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Wojczulanis-Jakubas K, Hoover B, Jakubas D, Fort J, Grémillet D, Gavrilo M, Zielińska S, Zagalska-Neubauer M. Diversity of major histocompatibility complex of II B gene and mate choice in a monogamous and long-lived seabird, the Little Auk (Alle alle). PLoS One 2024; 19:e0304275. [PMID: 38865310 PMCID: PMC11168636 DOI: 10.1371/journal.pone.0304275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 05/09/2024] [Indexed: 06/14/2024] Open
Abstract
The major histocompatibility complex (MHC) plays a key role in the adaptive immune system of vertebrates, and is known to influence mate choice in many species. In birds, the MHC has been extensively examined but mainly in galliforms and passerines while other taxa that represent specific ecological and evolutionary life-histories, like seabirds, are underexamined. Here, we characterized diversity of MHC Class II B exon 2 in a colonial pelagic seabird, the Little Auk (or Dovekie Alle alle). We further examined whether MHC variation could be maintained through balancing selection and disassortative mating. We found high polymorphism at the genotyped MHC fragment, characterizing 99 distinct alleles across 140 individuals from three populations. The alleles frequencies exhibited a similar skewed distribution in both sexes, with the four most commonly occurring alleles representing approximately 35% of allelic variation. The results of a Bayesian site-by-site selection analysis suggest evidence of balancing selection and no direct evidence for MHC-dependent disassortative mating preferences in the Little Auk. The latter result might be attributed to the high overall polymorphism of the examined fragment, which itself may be maintained by the large population size of the species.
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Affiliation(s)
| | - Brian Hoover
- Farallon Institute, Petaluma, California, United States of America
| | - Dariusz Jakubas
- Department of Vertebrate Ecology and Zoology, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Jérôme Fort
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS – La Rochelle University, 17000 La Rochelle, France
| | - David Grémillet
- Excellence Chair Nouvelle Aquitaine - CEBC UMR 7372 CNRS, La Rochelle Université, Villiers-en-Bois, France & FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa
| | | | - Sylwia Zielińska
- Department of Molecular Biology, Faculty of Biology, University of Gdansk, Gdansk, Poland
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Minias P, Edwards SV, Babik W. Ancient duplication, coevolution, and selection at the MHC class IIA and IIB genes of birds. Front Immunol 2023; 14:1250824. [PMID: 37965325 PMCID: PMC10641522 DOI: 10.3389/fimmu.2023.1250824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/18/2023] [Indexed: 11/16/2023] Open
Abstract
Introduction The Major Histocompatibility Complex (MHC) of vertebrates is a dynamically evolving multigene family primarily responsible for recognizing non-self peptide antigens and triggering a pathogen-specific adaptive immune response. In birds, the MHC was previously thought to evolve via concerted evolution with high degree of gene homogenization and the rapid loss of orthology. However, the discovery of two ancient avian MHC-IIB gene lineages (DAB1 and DAB2) originating before the radiation of extant birds indicated that despite the action of concerted evolution, orthology may be detectable for long evolutionary periods. Methods Here, we take advantage of rapidly accumulating digital genomic resources to search for the signal of an ancient duplication at the avian MHC-IIA genes, as well as to compare phylogenetic distribution and selection between MHC-IIA and IIB gene lineages. Results The analysis of MHC sequences from over 230 species representing ca. 70 bird families revealed the presence of two ancient MHC-IIA gene lineages (DAA1 and DAA2) and showed that their phylogenetic distribution matches exactly the distribution of DAB1 and DAB2 lineages, suggesting tight coevolution. The early post-duplication divergence of DAA1 and DAA2 was driven by positive selection fixing radical amino acid differences within the membrane-proximal domain and, most probably, being functionally related to the interactions between α2 and β2 chains of the MHC-II heterodimer. We detected no evidence for an overall (gene-wide) relaxation or intensification of selection at either DAA1/DAB1 or DAA2/DAB2, but codon-specific differences in selection signature were found at the peptide-binding sites between the two gene lineages, perhaps implying specialization to different pathogen regimes. Discussion Our results suggest that specific pairing of MHC-II α and β chains may have an adaptive significance, a conclusion that advances knowledge on the macroevolution of the avian MHC-II and opens exciting novel directions for future research.
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Affiliation(s)
- Piotr Minias
- University of Lodz, Faculty of Biology and Environmental Protection, Department of Biodiversity Studies and Bioeducation, Lodz, Poland
| | - Scott V. Edwards
- Harvard University, Museum of Comparative Zoology, Cambridge, MA, United States
- Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, United States
| | - Wiesław Babik
- Jagiellonian University, Institute of Environmental Sciences, Faculty of Biology, Kraków, Poland
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Mancilla-Morales MD, Velarde E, Contreras-Rodríguez A, Gómez-Lunar Z, Rosas-Rodríguez JA, Heras J, Soñanez-Organis JG, Ruiz EA. Characterization, Selection, and Trans-Species Polymorphism in the MHC Class II of Heermann’s Gull (Charadriiformes). Genes (Basel) 2022; 13:genes13050917. [PMID: 35627302 PMCID: PMC9140796 DOI: 10.3390/genes13050917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 11/16/2022] Open
Abstract
The major histocompatibility complex (MHC) enables vertebrates to cope with pathogens and maintain healthy populations, thus making it a unique set of loci for addressing ecology and evolutionary biology questions. The aim of our study was to examine the variability of Heermann’s Gull MHC class II (MHCIIB) and compare these loci with other Charadriiformes. Fifty-nine MHCIIB haplotypes were recovered from sixty-eight Heermann’s Gulls by cloning, of them, twelve were identified as putative true alleles, forty-five as unique alleles, and two as pseudogenes. Intra and interspecific relationships indicated at least two loci in Heermann’s Gull MHCIIB and trans-species polymorphism among Charadriiformes (coinciding with the documented evidence of two ancient avian MHCIIB lineages, except in the Charadriidae family). Additionally, sites under diversifying selection revealed a better match with peptide-binding sites inferred in birds than those described in humans. Despite the negative anthropogenic activity reported on Isla Rasa, Heermann’s Gull showed MHCIIB variability consistent with population expansion, possibly due to a sudden growth following conservation efforts. Duplication must play an essential role in shaping Charadriiformes MHCIIB variability, buffering selective pressures through balancing selection. These findings suggest that MHC copy number and protected islands can contribute to seabird conservation.
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Affiliation(s)
- Misael Daniel Mancilla-Morales
- Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Santo Tomás, Ciudad de Mexico CP 11340, Mexico
- Correspondence: (M.D.M.-M.); (J.G.S.-O.); (E.A.R.)
| | - Enriqueta Velarde
- Instituto de Ciencias Marinas y Pesquerías, Universidad Veracruzana, Hidalgo 617, Colonia Río Jamapa, Boca del Rio, Veracruz CP 94290, Mexico;
| | - Araceli Contreras-Rodríguez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Santo Tomás, Ciudad de Mexico CP 11340, Mexico; (A.C.-R.); (Z.G.-L.)
| | - Zulema Gómez-Lunar
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Santo Tomás, Ciudad de Mexico CP 11340, Mexico; (A.C.-R.); (Z.G.-L.)
| | - Jesús A. Rosas-Rodríguez
- Departamento de Ciencias Químico-Biológicas y Agropecuarias, Universidad de Sonora, Lázaro Cárdenas del Río No. 100, Francisco Villa, Navojoa CP 85880, Mexico;
| | - Joseph Heras
- Departament of Biology, California State University, San Bernardino, 5500 University Parkway, San Bernardino, CA 92407, USA;
| | - José G. Soñanez-Organis
- Departamento de Ciencias Químico-Biológicas y Agropecuarias, Universidad de Sonora, Lázaro Cárdenas del Río No. 100, Francisco Villa, Navojoa CP 85880, Mexico;
- Correspondence: (M.D.M.-M.); (J.G.S.-O.); (E.A.R.)
| | - Enrico A. Ruiz
- Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Santo Tomás, Ciudad de Mexico CP 11340, Mexico
- Correspondence: (M.D.M.-M.); (J.G.S.-O.); (E.A.R.)
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4
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Minias P, Włodarczyk R, Remisiewicz M, Cobzaru I, Janiszewski T. Distinct evolutionary trajectories of MHC class I and class II genes in Old World finches and buntings. Heredity (Edinb) 2021; 126:974-990. [PMID: 33824536 PMCID: PMC8178356 DOI: 10.1038/s41437-021-00427-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/08/2021] [Accepted: 03/15/2021] [Indexed: 02/01/2023] Open
Abstract
Major histocompatibility complex (MHC) genes code for key proteins of the adaptive immune system, which present antigens from intra-cellular (MHC class I) and extra-cellular (MHC class II) pathogens. Because of their unprecedented diversity, MHC genes have long been an object of scientific interest, but due to methodological difficulties in genotyping of duplicated loci, our knowledge on the evolution of the MHC across different vertebrate lineages is still limited. Here, we compared the evolution of MHC class I and class II genes in three sister clades of common passerine birds, finches (Fringillinae and Carduelinae) and buntings (Emberizidae) using a uniform methodological (genotyping and data processing) approach and uniform sample sizes. Our analyses revealed contrasting evolutionary trajectories of the two MHC classes. We found a stronger signature of pervasive positive selection and higher allele diversity (allele numbers) at the MHC class I than class II. In contrast, MHC class II genes showed greater allele divergence (in terms of nucleotide diversity) and a much stronger recombination (gene conversion) signal. Gene copy numbers at both MHC class I and class II evolved via fluctuating selection and drift (Brownian Motion evolution), but the evolutionary rate was higher at class I. Our study constitutes one of few existing examples, where evolution of MHC class I and class II genes was directly compared using a multi-species approach. We recommend that re-focusing MHC research from single-species and single-class approaches towards multi-species analyses of both MHC classes can substantially increase our understanding MHC evolution in a broad phylogenetic context.
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Affiliation(s)
- Piotr Minias
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, Poland.
| | - Radosław Włodarczyk
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, Poland
| | - Magdalena Remisiewicz
- Bird Migration Research Station, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
| | - Ioana Cobzaru
- Institute of Biology Bucharest, Romanian Academy, Bucharest, Romania
| | - Tomasz Janiszewski
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, Poland
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5
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Ghani MU, Bo L, Buyang A, Yanchun X, Hussain S, Yasir M. Molecular Characterization of MHC Class I Genes in Four Species of the Turdidae Family to Assess Genetic Diversity and Selection. BIOMED RESEARCH INTERNATIONAL 2021; 2021:5585687. [PMID: 33937397 PMCID: PMC8055405 DOI: 10.1155/2021/5585687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/09/2021] [Accepted: 03/19/2021] [Indexed: 11/17/2022]
Abstract
In vertebrate animals, the molecules encoded by major histocompatibility complex (MHC) genes play an essential role in the adaptive immunity. MHC class I deals with intracellular pathogens (virus) in birds. MHC class I diversity depends on the consequence of local and global environment selective pressure and gene flow. Here, we evaluated the MHC class I gene in four species of the Turdidae family from a broad geographical area of northeast China. We isolated 77 MHC class I sequences, including 47 putatively functional sequences and 30 pseudosequences from 80 individuals. Using the method based on analysis of cloned amplicons (n = 25) for each species, we found two and seven MHC I sequences per individual indicating more than one MHC I locus identified in all sampled species. Results revealed an overall elevated genetic diversity at MHC class I, evidence of different selection patterns among the domains of PBR and non-PBR. Alleles are found to be divergent with overall polymorphic sites per species ranging between 58 and 70 (out of 291 sites). Moreover, transspecies alleles were evident due to convergent evolution or recent speciation for the genus. Phylogenetic relationships among MHC I show an intermingling of alleles clustering among the Turdidae family rather than between other passerines. Pronounced MHC I gene diversity is essential for the existence of species. Our study signifies a valuable tool for the characterization of evolutionary relevant difference across a population of birds with high conservational concerns.
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Affiliation(s)
- Muhammad Usman Ghani
- College of Wildlife Resources and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - Li Bo
- College of Wildlife Resources and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - An Buyang
- Department of Stem Cell Biology and Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka 810-0000, Japan
| | - Xu Yanchun
- College of Wildlife Resources and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - Shakeel Hussain
- College of Wildlife Resources and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - Muhammad Yasir
- Department of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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6
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Gillingham MAF, Montero BK, Wihelm K, Grudzus K, Sommer S, Santos PSC. A novel workflow to improve genotyping of multigene families in wildlife species: An experimental set-up with a known model system. Mol Ecol Resour 2020; 21:982-998. [PMID: 33113273 DOI: 10.1111/1755-0998.13290] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/30/2022]
Abstract
Genotyping complex multigene families in novel systems is particularly challenging. Target primers frequently amplify simultaneously multiple loci leading to high PCR and sequencing artefacts such as chimeras and allele amplification bias. Most genotyping pipelines have been validated in nonmodel systems whereby the real genotype is unknown and the generation of artefacts may be highly repeatable. Further hindering accurate genotyping, the relationship between artefacts and genotype complexity (i.e. number of alleles per genotype) within a PCR remains poorly described. Here, we investigated the latter by experimentally combining multiple known major histocompatibility complex (MHC) haplotypes of a model organism (chicken, Gallus gallus, 43 artificial genotypes with 2-13 alleles per amplicon). In addition to well-defined 'optimal' primers, we simulated a nonmodel species situation by designing 'cross-species' primers based on sequence data from closely related Galliform species. We applied a novel open-source genotyping pipeline (ACACIA; https://gitlab.com/psc_santos/ACACIA), and compared its performance with another, previously published pipeline (AmpliSAS). Allele calling accuracy was higher when using ACACIA (98.5% versus 97% and 77.8% versus 75% for the 'optimal' and 'cross-species' data sets, respectively). Systematic allele dropout of three alleles owing to primer mismatch in the 'cross-species' data set explained high allele calling repeatability (100% when using ACACIA) despite low accuracy, demonstrating that repeatability can be misleading when evaluating genotyping workflows. Genotype complexity was positively associated with nonchimeric artefacts, chimeric artefacts (nonlinearly by levelling when amplifying more than 4-6 alleles) and allele amplification bias. Our study exemplifies and demonstrates pitfalls researchers should avoid to reliably genotype complex multigene families.
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Affiliation(s)
- Mark A F Gillingham
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm Universität, Ulm, Germany
| | - B Karina Montero
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm Universität, Ulm, Germany.,Zoological Institute, Animal Ecology and Conservation, Biocenter Grindel, Universität Hamburg, Hamburg,, Germany
| | - Kerstin Wihelm
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm Universität, Ulm, Germany
| | - Kara Grudzus
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm Universität, Ulm, Germany
| | - Simone Sommer
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm Universität, Ulm, Germany
| | - Pablo S C Santos
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm Universität, Ulm, Germany
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7
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Zhao B, Zhang X, Li B, Du P, Shi L, Dong Y, Gao X, Sha W, Zhang H. Evolution of major histocompatibility complex class I genes in the sable Martes zibellina (Carnivora, Mustelidae). Ecol Evol 2020; 10:3439-3449. [PMID: 32274000 PMCID: PMC7141072 DOI: 10.1002/ece3.6140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/31/2020] [Accepted: 02/04/2020] [Indexed: 11/10/2022] Open
Abstract
The molecules encoded by major histocompatibility complex (MHC) genes play an essential role in the adaptive immune response among vertebrates. We investigated the molecular evolution of MHC class I genes in the sable Martes zibellina. We isolated 26 MHC class I sequences, including 12 putatively functional sequences and 14 pseudogene sequences, from 24 individuals from two geographic areas of northeast China. The number of putatively functional sequences found in a single individual ranged from one to five, which might be at least 1-3 loci. We found that both balancing selection and recombination contribute to evolution of MHC class I genes in M. zibellina. In addition, we identified a candidate nonclassical MHC class I lineage in Carnivora, which may have preceded the divergence (about 52-57 Mya) of Caniformia and Feliformia. This may contribute to further understanding of the origin and evolution of nonclassical MHC class I genes. Our study provides important immune information of MHC for M. zibellina, as well as other carnivores.
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Affiliation(s)
- Baojun Zhao
- College of Life Science Qufu Normal University Qufu China
| | - Xue Zhang
- College of Life Science Qufu Normal University Qufu China
| | - Bo Li
- College of Wildlife and Protected Area Northeast Forestry University Harbin China
| | - Pengfei Du
- College of Life Science Qufu Normal University Qufu China
| | - Lupeng Shi
- College of Life Science Qufu Normal University Qufu China
| | - Yuehuan Dong
- College of Life Science Qufu Normal University Qufu China
| | - Xiaodong Gao
- College of Life Science Qufu Normal University Qufu China
| | - Weilai Sha
- College of Life Science Qufu Normal University Qufu China
| | - Honghai Zhang
- College of Life Science Qufu Normal University Qufu China
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O'Connor EA, Westerdahl H, Burri R, Edwards SV. Avian MHC Evolution in the Era of Genomics: Phase 1.0. Cells 2019; 8:E1152. [PMID: 31561531 PMCID: PMC6829271 DOI: 10.3390/cells8101152] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/16/2019] [Accepted: 09/20/2019] [Indexed: 12/14/2022] Open
Abstract
Birds are a wonderfully diverse and accessible clade with an exceptional range of ecologies and behaviors, making the study of the avian major histocompatibility complex (MHC) of great interest. In the last 20 years, particularly with the advent of high-throughput sequencing, the avian MHC has been explored in great depth in several dimensions: its ability to explain ecological patterns in nature, such as mating preferences; its correlation with parasite resistance; and its structural evolution across the avian tree of life. Here, we review the latest pulse of avian MHC studies spurred by high-throughput sequencing. Despite high-throughput approaches to MHC studies, substantial areas remain in need of improvement with regard to our understanding of MHC structure, diversity, and evolution. Recent studies of the avian MHC have nonetheless revealed intriguing connections between MHC structure and life history traits, and highlight the advantages of long-term ecological studies for understanding the patterns of MHC variation in the wild. Given the exceptional diversity of birds, their accessibility, and the ease of sequencing their genomes, studies of avian MHC promise to improve our understanding of the many dimensions and consequences of MHC variation in nature. However, significant improvements in assembling complete MHC regions with long-read sequencing will be required for truly transformative studies.
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Affiliation(s)
| | | | - Reto Burri
- Department of Population Ecology, Institute of Ecology & Evolution, Friedrich Schiller University Jena, 07737 Jena, Germany.
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA.
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Shultz AJ, Sackton TB. Immune genes are hotspots of shared positive selection across birds and mammals. eLife 2019; 8:e41815. [PMID: 30620335 PMCID: PMC6338464 DOI: 10.7554/elife.41815] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 01/08/2019] [Indexed: 12/16/2022] Open
Abstract
Consistent patterns of positive selection in functionally similar genes can suggest a common selective pressure across a group of species. We use alignments of orthologous protein-coding genes from 39 species of birds to estimate parameters related to positive selection for 11,000 genes conserved across birds. We show that functional pathways related to the immune system, recombination, lipid metabolism, and phototransduction are enriched for positively selected genes. By comparing our results with mammalian data, we find a significant enrichment for positively selected genes shared between taxa, and that these shared selected genes are enriched for viral immune pathways. Using pathogen-challenge transcriptome data, we show that genes up-regulated in response to pathogens are also enriched for positively selected genes. Together, our results suggest that pathogens, particularly viruses, consistently target the same genes across divergent clades, and that these genes are hotspots of host-pathogen conflict over deep evolutionary time.
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Affiliation(s)
- Allison J Shultz
- Informatics GroupHarvard UniversityCambridgeUnited States
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeUnited States
- Museum of Comparative ZoologyHarvard UniversityCambridgeUnited States
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10
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Minias P, Pikus E, Anderwald D. Allelic diversity and selection at the MHC class I and class II in a bottlenecked bird of prey, the White-tailed Eagle. BMC Evol Biol 2019; 19:2. [PMID: 30611206 PMCID: PMC6321662 DOI: 10.1186/s12862-018-1338-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/17/2018] [Indexed: 01/07/2023] Open
Abstract
Background Genes of the Major Histocompatibility Complex (MHC) are essential for adaptive immune response in vertebrates, as they encode receptors that recognize peptides derived from the processing of intracellular (MHC class I) and extracellular (MHC class II) pathogens. High MHC diversity in natural populations is primarily generated and maintained by pathogen-mediated diversifying and balancing selection. It is, however, debated whether selection at the MHC can counterbalance the effects of drift in bottlenecked populations. The aim of this study was to assess allelic diversity of MHC genes in a recently bottlenecked bird of prey, the White-tailed Eagle Haliaeetus albicilla, as well as to compare mechanisms that shaped the evolution of MHC class I and class II in this species. Results We showed that significant levels of MHC diversity were retained in the core Central European (Polish) population of White-tailed Eagles. Ten MHC class I and 17 MHC class II alleles were recovered in total and individual birds showed high average MHC diversity (3.80 and 6.48 MHC class I and class II alleles per individual, respectively). Distribution of alleles within individuals provided evidence for the presence of at least three class I and five class II loci the White-tailed Eagle, which suggests recent duplication events. MHC class II showed greater sequence polymorphism than MHC class I and there was much stronger signature of diversifying selection acting on MHC class II than class I. Phylogenetic analysis provided evidence for trans-species similarity of class II, but not class I, sequences, which is likely consistent with stronger balancing selection at MHC class II. Conclusions Relatively high MHC diversity retained in the White-tailed Eagles from northern Poland reinforces high conservation value of local eagle populations. At the same time, our study is the first to demonstrate contrasting patterns of allelic diversity and selection at MHC class I and class II in an accipitrid species, supporting the hypothesis that different mechanisms can shape evolutionary trajectories of MHC class I and class II genes. Electronic supplementary material The online version of this article (10.1186/s12862-018-1338-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Piotr Minias
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 1/3, 90-237, Łódź, Poland.
| | - Ewa Pikus
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 1/3, 90-237, Łódź, Poland
| | - Dariusz Anderwald
- Eagle Conservation Committee, Niepodległości 53/55, 10-044, Olsztyn, Poland
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11
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Minias P, Pikus E, Whittingham LA, Dunn PO. Evolution of Copy Number at the MHC Varies across the Avian Tree of Life. Genome Biol Evol 2019; 11:17-28. [PMID: 30476037 PMCID: PMC6319602 DOI: 10.1093/gbe/evy253] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2018] [Indexed: 12/24/2022] Open
Abstract
The evolution of the major histocompatibility complex (MHC) is shaped by frequent gene duplications and deletions, which generate extensive variation in the number of loci (gene copies) between different taxa. Here, we collected estimates of copy number at the MHC for over 250 bird species from 68 families. We found contrasting patterns of copy number evolution between MHC class I and class IIB, which encode receptors for intra- and extracellular pathogens, respectively. Across the avian evolutionary tree, there was evidence of accelerated evolution and stabilizing selection acting on copy number at class I, while copy number at class IIB was primarily influenced by fluctuating selection and drift. Reconstruction of MHC copy number variation showed ancestrally low numbers of MHC loci in nonpasserines and evolution toward larger numbers of loci in passerines. Different passerine lineages had the highest duplication rates for MHC class I (Sylvioidea) and class IIB (Muscicapoidea and Passeroidea). We also found support for the correlated evolution of MHC copy number and life-history traits such as lifespan and migratory behavior. These results suggest that MHC copy number evolution in birds has been driven by life histories and differences in exposure to intra- and extracellular pathogens.
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Affiliation(s)
- Piotr Minias
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Lódz, Poland
| | - Ewa Pikus
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Lódz, Poland
| | - Linda A Whittingham
- Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee
| | - Peter O Dunn
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Poland.,Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee
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12
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Sutton JT, Helmkampf M, Steiner CC, Bellinger MR, Korlach J, Hall R, Baybayan P, Muehling J, Gu J, Kingan S, Masuda BM, Ryder OA. A High-Quality, Long-Read De Novo Genome Assembly to Aid Conservation of Hawaii's Last Remaining Crow Species. Genes (Basel) 2018; 9:genes9080393. [PMID: 30071683 PMCID: PMC6115840 DOI: 10.3390/genes9080393] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/23/2018] [Accepted: 07/27/2018] [Indexed: 11/16/2022] Open
Abstract
Genome-level data can provide researchers with unprecedented precision to examine the causes and genetic consequences of population declines, which can inform conservation management. Here, we present a high-quality, long-read, de novo genome assembly for one of the world’s most endangered bird species, the ʻAlalā (Corvus hawaiiensis; Hawaiian crow). As the only remaining native crow species in Hawaiʻi, the ʻAlalā survived solely in a captive-breeding program from 2002 until 2016, at which point a long-term reintroduction program was initiated. The high-quality genome assembly was generated to lay the foundation for both comparative genomics studies and the development of population-level genomic tools that will aid conservation and recovery efforts. We illustrate how the quality of this assembly places it amongst the very best avian genomes assembled to date, comparable to intensively studied model systems. We describe the genome architecture in terms of repetitive elements and runs of homozygosity, and we show that compared with more outbred species, the ʻAlalā genome is substantially more homozygous. We also provide annotations for a subset of immunity genes that are likely to be important in conservation management, and we discuss how this genome is currently being used as a roadmap for downstream conservation applications.
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Affiliation(s)
- Jolene T Sutton
- Department of Biology, University of Hawaii at Hilo, Hilo, HI 96720, USA.
| | - Martin Helmkampf
- Department of Biology, University of Hawaii at Hilo, Hilo, HI 96720, USA.
| | - Cynthia C Steiner
- Institute for Conservation Research, San Diego Zoo, Escondido, CA 92027, USA.
| | - M Renee Bellinger
- Department of Biology, University of Hawaii at Hilo, Hilo, HI 96720, USA.
| | | | | | | | | | - Jenny Gu
- Pacific Biosciences, Menlo Park, CA 94025, USA.
| | | | - Bryce M Masuda
- Institute for Conservation Research, San Diego Zoo Global, Volcano, HI 96785, USA.
| | - Oliver A Ryder
- Institute for Conservation Research, San Diego Zoo, Escondido, CA 92027, USA.
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13
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Hoover B, Alcaide M, Jennings S, Sin SYW, Edwards SV, Nevitt GA. Ecology can inform genetics: Disassortative mating contributes to MHC polymorphism in Leach's storm-petrels (Oceanodroma leucorhoa). Mol Ecol 2018; 27:3371-3385. [PMID: 30010226 DOI: 10.1111/mec.14801] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/31/2018] [Accepted: 06/20/2018] [Indexed: 01/03/2023]
Abstract
Studies of MHC-based mate choice in wild populations often test hypotheses on species exhibiting female choice and male-male competition, which reflects the general prevalence of females as the choosy sex in natural systems. Here, we examined mutual mate-choice patterns in a small burrow-nesting seabird, the Leach's storm-petrel (Oceanodroma leucorhoa), using the major histocompatibility complex (MHC). The life history and ecology of this species are extreme: both partners work together to fledge a single chick during the breeding season, a task that requires regularly travelling hundreds of kilometres to and from foraging grounds over a 6- to 8-week provisioning period. Using a 5-year data set unprecedented for this species (n = 1078 adults and 925 chicks), we found a positive relationship between variation in the likelihood of female reproductive success and heterozygosity at Ocle-DAB2, a MHC class IIB locus. Contrary to previous reports rejecting disassortative mating as a mechanism for maintaining genetic polymorphism in this species, here we show that males make significant disassortative mate-choice decisions. Variability in female reproductive success suggests that the most common homozygous females (Ocle-DAB2*01/Ocle-DAB2*01) may be physiologically disadvantaged and, therefore, less preferred as lifelong partners for choosy males. The results from this study support the role of mate choice in maintaining high levels of MHC variability in a wild seabird species and highlight the need to incorporate a broader ecological framework and sufficient sample sizes into studies of MHC-based mating patterns in wild populations in general.
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Affiliation(s)
- Brian Hoover
- Graduate Group in Ecology, University of California, Davis, California
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - Miguel Alcaide
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sarah Jennings
- Graduate Group in Ecology, University of California, Davis, California
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - Simon Yung Wa Sin
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
| | - Gabrielle A Nevitt
- Graduate Group in Ecology, University of California, Davis, California
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
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14
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Minias P, Pikus E, Whittingham LA, Dunn PO. A global analysis of selection at the avian MHC. Evolution 2018; 72:1278-1293. [PMID: 29665025 DOI: 10.1111/evo.13490] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 03/29/2018] [Accepted: 04/09/2018] [Indexed: 12/29/2022]
Abstract
Recent advancements in sequencing technology have resulted in rapid progress in the study of the major histocompatibility complex (MHC) in non-model avian species. Here, we analyze a global dataset of avian MHC class I and class II sequences (ca. 11,000 sequences from over 250 species) to gain insight into the processes that govern macroevolution of MHC genes in birds. Analysis of substitution rates revealed striking differences in the patterns of diversifying selection between passerine and non-passerine birds. Non-passerines showed stronger selection at MHC class II, which is primarily involved in recognition of extracellular pathogens, while passerines showed stronger selection at MHC class I, which is involved in recognition of intracellular pathogens. Positions of positively selected amino-acid residues showed marked discrepancies with peptide-binding residues (PBRs) of human MHC molecules, suggesting that using a human classification of PBRs to assess selection patterns at the avian MHC may be unjustified. Finally, our analysis provided evidence that indel mutations can make a substantial contribution to adaptive variation at the avian MHC.
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Affiliation(s)
- Piotr Minias
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, 90-237, Poland
| | - Ewa Pikus
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, 90-237, Poland
| | - Linda A Whittingham
- Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53211
| | - Peter O Dunn
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, 90-237, Poland.,Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53211
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15
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Lee C, Moroldo M, Perdomo-Sabogal A, Mach N, Marthey S, Lecardonnel J, Wahlberg P, Chong AY, Estellé J, Ho SYW, Rogel-Gaillard C, Gongora J. Inferring the evolution of the major histocompatibility complex of wild pigs and peccaries using hybridisation DNA capture-based sequencing. Immunogenetics 2017; 70:401-417. [PMID: 29256177 DOI: 10.1007/s00251-017-1048-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/25/2017] [Indexed: 12/20/2022]
Abstract
The major histocompatibility complex (MHC) is a key genomic model region for understanding the evolution of gene families and the co-evolution between host and pathogen. To date, MHC studies have mostly focused on species from major vertebrate lineages. The evolution of MHC classical (Ia) and non-classical (Ib) genes in pigs has attracted interest because of their antigen presentation roles as part of the adaptive immune system. The pig family Suidae comprises over 18 extant species (mostly wild), but only the domestic pig has been extensively sequenced and annotated. To address this, we used a DNA-capture approach, with probes designed from the domestic pig genome, to generate MHC data for 11 wild species of pigs and their closest living family, Tayassuidae. The approach showed good efficiency for wild pigs (~80% reads mapped, ~87× coverage), compared to tayassuids (~12% reads mapped, ~4× coverage). We retrieved 145 MHC loci across both families. Phylogenetic analyses show that the class Ia and Ib genes underwent multiple duplications and diversifications before suids and tayassuids diverged from their common ancestor. The histocompatibility genes mostly form orthologous groups and there is genetic differentiation for most of these genes between Eurasian and sub-Saharan African wild pigs. Tests of selection showed that the peptide-binding region of class Ib genes was under positive selection. These findings contribute to better understanding of the evolutionary history of the MHC, specifically, the class I genes, and provide useful data for investigating the immune response of wild populations against pathogens.
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Affiliation(s)
- Carol Lee
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Marco Moroldo
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Alvaro Perdomo-Sabogal
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia.,Institute of Animal Science (460i), Department of Bioinformatics, University of Hohenheim, Stuttgart, Germany
| | - Núria Mach
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sylvain Marthey
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Jérôme Lecardonnel
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Per Wahlberg
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Amanda Y Chong
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia.,Earlham Institute, Norwich Research Park, Norwich, UK
| | - Jordi Estellé
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Simon Y W Ho
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, Australia
| | | | - Jaime Gongora
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Sydney, Australia.
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16
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Goebel J, Promerová M, Bonadonna F, McCoy KD, Serbielle C, Strandh M, Yannic G, Burri R, Fumagalli L. 100 million years of multigene family evolution: origin and evolution of the avian MHC class IIB. BMC Genomics 2017; 18:460. [PMID: 28610613 PMCID: PMC5470263 DOI: 10.1186/s12864-017-3839-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 06/01/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Gene duplication has led to a most remarkable adaptation involved in vertebrates' host-pathogen arms-race, the major histocompatibility complex (MHC). However, MHC duplication history is as yet poorly understood in non-mammalian vertebrates, including birds. RESULTS Here, we provide evidence for the evolution of two ancient avian MHC class IIB (MHCIIB) lineages by a duplication event prior to the radiation of all extant birds >100 million years ago, and document the role of concerted evolution in eroding the footprints of the avian MHCIIB duplication history. CONCLUSIONS Our results suggest that eroded footprints of gene duplication histories may mimic birth-death evolution and that in the avian MHC the presence of the two lineages may have been masked by elevated rates of concerted evolution in several taxa. Through the presence of a range of intermediate evolutionary stages along the homogenizing process of concerted evolution, the avian MHCIIB provides a remarkable illustration of the erosion of multigene family duplication history.
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Affiliation(s)
- Julien Goebel
- Laboratory for Conservation Biology, Department of Ecology and Evolution, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Marta Promerová
- Institute of Vertebrate Biology of the Czech Academy of Sciences, Kvetna 8, 60365 Brno, Czech Republic
- Present address: Max Planck Institute for the Science of Human History, Kahlaische Strasse 10, D-07745 Jena, Germany
| | - Francesco Bonadonna
- CNRS, UMR 5175, Centre for Functional and Evolutionary Ecology, F-34293 Montpellier, France
| | - Karen D. McCoy
- MIVEGEC UMR 5290 CNRS-IRD University of Montpellier, Centre IRD, F-34394 Montpellier, France
| | - Céline Serbielle
- MIVEGEC UMR 5290 CNRS-IRD University of Montpellier, Centre IRD, F-34394 Montpellier, France
| | - Maria Strandh
- CNRS, UMR 5175, Centre for Functional and Evolutionary Ecology, F-34293 Montpellier, France
- Present address: Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62 Lund, Sweden
| | - Glenn Yannic
- LECA – Laboratoire d’Écologie Alpine, UMR CNRS 5553, Université Savoie Mont Blanc, F-73376 Le Bourget-du-Lac, France
| | - Reto Burri
- Department of Population Ecology, Institute of Ecology, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
| | - Luca Fumagalli
- Laboratory for Conservation Biology, Department of Ecology and Evolution, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
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17
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Structure and polymorphisms of the major histocompatibility complex in the Oriental stork, Ciconia boyciana. Sci Rep 2017; 7:42864. [PMID: 28211522 PMCID: PMC5314415 DOI: 10.1038/srep42864] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/18/2017] [Indexed: 12/27/2022] Open
Abstract
The major histocompatibility complex (MHC) is highly polymorphic and plays a central role in the vertebrate immune system. Despite its functional consistency, the MHC genomic structure differs substantially among organisms. In birds, the MHCs of Galliformes and the Japanese crested ibis (Pelecaniformes) are well-characterized, but information about other avian MHCs remains scarce. The Oriental stork (Ciconia boyciana, order Ciconiiformes) is a large endangered migrant. The current Japanese population of this bird originates from a few founders; thus, understanding the genetic diversity among them is critical for effective population management. We report the structure and polymorphisms in C. boyciana MHC. One contig (approximately 128 kb) was assembled by screening of lambda phage genomic library and its complete sequence was determined, revealing a gene order of COL11A2, two copies of MHC-IIA/IIB pairs, BRD2, DMA/B1/B2, MHC-I, TAP1/2, and two copies each of pseudo MHC-I and TNXB. This structure was highly similar to that of the Japanese crested ibis, but largely different from that of Galliformes, at both the terminal regions. Genotyping of the MHC-II region detected 10 haplotypes among the six founders. These results provide valuable insights for future studies on the evolution of the avian MHCs and for conservation of C. boyciana.
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18
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Li D, Sun K, Zhao Y, Lin A, Li S, Jiang Y, Feng J. Polymorphism in the major histocompatibility complex (MHC class II B) genes of the Rufous-backed Bunting ( Emberiza jankowskii). PeerJ 2017; 5:e2917. [PMID: 28149689 PMCID: PMC5270597 DOI: 10.7717/peerj.2917] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 12/16/2016] [Indexed: 11/23/2022] Open
Abstract
Genetic diversity is one of the pillars of conservation biology research. High genetic diversity and abundant genetic variation in an organism may be suggestive of capacity to adapt to various environmental changes. The major histocompatibility complex (MHC) is known to be highly polymorphic and plays an important role in immune function. It is also considered an ideal model system to investigate genetic diversity in wildlife populations. The Rufous-backed Bunting (Emberiza jankowskii) is an endangered species that has experienced a sharp decline in both population and habitat size. Many historically significant populations are no longer present in previously populated regions, with only three breeding populations present in Inner Mongolia (i.e., the Aolunhua, Gahaitu and Lubei557 populations). Efforts focused on facilitating the conservation of the Rufous-backed Bunting (Emberiza jankowskii) are becoming increasingly important. However, the genetic diversity of E. jankowskii has not been investigated. In the present study, polymorphism in exon 2 of the MHCIIB of E. jankowskii was investigated. This polymorphism was subsequently compared with a related species, the Meadow Bunting (Emberiza cioides). A total of 1.59 alleles/individual were detected in E. jankowskii and 1.73 alleles/individual were identified in E. cioides. The maximum number of alleles per individual from the three E. jankowskii populations suggest the existence of at least three functional loci, while the maximum number of alleles per individual from the three E. cioides populations suggest the presence of at least four functional loci. Two of the alleles were shared between the E. jankowskii and E. cioides. Among the 12 unique alleles identified in E. jankowskii, 10.17 segregating sites per allele were detected, and the nucleotide diversity was 0.1865. Among the 17 unique alleles identified in E. cioides, eight segregating sites per allele were detected, and the nucleotide diversity was 0.1667. Overall, compared to other passerine birds, a relatively low level of MHC polymorphism was revealed in E. jankowskii, which was similar to that in E. cioides. Positive selection was detected by PAML/SLAC/FEL analyses in the region encoding the peptide-binding region in both species, and no recombination was detected. Phylogenetic analysis showed that the alleles from E. jankowskii and E. cioides belong to the same clade and the two species shared similar alleles, suggesting the occurrence of a trans-species polymorphism between the two Emberiza species.
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Affiliation(s)
- Dan Li
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China; College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
| | - Keping Sun
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University , Changchun , China
| | - Yunjiao Zhao
- College of Animal Science and Technology, Jilin Agricultural University , Changchun , China
| | - Aiqing Lin
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University , Changchun , China
| | - Shi Li
- College of Animal Science and Technology, Jilin Agricultural University , Changchun , China
| | - Yunlei Jiang
- College of Animal Science and Technology, Jilin Agricultural University , Changchun , China
| | - Jiang Feng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University , Changchun , China
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19
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MHC class II β exon 2 variation in pardalotes (Pardalotidae) is shaped by selection, recombination and gene conversion. Immunogenetics 2016; 69:101-111. [PMID: 27717988 DOI: 10.1007/s00251-016-0953-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/26/2016] [Indexed: 12/23/2022]
Abstract
The high levels of polymorphism and allelic diversity which characterise genes in the major histocompatibility complex (MHC) are thought to be generated and maintained through the combined effects of different evolutionary processes. Here, we characterised exon 2 of the MHC class II β genes in two congeneric passerine species, the spotted (Pardalotus punctatus) and striated pardalote (Pardalotus striatus). We estimated the levels of allelic diversity and tested for signatures of recombination, gene conversion and balancing selection to determine if these processes have influenced MHC variation in the two species. Both species showed high levels of polymorphism and allelic diversity, as well as evidence of multiple gene loci and putative pseudogenes based on the presence of stop codons. We found higher levels of MHC diversity in the striated pardalote than the spotted pardalote, based on the levels of individual heterozygosity, sequence divergence and number of polymorphic sites. The observed differences may reflect variable selection pressure on the species, resulting from differences in patterns of movement among populations. We identified strong signatures of historical balancing selection, recombination and gene conversion at the sequence level, indicating that MHC variation in the two species has been shaped by a combination of processes.
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20
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Eimes JA, Lee SI, Townsend AK, Jablonski P, Nishiumi I, Satta Y. Early Duplication of a Single MHC IIB Locus Prior to the Passerine Radiations. PLoS One 2016; 11:e0163456. [PMID: 27658204 PMCID: PMC5033386 DOI: 10.1371/journal.pone.0163456] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/08/2016] [Indexed: 01/01/2023] Open
Abstract
A key characteristic of MHC genes is the persistence of allelic lineages over macroevolutionary periods, often through multiple speciation events. This phenomenon, known as trans-species polymorphism (TSP), is well documented in several major taxonomic groups, but has less frequently been observed in birds. The order Passeriformes is arguably the most successful terrestrial vertebrate order in terms of diversity of species and ecological range, but the reasons for this success remain unclear. Passerines exhibit the most highly duplicated MHC genes of any major vertebrate taxonomic group, which may generate increased immune response relative to other avian orders with fewer MHC loci. Here, we describe phylogenetic patterns of the MHC IIB in the passerine family Corvidae. Our results indicate wide-spread TSP within this family, with at least four supported MHC IIB allelic lineages that predate speciation by many millions of years. Markov chain Monte Carlo simulations indicate that divergence of these lineages occurred near the time of the divergence of the Passeriformes and other avian orders. We suggest that the current MHC diversity observed in passerines is due in part to the multiple duplication of a single MHC locus, DAB1, early in passerine evolution and that subsequent duplications of these paralogues have contributed to the enormous success of this order by increasing their ability to recognize and mount immune responses to novel pathogens.
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Affiliation(s)
- John A. Eimes
- Seoul National University, Department of Biological Sciences, Seoul, Korea
| | - Sang-im Lee
- Seoul National University, Institute of Advanced Machines and Design, Seoul, Korea
- * E-mail:
| | - Andrea K. Townsend
- Hamilton College, Department of Biology, Clinton, NY, United States of America
| | - Piotr Jablonski
- Seoul National University, Department of Biological Sciences, Seoul, Korea
| | - Isao Nishiumi
- National Museum of Nature and Science, Department of Zoology, Tsukuba, Japan
| | - Yoko Satta
- The Graduate University for Advanced Studies, Department of Evolutionary Studies of Biosystems, Hayama, Japan
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21
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Balasubramaniam S, Bray RD, Mulder RA, Sunnucks P, Pavlova A, Melville J. New data from basal Australian songbird lineages show that complex structure of MHC class II β genes has early evolutionary origins within passerines. BMC Evol Biol 2016; 16:112. [PMID: 27206579 PMCID: PMC4875725 DOI: 10.1186/s12862-016-0681-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 05/10/2016] [Indexed: 11/10/2022] Open
Abstract
Background The major histocompatibility complex (MHC) plays a crucial role in the adaptive immune system and has been extensively studied across vertebrate taxa. Although the function of MHC genes appears to be conserved across taxa, there is great variation in the number and organisation of these genes. Among avian species, for instance, there are notable differences in MHC structure between passerine and non-passerine lineages: passerines typically have a high number of highly polymorphic MHC paralogs whereas non-passerines have fewer loci and lower levels of polymorphism. Although the occurrence of highly polymorphic MHC paralogs in passerines is well documented, their evolutionary origins are relatively unexplored. The majority of studies have focussed on the more derived passerine lineages and there is very little empirical information on the diversity of the MHC in basal passerine lineages. We undertook a study of MHC diversity and evolutionary relationships across seven species from four families (Climacteridae, Maluridae, Pardalotidae, Meliphagidae) that comprise a prominent component of the basal passerine lineages. We aimed to determine if highly polymorphic MHC paralogs have an early evolutionary origin within passerines or are a more derived feature of the infraorder Passerida. Results We identified 177 alleles of the MHC class II β exon 2 in seven basal passerine species, with variation in numbers of alleles across individuals and species. Overall, we found evidence of multiple gene loci, pseudoalleles, trans-species polymorphism and high allelic diversity in these basal lineages. Phylogenetic reconstruction of avian lineages based on MHC class II β exon 2 sequences strongly supported the monophyletic grouping of basal and derived passerine species. Conclusions Our study provides evidence of a large number of highly polymorphic MHC paralogs in seven basal passerine species, with strong similarities to the MHC described in more derived passerine lineages rather than the simpler MHC in non-passerine lineages. These findings indicate an early evolutionary origin of highly polymorphic MHC paralogs in passerines and shed light on the evolutionary forces shaping the avian MHC. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0681-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shandiya Balasubramaniam
- Department of Sciences, Museum Victoria, Melbourne, VIC, 3001, Australia. .,School of BioSciences, The University of Melbourne, Melbourne, VIC, 3010, Australia.
| | - Rebecca D Bray
- Terrestrial Vertebrates, Western Australian Museum, Perth, WA, 6986, Australia
| | - Raoul A Mulder
- School of BioSciences, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Paul Sunnucks
- School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia
| | - Alexandra Pavlova
- School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia
| | - Jane Melville
- Department of Sciences, Museum Victoria, Melbourne, VIC, 3001, Australia
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22
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Zeng QQ, He K, Sun DD, Ma MY, Ge YF, Fang SG, Wan QH. Balancing selection and recombination as evolutionary forces caused population genetic variations in golden pheasant MHC class I genes. BMC Evol Biol 2016; 16:42. [PMID: 26892934 PMCID: PMC4758006 DOI: 10.1186/s12862-016-0609-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 02/02/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The major histocompatibility complex (MHC) genes are vital partners in the acquired immune processes of vertebrates. MHC diversity may be directly associated with population resistance to infectious pathogens. Here, we screened for polymorphisms in exons 2 and 3 of the IA1 and IA2 genes in 12 golden pheasant populations across the Chinese mainland to characterize their genetic variation levels, to understand the effects of historical positive selection and recombination in shaping class I diversity, and to investigate the genetic structure of wild golden pheasant populations. RESULTS Among 339 individual pheasants, we identified 14 IA1 alleles in exon 2 (IA1-E2), 11 IA1-E3 alleles, 27 IA2-E2 alleles, and 28 IA2-E3 alleles. The non-synonymous substitution rate was significantly greater than the synonymous substitution rate at sequences in the IA2 gene encoding putative peptide-binding sites but not in the IA1 gene; we also found more positively selected sites in IA2 than in IA1. Frequent recombination events resulted in at least 9 recombinant IA2 alleles, in accordance with the intermingling pattern of the phylogenetic tree. Although some IA alleles are widely shared among studied populations, large variation occurs in the number of IA alleles across these populations. Allele frequency analysis across 2 IA loci showed low levels of genetic differentiation among populations on small geographic scales; however, significant genetic differentiation was observed between pheasants from the northern and southern regions of the Yangtze River. Both STRUCTURE analysis and F-statistic (F ST ) value comparison classified those populations into 2 major groups: the northern region of the Yangtze River (NYR) and the southern region of the Yangtze River (SYR). CONCLUSIONS More extensive polymorphisms in IA2 than IA1 indicate that IA2 has undergone much stronger positive-selection pressure during evolution. Moreover, the recombination events detected between the genes and the intermingled phylogenetic pattern indicate that interlocus recombination accounts for much of the allelic variation in IA2. Analysis of the population differentiation implied that homogenous balancing selection plays an important part in maintaining an even distribution of MHC variations. The natural barrier of the Yangtze River and heterogeneous balancing selection might help shape the NYR-SYR genetic structure in golden pheasants.
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Affiliation(s)
- Qian-Qian Zeng
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| | - Ke He
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
- College of Animal Science and Technology, Zhejiang A&F University, Lin'an, Zhejiang, 311300, China.
| | - Dan-Dan Sun
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| | - Mei-Ying Ma
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| | - Yun-Fa Ge
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| | - Sheng-Guo Fang
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| | - Qiu-Hong Wan
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
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Minias P, Bateson ZW, Whittingham LA, Johnson JA, Oyler-McCance S, Dunn PO. Contrasting evolutionary histories of MHC class I and class II loci in grouse--effects of selection and gene conversion. Heredity (Edinb) 2016; 116:466-76. [PMID: 26860199 DOI: 10.1038/hdy.2016.6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/18/2015] [Indexed: 11/09/2022] Open
Abstract
Genes of the major histocompatibility complex (MHC) encode receptor molecules that are responsible for recognition of intracellular and extracellular pathogens (class I and class II genes, respectively) in vertebrates. Given the different roles of class I and II MHC genes, one might expect the strength of selection to differ between these two classes. Different selective pressures may also promote different rates of gene conversion at each class. Despite these predictions, surprisingly few studies have looked at differences between class I and II genes in terms of both selection and gene conversion. Here, we investigated the molecular evolution of MHC class I and II genes in five closely related species of prairie grouse (Centrocercus and Tympanuchus) that possess one class I and two class II loci. We found striking differences in the strength of balancing selection acting on MHC class I versus class II genes. More than half of the putative antigen-binding sites (ABS) of class II were under positive or episodic diversifying selection, compared with only 10% at class I. We also found that gene conversion had a stronger role in shaping the evolution of MHC class II than class I. Overall, the combination of strong positive (balancing) selection and frequent gene conversion has maintained higher diversity of MHC class II than class I in prairie grouse. This is one of the first studies clearly demonstrating that macroevolutionary mechanisms can act differently on genes involved in the immune response against intracellular and extracellular pathogens.
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Affiliation(s)
- P Minias
- Department of Teacher Training and Biodiversity Studies, University of Łódź, Łódź, Poland.,Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Z W Bateson
- Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - L A Whittingham
- Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - J A Johnson
- Department of Biological Sciences, Institute of Applied Sciences, University of North Texas, Denton, TX, USA
| | - S Oyler-McCance
- Fort Collins Science Center, US Geological Survey, Fort Collins, CO, USA
| | - P O Dunn
- Behavioral and Molecular Ecology Group, Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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24
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Gillingham MAF, Courtiol A, Teixeira M, Galan M, Bechet A, Cezilly F. Evidence of gene orthology and trans-species polymorphism, but not of parallel evolution, despite high levels of concerted evolution in the major histocompatibility complex of flamingo species. J Evol Biol 2015; 29:438-54. [DOI: 10.1111/jeb.12798] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 11/12/2015] [Accepted: 11/15/2015] [Indexed: 11/30/2022]
Affiliation(s)
- M. A. F. Gillingham
- Equipe Ecologie Evolutive; UMR CNRS 6282 Biogéosciences; Université de Bourgogne; Dijon France
- Centre de Recherche de la Tour du Valat; Arles France
- Department of Evolutionary Genetics; Leibniz Institute for Zoo and Wildlife Research; Berlin Germany
- Institute of Evolutionary Ecology and Conservation Genomics; University of Ulm; Ulm Germany
| | - A. Courtiol
- Department of Evolutionary Genetics; Leibniz Institute for Zoo and Wildlife Research; Berlin Germany
| | - M. Teixeira
- Equipe Ecologie Evolutive; UMR CNRS 6282 Biogéosciences; Université de Bourgogne; Dijon France
| | - M. Galan
- UMR CBGP (INRA/IRD/Cirad/Montpellier SupAgro); INRA EFPA; Montferrier-sur-Lez Cedex France
| | - A. Bechet
- Centre de Recherche de la Tour du Valat; Arles France
| | - F. Cezilly
- Equipe Ecologie Evolutive; UMR CNRS 6282 Biogéosciences; Université de Bourgogne; Dijon France
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Kohyama TI, Omote K, Nishida C, Takenaka T, Saito K, Fujimoto S, Masuda R. Spatial and temporal variation at major histocompatibility complex class IIB genes in the endangered Blakiston's fish owl. ZOOLOGICAL LETTERS 2015; 1:13. [PMID: 26605058 PMCID: PMC4657285 DOI: 10.1186/s40851-015-0013-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 02/25/2015] [Indexed: 06/05/2023]
Abstract
INTRODUCTION Quantifying intraspecific genetic variation in functionally important genes, such as those of the major histocompatibility complex (MHC), is important in the establishment of conservation plans for endangered species. The MHC genes play a crucial role in the vertebrate immune system and generally show high levels of diversity, which is likely due to pathogen-driven balancing selection. The endangered Blakiston's fish owl (Bubo blakistoni) has suffered marked population declines on Hokkaido Island, Japan, during the past several decades due to human-induced habitat loss and fragmentation. We investigated the spatial and temporal patterns of genetic diversity in MHC class IIβ genes in Blakiston's fish owl, using massively parallel pyrosequencing. RESULTS We found that the Blakiston's fish owl genome contains at least eight MHC class IIβ loci, indicating recent gene duplications. An analysis of sequence polymorphism provided evidence that balancing selection acted in the past. The level of MHC variation, however, was low in the current fish owl populations in Hokkaido: only 19 alleles were identified from 174 individuals. We detected considerable spatial differences in MHC diversity among the geographically isolated populations. We also detected a decline of MHC diversity in some local populations during the past decades. CONCLUSIONS Our study demonstrated that the current spatial patterns of MHC variation in Blakiston's fish owl populations have been shaped by loss of variation due to the decline and fragmentation of populations, and that the short-term effects of genetic drift have counteracted the long-term effects of balancing selection.
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Affiliation(s)
- Tetsuo I Kohyama
- />Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan
| | - Keita Omote
- />Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Sapporo, 060-0810 Japan
| | - Chizuko Nishida
- />Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan
| | - Takeshi Takenaka
- />FILIN, Hachiken 2 Jo Nishi 2, Nishi-ku, Sapporo 063-0842 Japan
| | - Keisuke Saito
- />Institute for Raptor Biomedicine, Kushiro, 084-0922 Japan
| | | | - Ryuichi Masuda
- />Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan
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26
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Eimes JA, Townsend AK, Sepil I, Nishiumi I, Satta Y. Patterns of evolution of MHC class II genes of crows (Corvus) suggest trans-species polymorphism. PeerJ 2015; 3:e853. [PMID: 25802816 PMCID: PMC4369332 DOI: 10.7717/peerj.853] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/04/2015] [Indexed: 12/02/2022] Open
Abstract
A distinguishing characteristic of genes that code for the major histocompatibility complex (MHC) is that alleles often share more similarity between, rather than within species. There are two likely mechanisms that can explain this pattern: convergent evolution and trans-species polymorphism (TSP), in which ancient allelic lineages are maintained by balancing selection and retained by descendant species. Distinguishing between these two mechanisms has major implications in how we view adaptation of immune genes. In this study we analyzed exon 2 of the MHC class IIB in three passerine bird species in the genus Corvus: jungle crows (Corvus macrorhynchos japonensis) American crows (C. brachyrhynchos) and carrion crows (C. corone orientalis). Carrion crows and American crows are recently diverged, but allopatric, sister species, whereas carrion crows and jungle crows are more distantly related but sympatric species, and possibly share pathogens linked to MHC IIB polymorphisms. These patterns of evolutionary divergence and current geographic ranges enabled us to test for trans-species polymorphism and convergent evolution of the MHC IIB in crows. Phylogenetic reconstructions of MHC IIB sequences revealed several well supported interspecific clusters containing all three species, and there was no biased clustering of variants among the sympatric carrion crows and jungle crows. The topologies of phylogenetic trees constructed from putatively selected sites were remarkably different than those constructed from putatively neutral sites. In addition, trees constructed using non-synonymous substitutions from a continuous fragment of exon 2 had more, and generally more inclusive, supported interspecific MHC IIB variant clusters than those constructed from the same fragment using synonymous substitutions. These phylogenetic patterns suggest that recombination, especially gene conversion, has partially erased the signal of allelic ancestry in these species. While clustering of positively selected amino acids by supertyping revealed a single supertype shared by only jungle and carrion crows, a pattern consistent with convergence, the overall phylogenetic patterns we observed suggest that TSP, rather than convergence, explains the interspecific allelic similarity of MHC IIB genes in these species of crows.
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Affiliation(s)
- John A Eimes
- Department of Evolutionary Studies of Biosystems, Graduate University for Advanced Studies (SOKENDAI) , Hayama , Japan
| | | | - Irem Sepil
- Department of Zoology, University of Oxford , Oxford , UK
| | - Isao Nishiumi
- Department of Zoology, National Museum of Nature and Science , Tsukuba , Japan
| | - Yoko Satta
- Department of Evolutionary Studies of Biosystems, Graduate University for Advanced Studies (SOKENDAI) , Hayama , Japan
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27
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Chen LC, Lan H, Sun L, Deng YL, Tang KY, Wan QH. Genomic organization of the crested ibis MHC provides new insight into ancestral avian MHC structure. Sci Rep 2015; 5:7963. [PMID: 25608659 PMCID: PMC4302302 DOI: 10.1038/srep07963] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 12/31/2014] [Indexed: 01/06/2023] Open
Abstract
The major histocompatibility complex (MHC) plays an important role in immune response. Avian MHCs are not well characterized, only reporting highly compact Galliformes MHCs and extensively fragmented zebra finch MHC. We report the first genomic structure of an endangered Pelecaniformes (crested ibis) MHC containing 54 genes in three regions spanning ~500 kb. In contrast to the loose BG (26 loci within 265 kb) and Class I (11 within 150) genomic structures, the Core Region is condensed (17 within 85). Furthermore, this Region exhibits a COL11A2 gene, followed by four tandem MHC class II αβ dyads retaining two suites of anciently duplicated “αβ” lineages. Thus, the crested ibis MHC structure is entirely different from the known avian MHC architectures but similar to that of mammalian MHCs, suggesting that the fundamental structure of ancestral avian class II MHCs should be “COL11A2-IIαβ1-IIαβ2.” The gene structures, residue characteristics, and expression levels of the five class I genes reveal inter-locus functional divergence. However, phylogenetic analysis indicates that these five genes generate a well-supported intra-species clade, showing evidence for recent duplications. Our analyses suggest dramatic structural variation among avian MHC lineages, help elucidate avian MHC evolution, and provide a foundation for future conservation studies.
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Affiliation(s)
- Li-Cheng Chen
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, P. R. China
| | - Hong Lan
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, P. R. China
| | - Li Sun
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, P. R. China
| | - Yan-Li Deng
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, P. R. China
| | - Ke-Yi Tang
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, P. R. China
| | - Qiu-Hong Wan
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, P. R. China
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28
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Jaratlerdsiri W, Deakin J, Godinez RM, Shan X, Peterson DG, Marthey S, Lyons E, McCarthy FM, Isberg SR, Higgins DP, Chong AY, John JS, Glenn TC, Ray DA, Gongora J. Comparative genome analyses reveal distinct structure in the saltwater crocodile MHC. PLoS One 2014; 9:e114631. [PMID: 25503521 PMCID: PMC4263668 DOI: 10.1371/journal.pone.0114631] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 11/11/2014] [Indexed: 12/22/2022] Open
Abstract
The major histocompatibility complex (MHC) is a dynamic genome region with an essential role in the adaptive immunity of vertebrates, especially antigen presentation. The MHC is generally divided into subregions (classes I, II and III) containing genes of similar function across species, but with different gene number and organisation. Crocodylia (crocodilians) are widely distributed and represent an evolutionary distinct group among higher vertebrates, but the genomic organisation of MHC within this lineage has been largely unexplored. Here, we studied the MHC region of the saltwater crocodile (Crocodylus porosus) and compared it with that of other taxa. We characterised genomic clusters encompassing MHC class I and class II genes in the saltwater crocodile based on sequencing of bacterial artificial chromosomes. Six gene clusters spanning ∼452 kb were identified to contain nine MHC class I genes, six MHC class II genes, three TAP genes, and a TRIM gene. These MHC class I and class II genes were in separate scaffold regions and were greater in length (2-6 times longer) than their counterparts in well-studied fowl B loci, suggesting that the compaction of avian MHC occurred after the crocodilian-avian split. Comparative analyses between the saltwater crocodile MHC and that from the alligator and gharial showed large syntenic areas (>80% identity) with similar gene order. Comparisons with other vertebrates showed that the saltwater crocodile had MHC class I genes located along with TAP, consistent with birds studied. Linkage between MHC class I and TRIM39 observed in the saltwater crocodile resembled MHC in eutherians compared, but absent in avian MHC, suggesting that the saltwater crocodile MHC appears to have gene organisation intermediate between these two lineages. These observations suggest that the structure of the saltwater crocodile MHC, and other crocodilians, can help determine the MHC that was present in the ancestors of archosaurs.
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Affiliation(s)
- Weerachai Jaratlerdsiri
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Janine Deakin
- Evolution Ecology and Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory 2601, Australia
| | - Ricardo M. Godinez
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, United States of America
- Department of Genetics, Harvard Medical School, 77 Louis Pasteur Ave., Boston, Massachusetts 02115, United States of America
| | - Xueyan Shan
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, Mississippi 39762, United States of America
| | - Daniel G. Peterson
- Institute for Genomics, Biocomputing and Biotechnology (IGBB), Mississippi State University, Mississippi State, Mississippi 39762, United States of America
| | - Sylvain Marthey
- Animal Genetics and Integrative Biology, INRA, UMR 1313 Jouy-en-Josas 78352, France
| | - Eric Lyons
- School of Plant Science, University of Arizona, Tucson, Arizona 85721, United States of America
| | - Fiona M. McCarthy
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85721, United States of America
| | - Sally R. Isberg
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales 2006, Australia
- Center for Crocodile Research, P.O. Box 329, Noonamah, Northern Territory 0837, Australia
| | - Damien P. Higgins
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Amanda Y. Chong
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales 2006, Australia
| | - John St John
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California 95064, United States of America
| | - Travis C. Glenn
- Department of Environmental Health Science, University of Georgia, Athens, Georgia 30602, United States of America
| | - David A. Ray
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, Mississippi 39762, United States of America
- Institute for Genomics, Biocomputing and Biotechnology (IGBB), Mississippi State University, Mississippi State, Mississippi 39762, United States of America
| | - Jaime Gongora
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales 2006, Australia
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29
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Taniguchi Y, Matsumoto K, Matsuda H, Yamada T, Sugiyama T, Homma K, Kaneko Y, Yamagishi S, Iwaisaki H. Structure and polymorphism of the major histocompatibility complex class II region in the Japanese Crested Ibis, Nipponia nippon. PLoS One 2014; 9:e108506. [PMID: 25247679 PMCID: PMC4172706 DOI: 10.1371/journal.pone.0108506] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 08/21/2014] [Indexed: 12/15/2022] Open
Abstract
The major histocompatibility complex (MHC) is a highly polymorphic genomic region that plays a central role in the immune system. Despite its functional consistency, the genomic structure of the MHC differs substantially among organisms. In birds, the MHC-B structures of Galliformes, including chickens, have been well characterized, but information about other avian MHCs remains sparse. The Japanese Crested Ibis (Nipponia nippon, Pelecaniformes) is an internationally conserved, critically threatened species. The current Japanese population of N. nippon originates from only five founders; thus, understanding the genetic diversity among these founders is critical for effective population management. Because of its high polymorphism and importance for disease resistance and other functions, the MHC has been an important focus in the conservation of endangered species. Here, we report the structure and polymorphism of the Japanese Crested Ibis MHC class II region. Screening of genomic libraries allowed the construction of three contigs representing different haplotypes of MHC class II regions. Characterization of genomic clones revealed that the MHC class II genomic structure of N. nippon was largely different from that of chicken. A pair of MHC-IIA and -IIB genes was arranged head-to-head between the COL11A2 and BRD2 genes. Gene order in N. nippon was more similar to that in humans than to that in chicken. The three haplotypes contained one to three copies of MHC-IIA/IIB gene pairs. Genotyping of the MHC class II region detected only three haplotypes among the five founders, suggesting that the genetic diversity of the current Japanese Crested Ibis population is extremely low. The structure of the MHC class II region presented here provides valuable insight for future studies on the evolution of the avian MHC and for conservation of the Japanese Crested Ibis.
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Affiliation(s)
- Yukio Taniguchi
- Laboratory of Animal Breeding and Genetics, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
- * E-mail:
| | - Keisuke Matsumoto
- Laboratory of Animal Breeding and Genetics, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hirokazu Matsuda
- Laboratory of Animal Breeding and Genetics, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Takahisa Yamada
- Department of Agrobiology, Faculty of Agriculture, Niigata University, Niigata, Japan
| | - Toshie Sugiyama
- Department of Agrobiology, Faculty of Agriculture, Niigata University, Niigata, Japan
| | - Kosuke Homma
- Field Center for Sustainable Agriculture and Forestry, Niigata University, Niigata, Japan
| | | | | | - Hiroaki Iwaisaki
- Laboratory of Animal Breeding and Genetics, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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30
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Burri R, Promerová M, Goebel J, Fumagalli L. PCR-based isolation of multigene families: lessons from the avian MHC class IIB. Mol Ecol Resour 2014; 14:778-88. [PMID: 24479469 DOI: 10.1111/1755-0998.12234] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/22/2014] [Accepted: 01/22/2014] [Indexed: 11/30/2022]
Abstract
The amount of sequence data available today highly facilitates the access to genes from many gene families. Primers amplifying the desired genes over a range of species are readily obtained by aligning conserved gene regions, and laborious gene isolation procedures can often be replaced by quicker PCR-based approaches. However, in the case of multigene families, PCR-based approaches bear the often ignored risk of incomplete isolation of family members. This problem is most prominent in gene families with highly variable and thus unpredictable number of gene copies among species, such as in the major histocompatibility complex (MHC). In this study, we (i) report new primers for the isolation of the MHC class IIB (MHCIIB) gene family in birds and (ii) share our experience with isolating MHCIIB genes from an unprecedented number of avian species from all over the avian phylogeny. We report important and usually underappreciated problems encountered during PCR-based multigene family isolation and provide a collection of measures to help significantly improving the chance of successfully isolating complete multigene families using PCR-based approaches.
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Affiliation(s)
- R Burri
- Laboratory for Conservation Biology, Department of Ecology and Evolution, University of Lausanne, CH-1015, Lausanne, Switzerland; Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, SE-75236, Uppsala, Sweden
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31
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Alcaide M, Muñoz J, Martínez-de la Puente J, Soriguer R, Figuerola J. Extraordinary MHC class II B diversity in a non-passerine, wild bird: the Eurasian Coot Fulica atra (Aves: Rallidae). Ecol Evol 2014; 4:688-98. [PMID: 24683452 PMCID: PMC3967895 DOI: 10.1002/ece3.974] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/30/2013] [Accepted: 01/07/2014] [Indexed: 11/25/2022] Open
Abstract
The major histocompatibility complex (MHC) hosts the most polymorphic genes ever described in vertebrates. The MHC triggers the adaptive branch of the immune response, and its extraordinary variability is considered an evolutionary consequence of pathogen pressure. The last few years have witnessed the characterization of the MHC multigene family in a large diversity of bird species, unraveling important differences in its polymorphism, complexity, and evolution. Here, we characterize the first MHC class II B sequences isolated from a Rallidae species, the Eurasian Coot Fulica atra. A next-generation sequencing approach revealed up to 265 alleles that translated into 251 different amino acid sequences (β chain, exon 2) in 902 individuals. Bayesian inference identified up to 19 codons within the presumptive peptide-binding region showing pervasive evidence of positive, diversifying selection. Our analyses also detected a significant excess of high-frequency segregating sites (average Tajima's D = 2.36, P < 0.05), indicative of balancing selection. We found one to six different alleles per individual, consistent with the occurrence of at least three MHC class II B gene duplicates. However, the genotypes comprised of three alleles were by far the most abundant in the population investigated (49.4%), followed by those with two (29.6%) and four (17.5%) alleles. We suggest that these proportions are in agreement with the segregation of MHC haplotypes differing in gene copy number. The most widespread segregating haplotypes, according to our findings, would contain one single gene or two genes. The MHC class II of the Eurasian Coot is a valuable system to investigate the evolutionary implications of gene copy variation and extensive variability, the greatest ever found, to the best of our knowledge, in a wild population of a non-passerine bird.
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Affiliation(s)
- Miguel Alcaide
- Estación Biológica de Doñana – CSICAvda. Américo Vespucio s/n, 41092, Sevilla, Spain
| | - Joaquin Muñoz
- Estación Biológica de Doñana – CSICAvda. Américo Vespucio s/n, 41092, Sevilla, Spain
- The University of Oklahoma Biological Station15389 Station Road, Kingston, Oklahoma, 73439
| | | | - Ramón Soriguer
- Estación Biológica de Doñana – CSICAvda. Américo Vespucio s/n, 41092, Sevilla, Spain
| | - Jordi Figuerola
- Estación Biológica de Doñana – CSICAvda. Américo Vespucio s/n, 41092, Sevilla, Spain
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Jaratlerdsiri W, Isberg SR, Higgins DP, Miles LG, Gongora J. Selection and trans-species polymorphism of major histocompatibility complex class II genes in the order Crocodylia. PLoS One 2014; 9:e87534. [PMID: 24503938 PMCID: PMC3913596 DOI: 10.1371/journal.pone.0087534] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 12/30/2013] [Indexed: 12/26/2022] Open
Abstract
Major Histocompatibility Complex (MHC) class II genes encode for molecules that aid in the presentation of antigens to helper T cells. MHC characterisation within and between major vertebrate taxa has shed light on the evolutionary mechanisms shaping the diversity within this genomic region, though little characterisation has been performed within the Order Crocodylia. Here we investigate the extent and effect of selective pressures and trans-species polymorphism on MHC class II α and β evolution among 20 extant species of Crocodylia. Selection detection analyses showed that diversifying selection influenced MHC class II β diversity, whilst diversity within MHC class II α is the result of strong purifying selection. Comparison of translated sequences between species revealed the presence of twelve trans-species polymorphisms, some of which appear to be specific to the genera Crocodylus and Caiman. Phylogenetic reconstruction clustered MHC class II α sequences into two major clades representing the families Crocodilidae and Alligatoridae. However, no further subdivision within these clades was evident and, based on the observation that most MHC class II α sequences shared the same trans-species polymorphisms, it is possible that they correspond to the same gene lineage across species. In contrast, phylogenetic analyses of MHC class II β sequences showed a mixture of subclades containing sequences from Crocodilidae and/or Alligatoridae, illustrating orthologous relationships among those genes. Interestingly, two of the subclades containing sequences from both Crocodilidae and Alligatoridae shared specific trans-species polymorphisms, suggesting that they may belong to ancient lineages pre-dating the divergence of these two families from the common ancestor 85-90 million years ago. The results presented herein provide an immunogenetic resource that may be used to further assess MHC diversity and functionality in Crocodylia.
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Affiliation(s)
| | - Sally R. Isberg
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
- Centre for Crocodile Research, Noonamah, Northern Territory, Australia
| | - Damien P. Higgins
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
| | - Lee G. Miles
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
| | - Jaime Gongora
- Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
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Evolution of MHC class I in the order Crocodylia. Immunogenetics 2013; 66:53-65. [PMID: 24253731 DOI: 10.1007/s00251-013-0746-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 11/01/2013] [Indexed: 10/26/2022]
Abstract
The major histocompatibility complex (MHC) is a dynamic genomic region with an essential role in the adaptive immunity of jawed vertebrates. The evolution of the MHC has been dominated by gene duplication and gene loss, commonly known as the birth-and-death process. Evolutionary studies of the MHC have mostly focused on model species. However, the investigation of this region in non-avian reptiles is still in its infancy. To provide insights into the evolutionary mechanisms that have shaped the diversity of this region in the Order Crocodylia, we investigated MHC class I exon 3, intron 3, and exon 4 across 20 species of the families Alligatoridae and Crocodilidae. We generated 124 DNA sequences and identified 31 putative functional variants as well as 14 null variants. Phylogenetic analyses revealed three gene groups, all of which were present in Crocodilidae but only one in Alligatoridae. Within these groups, variants generally appear to cluster at the genus or family level rather than in species-specific groups. In addition, we found variation in gene copy number and some indication of interlocus recombination. These results suggest that MHC class I in Crocodylia underwent independent events of gene duplication, particularly in Crocodilidae. These findings enhance our understanding of MHC class I evolution and provide a preliminary framework for comparative studies of other non-avian reptiles as well as diversity assessment within Crocodylia.
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Wang Z, Zhou X, Lin Q, Fang W, Chen X. Characterization, polymorphism and selection of major histocompatibility complex (MHC) DAB genes in vulnerable Chinese egret (Egretta eulophotes). PLoS One 2013; 8:e74185. [PMID: 24019955 PMCID: PMC3760844 DOI: 10.1371/journal.pone.0074185] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/28/2013] [Indexed: 12/15/2022] Open
Abstract
The major histocompatibility complex (MHC) is an excellent molecular marker for the studies of evolutionary ecology and conservation genetics because it is a family of highly polymorphic genes that play a key role in vertebrate immune response. In this study, the functional genes of MHC Class II B (DAB) were isolated for the first time in a vulnerable species, the Chinese egret (Egrettaeulophotes). Using a full length DNA and cDNA produced by PCR and RACE methods, four potential MHC DAB loci were characterized in the genome of this egret and all four were expressed in liver and blood. At least four copies of the MHC gene complex were similar to two copies of the minimal essential MHC complex of chicken, but are less complex than the multiple copies expressed in passerine species. In MHC polymorphism, 19 alleles of exon 2 were isolated from 48 individuals using PCR. No stop codons or frameshift mutations were found in any of the coding regions. The signatures of positive selection detected in potential peptide-binding regions by Bayesian analysis, suggesting that all of these genes were functional. These data will provide the fundamental basis for further studies to elucidate the mechanisms and significance of MHC molecular adaptation in vulnerable Chinese egret and other ardeids.
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Affiliation(s)
- Zeng Wang
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People’s Republic of China
| | - Xiaoping Zhou
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People’s Republic of China
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People’s Republic of China
| | - Qingxian Lin
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People’s Republic of China
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People’s Republic of China
| | - Wenzhen Fang
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People’s Republic of China
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People’s Republic of China
- * E-mail: (WF); (XC)
| | - Xiaolin Chen
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People’s Republic of China
- Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People’s Republic of China
- * E-mail: (WF); (XC)
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Alcaide M, Liu M, Edwards SV. Major histocompatibility complex class I evolution in songbirds: universal primers, rapid evolution and base compositional shifts in exon 3. PeerJ 2013; 1:e86. [PMID: 23781408 PMCID: PMC3685324 DOI: 10.7717/peerj.86] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 05/23/2013] [Indexed: 01/04/2023] Open
Abstract
Genes of the Major Histocompatibility Complex (MHC) have become an important marker for the investigation of adaptive genetic variation in vertebrates because of their critical role in pathogen resistance. However, despite significant advances in the last few years the characterization of MHC variation in non-model species still remains a challenging task due to the redundancy and high variation of this gene complex. Here we report the utility of a single pair of primers for the cross-amplification of the third exon of MHC class I genes, which encodes the more polymorphic half of the peptide-binding region (PBR), in oscine passerines (songbirds; Aves: Passeriformes), a group especially challenging for MHC characterization due to the presence of large and complex MHC multigene families. In our survey, although the primers failed to amplify exon 3 from two suboscine passerine birds, they amplified exon 3 of multiple MHC class I genes in all 16 species of oscine songbirds tested, yielding a total of 120 sequences. The 16 songbird species belong to 14 different families, primarily within the Passerida, but also in the Corvida. Using a conservative approach based on the analysis of cloned amplicons (n = 16) from each species, we found between 3 and 10 MHC sequences per individual. Each allele repertoire was highly divergent, with the overall number of polymorphic sites per species ranging from 33 to 108 (out of 264 sites) and the average number of nucleotide differences between alleles ranging from 14.67 to 43.67. Our survey in songbirds allowed us to compare macroevolutionary dynamics of exon 3 between songbirds and non-passerine birds. We found compelling evidence of positive selection acting specifically upon peptide-binding codons across birds, and we estimate the strength of diversifying selection in songbirds to be about twice that in non-passerines. Analysis using comparative methods suggest weaker evidence for a higher GC content in the 3rd codon position of exon 3 in non-passerine birds, a pattern that contrasts with among-clade GC patterns found in other avian studies and may suggests different mutational mechanisms. Our primers represent a useful tool for the characterization of functional and evolutionarily relevant MHC variation across the hyperdiverse songbirds.
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Affiliation(s)
- Miguel Alcaide
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA
| | - Mark Liu
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA
| | - Scott V. Edwards
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA
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Sutton JT, Robertson BC, Grueber CE, Stanton JAL, Jamieson IG. Characterization of MHC class II B polymorphism in bottlenecked New Zealand saddlebacks reveals low levels of genetic diversity. Immunogenetics 2013; 65:619-33. [DOI: 10.1007/s00251-013-0708-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/23/2013] [Indexed: 12/13/2022]
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Lenz TL, Eizaguirre C, Kalbe M, Milinski M. EVALUATING PATTERNS OF CONVERGENT EVOLUTION AND TRANS-SPECIES POLYMORPHISM AT MHC IMMUNOGENES IN TWO SYMPATRIC STICKLEBACK SPECIES. Evolution 2013; 67:2400-12. [DOI: 10.1111/evo.12124] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/26/2013] [Indexed: 01/15/2023]
Affiliation(s)
- Tobias L. Lenz
- Department of Evolutionary Ecology; Max Planck Institute for Evolutionary Biology; August-Thienemann-Str 2 24306 Plön Germany
| | - Christophe Eizaguirre
- Department of Evolutionary Ecology; Max Planck Institute for Evolutionary Biology; August-Thienemann-Str 2 24306 Plön Germany
- Department of Evolutionary Ecology of Marine Fishes; GEOMAR
- Helmholtz Center for Ocean Research; Düsternbrooker Weg 20 24105 Kiel Germany
| | - Martin Kalbe
- Department of Evolutionary Ecology; Max Planck Institute for Evolutionary Biology; August-Thienemann-Str 2 24306 Plön Germany
| | - Manfred Milinski
- Department of Evolutionary Ecology; Max Planck Institute for Evolutionary Biology; August-Thienemann-Str 2 24306 Plön Germany
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Strand T, Wang B, Meyer-Lucht Y, Höglund J. Evolutionary history of black grouse major histocompatibility complex class IIB genes revealed through single locus sequence-based genotyping. BMC Genet 2013; 14:29. [PMID: 23617616 PMCID: PMC3652749 DOI: 10.1186/1471-2156-14-29] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 04/12/2013] [Indexed: 11/10/2022] Open
Abstract
Background Gene duplications are frequently observed in the Major Histocompatibility Complex (MHC) of many species, and as a consequence loci belonging to the same MHC class are often too similar to tell apart. In birds, single locus genotyping of MHC genes has proven difficult due to concerted evolution homogenizing sequences at different loci. But studies on evolutionary history, mode of selection and heterozygosity correlations on the MHC cannot be performed before it is possible to analyse duplicated genes separately. In this study we investigate the architecture and evolution of the MHC class IIB genes in black grouse. We developed a sequence-based genotyping method for separate amplification of the two black grouse MHC class IIB genes BLB1 and BLB2. Based on this approach we are able to study differences in structure and selection between the two genes in black grouse and relate these results to the chicken MHC structure and organization. Results Sequences were obtained from 12 individuals and separated into alleles using the software PHASE. We compared nucleotide diversity measures and employed selection tests for BLB1 and BLB2 to explore their modes of selection. Both BLB1 and BLB2 are transcribed and display classic characteristics of balancing selection as predicted for expressed MHC class IIB genes. We found evidence for both intra- and interlocus recombination or gene conversion, as well as indication for positive but differential selection at both loci. Moreover, the two loci appear to be linked. Phylogenetic analyses revealed orthology of the black grouse MHC class IIB genes to the respective BLB loci in chicken. Conclusions The results indicate that the duplication of the BLB gene occurred before the species divergence into black grouse, chicken and pheasant. Further, we conclude that BLB1 and BLB2 in black grouse are subjected to homogenizing concerted evolution due to interlocus genetic exchange after species divergence. The loci are in linkage disequilibrium, which is in line with the theory of tightly coevolving genes within the MHC under the minimal essential MHC hypothesis. Our results support the conclusion that MHC form and function in birds derived from studies on the domesticated chicken are not artefacts of the domestication process.
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Affiliation(s)
- Tanja Strand
- Population Biology and Conservation Biology, Department of Ecology and Genetics, Evolutionary Biology Center, Uppsala University, Norbyvägen 18D, Uppsala, SE-752 36, Sweden
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Gohli J, Anmarkrud JA, Johnsen A, Kleven O, Borge T, Lifjeld JT. FEMALE PROMISCUITY IS POSITIVELY ASSOCIATED WITH NEUTRAL AND SELECTED GENETIC DIVERSITY IN PASSERINE BIRDS. Evolution 2013; 67:1406-19. [DOI: 10.1111/evo.12045] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 12/17/2012] [Indexed: 12/16/2022]
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40
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Wutzler R, Foerster K, Kempenaers B. MHC class I variation in a natural blue tit population (Cyanistes caeruleus). Genetica 2012; 140:349-64. [PMID: 23073914 DOI: 10.1007/s10709-012-9679-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 09/03/2012] [Indexed: 12/13/2022]
Abstract
The major histocompatibility complex (MHC) is central to the vertebrate immune system and its highly polymorphic genes are considered to influence several life-history traits of individuals. To characterize the MHC in a natural population of blue tits (Cyanistes caeruleus) we investigated the class I exon 3 diversity of more than 900 individuals. We designed two pairs of motif-specific primers that reliably amplify independent subsets of MHC alleles. Applying denaturing gradient gel electrophoresis (DGGE) we obtained 48 independently inherited units of unique band patterns (DGGE-haplogroups), which were validated in a segregation analysis within 105 families. In a second approach, we extensively sequenced 6 unrelated individuals to confirm that DGGE-haplogroup composition reflects individual allelic variation. The highest number of different DGGE-haplogroups in a single individual corresponded in 19 MHC exon 3 sequences, suggesting a minimum of 10 amplified MHC class I loci in the blue tit. In total, we identified 50 unique functional and 3 non-functional sequences. Functional sequences showed high levels of recombination and strong positive selection in the antigen binding region, whereas nucleotide diversity was comparatively low in the range of all passerine species. Finally, in a phylogenetic comparison of passerine MHC class I exon 3 sequences we discuss conflicting evolutionary signals possibly due to recent gene duplication, recombination events and concerted evolution. Our results indicate that the described method is suitable to effectively explore the MHC diversity and its ecological impacts in blue tits in future studies.
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Affiliation(s)
- R Wutzler
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, 82305 Seewiesen, Germany.
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41
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Sin YW, Dugdale HL, Newman C, Macdonald DW, Burke T. Evolution of MHC class I genes in the European badger (Meles meles). Ecol Evol 2012; 2:1644-62. [PMID: 22957169 PMCID: PMC3434948 DOI: 10.1002/ece3.285] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 04/27/2012] [Indexed: 02/01/2023] Open
Abstract
The major histocompatibility complex (MHC) plays a central role in the adaptive immune system and provides a good model with which to understand the evolutionary processes underlying functional genes. Trans-species polymorphism and orthology are both commonly found in MHC genes; however, mammalian MHC class I genes tend to cluster by species. Concerted evolution has the potential to homogenize different loci, whereas birth-and-death evolution can lead to the loss of orthologs; both processes result in monophyletic groups within species. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. We present the first study of MHC class I genes in a species from the superfamily Musteloidea. The European badger (Meles meles) exhibits moderate variation in MHC class I sequences when compared to other carnivores. We identified seven putatively functional sequences and nine pseudogenes from genomic (gDNA) and complementary (cDNA) DNA, signifying at least two functional class I loci. We found evidence for separate evolutionary histories of the α1 and α2/α3 domains. In the α1 domain, several sequences from different species were more closely related to each other than to sequences from the same species, resembling orthology or trans-species polymorphism. Balancing selection and probable recombination maintain genetic diversity in the α1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the α2/α3 domains have most likely undergone concerted evolution, where recombination has homogenized the α2/α3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately.
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Affiliation(s)
- Yung Wa Sin
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan CentreTubney House, Abingdon Road, Tubney, Abingdon, Oxfordshire OX13 5QL, United Kingdom
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of SheffieldWestern Bank, Sheffield, South Yorkshire, S10 2TN, United Kingdom
| | - Hannah L Dugdale
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of SheffieldWestern Bank, Sheffield, South Yorkshire, S10 2TN, United Kingdom
- Behavioural Ecology and Self-Organization, University of GroningenP.O. Box 11103, 9700 CC Groningen, The Netherlands
- Theoretical Biology, University of GroningenP.O. Box 11103, 9700 CC Groningen, The Netherlands
| | - Chris Newman
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan CentreTubney House, Abingdon Road, Tubney, Abingdon, Oxfordshire OX13 5QL, United Kingdom
| | - David W Macdonald
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan CentreTubney House, Abingdon Road, Tubney, Abingdon, Oxfordshire OX13 5QL, United Kingdom
| | - Terry Burke
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of SheffieldWestern Bank, Sheffield, South Yorkshire, S10 2TN, United Kingdom
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Knafler GJ, Clark JA, Boersma PD, Bouzat JL. MHC diversity and mate choice in the magellanic penguin, Spheniscus magellanicus. ACTA ACUST UNITED AC 2012; 103:759-68. [PMID: 22952272 DOI: 10.1093/jhered/ess054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We estimated levels of diversity at the major histocompatibility complex (MHC) class II DRß1 gene in 50 breeding pairs of the Magellanic penguin and compared those to estimates from Humboldt and Galapagos penguins. We tested for positive selection and 2 conditions required for the evolution of MHC-based disassortative mating: 1) greater MHC diversity between breeding pairs compared to random mating, and 2) associations between MHC genotype and fitness. Cloning and sequencing of the DRß1 gene showed that Magellanic penguins had higher levels of genetic variation than Galapagos and Humboldt penguins. Sequence analysis revealed 45 alleles with 3.6% average proportion of nucleotide differences, nucleotide diversity of 0.030, and observed heterozygosity of 0.770. A gene phylogeny showed 9 allelic lineages with interspersed DRß1 sequences from Humboldt and Galapagos penguins, indicating ancestral polymorphisms. d (N)/d (S) ratios revealed evidence for positive selection. Analysis of breeding pairs showed no disassortative mating preferences. Significant MHC genotype/fitness associations in females suggest, however, that selection for pathogen resistance plays a more important role than mate choice in maintaining diversity at the MHC in the Magellanic penguin. The differential effect of MHC heterozygosity on fitness between the sexes is likely associated with the relative role of hatching and fledging rates as reliable indicators of overall fitness in males and females.
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Independent evolution of functional MHC class II DRB genes in New World bat species. Immunogenetics 2012; 64:535-47. [PMID: 22426641 DOI: 10.1007/s00251-012-0609-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/23/2012] [Indexed: 12/21/2022]
Abstract
Genes of the major histocompatibility complex (MHC) play a pivotal role in the vertebrate immune system and are attractive markers for functional, fitness-related, genetic variation. Although bats (Chiroptera) represent the second largest mammalian order and are prone to various emerging infectious diseases, little is known about MHC evolution in bats. In the present study, we examined expressed MHC class II DRB sequences (exons 1 to 4) of New World bat species, Saccopteryx bilineata, Carollia perspicillata, Noctilio albiventris and Noctilio leporinus (only exon 2). We found a wide range of copy number variation of DRB loci with one locus detected in the genus Noctilio and up to ten functional loci observed in S. bilineata. Sequence variation between alleles of the same taxa was high with evidence for positive selection. We found statistical support for recombination or gene conversion events among sequences within the same but not between bat species. Phylogenetic relationships among DRB alleles provided strong evidence for independent evolution of the functional MHC class II DRB genes in the three investigated species, either by recent gene duplication, or homogenization of duplicated loci by frequent gene conversion events. Phylogenetic analysis of all available chiropteran DRB exon 2 sequences confirmed their monophyletic origin within families, but revealed a possible trans-species mode of evolution pattern in congeneric bat species, e.g. within the genera Noctilio and Myotis. This is the first study investigating phylogenetic relationships of MHC genes within bats and therefore contributes to a better understanding of MHC evolution in one of the most dominant mammalian order.
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Whittaker DJ, Dapper AL, Peterson MP, Atwell JW, Ketterson ED. Maintenance of MHC Class IIB diversity in a recently established songbird population. JOURNAL OF AVIAN BIOLOGY 2012; 43:109-118. [PMID: 22685370 PMCID: PMC3368239 DOI: 10.1111/j.1600-048x.2012.05504.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We examined variation at MHC Class IIB genes in a recently established population of dark-eyed juncos (Junco hyemalis) in a coastal urban environment in southern California, USA relative to an ancestral-range population from a nearby species-typical montane environment. The founding population is estimated to have been quite small, but we predicted that variation at the major histocompatibility complex (MHC) among the founders would nevertheless be preserved owing to the high functional significance of MHC. Previous studies of MHC in songbirds have had varying degrees of success in isolating loci, as passerines show extensive MHC gene duplication. In order to compare diversity in the two populations, we employed two published approaches to sequencing MHC Class II exon 2: direct sequencing with exon-based primers, and traditional cloning and sequencing with intron-based primers. Results from both methods show that the colonist population has maintained high levels of variation. Our results also indicate varying numbers of alleles across individuals, corroborating evidence for gene duplication in songbird MHC. While future studies in songbirds may need to take a genomic approach to fully understand the structure of MHC in this lineage, our results show that it is possible to use traditional methods to reveal functional variation across populations.
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Affiliation(s)
- Danielle J. Whittaker
- BEACON Center for the Study of Evolution in Action, Michigan State University, 1441 Biomedical and Physical Sciences, East Lansing, MI, 48824
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Amy L. Dapper
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Mark P. Peterson
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Jonathan W. Atwell
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Ellen D. Ketterson
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
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Strand TM, Höglund J. Genotyping of black grouse MHC class II B using reference Strand-Mediated Conformational Analysis (RSCA). BMC Res Notes 2011; 4:183. [PMID: 21672220 PMCID: PMC3141517 DOI: 10.1186/1756-0500-4-183] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 06/14/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Major Histocompatibility Complex (MHC) is a cluster of genes involved in the vertebrate immune system and includes loci with an extraordinary number of alleles. Due to the complex evolution of MHC genes, alleles from different loci within the same MHC class can be very similar and therefore difficult to assign to separate loci. Consequently, single locus amplification of MHC genes is hard to carry out in species with recently duplicated genes in the same MHC class, and multiple MHC loci have to be genotyped simultaneously. Since amplified alleles have the same length, accurate genotyping is difficult. Reference Strand-Mediated Conformational Analysis (RSCA), which is increasingly used in studies of natural populations with multiple MHC genes, is a genotyping method capable to provide high resolution and accuracy in such cases. FINDINGS We adapted the RSCA method to genotype multiple MHC class II B (BLB) genes in black grouse (Tetrao tetrix), a non-model galliform bird species, using a 96-Capillary Array Electrophoresis, the MegaBACE™ 1000 DNA Analysing System (GE Healthcare). In this study we used fluorescently labelled reference strands from both black grouse and hazel grouse and observed good agreement between RSCA and cloning/sequencing since 71 alleles were observed by cloning/sequencing and 76 alleles by RSCA among the 24 individuals included in the comparison. At the individual level however, there was a trend towards more alleles scored with RSCA (1-6 per individual) than cloning/sequencing (1-4 per individual). In 63% of the pair-wise comparison, the identical allele was scored in RSCA as in cloning/sequencing. Nine out of 24 individuals had the same number of alleles in RSCA as in cloning/sequencing. Our RSCA protocol allows a faster RSCA genotyping than presented in many other RSCA studies. CONCLUSIONS In this study, we have developed the RSCA typing method further to work on a 96-Capillary Array Electrophoresis (MegaBACE™ 1000). Our RSCA protocol can be applied to fast and reliable screening of MHC class II B diversity of black grouse populations. This will facilitate future large-scale population studies of black grouse and other galliformes species with multiple inseparable MHC loci.
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Affiliation(s)
- Tanja M Strand
- Population Biology and Conservation Biology, Dept. of Ecology & Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
| | - Jacob Höglund
- Population Biology and Conservation Biology, Dept. of Ecology & Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
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Ekblom R, Stapley J, Ball AD, Birkhead T, Burke T, Slate J. Genetic mapping of the major histocompatibility complex in the zebra finch (Taeniopygia guttata). Immunogenetics 2011; 63:523-30. [PMID: 21494955 DOI: 10.1007/s00251-011-0525-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 04/04/2011] [Indexed: 12/29/2022]
Abstract
Genes of the major histocompatibility complex (MHC) have received much attention in immunology, genetics, and ecology because they are highly polymorphic and play important roles in parasite resistance and mate choice. Until recently, the MHC of passerine birds was not well-described. However, the genome sequencing of the zebra finch (Taeniopygia guttata) has partially redressed this gap in our knowledge of avian MHC genes. Here, we contribute further to the understanding of the zebra finch MHC organization by mapping SNPs within or close to known MHC genes in the zebra finch genome. MHC class I and IIB genes were both mapped to zebra finch chromosome 16, and there was no evidence that MHC class I genes are located on chromosome 22 (as suggested by the genome assembly). We confirm the location in the MHC region on chromosome 16 for several other genes (BRD2, FLOT1, TRIM7.2, GNB2L1, and CSNK2B). Two of these (CSNK2B and FLOT1) have not previously been mapped in any other bird species. In line with previous results, we also find that orthologs to the immune-related genes B-NK and CLEC2D, which are part of the MHC region in chicken, are situated on zebra finch chromosome Z and not among other MHC genes in the zebra finch.
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Affiliation(s)
- Robert Ekblom
- Department of Population Biology and Conservation Biology, Uppsala University, Norbyvägen, Sweden.
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Characterisation of class II B MHC genes from a ratite bird, the little spotted kiwi (Apteryx owenii). Immunogenetics 2011; 63:223-33. [PMID: 21221966 DOI: 10.1007/s00251-010-0503-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 12/11/2010] [Indexed: 12/15/2022]
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Zagalska-Neubauer M, Babik W, Stuglik M, Gustafsson L, Cichoń M, Radwan J. 454 sequencing reveals extreme complexity of the class II Major Histocompatibility Complex in the collared flycatcher. BMC Evol Biol 2010; 10:395. [PMID: 21194449 PMCID: PMC3024992 DOI: 10.1186/1471-2148-10-395] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 12/31/2010] [Indexed: 11/24/2022] Open
Abstract
Background Because of their functional significance, the Major Histocompatibility Complex (MHC) class I and II genes have been the subject of continuous interest in the fields of ecology, evolution and conservation. In some vertebrate groups MHC consists of multiple loci with similar alleles; therefore, the multiple loci must be genotyped simultaneously. In such complex systems, understanding of the evolutionary patterns and their causes has been limited due to challenges posed by genotyping. Results Here we used 454 amplicon sequencing to characterize MHC class IIB exon 2 variation in the collared flycatcher, an important organism in evolutionary and immuno-ecological studies. On the basis of over 152,000 sequencing reads we identified 194 putative alleles in 237 individuals. We found an extreme complexity of the MHC class IIB in the collared flycatchers, with our estimates pointing to the presence of at least nine expressed loci and a large, though difficult to estimate precisely, number of pseudogene loci. Many similar alleles occurred in the pseudogenes indicating either a series of recent duplications or extensive concerted evolution. The expressed alleles showed unambiguous signals of historical selection and the occurrence of apparent interlocus exchange of alleles. Placing the collared flycatcher's MHC sequences in the context of passerine diversity revealed transspecific MHC class II evolution within the Muscicapidae family. Conclusions 454 amplicon sequencing is an effective tool for advancing our understanding of the MHC class II structure and evolutionary patterns in Passeriformes. We found a highly dynamic pattern of evolution of MHC class IIB genes with strong signals of selection and pronounced sequence divergence in expressed genes, in contrast to the apparent sequence homogenization in pseudogenes. We show that next generation sequencing offers a universal, affordable method for the characterization and, in perspective, genotyping of MHC systems of virtually any complexity.
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Ekblom R, French L, Slate J, Burke T. Evolutionary analysis and expression profiling of zebra finch immune genes. Genome Biol Evol 2010; 2:781-90. [PMID: 20884724 PMCID: PMC2975445 DOI: 10.1093/gbe/evq061] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Genes of the immune system are generally considered to evolve rapidly due to host-parasite coevolution. They are therefore of great interest in evolutionary biology and molecular ecology. In this study, we manually annotated 144 avian immune genes from the zebra finch (Taeniopygia guttata) genome and conducted evolutionary analyses of these by comparing them with their orthologs in the chicken (Gallus gallus). Genes classified as immune receptors showed elevated d(N)/d(S) ratios compared with other classes of immune genes. Immune genes in general also appear to be evolving more rapidly than other genes, as inferred from a higher d(N)/d(S) ratio compared with the rest of the genome. Furthermore, ten genes (of 27) for which sequence data were available from at least three bird species showed evidence of positive selection acting on specific codons. From transcriptome data of eight different tissues, we found evidence for expression of 106 of the studied immune genes, with primary expression of most of these in bursa, blood, and spleen. These immune-related genes showed a more tissue-specific expression pattern than other genes in the zebra finch genome. Several of the avian immune genes investigated here provide strong candidates for in-depth studies of molecular adaptation in birds.
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Affiliation(s)
- Robert Ekblom
- University of Sheffield, Department of Animal and Plant Sciences, Sheffield, UK.
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Canal D, Alcaide M, Anmarkrud JA, Potti J. Towards the simplification of MHC typing protocols: targeting classical MHC class II genes in a passerine, the pied flycatcher Ficedula hypoleuca. BMC Res Notes 2010; 3:236. [PMID: 20815923 PMCID: PMC2944132 DOI: 10.1186/1756-0500-3-236] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 09/05/2010] [Indexed: 11/13/2022] Open
Abstract
Background Major Histocompatibility Complex (MHC) has drawn the attention of evolutionary biologists due to its importance in crucial biological processes, such as sexual selection and immune response in jawed vertebrates. However, the characterization of classical MHC genes subjected to the effects of natural selection still remains elusive in many vertebrate groups. Here, we have tested the suitability of flanking intron sequences to guide the selective exploration of classical MHC genes driving the co-evolutionary dynamics between pathogens and their passerine (Aves, Order Passeriformes) hosts. Findings Intronic sequences flanking the usually polymorphic exon 2 were isolated from different species using primers sitting on conserved coding regions of MHC class II genes (β chain). Taking the pied flycatcher Ficedula hypoleuca as an example, we demonstrate that careful primer design can evade non-classical MHC gene and pseudogene amplification. At least four polymorphic and expressed loci were co-replicated using a single pair of primers in five non-related individuals (N = 28 alleles). The cross-amplification and preliminary inspection of similar MHC fragments in eight unrelated songbird taxa suggests that similar approaches can also be applied to other species. Conclusions Intron sequences flanking the usually polymorphic exon 2 may assist the specific investigation of classical MHC class II B genes in species characterized by extensive gene duplication and pseudogenization. Importantly, the evasion of non-classical MHC genes with a more specific function and non-functional pseudogenes may accelerate data collection and diminish lab costs. Comprehensive knowledge of gene structure, polymorphism and expression profiles may be useful not only for the selective examination of evolutionarily relevant genes but also to restrict chimera formation by minimizing the number of co-amplifying loci.
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Affiliation(s)
- David Canal
- Estación Biológica de Doñana - CSIC, Department of Evolutionary Ecology, Av, Américo Vespucio s/n, 41092 Seville, Spain.
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