several gene conversion events were detected. In phylogenetic analysis of galliform MHCIIB, the Grey partridge alleles do not cluster together, but are scattered through the tree instead. Thus, our results indicate that the Grey partridge MHCIIB is comparable to most other galliforms in terms of copy number and population polymorphism.

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“…For example, MHC class I and class II molecules are necessary for antigen presentation to T lymphocytes and are common to the galliform MHC [229][230][231][232][233][234][235][236][237]. In turkeys and chickens, the MHC is composed of 2 genetically unlinked regions, the B-locus (MHC-B) and Y-locus (MHC-Y), co-located on a single microchromosome (GGA16 or MGA18, respectively) [229][230][231][232][233][234][235][236][237]. Although some genes are well characterized, the functions and expression patterns of many poultry MHC genes are still unknown.…”

Section: Cytokines and The Mhcmentioning

confidence: 99%

Aflatoxicosis: Lessons from Toxicity and Responses to Aflatoxin B1 in Poultry

2015

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This review is a comprehensive introduction to the effects of poultry exposure to the toxic and carcinogenic mycotoxin aflatoxin B1 (AFB1). The relationship between AFB1 sensitivity and metabolism, major direct and indirect effects of AFB1, recent studies of gene expression and transcriptome responses to exposure, and mitigation strategies to reduce toxicity are discussed. Exposure to AFB1 primarily occurs by consumption of contaminated corn, grain or other feed components. Low levels of residual AFB1 in poultry feeds can cause reduction in growth, feed conversion, egg production, and compromised immune functions, resulting in significant economic costs to producers. Thus, AFB1 acts as a "force multiplier" synergizing the adverse effects of microbial pathogens and other agents, and factors detrimental to poultry health. Domestic turkeys (Meleagris gallopavo) are one of the most sensitive animals known to AFB1 due, in large part, to a combination of efficient hepatic bioactivation by cytochromes P450 1A5 and 3A37, and deficient hepatic glutathione-S-transferase (GST)-mediated detoxification. Because of their sensitivity, turkeys are a good model to investigate chemopreventive treatments and feed additives for their ability to reduce AFB1 toxicity. Transcriptome analysis (RNA-seq) of turkey poults (liver and spleen) has identified AFB1-induced gene expression changes in pathways of apoptosis, carcinogenesis, lipid regulation, antimicrobial activity, cytotoxicity and antigen presentation. Current research focuses on further identifying the molecular mechanisms OPEN ACCESSAgriculture 2015, 5 743 underlying AFB1 toxicity with the goal of reducing aflatoxicosis and improving poultry health.

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Defining the Turkey MHC: identification of expressed class I- and class IIB-like genes independent of the MHC-B

Cited by 29 publications

References 77 publications

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

MHC Class IIB Exon 2 Polymorphism in the Grey Partridge (Perdix perdix) Is Shaped by Selection, Recombination and Gene Conversion

Aflatoxicosis: Lessons from Toxicity and Responses to Aflatoxin B1 in Poultry

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