Characterization of the turkey MHC chromosome through genetic and physical mapping

Chaves, Lee; Krueth, Stacy B.; Reed, Kent M.

doi:10.1159/000103182

Cited by 34 publications

(29 citation statements)

References 40 publications

(36 reference statements)

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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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Section: Cytokines and The Mhcmentioning

confidence: 99%

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

2015

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“…A clone from the library (97E05) containing a portion of the MHC-B region was isolated previously (27). Screening for additional BAC clones was performed as previously described (33) using overlapping oligonucleotide probes based on the end sequences of clone 97E05 (GenBank accession nos.…”

Section: Sequencing Strategymentioning

confidence: 99%

“…Recent work (27) in the turkey has identified two MHC regions homologous to the chicken B and Y loci. Bacterial artificial chromosome (BAC) 4 clones containing portions of these regions were physically mapped to turkey metaphase chromosomes through fluorescent in situ hybridization and genetically mapped by segregation analysis using a resource population.…”

mentioning

confidence: 99%

“…Bacterial artificial chromosome (BAC) 4 clones containing portions of these regions were physically mapped to turkey metaphase chromosomes through fluorescent in situ hybridization and genetically mapped by segregation analysis using a resource population. Like the chicken, these two regions were genetically unlinked and located on the same nucleolar organizer region-containing microchromosome (27).…”

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confidence: 99%

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Defining the Turkey MHC: Sequence and Genes of the B Locus

Chaves

Krueth

Reed

2009

The Journal of Immunology

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The MHC, the most polymorphic and gene dense region in the vertebrate genome, contains many loci essential to immunity. In mammals, this region spans ∼4 Mb. Studies of avian species have found the MHC to be greatly reduced in size and gene content with an overall locus organization differing from that of mammals. The chicken MHC has been mapped to two distinct regions (MHC-B and -Y) of a single chromosome. MHC-B haplotypes possess tightly linked genes encoding the classical MHC molecules and few other disease resistance genes. Furthermore, chicken haplotypes possess a dominantly expressed class I and class II B locus that have a significant effect on the progression or regression of pathogenic disease. In this study, we present the MHC-B region of the turkey (Meleagris gallopavo) as a similarly constricted locus, with 34 genes identified within a 0.2-Mb region in near-perfect synteny with that of the chicken MHC-B. Notable differences between the two species are three BG and class II B loci in the turkey compared with one BG and two class II B loci in the chicken MHC-B. The relative size and high level of similarity of the turkey MHC in relation to that of the chicken suggest that similar associations with disease susceptibility and resistance may also be found in turkey.

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“…SSCP analysis showed that chicken TAP genes are highly polymorphic (Walker et al, 2005). For turkey, by characterization of the chromosome bearing the MHC locus, sequence homology between chicken and turkey was identified, and the presence of TAP1 gene was reported, but not TAP2 (Chaves et al, 2007). Recently, the same authors have updated the MHC partial sequence and added the TAP2 gene sequence data (Accession #DQ993255).…”

Section: Introductionmentioning

confidence: 99%

Avian TAP genes: detection of nucleotide polymorphisms and comparative analysis across species

Sironi

Lazzari²,

Ramelli³

et al. 2008

Genet. Mol. Res.

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ABSTRACT. TAP1 and TAP2 genes code for the two subunits of the transporter associated with antigen processing (TAP), and in chicken they are located between the two MHC class I genes. Using primers based on chicken sequences, the genomic regions corresponding to chicken TAP1 exons 6 to 7 and TAP2 exons 4 to 6 (which encode portions of the chicken TAP1 and TAP2 molecules corresponding to the human peptide-binding regions) were amplified and sequenced from chicken (70 birds), turkey (24), pheasant (6), and guinea fowl (7). A total of 80 within-species single nucleotide polymorphisms (SNPs) were identified. None of the chicken SNPs detected here was present in public databases. The SNP frequencies in chicken were 9.57 SNP/kb in TAP1 and 19.16 SNP/kb in TAP2, while turkey showed similar SNP frequencies in the two genes. Putative amino acid sequences were inferred to identify non-synonymous substitutions. The alignment of the consensus polypeptide sequences showed that most of the amino acid variations were conserved or semi-conserved substitutions. In conclusion, a high variability in the level of nucleotide polymorphism was observed within the two genes, with chicken showing the highest polymorphism rate in both genes. Most of the SNPs identified were within introns, and a general conservation of both amino acid numbers and characteristics of residues among and within the species was found. These data underline the functional importance of these molecules, but also suggest their capacity to bind different antigenic peptides.

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Characterization of the turkey MHC chromosome through genetic and physical mapping

Cited by 34 publications

References 40 publications

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

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

Defining the Turkey MHC: Sequence and Genes of the B Locus

Avian TAP genes: detection of nucleotide polymorphisms and comparative analysis across species

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