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Venu V, Harjunmaa E, Dreau A, Brady S, Absher D, Kingsley DM, Jones FC. Fine-scale contemporary recombination variation and its fitness consequences in adaptively diverging stickleback fish. Nat Ecol Evol 2024; 8:1337-1352. [PMID: 38839849 PMCID: PMC11239493 DOI: 10.1038/s41559-024-02434-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 05/02/2024] [Indexed: 06/07/2024]
Abstract
Despite deep evolutionary conservation, recombination rates vary greatly across the genome and among individuals, sexes and populations. Yet the impact of this variation on adaptively diverging populations is not well understood. Here we characterized fine-scale recombination landscapes in an adaptively divergent pair of marine and freshwater populations of threespine stickleback from River Tyne, Scotland. Through whole-genome sequencing of large nuclear families, we identified the genomic locations of almost 50,000 crossovers and built recombination maps for marine, freshwater and hybrid individuals at a resolution of 3.8 kb. We used these maps to quantify the factors driving variation in recombination rates. We found strong heterochiasmy between sexes but also differences in recombination rates among ecotypes. Hybrids showed evidence of significant recombination suppression in overall map length and in individual loci. Recombination rates were lower not only within individual marine-freshwater-adaptive loci, but also between loci on the same chromosome, suggesting selection on linked gene 'cassettes'. Through temporal sampling along a natural hybrid zone, we found that recombinants showed traits associated with reduced fitness. Our results support predictions that divergence in cis-acting recombination modifiers, whose functions are disrupted in hybrids, may play an important role in maintaining differences among adaptively diverging populations.
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Affiliation(s)
- Vrinda Venu
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany.
- Los Alamos National Laboratory, New Mexico, NM, USA.
| | - Enni Harjunmaa
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
- CeGAT GmbH, Tübingen, Germany
| | - Andreea Dreau
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
- Evotec SE 'Campus Curie', Toulouse, France
| | - Shannon Brady
- Deptartment of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Devin Absher
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | - David M Kingsley
- Deptartment of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Felicity C Jones
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany.
- Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, the Netherlands.
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2
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Niu Y, Fan X, Yang Y, Li J, Lian J, Wang L, Zhang Y, Tang Y, Tang Z. Haplotype-resolved assembly of a pig genome using single-sperm sequencing. Commun Biol 2024; 7:738. [PMID: 38890535 PMCID: PMC11189477 DOI: 10.1038/s42003-024-06397-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 05/29/2024] [Indexed: 06/20/2024] Open
Abstract
Single gamete cell sequencing together with long-read sequencing can reliably produce chromosome-level phased genomes. In this study, we employed PacBio HiFi and Hi-C sequencing on a male Landrace pig, coupled with single-sperm sequencing of its 102 sperm cells. A haplotype assembly method was developed based on long-read sequencing and sperm-phased markers. The chromosome-level phased assembly showed higher phasing accuracy than methods that rely only on HiFi reads. The use of single-sperm sequencing data enabled the construction of a genetic map, successfully mapping the sperm motility trait to a specific region on chromosome 1 (105.40-110.70 Mb). Furthermore, with the assistance of Y chromosome-bearing sperm data, 26.16 Mb Y chromosome sequences were assembled. We report a reliable approach for assembling chromosome-level phased genomes and reveal the potential of sperm population in basic biology research and sperm phenotype research.
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Affiliation(s)
- Yongchao Niu
- Kunpeng Institute of Modern Agriculture at Foshan, Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Foshan, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Xinhao Fan
- Kunpeng Institute of Modern Agriculture at Foshan, Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Foshan, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
- GuangXi Engineering Centre for Resource Development of Bama Xiang Pig, Bama, China
- Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Yalan Yang
- Kunpeng Institute of Modern Agriculture at Foshan, Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Foshan, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
- Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Jiang Li
- Biozeron Shenzhen, Inc., Shenzhen, China
| | | | - Liu Wang
- Kunpeng Institute of Modern Agriculture at Foshan, Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Foshan, China
| | - Yongjin Zhang
- GuangXi Engineering Centre for Resource Development of Bama Xiang Pig, Bama, China
| | - Yijie Tang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
- Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Zhonglin Tang
- Kunpeng Institute of Modern Agriculture at Foshan, Agricultural Genomics Institute, Chinese Academy of Agricultural Sciences, Foshan, China.
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
- GuangXi Engineering Centre for Resource Development of Bama Xiang Pig, Bama, China.
- Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
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3
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Morgan AP, Payseur BA. Genetic background affects the strength of crossover interference in house mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.28.596233. [PMID: 38854148 PMCID: PMC11160618 DOI: 10.1101/2024.05.28.596233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Meiotic recombination is required for faithful chromosome segregation in most sexually reproducing organisms and shapes the distribution of genetic variation in populations. Both the overall rate and the spatial distribution of crossovers vary within and between species. Adjacent crossovers on the same chromosome tend to be spaced more evenly than expected at random, a phenomenon known as crossover interference. Although interference has been observed in many taxa, the factors that influence the strength of interference are not well understood. We used house mice (Mus musculus), a well-established model system for understanding recombination, to study the effects of genetics and age on recombination rate and interference in the male germline. We analyzed crossover positions in 503 progeny from reciprocal F1 hybrids between inbred strains representing the three major subspecies of house mice. Consistent with previous studies, autosomal alleles from M. m. musculus tend to increase recombination rate, while inheriting a M. m. musculus X chromosome decreases recombination rate. Old males transmit an average of 0.6 more crossovers per meiosis (5.0%) than young males, though the effect varies across genetic backgrounds. We show that the strength of crossover interference depends on genotype, providing a rare demonstration that interference evolves over short timescales. Differences between reciprocal F1s suggest that X-linked factors modulate the strength of interference. Our findings motivate additional comparisons of interference among recently diverged species and further examination of the role of paternal age in determining the number and positioning of crossovers.
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Affiliation(s)
- Andrew P Morgan
- Department of Medicine, University of North Carolina, Chapel Hill, NC
| | - Bret A Payseur
- Laboratory of Genetics, University of Wisconsin, Madison, WI
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4
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Chen Z, Zhou M, Sun Y, Tang X, Zhang Z, Huang L. Exploration of Genome-Wide Recombination Rate Variation Patterns at Different Scales in Pigs. Animals (Basel) 2024; 14:1345. [PMID: 38731349 PMCID: PMC11083071 DOI: 10.3390/ani14091345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 04/27/2024] [Accepted: 04/28/2024] [Indexed: 05/13/2024] Open
Abstract
Meiotic recombination is a prevalent process in eukaryotic sexual reproduction organisms that plays key roles in genetic diversity, breed selection, and species evolution. However, the recombination events differ across breeds and even within breeds. In this study, we initially computed large-scale population recombination rates of both sexes using approximately 52 K SNP genotypes in a total of 3279 pigs from four different Chinese and Western breeds. We then constructed a high-resolution historical recombination map using approximately 16 million SNPs from a sample of unrelated individuals. Comparative analysis of porcine recombination events from different breeds and at different resolutions revealed the following observations: Firstly, the 1Mb-scale pig recombination maps of the same sex are moderately conserved among different breeds, with the similarity of recombination events between Western pigs and Chinese indigenous pigs being lower than within their respective groups. Secondly, we identified 3861 recombination hotspots in the genome and observed medium- to high-level correlation between historical recombination rates (0.542~0.683) and estimates of meiotic recombination rates. Third, we observed that recombination hotspots are significantly far from the transcription start sites of pig genes, and the silico-predicted PRDM9 zinc finger domain DNA recognition motif is significantly enriched in the regions of recombination hotspots compared to recombination coldspots, highlighting the potential role of PRDM9 in regulating recombination hotspots in pigs. Our study analyzed the variation patterns of the pig recombination map at broad and fine scales, providing a valuable reference for genomic selection breeding and laying a crucial foundation for further understanding the molecular mechanisms of pig genome recombination.
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Affiliation(s)
| | | | | | | | - Zhiyan Zhang
- National Key Laboratory for Swine Genetic Improvement and Germplasm Innovation, Jiangxi Agricultural University, Nanchang 330045, China
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5
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Zou M, Shabala S, Zhao C, Zhou M. Molecular mechanisms and regulation of recombination frequency and distribution in plants. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2024; 137:86. [PMID: 38512498 PMCID: PMC10957645 DOI: 10.1007/s00122-024-04590-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 02/28/2024] [Indexed: 03/23/2024]
Abstract
KEY MESSAGE Recent developments in understanding the distribution and distinctive features of recombination hotspots are reviewed and approaches are proposed to increase recombination frequency in coldspot regions. Recombination events during meiosis provide the foundation and premise for creating new varieties of crops. The frequency of recombination in different genomic regions differs across eukaryote species, with recombination generally occurring more frequently at the ends of chromosomes. In most crop species, recombination is rare in centromeric regions. If a desired gene variant is linked in repulsion with an undesired variant of a second gene in a region with a low recombination rate, obtaining a recombinant plant combining two favorable alleles will be challenging. Traditional crop breeding involves combining desirable genes from parental plants into offspring. Therefore, understanding the mechanisms of recombination and factors affecting the occurrence of meiotic recombination is important for crop breeding. Here, we review chromosome recombination types, recombination mechanisms, genes and proteins involved in the meiotic recombination process, recombination hotspots and their regulation systems and discuss how to increase recombination frequency in recombination coldspot regions.
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Affiliation(s)
- Meilin Zou
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 1375, Prospect, TAS, 7250, Australia
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 1375, Prospect, TAS, 7250, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Perth, 6009, Australia
| | - Chenchen Zhao
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 1375, Prospect, TAS, 7250, Australia
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 1375, Prospect, TAS, 7250, Australia.
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6
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Úbeda F, Fyon F, Bürger R. The Recombination Hotspot Paradox: Co-evolution between PRDM9 and its target sites. Theor Popul Biol 2023; 153:69-90. [PMID: 37451508 DOI: 10.1016/j.tpb.2023.07.001] [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: 12/21/2022] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/18/2023]
Abstract
Recombination often concentrates in small regions called recombination hotspots where recombination is much higher than the genome's average. In many vertebrates, including humans, gene PRDM9 specifies which DNA motifs will be the target for breaks that initiate recombination, ultimately determining the location of recombination hotspots. Because the sequence that breaks (allowing recombination) is converted into the sequence that does not break (preventing recombination), the latter sequence is over-transmitted to future generations and recombination hotspots are self-destructive. Given their self-destructive nature, recombination hotspots should eventually become extinct in genomes where they are found. While empirical evidence shows that individual hotspots do become inactive over time (die), hotspots are abundant in many vertebrates: a contradiction called the Recombination Hotspot Paradox. What saves recombination hotspots from their foretold extinction? Here we formulate a co-evolutionary model of the interaction among sequence-specific gene conversion, fertility selection, and recurrent mutation. We find that allelic frequencies oscillate leading to stable limit cycles. From a biological perspective this means that when fertility selection is weaker than gene conversion, it cannot stop individual hotspots from dying but can save them from extinction by driving their re-activation (resuscitation). In our model, mutation balances death and resuscitation of hotspots, thus maintaining their number over evolutionary time. Interestingly, we find that multiple alleles result in oscillations that are chaotic and multiple targets in oscillations that are asynchronous between targets thus helping to maintain the average genomic recombination probability constant. Furthermore, we find that the level of expression of PRDM9 should control for the fraction of targets that are hotspots and the overall temperature of the genome. Therefore, our co-evolutionary model improves our understanding of how hotspots may be replaced, thus contributing to solve the Recombination Hotspot Paradox. From a more applied perspective our work provides testable predictions regarding the relation between mutation probability and fertility selection with life expectancy of hotspots.
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Affiliation(s)
- Francisco Úbeda
- Department of Biology, Royal Holloway University of London, Egham TW20 0EX, UK.
| | - Frédéric Fyon
- Department of Biology, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Reinhard Bürger
- Faculty of Mathematics, University of Vienna, 1090 Vienna, Austria
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7
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Valero-Regalón FJ, Solé M, López-Jiménez P, Valerio-de Arana M, Martín-Ruiz M, de la Fuente R, Marín-Gual L, Renfree MB, Shaw G, Berríos S, Fernández-Donoso R, Waters PD, Ruiz-Herrera A, Gómez R, Page J. Divergent patterns of meiotic double strand breaks and synapsis initiation dynamics suggest an evolutionary shift in the meiosis program between American and Australian marsupials. Front Cell Dev Biol 2023; 11:1147610. [PMID: 37181752 PMCID: PMC10166821 DOI: 10.3389/fcell.2023.1147610] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/06/2023] [Indexed: 05/16/2023] Open
Abstract
In eutherian mammals, hundreds of programmed DNA double-strand breaks (DSBs) are generated at the onset of meiosis. The DNA damage response is then triggered. Although the dynamics of this response is well studied in eutherian mammals, recent findings have revealed different patterns of DNA damage signaling and repair in marsupial mammals. To better characterize these differences, here we analyzed synapsis and the chromosomal distribution of meiotic DSBs markers in three different marsupial species (Thylamys elegans, Dromiciops gliorides, and Macropus eugenii) that represent South American and Australian Orders. Our results revealed inter-specific differences in the chromosomal distribution of DNA damage and repair proteins, which were associated with differing synapsis patterns. In the American species T. elegans and D. gliroides, chromosomal ends were conspicuously polarized in a bouquet configuration and synapsis progressed exclusively from the telomeres towards interstitial regions. This was accompanied by sparse H2AX phosphorylation, mainly accumulating at chromosomal ends. Accordingly, RAD51 and RPA were mainly localized at chromosomal ends throughout prophase I in both American marsupials, likely resulting in reduced recombination rates at interstitial positions. In sharp contrast, synapsis initiated at both interstitial and distal chromosomal regions in the Australian representative M. eugenii, the bouquet polarization was incomplete and ephemeral, γH2AX had a broad nuclear distribution, and RAD51 and RPA foci displayed an even chromosomal distribution. Given the basal evolutionary position of T. elegans, it is likely that the meiotic features reported in this species represent an ancestral pattern in marsupials and that a shift in the meiotic program occurred after the split of D. gliroides and the Australian marsupial clade. Our results open intriguing questions about the regulation and homeostasis of meiotic DSBs in marsupials. The low recombination rates observed at the interstitial chromosomal regions in American marsupials can result in the formation of large linkage groups, thus having an impact in the evolution of their genomes.
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Affiliation(s)
| | - Mireia Solé
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
- Genetics of Male Fertility Group, Unitat de Biologia Cel·lular, Universitat Autònoma de Barcelona, Spain
| | - Pablo López-Jiménez
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - María Valerio-de Arana
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Martín-Ruiz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Roberto de la Fuente
- Department of Experimental Embryology, Institute of Genetics and Animal Biotechnology of The Polish Academy of Sciences, Jastrzębiec, Poland
| | - Laia Marín-Gual
- Departament de Biologia Cel·lular, Universitat Autònoma de Barcelona, Barcelona, Spain
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Barcelona, Spain
| | - Marilyn B. Renfree
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Geoff Shaw
- School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Soledad Berríos
- Programa de Genética Humana, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - Raúl Fernández-Donoso
- Programa de Genética Humana, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - Paul D. Waters
- School of Biotechnology and Biomolecular Science, Faculty of Science, University of New South Wales, Sydney, NSW, Australia
| | - Aurora Ruiz-Herrera
- Departament de Biologia Cel·lular, Universitat Autònoma de Barcelona, Barcelona, Spain
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Barcelona, Spain
| | - Rocío Gómez
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Jesús Page
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
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8
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McManus JN, Lovelett RJ, Lowengrub D, Christensen S. A unifying statistical framework to discover disease genes from GWASs. CELL GENOMICS 2023; 3:100264. [PMID: 36950381 PMCID: PMC10025450 DOI: 10.1016/j.xgen.2023.100264] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 09/07/2022] [Accepted: 01/19/2023] [Indexed: 03/10/2023]
Abstract
Genome-wide association studies (GWASs) identify genomic loci associated with complex traits, but it remains a challenge to identify the genes affected by causal genetic variants in these loci. Attempts to solve this challenge are frustrated by a number of compounding problems. Here, we show how to combine solutions to these problems into a unified mathematical framework. From this synthesis, it becomes possible to compute the probability that each gene in the genome is affected by a causal variant, given a particular trait, without making assumptions about the relevant cell types or tissues. We validate each component of the framework individually and in combination. When applied to large GWASs of human disease, the resulting paradigm can rediscover the majority of well-known disease genes. Moreover, it establishes human genetics support for many genes previously implicated only by clinical or preclinical evidence, and it uncovers a plethora of novel disease genes with compelling biological rationale.
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Affiliation(s)
- Justin N.J. McManus
- Kallyope, Inc., 430 East 29th Street, New York, NY 10016, USA
- Corresponding author
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9
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Wang X, Li Z, Feng T, Luo X, Xue L, Mao C, Cui K, Li H, Huang J, Huang K, Rehman SU, Shi D, Wu D, Ruan J, Liu Q. Chromosome-level genome and recombination map of the male buffalo. Gigascience 2022; 12:giad063. [PMID: 37589307 PMCID: PMC10433102 DOI: 10.1093/gigascience/giad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/20/2023] [Accepted: 07/13/2023] [Indexed: 08/18/2023] Open
Abstract
BACKGROUND The swamp buffalo (Bubalus bubalis carabanesis) is an economically important livestock supplying milk, meat, leather, and draft power. Several female buffalo genomes have been available, but the lack of high-quality male genomes hinders studies on chromosome evolution, especially Y, as well as meiotic recombination. RESULTS Here, a chromosome-level genome with a contig N50 of 72.2 Mb and a fine-scale recombination map of male buffalo were reported. We found that transposable elements (TEs) and structural variants (SVs) may contribute to buffalo evolution by influencing adjacent gene expression. We further found that the pseudoautosomal region (PAR) of the Y chromosome is subject to stronger purification selection. The meiotic recombination map showed that there were 2 obvious recombination hotspots on chromosome 8, and the genes around them were mainly related to tooth development, which may have helped to enhance the adaption of buffalo to inferior feed. Among several genomic features, TE density has the strongest correlation with recombination rates. Moreover, the TE subfamily, SINE/tRNA, is likely to play a role in driving recombination into SVs. CONCLUSIONS The male genome and sperm sequencing will facilitate the understanding of the buffalo genomic evolution and functional research.
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Affiliation(s)
- Xiaobo Wang
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and Engineering, Foshan University, Foshan 528225, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Zhipeng Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Tong Feng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Xier Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Lintao Xue
- Reproductive Medical and Genetic Center, The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530021, China
| | - Chonghui Mao
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Kuiqing Cui
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and Engineering, Foshan University, Foshan 528225, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Hui Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Jieping Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Kongwei Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Saif-ur Rehman
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Deshun Shi
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
| | - Dongdong Wu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Jue Ruan
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Qingyou Liu
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and Engineering, Foshan University, Foshan 528225, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530005, China
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10
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Winbush A, Singh ND. Variation in fine-scale recombination rate in temperature-evolved Drosophila melanogaster populations in response to selection. G3 GENES|GENOMES|GENETICS 2022; 12:6663992. [PMID: 35961026 PMCID: PMC9526048 DOI: 10.1093/g3journal/jkac208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/05/2022] [Indexed: 11/16/2022]
Abstract
Meiotic recombination plays a critical evolutionary role in maintaining fitness in response to selective pressures due to changing environments. Variation in recombination rate has been observed amongst and between species and populations and within genomes across numerous taxa. Studies have demonstrated a link between changes in recombination rate and selection, but the extent to which fine-scale recombination rate varies between evolved populations during the evolutionary period in response to selection is under active research. Here, we utilize a set of 3 temperature-evolved Drosophila melanogaster populations that were shown to have diverged in several phenotypes, including recombination rate, based on the temperature regime in which they evolved. Using whole-genome sequencing data from these populations, we generated linkage disequilibrium-based fine-scale recombination maps for each population. With these maps, we compare recombination rates and patterns among the 3 populations and show that they have diverged at fine scales but are conserved at broader scales. We further demonstrate a correlation between recombination rates and genomic variation in the 3 populations. Lastly, we show variation in localized regions of enhanced recombination rates, termed warm spots, between the populations with these warm spots and associated genes overlapping areas previously shown to have diverged in the 3 populations due to selection. These data support the existence of recombination modifiers in these populations which are subject to selection during evolutionary change.
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Affiliation(s)
- Ari Winbush
- Department of Biology, Institute of Ecology and Evolution, University of Oregon , Eugene, OR 97403, USA
| | - Nadia D Singh
- Department of Biology, Institute of Ecology and Evolution, University of Oregon , Eugene, OR 97403, USA
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11
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R-Loop Formation in Meiosis: Roles in Meiotic Transcription-Associated DNA Damage. EPIGENOMES 2022; 6:epigenomes6030026. [PMID: 36135313 PMCID: PMC9498298 DOI: 10.3390/epigenomes6030026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/24/2022] [Accepted: 08/20/2022] [Indexed: 11/16/2022] Open
Abstract
Meiosis is specialized cell division during gametogenesis that produces genetically unique gametes via homologous recombination. Meiotic homologous recombination entails repairing programmed 200–300 DNA double-strand breaks generated during the early prophase. To avoid interference between meiotic gene transcription and homologous recombination, mammalian meiosis is thought to employ a strategy of exclusively transcribing meiotic or post-meiotic genes before their use. Recent studies have shown that R-loops, three-stranded DNA/RNA hybrid nucleotide structures formed during transcription, play a crucial role in transcription and genome integrity. Although our knowledge about the function of R-loops during meiosis is limited, recent findings in mouse models have suggested that they play crucial roles in meiosis. Given that defective formation of an R-loop can cause abnormal transcription and transcription-coupled DNA damage, the precise regulatory network of R-loops may be essential in vivo for the faithful progression of mammalian meiosis and gametogenesis.
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Yang L, Gao Y, Li M, Park KE, Liu S, Kang X, Liu M, Oswalt A, Fang L, Telugu BP, Sattler CG, Li CJ, Cole JB, Seroussi E, Xu L, Yang L, Zhou Y, Li L, Zhang H, Rosen BD, Van Tassell CP, Ma L, Liu GE. Genome-wide recombination map construction from single sperm sequencing in cattle. BMC Genomics 2022; 23:181. [PMID: 35247961 PMCID: PMC8898482 DOI: 10.1186/s12864-022-08415-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 02/24/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Meiotic recombination is one of the important phenomena contributing to gamete genome diversity. However, except for human and a few model organisms, it is not well studied in livestock, including cattle. RESULTS To investigate their distributions in the cattle sperm genome, we sequenced 143 single sperms from two Holstein bulls. We mapped meiotic recombination events at high resolution based on phased heterozygous single nucleotide polymorphism (SNP). In the absence of evolutionary selection pressure in fertilization and survival, recombination events in sperm are enriched near distal chromosomal ends, revealing that such a pattern is intrinsic to the molecular mechanism of meiosis. Furthermore, we further validated these findings in single sperms with results derived from sequencing its family trio of diploid genomes and our previous studies of recombination in cattle. CONCLUSIONS To our knowledge, this is the first large-scale single sperm whole-genome sequencing effort in livestock, which provided useful information for future studies of recombination, genome instability, and male infertility.
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Affiliation(s)
- Liu Yang
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130 China
| | - Yahui Gao
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742 USA
| | - Mingxun Li
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009 China
| | - Ki-Eun Park
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742 USA
| | - Shuli Liu
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
- College of Animal Science and Technology, China Agricultural University, Beijing, 100193 China
| | - Xiaolong Kang
- College of Agriculture, Ningxia University, Yinchuan, 750021 China
| | - Mei Liu
- Animal Nutritional Genome and Germplasm Innovation Research Center, College of Animal Science and Technology, Hunan Agricultural University, Changsha, 410128 China
| | - Adam Oswalt
- Select Sires Inc, 11740 U.S. 42 North, Plain City, OH 43064 USA
| | - Lingzhao Fang
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, EH25 9RG UK
| | - Bhanu P. Telugu
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742 USA
- Division of Animal Sciences, University of Missouri, Columbia, MO 65201 USA
| | | | - Cong-jun Li
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
| | - John B. Cole
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
| | - Eyal Seroussi
- Agricultural Research Organization (ARO), Volcani Center, Institute of Animal Science, P.O.B 15159, HaMaccabim Road, 7528809 Rishon LeTsiyon, Israel
| | - Lingyang Xu
- Innovation Team of Cattle Genetic Breeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193 China
| | - Lv Yang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070 China
| | - Yang Zhou
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070 China
| | - Li Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130 China
| | - Hongping Zhang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130 China
| | - Benjamin D. Rosen
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
| | - Curtis P. Van Tassell
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
| | - Li Ma
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742 USA
| | - George E. Liu
- Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705 USA
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Keshavarz M, Savriama Y, Refki P, Reeves RG, Tautz D. Natural copy number variation of tandemly repeated regulatory SNORD RNAs leads to individual phenotypic differences in mice. Mol Ecol 2021; 30:4708-4722. [PMID: 34252239 DOI: 10.1111/mec.16076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/05/2021] [Indexed: 12/01/2022]
Abstract
Genic copy number differences can have phenotypic consequences, but so far this has not been studied in detail in natural populations. Here, we analysed the natural variation of two families of tandemly repeated regulatory small nucleolar RNAs (SNORD115 and SNORD116) in the house mouse (Mus musculus). They are encoded within the Prader-Willi Syndrome gene region, known to be involved in behavioural, metabolic, and osteogenic functions in mammals. We determined that the copy numbers of these SNORD RNAs show substantial natural variation, both in wild-derived mice as well as in an inbred mouse strain (C57BL/6J). We show that copy number differences are subject to change across generations, making them highly variable and resulting in individual differences. In transcriptome data from brain samples, we found SNORD copy-number correlated regulation of possible target genes, including Htr2c, a predicted target gene of SNORD115, as well as Ankrd11, a predicted target gene of SNORD116. Ankrd11 is a chromatin regulator, which has previously been implicated in regulating the development of the skull. Based on morphometric shape analysis of the skulls of individual mice of the inbred strain, we show that shape measures correlate with SNORD116 copy numbers in the respective individuals. Our results suggest that the variable dosage of regulatory RNAs can lead to phenotypic variation between individuals that would typically have been ascribed to environmentally induced variation, while it is actually encoded in individual differences of copy numbers of regulatory molecules.
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Affiliation(s)
| | - Yoland Savriama
- Max-Planck Institute for Evolutionary Biology, Plön, Germany
| | - Peter Refki
- Max-Planck Institute for Evolutionary Biology, Plön, Germany
| | - R Guy Reeves
- Max-Planck Institute for Evolutionary Biology, Plön, Germany
| | - Diethard Tautz
- Max-Planck Institute for Evolutionary Biology, Plön, Germany
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Legoff L, Dali O, De La Mata Santaella E, Jaulin C, D'Cruz SC, Smagulova F. Histone deacetylase inhibition leads to regulatory histone mark alterations and impairs meiosis in oocytes. Epigenetics Chromatin 2021; 14:39. [PMID: 34384478 PMCID: PMC8359552 DOI: 10.1186/s13072-021-00413-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 08/02/2021] [Indexed: 02/07/2023] Open
Abstract
Background Panobinostat (PB), a histone deacetylase (HDAC) inhibitor drug, is clinically used in the treatment of cancers. We investigated the effects of PB on murine ovarian functions in embryos and adult animals. Methods C57BL/6J mice were treated with 5 mg/kg PB on alternate days from embryonic day (E) 6.5 to E15.5. We analysed the effects of PB on the ovaries by using immunofluorescence, gene expression analysis and DNA methylation analysis techniques. Results At E15.5, we observed increases in histone H3K9Ac, H4Ac and H3K4me3 marks, while the level of the silencing H3K9me3 mark decreased. Synaptonemal complex examination at E15.5, E17.5 and E18.5 showed a delay in meiotic progression characterized by the absence of synaptonemal complexes at E15.5 and the persistence of double-strand breaks (DSBs) at E17.5 and E18.5 in PB-exposed oocytes. We found that exposure to PB led to changes in the expression of 1169 transcripts at E15.5. Genes regulated by the male-specific factors SRY-Box Transcription Factor 9 (SOX9) and Doublesex and Mab-3-related Transcription factor 1 (DMRT1) were among the most upregulated genes in the ovaries of PB-exposed mice. In contrast, PB treatment led to decreases in the expression of genes regulated by the WNT4 pathway. Notably, we observed 119 deregulated genes encoding Zn-finger proteins. The observed alterations in epigenetic marks and gene expression correlated with decreases in the numbers of germ cells at E15.5. After birth, PB-exposed ovaries showed increased proliferation of primary and secondary follicles. We also observed decreases in the numbers of primordial, primary and secondary follicles in adult ovaries from mice that were exposed to PB in utero. Finally, epigenetic alterations such as decreased H3K4me3 and increased H4 acetylation levels were also detected in somatic cells surrounding fully grown oocytes. Conclusion Our data suggest that inhibition of histone deacetylase by PB during a critical developmental window affects reprogramming and germ cell specification via alteration of epigenetic marks. Supplementary Information The online version contains supplementary material available at 10.1186/s13072-021-00413-8.
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Affiliation(s)
- Louis Legoff
- Univ. Rennes, EHESP, Inserm, Irset (Institut de Recherche en Santé, environnement et travail) - UMR_S 1085, 35000, Rennes, France
| | - Ouzna Dali
- Univ. Rennes, EHESP, Inserm, Irset (Institut de Recherche en Santé, environnement et travail) - UMR_S 1085, 35000, Rennes, France
| | - Elena De La Mata Santaella
- Univ. Rennes, EHESP, Inserm, Irset (Institut de Recherche en Santé, environnement et travail) - UMR_S 1085, 35000, Rennes, France
| | - Christian Jaulin
- Univ. Rennes, EHESP, Inserm, Irset (Institut de Recherche en Santé, environnement et travail) - UMR_S 1085, 35000, Rennes, France
| | - Shereen Cynthia D'Cruz
- Univ. Rennes, EHESP, Inserm, Irset (Institut de Recherche en Santé, environnement et travail) - UMR_S 1085, 35000, Rennes, France.
| | - Fatima Smagulova
- Univ. Rennes, EHESP, Inserm, Irset (Institut de Recherche en Santé, environnement et travail) - UMR_S 1085, 35000, Rennes, France.
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Jin X, Fudenberg G, Pollard KS. Genome-wide variability in recombination activity is associated with meiotic chromatin organization. Genome Res 2021; 31:1561-1572. [PMID: 34301629 PMCID: PMC8415379 DOI: 10.1101/gr.275358.121] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 07/22/2021] [Indexed: 11/24/2022]
Abstract
Recombination enables reciprocal exchange of genomic information between parental chromosomes and successful segregation of homologous chromosomes during meiosis. Errors in this process lead to negative health outcomes, whereas variability in recombination rate affects genome evolution. In mammals, most crossovers occur in hotspots defined by PRDM9 motifs, although PRDM9 binding peaks are not all equally hot. We hypothesize that dynamic patterns of meiotic genome folding are linked to recombination activity. We apply an integrative bioinformatics approach to analyze how three-dimensional (3D) chromosomal organization during meiosis relates to rates of double-strand-break (DSB) and crossover (CO) formation at PRDM9 binding peaks. We show that active, spatially accessible genomic regions during meiotic prophase are associated with DSB-favored loci, which further adopt a transient locally active configuration in early prophase. Conversely, crossover formation is depleted among DSBs in spatially accessible regions during meiotic prophase, particularly within gene bodies. We also find evidence that active chromatin regions have smaller average loop sizes in mammalian meiosis. Collectively, these findings establish that differences in chromatin architecture along chromosomal axes are associated with variable recombination activity. We propose an updated framework describing how 3D organization of brush-loop chromosomes during meiosis may modulate recombination.
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Affiliation(s)
- Xiaofan Jin
- Gladstone Institutes, San Francisco, California 94158, USA
| | - Geoff Fudenberg
- Gladstone Institutes, San Francisco, California 94158, USA.,Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California 90089, USA
| | - Katherine S Pollard
- Gladstone Institutes, San Francisco, California 94158, USA.,University of California San Francisco, San Francisco, California 94143, USA.,Chan-Zuckerberg Biohub, San Francisco, California 94158, USA
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16
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Wang X, Pepling ME. Regulation of Meiotic Prophase One in Mammalian Oocytes. Front Cell Dev Biol 2021; 9:667306. [PMID: 34095134 PMCID: PMC8172968 DOI: 10.3389/fcell.2021.667306] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/28/2021] [Indexed: 11/23/2022] Open
Abstract
In female mammals, meiotic prophase one begins during fetal development. Oocytes transition through the prophase one substages consisting of leptotene, zygotene, and pachytene, and are finally arrested at the diplotene substage, for months in mice and years in humans. After puberty, luteinizing hormone induces ovulation and meiotic resumption in a cohort of oocytes, driving the progression from meiotic prophase one to metaphase two. If fertilization occurs, the oocyte completes meiosis two followed by fusion with the sperm nucleus and preparation for zygotic divisions; otherwise, it is passed into the uterus and degenerates. Specifically in the mouse, oocytes enter meiosis at 13.5 days post coitum. As meiotic prophase one proceeds, chromosomes find their homologous partner, synapse, exchange genetic material between homologs and then begin to separate, remaining connected at recombination sites. At postnatal day 5, most of the oocytes have reached the late diplotene (or dictyate) substage of prophase one where they remain arrested until ovulation. This review focuses on events and mechanisms controlling the progression through meiotic prophase one, which include recombination, synapsis and control by signaling pathways. These events are prerequisites for proper chromosome segregation in meiotic divisions; and if they go awry, chromosomes mis-segregate resulting in aneuploidy. Therefore, elucidating the mechanisms regulating meiotic progression is important to provide a foundation for developing improved treatments of female infertility.
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17
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Halo JV, Pendleton AL, Shen F, Doucet AJ, Derrien T, Hitte C, Kirby LE, Myers B, Sliwerska E, Emery S, Moran JV, Boyko AR, Kidd JM. Long-read assembly of a Great Dane genome highlights the contribution of GC-rich sequence and mobile elements to canine genomes. Proc Natl Acad Sci U S A 2021; 118:e2016274118. [PMID: 33836575 PMCID: PMC7980453 DOI: 10.1073/pnas.2016274118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Technological advances have allowed improvements in genome reference sequence assemblies. Here, we combined long- and short-read sequence resources to assemble the genome of a female Great Dane dog. This assembly has improved continuity compared to the existing Boxer-derived (CanFam3.1) reference genome. Annotation of the Great Dane assembly identified 22,182 protein-coding gene models and 7,049 long noncoding RNAs, including 49 protein-coding genes not present in the CanFam3.1 reference. The Great Dane assembly spans the majority of sequence gaps in the CanFam3.1 reference and illustrates that 2,151 gaps overlap the transcription start site of a predicted protein-coding gene. Moreover, a subset of the resolved gaps, which have an 80.95% median GC content, localize to transcription start sites and recombination hotspots more often than expected by chance, suggesting the stable canine recombinational landscape has shaped genome architecture. Alignment of the Great Dane and CanFam3.1 assemblies identified 16,834 deletions and 15,621 insertions, as well as 2,665 deletions and 3,493 insertions located on secondary contigs. These structural variants are dominated by retrotransposon insertion/deletion polymorphisms and include 16,221 dimorphic canine short interspersed elements (SINECs) and 1,121 dimorphic long interspersed element-1 sequences (LINE-1_Cfs). Analysis of sequences flanking the 3' end of LINE-1_Cfs (i.e., LINE-1_Cf 3'-transductions) suggests multiple retrotransposition-competent LINE-1_Cfs segregate among dog populations. Consistent with this conclusion, we demonstrate that a canine LINE-1_Cf element with intact open reading frames can retrotranspose its own RNA and that of a SINEC_Cf consensus sequence in cultured human cells, implicating ongoing retrotransposon activity as a driver of canine genetic variation.
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Affiliation(s)
- Julia V Halo
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - Amanda L Pendleton
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - Feichen Shen
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - Aurélien J Doucet
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
- Université Côte d'Azur, CNRS, INSERM, Institut de Recherche sur le Cancer et le Vieillissement de Nice, F-06100 Nice, France
| | - Thomas Derrien
- Université de Rennes 1, CNRS, Institut de Génétique et Développement de Rennes-UMR 6290, F-35000 Rennes, France
| | - Christophe Hitte
- Université de Rennes 1, CNRS, Institut de Génétique et Développement de Rennes-UMR 6290, F-35000 Rennes, France
| | - Laura E Kirby
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - Bridget Myers
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - Elzbieta Sliwerska
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - Sarah Emery
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - John V Moran
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Adam R Boyko
- Department of Biomedical Sciences, Cornell University, Ithaca, NY 14850
| | - Jeffrey M Kidd
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109;
- Department Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109
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18
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Qanbari S, Wittenburg D. Male recombination map of the autosomal genome in German Holstein. Genet Sel Evol 2020; 52:73. [PMID: 33317445 PMCID: PMC7734841 DOI: 10.1186/s12711-020-00593-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/26/2020] [Indexed: 11/10/2022] Open
Abstract
Background Recombination is a process by which chromosomes are broken and recombine to generate new combinations of alleles, therefore playing a major role in shaping genome variation. Recombination frequencies (\documentclass[12pt]{minimal}
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\begin{document}$$\theta$$\end{document}θ) between markers are used to construct genetic maps, which have important implications in genomic studies. Here, we report a recombination map for 44,696 autosomal single nucleotide polymorphisms (SNPs) according to the coordinates of the most recent bovine reference assembly. The recombination frequencies were estimated across 876 half-sib families with a minimum number of 39 and maximum number of 4236 progeny, comprising over 367 K genotyped German Holstein animals. Results Genome-wide, over 8.9 million paternal recombination events were identified by investigating adjacent markers. The recombination map spans 24.43 Morgan (M) for a chromosomal length of 2486 Mbp and an average of ~ 0.98 cM/Mbp, which concords with the available pedigree-based linkage maps. Furthermore, we identified 971 putative recombination hotspot intervals (defined as \documentclass[12pt]{minimal}
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\begin{document}$$\theta$$\end{document}θ > 2.5 standard deviations greater than the mean). The hotspot regions were non-uniformly distributed as sharp and narrow peaks, corresponding to ~ 5.8% of the recombination that has taken place in only ~ 2.4% of the genome. We verified genetic map length by applying a likelihood-based approach for the estimation of recombination rate between all intra-chromosomal marker pairs. This resulted in a longer autosomal genetic length for male cattle (25.35 cM) and in the localization of 51 putatively misplaced SNPs in the genome assembly. Conclusions Given the fact that this map is built on the coordinates of the ARS-UCD1.2 assembly, our results provide the most updated genetic map yet available for the cattle genome.
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Affiliation(s)
- Saber Qanbari
- Leibniz Institute for Farm Animal Biology (FBN), Institute of Genetics and Biometry, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany.
| | - Dörte Wittenburg
- Leibniz Institute for Farm Animal Biology (FBN), Institute of Genetics and Biometry, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
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19
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Proteome landscape and spatial map of mouse primordial germ cells. SCIENCE CHINA-LIFE SCIENCES 2020; 64:966-981. [PMID: 32860578 DOI: 10.1007/s11427-020-1762-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/19/2020] [Indexed: 10/23/2022]
Abstract
Primordial germ cells (PGCs) are precursors of both male and female gametes as fundamental materials for organism development. The transcriptome, methylome, and chromatin accessibility profiles of PGCs in both mice and humans have been recently reported. However, little is known about the characteristics of PGCs at the protein levels, which directly exert cellular functions. Here, we construct landscapes of both proteome and 3D spatial distribution of mouse PGCs at E11.5, E13.5 and E16.5 days, the three critical developmental windows for PGCs' sex differentiation, female meiosis initiation and male mitotic arrest. In each developmental stage of PGCs, nearly 2,000-3,000 proteins are identified, among which specific functional pathways such as oxidative phosphorylation, DNA damage repair, and meiotic cell cycle are involved for different events during PGCs development. Interestingly, by 3D modeling we find that PGCs spatially cluster into around 1,300 nests in genital ridge at E11.5 and the nest number is not increased by the exponential proliferation of PGCs. Comparative analysis of our proteomic data with published transcriptomic data does not show a close correlation, meaning that the practically executive factors are beyond the transcriptome. Thus, our work offers a valuable resource for the systematic investigations of PGC development at protein level and spatial map.
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20
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From molecules to populations: appreciating and estimating recombination rate variation. Nat Rev Genet 2020; 21:476-492. [DOI: 10.1038/s41576-020-0240-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2020] [Indexed: 02/07/2023]
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21
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Jiang Y, Zhang HY, Lin Z, Zhu YZ, Yu C, Sha QQ, Tong MH, Shen L, Fan HY. CXXC finger protein 1-mediated histone H3 lysine-4 trimethylation is essential for proper meiotic crossover formation in mice. Development 2020; 147:dev183764. [PMID: 32094118 DOI: 10.1242/dev.183764] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 02/14/2020] [Indexed: 12/20/2022]
Abstract
The most significant feature of meiosis is the recombination process during prophase I. CXXC finger protein 1 (CXXC1) binds to CpG islands and mediates the deposition of H3K4me3 by the SETD1 complex. CXXC1 is also predicted to recruit H3K4me3-marked regions to the chromosome axis for the generation of double-strand breaks (DSBs) in the prophase of meiosis. Therefore, we deleted Cxxc1 before the onset of meiosis with Stra8-Cre The conditional knockout mice were completely sterile with spermatogenesis arrested at MII. Knockout of Cxxc1 led to a decrease in the H3K4me3 level from the pachytene to the MII stage and caused transcriptional disorder. Many spermatogenesis pathway genes were expressed early leading to abnormal acrosome formation in arrested MII cells. In meiotic prophase, deletion of Cxxc1 caused delayed DSB repair and improper crossover formation in cells at the pachytene stage, and more than half of the diplotene cells exhibited precocious homologous chromosome segregation in both male and female meiosis. Cxxc1 deletion also led to a significant decrease of H3K4me3 enrichment at DMC1-binding sites, which might compromise DSB generation. Taken together, our results show that CXXC1 is essential for proper meiotic crossover formation in mice and suggest that CXXC1-mediated H3K4me3 plays an essential role in meiotic prophase of spermatogenesis and oogenesis.
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Affiliation(s)
- Yu Jiang
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Hui-Ying Zhang
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Zhen Lin
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Ye-Zhang Zhu
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Chao Yu
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Qian-Qian Sha
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Ming-Han Tong
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Li Shen
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Heng-Yu Fan
- MOE Key Laboratory for Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China
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Abstract
Sex differences in overall recombination rates are well known, but little theoretical or empirical attention has been given to how and why sexes differ in their recombination landscapes: the patterns of recombination along chromosomes. In the first scientific review of this phenomenon, we find that recombination is biased toward telomeres in males and more uniformly distributed in females in most vertebrates and many other eukaryotes. Notable exceptions to this pattern exist, however. Fine-scale recombination patterns also frequently differ between males and females. The molecular mechanisms responsible for sex differences remain unclear, but chromatin landscapes play a role. Why these sex differences evolve also is unclear. Hypotheses suggest that they may result from sexually antagonistic selection acting on coding genes and their regulatory elements, meiotic drive in females, selection during the haploid phase of the life cycle, selection against aneuploidy, or mechanistic constraints. No single hypothesis, however, can adequately explain the evolution of sex differences in all cases. Sex-specific recombination landscapes have important consequences for population differentiation and sex chromosome evolution.
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Affiliation(s)
- Jason M. Sardell
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712
| | - Mark Kirkpatrick
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712
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23
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Li G, Figueiró HV, Eizirik E, Murphy WJ. Recombination-Aware Phylogenomics Reveals the Structured Genomic Landscape of Hybridizing Cat Species. Mol Biol Evol 2020; 36:2111-2126. [PMID: 31198971 PMCID: PMC6759079 DOI: 10.1093/molbev/msz139] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Current phylogenomic approaches implicitly assume that the predominant phylogenetic signal within a genome reflects the true evolutionary history of organisms, without assessing the confounding effects of postspeciation gene flow that can produce a mosaic of phylogenetic signals that interact with recombinational variation. Here, we tested the validity of this assumption with a phylogenomic analysis of 27 species of the cat family, assessing local effects of recombination rate on species tree inference and divergence time estimation across their genomes. We found that the prevailing phylogenetic signal within the autosomes is not always representative of the most probable speciation history, due to ancient hybridization throughout felid evolution. Instead, phylogenetic signal was concentrated within regions of low recombination, and notably enriched within large X chromosome recombination cold spots that exhibited recurrent patterns of strong genetic differentiation and selective sweeps across mammalian orders. By contrast, regions of high recombination were enriched for signatures of ancient gene flow, and these sequences inflated crown-lineage divergence times by ∼40%. We conclude that existing phylogenomic approaches to infer the Tree of Life may be highly misleading without considering the genomic architecture of phylogenetic signal relative to recombination rate and its interplay with historical hybridization.
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Affiliation(s)
- Gang Li
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Henrique V Figueiró
- PUCRS, Escola de Ciências, Laboratory of Genomics and Molecular Biology, Porto Alegre, Brazil.,INCT-EECBio, Brazil
| | - Eduardo Eizirik
- PUCRS, Escola de Ciências, Laboratory of Genomics and Molecular Biology, Porto Alegre, Brazil.,INCT-EECBio, Brazil
| | - William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
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24
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Pearse DE, Barson NJ, Nome T, Gao G, Campbell MA, Abadía-Cardoso A, Anderson EC, Rundio DE, Williams TH, Naish KA, Moen T, Liu S, Kent M, Moser M, Minkley DR, Rondeau EB, Brieuc MSO, Sandve SR, Miller MR, Cedillo L, Baruch K, Hernandez AG, Ben-Zvi G, Shem-Tov D, Barad O, Kuzishchin K, Garza JC, Lindley ST, Koop BF, Thorgaard GH, Palti Y, Lien S. Sex-dependent dominance maintains migration supergene in rainbow trout. Nat Ecol Evol 2019; 3:1731-1742. [DOI: 10.1038/s41559-019-1044-6] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/18/2019] [Indexed: 11/09/2022]
Abstract
AbstractMales and females often differ in their fitness optima for shared traits that have a shared genetic basis, leading to sexual conflict. Morphologically differentiated sex chromosomes can resolve this conflict and protect sexually antagonistic variation, but they accumulate deleterious mutations. However, how sexual conflict is resolved in species that lack differentiated sex chromosomes is largely unknown. Here we present a chromosome-anchored genome assembly for rainbow trout (Oncorhynchus mykiss) and characterize a 55-Mb double-inversion supergene that mediates sex-specific migratory tendency through sex-dependent dominance reversal, an alternative mechanism for resolving sexual conflict. The double inversion contains key photosensory, circadian rhythm, adiposity and sex-related genes and displays a latitudinal frequency cline, indicating environmentally dependent selection. Our results show sex-dependent dominance reversal across a large autosomal supergene, a mechanism for sexual conflict resolution capable of protecting sexually antagonistic variation while avoiding the homozygous lethality and deleterious mutations associated with typical heteromorphic sex chromosomes.
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25
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Mouresan EF, González-Rodríguez A, Cañas-Álvarez JJ, Munilla S, Altarriba J, Díaz C, Baró JA, Molina A, Lopez-Buesa P, Piedrafita J, Varona L. Mapping Recombination Rate on the Autosomal Chromosomes Based on the Persistency of Linkage Disequilibrium Phase Among Autochthonous Beef Cattle Populations in Spain. Front Genet 2019; 10:1170. [PMID: 31824571 PMCID: PMC6880760 DOI: 10.3389/fgene.2019.01170] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 10/23/2019] [Indexed: 01/14/2023] Open
Abstract
In organisms with sexual reproduction, genetic diversity, and genome evolution are governed by meiotic recombination caused by crossing-over, which is known to vary within the genome. In this study, we propose a simple method to estimate the recombination rate that makes use of the persistency of linkage disequilibrium (LD) phase among closely related populations. The biological material comprised 171 triplets (sire/dam/offspring) from seven populations of autochthonous beef cattle in Spain (Asturiana de los Valles, Avileña-Negra Ibérica, Bruna dels Pirineus, Morucha, Pirenaica, Retinta, and Rubia Gallega), which were genotyped for 777,962 SNPs with the BovineHD BeadChip. After standard quality filtering, we reconstructed the haplotype phases in the parental individuals and calculated the LD by the correlation -r- between each pair of markers that had a genetic distance < 1 Mb. Subsequently, these correlations were used to calculate the persistency of LD phase between each pair of populations along the autosomal genome. Therefore, the distribution of the recombination rate along the genome can be inferred since the effect of the number of generations of divergence should be equivalent throughout the genome. In our study, the recombination rate was highest in the largest chromosomes and at the distal portion of the chromosomes. In addition, the persistency of LD phase was highly heterogeneous throughout the genome, with a ratio of 25.4 times between the estimates of the recombination rates from the genomic regions that had the highest (BTA18-7.1 Mb) and the lowest (BTA12-42.4 Mb) estimates. Finally, an overrepresentation enrichment analysis (ORA) showed differences in the enriched gene ontology (GO) terms between the genes located in the genomic regions with estimates of the recombination rate over (or below) the 95th (or 5th) percentile throughout the autosomal genome.
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Affiliation(s)
- Elena Flavia Mouresan
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
| | | | | | - Sebastián Munilla
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain.,Departamento de Producción Animal, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Juan Altarriba
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
| | - Clara Díaz
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
| | - Jesús A Baró
- Instituto Agroalimentario de Aragón (IA2), Zaragoza, Spain
| | - Antonio Molina
- Departamento de Ciencias Agroforestales, Universidad de Valladolid, Valladolid, Spain
| | - Pascual Lopez-Buesa
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
| | - Jesús Piedrafita
- Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luis Varona
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
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26
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Rowan BA, Heavens D, Feuerborn TR, Tock AJ, Henderson IR, Weigel D. An Ultra High-Density Arabidopsis thaliana Crossover Map That Refines the Influences of Structural Variation and Epigenetic Features. Genetics 2019; 213:771-787. [PMID: 31527048 PMCID: PMC6827372 DOI: 10.1534/genetics.119.302406] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/28/2019] [Indexed: 11/18/2022] Open
Abstract
Many environmental, genetic, and epigenetic factors are known to affect the frequency and positioning of meiotic crossovers (COs). Suppression of COs by large, cytologically visible inversions and translocations has long been recognized, but relatively little is known about how smaller structural variants (SVs) affect COs. To examine fine-scale determinants of the CO landscape, including SVs, we used a rapid, cost-effective method for high-throughput sequencing to generate a precise map of >17,000 COs between the Col-0 and Ler-0 accessions of Arabidopsis thaliana COs were generally suppressed in regions with SVs, but this effect did not depend on the size of the variant region, and was only marginally affected by the variant type. CO suppression did not extend far beyond the SV borders and CO rates were slightly elevated in the flanking regions. Disease resistance gene clusters, which often exist as SVs, exhibited high CO rates at some loci, but there was a tendency toward depressed CO rates at loci where large structural differences exist between the two parents. Our high-density map also revealed in fine detail how CO positioning relates to genetic (DNA motifs) and epigenetic (chromatin structure) features of the genome. We conclude that suppression of COs occurs over a narrow region spanning large- and small-scale SVs, representing an influence on the CO landscape in addition to sequence and epigenetic variation along chromosomes.
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Affiliation(s)
- Beth A Rowan
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | | | - Tatiana R Feuerborn
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Andrew J Tock
- Department of Plant Sciences, University of Cambridge, CB2 3EA, United Kingdom
| | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, CB2 3EA, United Kingdom
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
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27
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Rapp JP, Joe B. Dissecting Epistatic QTL for Blood Pressure in Rats: Congenic Strains versus Heterogeneous Stocks, a Reality Check. Compr Physiol 2019; 9:1305-1337. [PMID: 31688958 DOI: 10.1002/cphy.c180038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Advances in molecular genetics have provided well-defined physical genetic maps and large numbers of genetic markers for both model organisms and humans. It is now possible to gain a fundamental understanding of the genetic architecture underlying quantitative traits, of which blood pressure (BP) is an important example. This review emphasizes analytical techniques and results obtained using the Dahl salt-sensitive (S) rat as a model of hypertension by presenting results in detail for three specific chromosomal regions harboring genetic elements of increasing complexity controlling BP. These results highlight the critical importance of genetic interactions (epistasis) on BP at all levels of structure, intragenic, intergenic, intrachromosomal, interchromosomal, and across whole genomes. In two of the three examples presented, specific DNA structural variations leading to biochemical, physiological, and pathological mechanisms are well defined. This proves the usefulness of the techniques involving interval mapping followed by substitution mapping using congenic strains. These classic techniques are compared to newer approaches using sophisticated statistical analysis on various segregating or outbred model-organism populations, which in some cases are uniquely useful in demonstrating the existence of higher-order interactions. It is speculated that hypertension as an outlier quantitative phenotype is dependent on higher-order genetic interactions. The obstacle to the identification of genetic elements and the biochemical/physiological mechanisms involved in higher-order interactions is not theoretical or technical but the lack of future resources to finish the job of identifying the individual genetic elements underlying the quantitative trait loci for BP and ascertaining their molecular functions. © 2019 American Physiological Society. Compr Physiol 9:1305-1337, 2019.
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Affiliation(s)
- John P Rapp
- Physiological Genomics Laboratory, Department of Physiology and Pharmacology, Center for Hypertension and Precision Medicine, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Bina Joe
- Physiological Genomics Laboratory, Department of Physiology and Pharmacology, Center for Hypertension and Precision Medicine, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
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28
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Li R, Bitoun E, Altemose N, Davies RW, Davies B, Myers SR. A high-resolution map of non-crossover events reveals impacts of genetic diversity on mammalian meiotic recombination. Nat Commun 2019; 10:3900. [PMID: 31467277 PMCID: PMC6715734 DOI: 10.1038/s41467-019-11675-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 07/17/2019] [Indexed: 12/21/2022] Open
Abstract
During meiotic recombination, homologue-templated repair of programmed DNA double-strand breaks (DSBs) produces relatively few crossovers and many difficult-to-detect non-crossovers. By intercrossing two diverged mouse subspecies over five generations and deep-sequencing 119 offspring, we detect thousands of crossover and non-crossover events genome-wide with unprecedented power and spatial resolution. We find that both crossovers and non-crossovers are strongly depleted at DSB hotspots where the DSB-positioning protein PRDM9 fails to bind to the unbroken homologous chromosome, revealing that PRDM9 also functions to promote homologue-templated repair. Our results show that complex non-crossovers are much rarer in mice than humans, consistent with complex events arising from accumulated non-programmed DNA damage. Unexpectedly, we also find that GC-biased gene conversion is restricted to non-crossover tracts containing only one mismatch. These results demonstrate that local genetic diversity profoundly alters meiotic repair pathway decisions via at least two distinct mechanisms, impacting genome evolution and Prdm9-related hybrid infertility. During meiotic recombination, genetic information is transferred or exchanged between parental chromosome copies. Using a large hybrid mouse pedigree, the authors generated high-resolution maps of these transfer/exchange events and discovered new properties governing their processing and resolution.
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Affiliation(s)
- Ran Li
- The Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, OX3 7BN, UK.,Department of Statistics, University of Oxford, 24-29 St Giles', Oxford, OX1 3LB, UK.,Target Discovery Institute, NDM Research Building, University of Oxford, Old Road Campus, Headington, Oxford, OX3 7FZ, UK
| | - Emmanuelle Bitoun
- The Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, OX3 7BN, UK.,Department of Statistics, University of Oxford, 24-29 St Giles', Oxford, OX1 3LB, UK
| | - Nicolas Altemose
- The Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, OX3 7BN, UK.,Department of Statistics, University of Oxford, 24-29 St Giles', Oxford, OX1 3LB, UK.,Department of Bioengineering, Stanley Hall, University of California, Berkeley, CA, 94720, USA
| | - Robert W Davies
- The Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, OX3 7BN, UK.,Department of Statistics, University of Oxford, 24-29 St Giles', Oxford, OX1 3LB, UK
| | - Benjamin Davies
- The Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, OX3 7BN, UK
| | - Simon R Myers
- The Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, OX3 7BN, UK. .,Department of Statistics, University of Oxford, 24-29 St Giles', Oxford, OX1 3LB, UK.
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29
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Beeson SK, Mickelson JR, McCue ME. Exploration of fine-scale recombination rate variation in the domestic horse. Genome Res 2019; 29:1744-1752. [PMID: 31434677 PMCID: PMC6771410 DOI: 10.1101/gr.243311.118] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 08/15/2019] [Indexed: 01/17/2023]
Abstract
Total genetic map length and local recombination landscapes typically vary within and across populations. As a first step to understanding the recombination landscape in the domestic horse, we calculated population recombination rates and identified likely recombination hotspots using approximately 1.8 million SNP genotypes for 485 horses from 32 distinct breeds. The resulting breed-averaged recombination map spans 2.36 Gb and accounts for 2939.07 cM. Recombination hotspots occur once per 23.8 Mb on average and account for ∼9% of the physical map length. Regions with elevated recombination rates in the entire cohort were enriched for genes in pathways involving interaction with the environment: immune system processes (specifically, MHC class I and class II genes), responses to stimuli, and serotonin receptor pathways. We found significant correlations between differences in local recombination rates and population differentiation quantified by F ST Analysis of breed-specific maps revealed thousands of hotspot regions unique to particular breeds, as well as unique "coldspots," regions where a particular breed showed below-average recombination, whereas all other breeds had evidence of a hotspot. Finally, we identified relative enrichment (P = 5.88 × 10-27) for the in silico-predicted recognition motif for equine PR/SET domain 9 (PRDM9) in recombination hotspots. These results indicate that selective pressures and PRDM9 function contribute to variation in recombination rates across the domestic horse genome.
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Affiliation(s)
- Samantha K Beeson
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, Minnesota 55108, USA
| | - James R Mickelson
- Veterinary and Biomedical Sciences Department, University of Minnesota, St. Paul, Minnesota 55108, USA
| | - Molly E McCue
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, Minnesota 55108, USA
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30
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Jones JC, Wallberg A, Christmas MJ, Kapheim KM, Webster MT. Extreme Differences in Recombination Rate between the Genomes of a Solitary and a Social Bee. Mol Biol Evol 2019; 36:2277-2291. [DOI: 10.1093/molbev/msz130] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Abstract
Social insect genomes exhibit the highest rates of crossing over observed in plants and animals. The evolutionary causes of these extreme rates are unknown. Insight can be gained by comparing recombination rate variation across the genomes of related social and solitary insects. Here, we compare the genomic recombination landscape of the highly social honey bee, Apis mellifera, with the solitary alfalfa leafcutter bee, Megachile rotundata, by analyzing patterns of linkage disequilibrium in population-scale genome sequencing data. We infer that average recombination rates are extremely elevated in A. mellifera compared with M. rotundata. However, our results indicate that similar factors control the distribution of crossovers in the genomes of both species. Recombination rate is significantly reduced in coding regions in both species, with genes inferred to be germline methylated having particularly low rates. Genes with worker-biased patterns of expression in A. mellifera and their orthologs in M. rotundata have higher than average recombination rates in both species, suggesting that selection for higher diversity in genes involved in worker caste functions in social taxa is not the explanation for these elevated rates. Furthermore, we find no evidence that recombination has modulated the efficacy of selection among genes during bee evolution, which does not support the hypothesis that high recombination rates facilitated positive selection for new functions in social insects. Our results indicate that the evolution of sociality in insects likely entailed selection on modifiers that increased recombination rates genome wide, but that the genomic recombination landscape is determined by the same factors.
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Affiliation(s)
- Julia C Jones
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Andreas Wallberg
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Matthew J Christmas
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | | | - Matthew T Webster
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
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31
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Heissl A, Betancourt AJ, Hermann P, Povysil G, Arbeithuber B, Futschik A, Ebner T, Tiemann-Boege I. The impact of poly-A microsatellite heterologies in meiotic recombination. Life Sci Alliance 2019; 2:2/2/e201900364. [PMID: 31023833 PMCID: PMC6485458 DOI: 10.26508/lsa.201900364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/27/2019] [Accepted: 03/29/2019] [Indexed: 12/12/2022] Open
Abstract
Meiosis strongly influences the transmission and evolution of heterozygous poly-A repeats as measured experimentally in a large collection of single recombination products in a human hotspot. Meiotic recombination has strong, but poorly understood effects on short tandem repeat (STR) instability. Here, we screened thousands of single recombinant products with sperm typing to characterize the role of polymorphic poly-A repeats at a human recombination hotspot in terms of hotspot activity and STR evolution. We show that the length asymmetry between heterozygous poly-A’s strongly influences the recombination outcome: a heterology of 10 A’s (9A/19A) reduces the number of crossovers and elevates the frequency of non-crossovers, complex recombination products, and long conversion tracts. Moreover, the length of the heterology also influences the STR transmission during meiotic repair with a strong and significant insertion bias for the short heterology (6A/7A) and a deletion bias for the long heterology (9A/19A). In spite of this opposing insertion-/deletion-biased gene conversion, we find that poly-A’s are enriched at human recombination hotspots that could have important consequences in hotspot activation.
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Affiliation(s)
- Angelika Heissl
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | | | - Philipp Hermann
- Institute of Applied Statistics, Johannes Kepler University, Linz, Austria
| | - Gundula Povysil
- Institute of Bioinformatics, Johannes Kepler University, Linz, Austria
| | | | - Andreas Futschik
- Institute of Applied Statistics, Johannes Kepler University, Linz, Austria
| | - Thomas Ebner
- Department of Gynecology, Obstetrics and Gynecological Endocrinology, Kepler University Clinic, Linz, Austria
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32
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Marand AP, Zhao H, Zhang W, Zeng Z, Fang C, Jiang J. Historical Meiotic Crossover Hotspots Fueled Patterns of Evolutionary Divergence in Rice. THE PLANT CELL 2019; 31:645-662. [PMID: 30705136 PMCID: PMC6482639 DOI: 10.1105/tpc.18.00750] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 01/28/2019] [Indexed: 05/15/2023]
Abstract
Recombination plays an integral role in the creation of novel genetic variation in sexually reproducing species. Despite this important role, the determinants and evolution of crossover hotspots have remained poorly understood in plants. Here, we present a comparative analysis of two rice (Oryza sativa) historical recombination maps from two subspecies (indica and japonica) using 150 resequenced genomes. Fine-scale recombination rates and crossover hotspots were validated by comparison with a consensus genetic map and empirically derived crossovers, respectively. Strikingly, nearly 80% of crossover hotspots were unique to each subspecies, despite their relatively recent divergence and broad-scale correlated recombination rates. Crossover hotspots were enriched with Stowaway and P instability factor (PIF)/Harbinger transposons and overlapped accessible chromatin regions. Increased nucleotide diversity and signatures of population differentiation augmented by Stowaway and PIF/Harbinger transposons were prevalent at subspecies-specific crossover hotspots. Motifs derived from lineage-specific indica and japonica crossover hotspots were nearly identical in the two subspecies, implicating a core set of crossover motifs in rice. Finally, Stowaway and PIF/Harbinger transposons were associated with stabilized G/C bias within highly active hotspots, suggesting that hotspot activity can be fueled by de novo variation. These results provide evolutionary insight into historical crossover hotspots as potentially powerful drivers of sequence and subspecies evolution in plants.
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Affiliation(s)
- Alexandre P Marand
- Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Hainan Zhao
- Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Horticulture, Michigan State University, East Lansing, Michigan 48824
| | - Wenli Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agriculture University, Nanjing, Jiangsu 210095, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agriculture University, Nanjing, Jiangsu 210095, China
| | - Zixian Zeng
- Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Horticulture, Michigan State University, East Lansing, Michigan 48824
| | - Chao Fang
- Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Horticulture, Michigan State University, East Lansing, Michigan 48824
| | - Jiming Jiang
- Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Horticulture, Michigan State University, East Lansing, Michigan 48824
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33
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Weng Z, Wolc A, Su H, Fernando RL, Dekkers JCM, Arango J, Settar P, Fulton JE, O'Sullivan NP, Garrick DJ. Identification of recombination hotspots and quantitative trait loci for recombination rate in layer chickens. J Anim Sci Biotechnol 2019; 10:20. [PMID: 30891237 PMCID: PMC6390344 DOI: 10.1186/s40104-019-0332-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/31/2019] [Indexed: 12/15/2022] Open
Abstract
Background The frequency of recombination events varies across the genome and between individuals, which may be related to some genomic features. The objective of this study was to assess the frequency of recombination events and to identify QTL (quantitative trait loci) for recombination rate in two purebred layer chicken lines. Methods A total of 1200 white-egg layers (WL) were genotyped with 580 K SNPs and 5108 brown-egg layers (BL) were genotyped with 42 K SNPs (single nucleotide polymorphisms). Recombination events were identified within half-sib families and both the number of recombination events and the recombination rate was calculated within each 0.5 Mb window of the genome. The 10% of windows with the highest recombination rate on each chromosome were considered to be recombination hotspots. A BayesB model was used separately for each line to identify genomic regions associated with the genome-wide number of recombination event per meiosis. Regions that explained more than 0.8% of genetic variance of recombination rate were considered to harbor QTL. Results Heritability of recombination rate was estimated at 0.17 in WL and 0.16 in BL. On average, 11.3 and 23.2 recombination events were detected per individual across the genome in 1301 and 9292 meioses in the WL and BL, respectively. The estimated recombination rates differed significantly between the lines, which could be due to differences in inbreeding levels, and haplotype structures. Dams had about 5% to 20% higher recombination rates per meiosis than sires in both lines. Recombination rate per 0.5 Mb window had a strong negative correlation with chromosome size and a strong positive correlation with GC content and with CpG island density across the genome in both lines. Different QTL for recombination rate were identified in the two lines. There were 190 and 199 non-overlapping recombination hotspots detected in WL and BL respectively, 28 of which were common to both lines. Conclusions Differences in the recombination rates, hotspot locations, and QTL regions associated with genome-wide recombination were observed between lines, indicating the breed-specific feature of detected recombination events and the control of recombination events is a complex polygenic trait. Electronic supplementary material The online version of this article (10.1186/s40104-019-0332-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ziqing Weng
- 1Department of Animal Science, Iowa State University, Ames, IA 50010 USA
| | - Anna Wolc
- 1Department of Animal Science, Iowa State University, Ames, IA 50010 USA.,2Hy-Line International, Dallas Center, IA 50063 USA
| | - Hailin Su
- 1Department of Animal Science, Iowa State University, Ames, IA 50010 USA
| | - Rohan L Fernando
- 1Department of Animal Science, Iowa State University, Ames, IA 50010 USA
| | - Jack C M Dekkers
- 1Department of Animal Science, Iowa State University, Ames, IA 50010 USA
| | - Jesus Arango
- 2Hy-Line International, Dallas Center, IA 50063 USA
| | - Petek Settar
- 2Hy-Line International, Dallas Center, IA 50063 USA
| | | | | | - Dorian J Garrick
- 1Department of Animal Science, Iowa State University, Ames, IA 50010 USA.,3AL Rae Centre for Genetics and Breeding, Massey University, Palmerston North, 4442 New Zealand
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Úbeda F, Russell TW, Jansen VAA. PRDM9 and the evolution of recombination hotspots. Theor Popul Biol 2019; 126:19-32. [PMID: 30660607 DOI: 10.1016/j.tpb.2018.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 12/29/2018] [Accepted: 12/30/2018] [Indexed: 02/05/2023]
Abstract
Recombination in mammals is not uniformly distributed along the chromosome but concentrated in small regions known as recombination hotspots. Recombination starts with the double-strand break of a chromosomal sequence and results in the transmission of the sequence that does not break (preventing recombination) more often than the sequence that breaks (allowing recombination). Thus recombination itself renders individual recombination hotspots inactive and over time should drive them to extinction in the genome. Empirical evidence shows that individual recombination hotspots die but, far from being driven to extinction, they are abundant in the genome: a contradiction referred to as the Recombination Hotspot Paradox. What saves recombination hotspots from extinction? The current answer relies in the formation of new recombination hotspots in new genomic sites driven by viability selection in favor of recombination. Here we formulate a population genetics model that incorporates the molecular mechanism initiating recombination in mammals (PRDM9-like genes), to provide an alternative solution to the paradox. We find that weak selection allows individual recombination hotspots to become inactive (die) while saving them from extinction in the genome by driving their re-activation (resurrection). Our model shows that when selection for recombination is weak, the introduction of rare variants causes recombination sites to oscillate between hot and cold phenotypes with a recombination hotspot dying only to come back. Counter-intuitively, we find that low viability selection leaves a hard selective sweep signature in the genome, with the selective sweep at the recombination hotspot being the hardest when viability selection is the lowest. Our model can help to understand the rapid evolution of PRDM9, the co-existence of two types of hotspots, the life expectancy of hotspots, and the volatility of the recombinational landscape (with hotspots rarely being shared between closely related species).
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Affiliation(s)
- Francisco Úbeda
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK.
| | - Timothy W Russell
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Vincent A A Jansen
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
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35
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Bouwman BAM, Crosetto N. Endogenous DNA Double-Strand Breaks during DNA Transactions: Emerging Insights and Methods for Genome-Wide Profiling. Genes (Basel) 2018; 9:E632. [PMID: 30558210 PMCID: PMC6316733 DOI: 10.3390/genes9120632] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 02/07/2023] Open
Abstract
DNA double-strand breaks (DSBs) jeopardize genome integrity and can-when repaired unfaithfully-give rise to structural rearrangements associated with cancer. Exogenous agents such as ionizing radiation or chemotherapy can invoke DSBs, but a vast amount of breakage arises during vital endogenous DNA transactions, such as replication and transcription. Additionally, chromatin looping involved in 3D genome organization and gene regulation is increasingly recognized as a possible contributor to DSB events. In this review, we first discuss insights into the mechanisms of endogenous DSB formation, showcasing the trade-off between essential DNA transactions and the intrinsic challenges that these processes impose on genomic integrity. In the second part, we highlight emerging methods for genome-wide profiling of DSBs, and discuss future directions of research that will help advance our understanding of genome-wide DSB formation and repair.
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Affiliation(s)
- Britta A M Bouwman
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17165 Stockholm, Sweden.
| | - Nicola Crosetto
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17165 Stockholm, Sweden.
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36
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Structured illumination microscopy imaging reveals localization of replication protein A between chromosome lateral elements during mammalian meiosis. Exp Mol Med 2018; 50:1-12. [PMID: 30154456 PMCID: PMC6113238 DOI: 10.1038/s12276-018-0139-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/29/2018] [Accepted: 05/31/2018] [Indexed: 11/08/2022] Open
Abstract
An important event enabling meiotic prophase I to proceed is the close juxtaposition of conjoined chromosome axes of homologs and their assembly via an array of transverse filaments and meiosis-specific axial elements into the synaptonemal complex (SC). During meiosis, recombination requires the establishment of a platform for recombinational interactions between the chromosome axes and their subsequent stabilization. This is essential for ensuring crossover recombination and proper segregation of homologous chromosomes. Thus, well-established SCs are essential for supporting these processes. The regulation of recombination intermediates on the chromosome axis/SC and dynamic positioning of double-strand breaks are not well understood. Here, using super-resolution microscopy (structured illumination microscopy), we determined the localization of the replication protein A (RPA) complex on the chromosome axes in the early phase of leptonema/zygonema and within the CEs of SC in the pachynema during meiotic prophase in mouse spermatocytes. RPA, which marks the intermediate steps of pairing and recombination, appears in large numbers and is positioned on the chromosome axes at the zygonema. In the pachynema, RPA foci are reduced but do not completely disappear; instead, they are placed between lateral elements. Our results reveal the precise structure of SC and localization dynamics of recombination intermediates on meiocyte chromosomes undergoing homolog pairing and meiotic recombination.
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Edera AA, Gandini CL, Sanchez-Puerta MV. Towards a comprehensive picture of C-to-U RNA editing sites in angiosperm mitochondria. PLANT MOLECULAR BIOLOGY 2018; 97:215-231. [PMID: 29761268 DOI: 10.1007/s11103-018-0734-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
Our understanding of the dynamic and evolution of RNA editing in angiosperms is in part limited by the few editing sites identified to date. This study identified 10,217 editing sites from 17 diverse angiosperms. Our analyses confirmed the universality of certain features of RNA editing, and offer new evidence behind the loss of editing sites in angiosperms. RNA editing is a post-transcriptional process that substitutes cytidines (C) for uridines (U) in organellar transcripts of angiosperms. These substitutions mostly take place in mitochondrial messenger RNAs at specific positions called editing sites. By means of publicly available RNA-seq data, this study identified 10,217 editing sites in mitochondrial protein-coding genes of 17 diverse angiosperms. Even though other types of mismatches were also identified, we did not find evidence of non-canonical editing processes. The results showed an uneven distribution of editing sites among species, genes, and codon positions. The analyses revealed that editing sites were conserved across angiosperms but there were some species-specific sites. Non-synonymous editing sites were particularly highly conserved (~ 80%) across the plant species and were efficiently edited (80% editing extent). In contrast, editing sites at third codon positions were poorly conserved (~ 30%) and only partially edited (~ 40% editing extent). We found that the loss of editing sites along angiosperm evolution is mainly occurring by replacing editing sites with thymidines, instead of a degradation of the editing recognition motif around editing sites. Consecutive and highly conserved editing sites had been replaced by thymidines as result of retroprocessing, by which edited transcripts are reverse transcribed to cDNA and then integrated into the genome by homologous recombination. This phenomenon was more pronounced in eudicots, and in the gene cox1. These results suggest that retroprocessing is a widespread driving force underlying the loss of editing sites in angiosperm mitochondria.
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Affiliation(s)
- Alejandro A Edera
- IBAM, Facultad de Ciencias Agrarias, CONICET, Universidad Nacional de Cuyo, M5528AHB, Chacras de Coria, Argentina.
| | - Carolina L Gandini
- IBAM, Facultad de Ciencias Agrarias, CONICET, Universidad Nacional de Cuyo, M5528AHB, Chacras de Coria, Argentina
| | - M Virginia Sanchez-Puerta
- IBAM, Facultad de Ciencias Agrarias, CONICET, Universidad Nacional de Cuyo, M5528AHB, Chacras de Coria, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
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Tiemann-Boege I, Schwarz T, Striedner Y, Heissl A. The consequences of sequence erosion in the evolution of recombination hotspots. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0462. [PMID: 29109225 PMCID: PMC5698624 DOI: 10.1098/rstb.2016.0462] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2017] [Indexed: 12/18/2022] Open
Abstract
Meiosis is initiated by a double-strand break (DSB) introduced in the DNA by a highly controlled process that is repaired by recombination. In many organisms, recombination occurs at specific and narrow regions of the genome, known as recombination hotspots, which overlap with regions enriched for DSBs. In recent years, it has been demonstrated that conversions and mutations resulting from the repair of DSBs lead to a rapid sequence evolution at recombination hotspots eroding target sites for DSBs. We still do not fully understand the effect of this erosion in the recombination activity, but evidence has shown that the binding of trans-acting factors like PRDM9 is affected. PRDM9 is a meiosis-specific, multi-domain protein that recognizes DNA target motifs by its zinc finger domain and directs DSBs to these target sites. Here we discuss the changes in affinity of PRDM9 to eroded recognition sequences, and explain how these changes in affinity of PRDM9 can affect recombination, leading sometimes to sterility in the context of hybrid crosses. We also present experimental data showing that DNA methylation reduces PRDM9 binding in vitro. Finally, we discuss PRDM9-independent hotspots, posing the question how these hotspots evolve and change with sequence erosion. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’.
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Affiliation(s)
- Irene Tiemann-Boege
- Institute of Biophysics, Johannes Kepler University, Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Theresa Schwarz
- Institute of Biophysics, Johannes Kepler University, Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Yasmin Striedner
- Institute of Biophysics, Johannes Kepler University, Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Angelika Heissl
- Institute of Biophysics, Johannes Kepler University, Linz, Gruberstraße 40, 4020 Linz, Austria
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Abstract
Recombination often differs markedly between males and females. Here we present the first analysis of sex-specific recombination in Gasterosteus sticklebacks. Using whole-genome sequencing of 15 crosses between G. aculeatus and G. nipponicus, we localized 698 crossovers with a median resolution of 2.3 kb. We also used a bioinformatic approach to infer historical sex-averaged recombination patterns for both species. Recombination is greater in females than males on all chromosomes, and overall map length is 1.64 times longer in females. The locations of crossovers differ strikingly between sexes. Crossovers cluster toward chromosome ends in males, but are distributed more evenly across chromosomes in females. Suppression of recombination near the centromeres in males causes crossovers to cluster at the ends of long arms in acrocentric chromosomes, and greatly reduces crossing over on short arms. The effect of centromeres on recombination is much weaker in females. Genomic differentiation between G. aculeatus and G. nipponicus is strongly correlated with recombination rate, and patterns of differentiation along chromosomes are strongly influenced by male-specific telomere and centromere effects. We found no evidence for fine-scale correlations between recombination and local gene content in either sex. We discuss hypotheses for the origin of sexual dimorphism in recombination and its consequences for sexually antagonistic selection and sex chromosome evolution.
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Abstract
Homologous recombination is required for proper segregation of homologous chromosomes during meiosis. It occurs predominantly at recombination hotspots that are defined by the DNA binding specificity of the PRDM9 protein. PRDM9 contains three conserved domains typically involved in regulation of transcription; yet, the role of PRDM9 in gene expression control is not clear. Here, we analyze the germline transcriptome of Prdm9−/− male mice in comparison to Prdm9+/+ males and find no apparent differences in the mRNA and miRNA profiles. We further explore the role of PRDM9 in meiosis by analyzing the effect of the KRAB, SSXRD, and post-SET zinc finger deletions in a cell culture expression system and the KRAB domain deletion in mice. We found that although the post-SET zinc finger and the KRAB domains are not essential for the methyltransferase activity of PRDM9 in cell culture, the KRAB domain mutant mice show only residual PRDM9 methyltransferase activity and undergo meiotic arrest. In aggregate, our data indicate that domains typically involved in regulation of gene expression do not serve that role in PRDM9, but are likely involved in setting the proper chromatin environment for initiation and completion of homologous recombination.
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Zhou Y, Shen B, Jiang J, Padhi A, Park KE, Oswalt A, Sattler CG, Telugu BP, Chen H, Cole JB, Liu GE, Ma L. Construction of PRDM9 allele-specific recombination maps in cattle using large-scale pedigree analysis and genome-wide single sperm genomics. DNA Res 2018; 25:183-194. [PMID: 29186399 PMCID: PMC5909443 DOI: 10.1093/dnares/dsx048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 11/09/2017] [Indexed: 11/23/2022] Open
Abstract
PRDM9 contributes to hybrid sterility and species evolution. However, its role is to be confirmed in cattle, a major domesticated livestock species. We previously found an association near PRDM9 with cattle recombination features, but the causative variants are still unknown. Using millions of genotyped cattle with pedigree information, we characterized five PRDM9 alleles and generated allele-specific recombination maps. By examining allele-specific recombination patterns, we observed the impact of PRDM9 on global distribution of recombination, especially in the two ends of chromosomes. We also showed strong associations between recombination hotspot regions and functional mutations within PRDM9 zinc finger domain. More importantly, we found one allele of PRDM9 to be very different from others in both protein composition and recombination landscape, indicating the causative role of this allele on the association between PRDM9 and cattle recombination. When comparing recombination maps from sperm and pedigree data, we observed similar genome-wide recombination patterns, validating the quality of pedigree-based results. Collectively, these evidence supported PRDM9 alleles as causal variants for the reported association with cattle recombination. Our study comprehensively surveyed the bovine PRDM9 alleles, generated allele-specific recombination maps, and expanded our understanding of the role of PRDM9 on genome distribution of recombination.
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Affiliation(s)
- Yang Zhou
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, Beltsville, MD 20705, USA
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Education Ministry of China, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Botong Shen
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Jicai Jiang
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Abinash Padhi
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Ki-Eun Park
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Adam Oswalt
- Select Sires Inc. 11740 U.S. 42 North, Plain City, Ohio 43064, USA
| | | | - Bhanu P Telugu
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Hong Chen
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - John B Cole
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, Beltsville, MD 20705, USA
| | - George E Liu
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, Beltsville, MD 20705, USA
| | - Li Ma
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
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Brick K, Pratto F, Sun CY, Camerini-Otero RD, Petukhova G. Analysis of Meiotic Double-Strand Break Initiation in Mammals. Methods Enzymol 2018. [PMID: 29523240 DOI: 10.1016/bs.mie.2017.11.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The repair of programmed DNA double-strand breaks (DSBs) physically tethers homologous chromosomes in meiosis to allow for accurate segregation through meiotic cell divisions. This process, known as recombination, also results in the exchange of alleles between parental chromosomes and contributes to genetic diversity. In mammals, meiotic DSBs occur predominantly in a small fraction of the genome, at sites known as hotspots. Studies of the formation and repair of meiotic DSBs in mammals are challenging, because few cells undergo meiotic DSB formation at a given time. To better understand the initiation and control of meiotic recombination in mammals, we have devised a highly sensitive method to map the sites of meiotic DSBs genome wide. Our method first isolates DNA bound to DSB repair proteins and then specifically sequences the associated single-stranded DNA. This protocol has generated the first meiotic DSB maps in several mammals and the only map of meiotic DSBs in humans.
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Affiliation(s)
- Kevin Brick
- Genetics & Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, MD, United States
| | - Florencia Pratto
- Genetics & Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, MD, United States
| | - Chi-Yu Sun
- Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Rafael D Camerini-Otero
- Genetics & Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, MD, United States.
| | - Galina Petukhova
- Uniformed Services University of the Health Sciences, Bethesda, MD, United States.
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Zavodna M, Bagshaw A, Brauning R, Gemmell NJ. The effects of transcription and recombination on mutational dynamics of short tandem repeats. Nucleic Acids Res 2018; 46:1321-1330. [PMID: 29300948 PMCID: PMC5814968 DOI: 10.1093/nar/gkx1253] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 11/27/2017] [Accepted: 12/27/2017] [Indexed: 01/07/2023] Open
Abstract
Short tandem repeats (STR) are ubiquitous components of the genomic architecture of most living organisms. Recent work has highlighted the widespread functional significance of such repeats, particularly around gene regulation, but the mutational processes underlying the evolution of these highly abundant and highly variable sequences are not fully understood. Traditional models assume that strand misalignment during replication is the predominant mechanism, but empirical data suggest the involvement of other processes including recombination and transcription. Despite this evidence, the relative influences of these processes have not previously been tested experimentally on a genome-wide scale. Using deep sequencing, we identify mutations at >200 microsatellites, across 700 generations in replicated populations of two otherwise identical sexual and asexual Saccharomyces cerevisiae strains. Using generalized linear models, we investigate correlates of STR mutability including the nature of the mutation, STR composition and contextual factors including recombination, transcription and replication origins. Sexual capability was not a significant predictor of microsatellite mutability, but, intriguingly, we identify transcription as a significant positive predictor. We also find that STR density is substantially increased in regions neighboring, but not within, recombination hotspots.
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Affiliation(s)
- Monika Zavodna
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - Andrew Bagshaw
- Department of Pathology, University of Otago, Christchurch 8140, New Zealand
| | - Rudiger Brauning
- AgResearch Limited, Invermay Agricultural Centre, Mosgiel, New Zealand
| | - Neil J Gemmell
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
- Allan Wilson Centre for Molecular Ecology and Evolution, University of Otago, Dunedin 9054, New Zealand
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44
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Muraille E. Diversity Generator Mechanisms Are Essential Components of Biological Systems: The Two Queen Hypothesis. Front Microbiol 2018; 9:223. [PMID: 29487592 PMCID: PMC5816788 DOI: 10.3389/fmicb.2018.00223] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 01/30/2018] [Indexed: 01/02/2023] Open
Abstract
Diversity is widely known to fuel adaptation and evolutionary processes and increase robustness at the population, species and ecosystem levels. The Neo-Darwinian paradigm proposes that the diversity of biological entities is the consequence of genetic changes arising spontaneously and randomly, without regard for their usefulness. However, a growing body of evidence demonstrates that the evolutionary process has shaped mechanisms, such as horizontal gene transfer mechanisms, meiosis and the adaptive immune system, which has resulted in the regulated generation of diversity among populations. Though their origins are unrelated, these diversity generator (DG) mechanisms share common functional properties. They (i) contribute to the great unpredictability of the composition and/or behavior of biological systems, (ii) favor robustness and collectivism among populations and (iii) operate mainly by manipulating the systems that control the interaction of living beings with their environment. The definition proposed here for DGs is based on these properties and can be used to identify them according to function. Interestingly, prokaryotic DGs appear to be mainly reactive, as they generate diversity in response to environmental stress. They are involved in the widely described Red Queen/arms race/Cairnsian dynamic. The emergence of multicellular organisms harboring K selection traits (longer reproductive life cycle and smaller population size) has led to the acquisition of a new class of DGs that act anticipatively to stress pressures and generate a distinct dynamic called the “White Queen” here. The existence of DGs leads to the view of evolution as a more “intelligent” and Lamarckian-like process. Their repeated selection during evolution could be a neglected example of convergent evolution and suggests that some parts of the evolutionary process are tightly constrained by ecological factors, such as the population size, the generation time and the intensity of selective pressure. The ubiquity of DGs also suggests that regulated auto-generation of diversity is a fundamental property of life.
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Affiliation(s)
- Eric Muraille
- Laboratoire de Parasitologie, Faculté de Médecine, Université Libre de Bruxelles, Brussels, Belgium
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45
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Laurent B, Palaiokostas C, Spataro C, Moinard M, Zehraoui E, Houston RD, Foulongne‐Oriol M. High-resolution mapping of the recombination landscape of the phytopathogen Fusarium graminearum suggests two-speed genome evolution. MOLECULAR PLANT PATHOLOGY 2018; 19:341-354. [PMID: 27998012 PMCID: PMC6638080 DOI: 10.1111/mpp.12524] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/01/2016] [Accepted: 12/03/2016] [Indexed: 05/25/2023]
Abstract
Recombination is a major evolutionary force, increasing genetic diversity and permitting efficient coevolution of fungal pathogen(s) with their host(s). The ascomycete Fusarium graminearum is a devastating pathogen of cereal crops, and can contaminate food and feed with harmful mycotoxins. Previous studies have suggested a high adaptive potential of this pathogen, illustrated by an increase in pathogenicity and resistance to fungicides. In this study, we provide the first detailed picture of the crossover events occurring during meiosis and discuss the role of recombination in pathogen evolution. An experimental recombinant population (n = 88) was created and genotyped using 1306 polymorphic markers obtained from restriction site-associated DNA sequencing (RAD-seq) and aligned to the reference genome. The construction of a high-density linkage map, anchoring 99% of the total length of the reference genome, allowed the identification of 1451 putative crossovers, positioned at a median resolution of 24 kb. The majority of crossovers (87.2%) occurred in a relatively small portion of the genome (30%). All chromosomes demonstrated recombination-active sections, which had a near 15-fold higher crossover rate than non-active recombinant sections. The recombination rate showed a strong positive correlation with nucleotide diversity, and recombination-active regions were enriched for genes with a putative role in host-pathogen interaction, as well as putative diversifying genes. Our results confirm the preliminary analysis observed in other F. graminearum strains and suggest a conserved 'two-speed' recombination landscape. The consequences with regard to the evolutionary potential of this major fungal pathogen are also discussed.
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Affiliation(s)
- Benoit Laurent
- MycSA, INRA, Université de Bordeaux33882Villenave d'OrnonFrance
| | | | - Cathy Spataro
- MycSA, INRA, Université de Bordeaux33882Villenave d'OrnonFrance
| | - Magalie Moinard
- MycSA, INRA, Université de Bordeaux33882Villenave d'OrnonFrance
| | - Enric Zehraoui
- MycSA, INRA, Université de Bordeaux33882Villenave d'OrnonFrance
| | - Ross D. Houston
- The Roslin Institute, University of EdinburghMidlothianEH25 9RGUK
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46
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Paigen K, Petkov PM. PRDM9 and Its Role in Genetic Recombination. Trends Genet 2018; 34:291-300. [PMID: 29366606 DOI: 10.1016/j.tig.2017.12.017] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/14/2017] [Accepted: 12/20/2017] [Indexed: 12/22/2022]
Abstract
PRDM9 is a zinc finger protein that binds DNA at specific locations in the genome where it trimethylates histone H3 at lysines 4 and 36 at surrounding nucleosomes. During meiosis in many species, including humans and mice where PRDM9 has been most intensely studied, these actions determine the location of recombination hotspots, where genetic recombination occurs. In addition, PRDM9 facilitates the association of hotspots with the chromosome axis, the site of the programmed DNA double-strand breaks (DSBs) that give rise to genetic exchange between chromosomes. In the absence of PRDM9 DSBs are not properly repaired. Collectively, these actions determine patterns of genetic linkage and the possibilities for chromosome reorganization over successive generations.
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47
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Lenormand T, Engelstädter J, Johnston SE, Wijnker E, Haag CR. Evolutionary mysteries in meiosis. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2016.0001. [PMID: 27619705 DOI: 10.1098/rstb.2016.0001] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2016] [Indexed: 01/25/2023] Open
Abstract
Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Thomas Lenormand
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Erik Wijnker
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Christoph R Haag
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
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Tetrad analysis in plants and fungi finds large differences in gene conversion rates but no GC bias. Nat Ecol Evol 2017; 2:164-173. [PMID: 29158556 PMCID: PMC5733138 DOI: 10.1038/s41559-017-0372-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 10/09/2017] [Indexed: 11/29/2022]
Abstract
GC-favoring gene conversion enables fixation of deleterious alleles, disturbs tests of natural selection and potentially explains both the evolution of recombination as well as the commonly reported intra-genomic correlation between G+C content and recombination rate. In addition, gene conversion disturbs linkage disequilibrium, potentially affecting the ability to detect causative variants. However, the importance and generality of these effects is unresolved, not simply because direct analyses are technically challenging but also because prior within- and between-species discrepant results can be hard to appraise owing to methodological differences. Here we report results of methodologically uniform whole-genome sequencing of all tetrad products in Saccharomyces, Neurospora, Chlamydomonas and Arabidopsis. The proportion of polymorphic markers converted varies over three orders of magnitude between species (from 2% of markers converted in yeast to only ~0.005% in the two plants) with at least 87.5% of the variance in per tetrad conversion rates being between-species. This is largely owing to differences in recombination rate and median tract length. Despite three of the species showing a positive GC-recombination correlation, there is no significant net AT->GC conversion bias in any, despite relatively high resolution in the two taxa (Saccharomyces and Neurospora) with relatively common gene conversion. The absence of a GC bias means: 1) that there should be no presumption that gene conversion is GC biased, nor 2) that a GC-recombination correlation necessarily implies biased gene conversion, 3) that Ka/Ks tests should be unaffected in these species and 4) it is unlikely that gene conversion explains the evolution of recombination.
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Booker TR, Ness RW, Keightley PD. The Recombination Landscape in Wild House Mice Inferred Using Population Genomic Data. Genetics 2017; 207:297-309. [PMID: 28751421 PMCID: PMC5586380 DOI: 10.1534/genetics.117.300063] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/19/2017] [Indexed: 11/29/2022] Open
Abstract
Characterizing variation in the rate of recombination across the genome is important for understanding several evolutionary processes. Previous analysis of the recombination landscape in laboratory mice has revealed that the different subspecies have different suites of recombination hotspots. It is unknown, however, whether hotspots identified in laboratory strains reflect the hotspot diversity of natural populations or whether broad-scale variation in the rate of recombination is conserved between subspecies. In this study, we constructed fine-scale recombination rate maps for a natural population of the Eastern house mouse, Mus musculus castaneus We performed simulations to assess the accuracy of recombination rate inference in the presence of phase errors, and we used a novel approach to quantify phase error. The spatial distribution of recombination events is strongly positively correlated between our castaneus map, and a map constructed using inbred lines derived predominantly from M. m. domesticus Recombination hotspots in wild castaneus show little overlap, however, with the locations of double-strand breaks in wild-derived house mouse strains. Finally, we also find that genetic diversity in M. m. castaneus is positively correlated with the rate of recombination, consistent with pervasive natural selection operating in the genome. Our study suggests that recombination rate variation is conserved at broad scales between house mouse subspecies, but it is not strongly conserved at fine scales.
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Affiliation(s)
- Tom R Booker
- Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, United Kingdom
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, Ontario, L5L 1C6, Canada
| | - Peter D Keightley
- Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, United Kingdom
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Bagshaw AT. Functional Mechanisms of Microsatellite DNA in Eukaryotic Genomes. Genome Biol Evol 2017; 9:2428-2443. [PMID: 28957459 PMCID: PMC5622345 DOI: 10.1093/gbe/evx164] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2017] [Indexed: 02/06/2023] Open
Abstract
Microsatellite repeat DNA is best known for its length mutability, which is implicated in several neurological diseases and cancers, and often exploited as a genetic marker. Less well-known is the body of work exploring the widespread and surprisingly diverse functional roles of microsatellites. Recently, emerging evidence includes the finding that normal microsatellite polymorphism contributes substantially to the heritability of human gene expression on a genome-wide scale, calling attention to the task of elucidating the mechanisms involved. At present, these are underexplored, but several themes have emerged. I review evidence demonstrating roles for microsatellites in modulation of transcription factor binding, spacing between promoter elements, enhancers, cytosine methylation, alternative splicing, mRNA stability, selection of transcription start and termination sites, unusual structural conformations, nucleosome positioning and modification, higher order chromatin structure, noncoding RNA, and meiotic recombination hot spots.
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