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Minias P. Evolutionary variation in gene conversion at the avian MHC is explained by fluctuating selection, gene copy numbers and life history. Mol Ecol 2024; 33:e17453. [PMID: 38953291 DOI: 10.1111/mec.17453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 06/05/2024] [Accepted: 06/14/2024] [Indexed: 07/03/2024]
Abstract
The major histocompatibility complex (MHC) multigene family encodes key pathogen-recognition molecules of the vertebrate adaptive immune system. Hyper-polymorphism of MHC genes is de novo generated by point mutations, but new haplotypes may also arise by re-shuffling of existing variation through intra- and inter-locus gene conversion. Although the occurrence of gene conversion at the MHC has been known for decades, we still have limited understanding of its functional importance. Here, I took advantage of extensive genetic resources (~9000 sequences) to investigate broad scale macroevolutionary patterns in gene conversion processes at the MHC across nearly 200 avian species. Gene conversion was found to constitute a universal mechanism in birds, as 83% of species showed footprints of gene conversion at either MHC class and 25% of all allelic variants were attributed to gene conversion. Gene conversion processes were stronger at MHC-II than MHC-I, but inter-specific variation at both MHC classes was explained by similar evolutionary scenarios, reflecting fluctuating selection towards different optima and drift. Gene conversion showed uneven phylogenetic distribution across birds and was driven by gene copy number variation, supporting significant role of inter-locus gene conversion processes in the evolution of the avian MHC. Finally, MHC gene conversion was stronger in species with fast life histories (high fecundity) and in long-distance migrants, likely reflecting variation in population sizes and host-pathogen coevolutionary dynamics. The results provide a robust comparative framework for understanding macroevolutionary variation in gene conversion at the avian MHC and reinforce important contribution of this mechanism to functional MHC diversity.
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Affiliation(s)
- Piotr Minias
- Department of Biodiversity Studies and Bioeducation, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland
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Minias P, Peng WXVH, Matson KD. Evolutionary trade-off between innate and acquired immune defences in birds. Front Zool 2023; 20:32. [PMID: 37684615 PMCID: PMC10486109 DOI: 10.1186/s12983-023-00511-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/01/2023] [Indexed: 09/10/2023] Open
Abstract
BACKGROUND The development, maintenance, and use of immune defences are costly. Therefore, animals face trade-offs in terms of resource allocation within their immune system and between their immune system and other physiological processes. To maximize fitness, evolution may favour investment in one immunological defence or subsystem over another in a way that matches a species broader life history strategy. Here, we used phylogenetically-informed comparative analyses to test for relationships between two immunological components. Natural antibodies and complement were used as proxies for the innate branch; structural complexity of the major histocompatibility complex (MHC) region was used for the acquired branch. RESULTS We found a negative association between the levels of natural antibodies (i.e., haemagglutination titre) and the total MHC gene copy number across the avian phylogeny, both at the species and family level. The family-level analysis indicated that this association was apparent for both MHC-I and MHC-II, when copy numbers within these two MHC regions were analysed separately. The association remained significant after controlling for basic life history components and for ecological traits commonly linked to pathogen exposure. CONCLUSION Our results provide the first phylogenetically robust evidence for an evolutionary trade-off within the avian immune system, with a more developed acquired immune system (i.e., more complex MHC architecture) in more derived bird lineages (e.g., passerines) being accompanied by an apparent downregulation of the innate immune system.
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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.
| | - Wei-Xuan V-H Peng
- Wildlife Ecology and Conservation Group, Wageningen University & Research, Droevendaalsesteeg 3a, 6708PB, Wageningen, Netherlands
| | - Kevin D Matson
- Wildlife Ecology and Conservation Group, Wageningen University & Research, Droevendaalsesteeg 3a, 6708PB, Wageningen, Netherlands
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Minias P, Palomar G, Dudek K, Babik W. Salamanders reveal novel trajectories of amphibian MHC evolution. Evolution 2022; 76:2436-2449. [PMID: 36000494 DOI: 10.1111/evo.14601] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 07/06/2022] [Accepted: 07/29/2022] [Indexed: 01/22/2023]
Abstract
Genes of the major histocompatibility complex (MHC) code for immune proteins that are crucial for pathogen recognition in vertebrates. MHC research in nonmodel taxa has long been hampered by its genomic complexity that makes the locus-specific genotyping challenging. The recent progress in sequencing and genotyping methodologies allows an extensive phylogenetic coverage in studies of MHC evolution. Here, we analyzed the peptide-binding region of MHC class I (MHC-I) in 30 species of salamanders from six families representative of Urodela phylogeny. This extensive dataset revealed an extreme diversity of MHC-I in salamanders, both in terms of sequence diversity (about 3000 variants) and architecture (2-22 gene copies per species). The signal of positive selection was moderate and consistent between both peptide-binding domains, but varied greatly between genera. Positions of positively selected sites mostly coincided with human peptide-binding sites, suggesting similar structural properties of MHC-I molecules across distant vertebrate lineages. Finally, we provided evidence for the common intraexonic recombination at MHC-I and for the role of life history traits in the processes of MHC-I expansion/contraction. Our study revealed novel evolutionary trajectories of amphibian MHC and it contributes to the understanding of the mechanisms that generated extraordinary MHC diversity throughout vertebrate evolution.
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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
| | - Gemma Palomar
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, 30-387, Poland.,Parasitology Unit, Department of Biomedicine and Biotechnology, Faculty of Pharmacy, Universidad de Alcalá (UAH), Alcalá de Henares, Madrid, 28805, Spain
| | - Katarzyna Dudek
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, 30-387, Poland
| | - Wiesław Babik
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, 30-387, Poland
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Wong ATC, Lam DK, Poon ESK, Chan DTC, Sin SYW. Intra-specific copy number variation of MHC class II genes in the Siamese fighting fish. Immunogenetics 2022; 74:327-346. [PMID: 35229174 DOI: 10.1007/s00251-022-01255-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 02/04/2022] [Indexed: 11/28/2022]
Abstract
Duplicates of genes for major histocompatibility complex (MHC) molecules can be subjected to selection independently and vary markedly in their evolutionary rates, sequence polymorphism, and functional roles. Therefore, without a thorough understanding of their copy number variation (CNV) in the genome, the MHC-dependent fitness consequences within a species could be misinterpreted. Studying the intra-specific CNV of this highly polymorphic gene, however, has long been hindered by the difficulties in assigning alleles to loci and the lack of high-quality genomic data. Here, using the high-quality genome of the Siamese fighting fish (Betta splendens), a model for mate choice studies, and the whole-genome sequencing (WGS) data of 17 Betta species, we achieved locus-specific amplification of their three classical MHC class II genes - DAB1, DAB2, and DAB3. By performing quantitative PCR and depth-of-coverage analysis using the WGS data, we revealed intra-specific CNV at the DAB3 locus. We identified individuals that had two allelic copies (i.e., heterozygous or homozygous) or one allele (i.e., hemizygous) and individuals without this gene. The CNV was due to the deletion of a 20-kb-long genomic region harboring both the DAA3 and DAB3 genes. We further showed that the three DAB genes were under different modes of selection, which also applies to their corresponding DAA genes that share similar pattern of polymorphism. Our study demonstrates a combined approach to study CNV within a species, which is crucial for the understanding of multigene family evolution and the fitness consequences of CNV.
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Affiliation(s)
- Anson Tsz Chun Wong
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China
| | - Derek Kong Lam
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China
| | - Emily Shui Kei Poon
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China
| | - David Tsz Chung Chan
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China
| | - Simon Yung Wa Sin
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China.
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Fu Q, Li Y, Zhang H, Cao M, Zhang L, Gao C, Cai X, Chen D, Yang Z, Li J, Yang N, Li C. Comparative Transcriptome Analysis of Spleen Reveals Potential Regulation of Genes and Immune Pathways Following Administration of Aeromonas salmonicida subsp. masoucida Vaccine in Atlantic Salmon (Salmo salar). MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:97-115. [PMID: 35084599 PMCID: PMC8792528 DOI: 10.1007/s10126-021-10089-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Aeromonas salmonicida is a global fish pathogen. Aeromonas salmonicida subsp. masoucida (ASM) is classified as atypical A. salmonicida and caused huge losses to salmonid industry in China. Hence, it is of great significance to develop ASM vaccine and explore its protection mechanism in salmonids. In this regard, we conducted RNA-seq analysis with spleen tissue of Atlantic salmon after ASM vaccination to reveal genes, their expression patterns, and pathways involved in immune protections. In our results, a total of 441.63 million clean reads were obtained, and 389.37 million reads were mapped onto the Atlantic salmon reference genome. In addition, 1125, 2126, 1098, 820, and 1351 genes were significantly up-regulated, and 747, 2626, 818, 254, and 908 genes were significantly down-regulated post-ASM vaccination at 12 h, 24 h, 1 month, 2 months, and 3 months, respectively. Subsequent pathway analysis revealed that many differentially expressed genes (DEGs) following ASM vaccination were involved in cytokine-cytokine receptor interaction (TNFRSF11b, IL-17RA, CCR9, and CXCL11), HTLV-I infection (MR1 and HTLV-1), MAPK signaling pathway (MAPK, IL8, and TNF-α-1), PI3K-Akt signaling pathway (PIK3R3, THBS4, and COL2A1), and TNF signaling pathway (PTGS2, TNFRSF21-l, and CXCL10). Finally, the results of qRT-PCR showed a significant correlation with RNA-seq results, suggesting the reliability of RNA-seq for gene expression analysis. This study provided insights into regulation of gene expression and their involved pathways in Atlantic salmon spleen in responses to vaccine, and set the foundation for further study on the vaccine protective mechanism in Atlantic salmon as well as other teleost species.
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Affiliation(s)
- Qiang Fu
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yuqing Li
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Hao Zhang
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Min Cao
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Lu Zhang
- Shandong Sinder Technology Co., Ltd, Zhucheng, 262200, China
| | - Chengbin Gao
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Xin Cai
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Defeng Chen
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Ziying Yang
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Jie Li
- Key Laboratory of Maricultural Organism Disease Control, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Ning Yang
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Chao Li
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China.
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Vincze O, Loiseau C, Giraudeau M. Avian blood parasite richness decreases with major histocompatibility complex class I loci number. Biol Lett 2021; 17:20210253. [PMID: 34343440 DOI: 10.1098/rsbl.2021.0253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Major histocompatibility complex (MHC) genes are among the most polymorphic in the vertebrate genome. The high allele diversity is believed to be maintained primarily by sexual and pathogen-mediated balancing selection. The number of MHC loci also varies greatly across vertebrates, most notably across birds. MHC proteins play key roles in presenting antigens on the cell surface for recognition by T cells, with class I proteins specifically targeting intracellular pathogens. Here, we explore the hypothesis that MHC class I diversity (measured as loci number) coevolves with haemosporidian parasite burden of the host. Using data on 54 bird species, we demonstrate that high-MHC class I diversity is associated with significantly lower richness of Plasmodium, Haemoproteus as well as overall haemosporidian parasite lineages, the former thus indicating more efficient protection against intracellular pathogens. Nonetheless, the latter associations were only detected when MHC diversity was assessed using cloning and not 454 pyrosequencing-based studies, nor across all genotyping methods combined. Our results indicate that high-MHC class I diversity might play a key role in providing qualitative resistance against diverse haemosporidian parasites in birds, but further clarification is needed for the origin of contrasting results when using different genotyping methods for MHC loci quantification.
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Affiliation(s)
- Orsolya Vincze
- CREEC, MIVEGEC, UMR IRD 224-CNRS 5290-Université de Montpellier, Montpellier, France.,CREES Centre for Research on the Ecology and Evolution of Disease, Montpellier, France.,Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, FR-17000 La Rochelle, France.,Institute of Aquatic Ecology, Centre for Ecological Research, 4026 Debrecen, Hungary.,Evolutionary Ecology Group, Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Clinicilor Street 5-7, RO-400006 Cluj-Napoca, Romania
| | - Claire Loiseau
- CIBIO-InBIO - Research Center in Biodiversity and Genetic Resources, InBIO Associate Laboratory, Campus de Vairão, 7 Rua Padre Armando Quintas, 4485-661 Vairão, Portugal.,CEFE, Université de Montpellier, CNRS, Montpellier, France
| | - Mathieu Giraudeau
- CREEC, MIVEGEC, UMR IRD 224-CNRS 5290-Université de Montpellier, Montpellier, France.,CREES Centre for Research on the Ecology and Evolution of Disease, Montpellier, France
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