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Logares R. Decoding populations in the ocean microbiome. MICROBIOME 2024; 12:67. [PMID: 38561814 PMCID: PMC10983722 DOI: 10.1186/s40168-024-01778-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 02/12/2024] [Indexed: 04/04/2024]
Abstract
Understanding the characteristics and structure of populations is fundamental to comprehending ecosystem processes and evolutionary adaptations. While the study of animal and plant populations has spanned a few centuries, microbial populations have been under scientific scrutiny for a considerably shorter period. In the ocean, analyzing the genetic composition of microbial populations and their adaptations to multiple niches can yield important insights into ecosystem function and the microbiome's response to global change. However, microbial populations have remained elusive to the scientific community due to the challenges associated with isolating microorganisms in the laboratory. Today, advancements in large-scale metagenomics and metatranscriptomics facilitate the investigation of populations from many uncultured microbial species directly from their habitats. The knowledge acquired thus far reveals substantial genetic diversity among various microbial species, showcasing distinct patterns of population differentiation and adaptations, and highlighting the significant role of selection in structuring populations. In the coming years, population genomics is expected to significantly increase our understanding of the architecture and functioning of the ocean microbiome, providing insights into its vulnerability or resilience in the face of ongoing global change. Video Abstract.
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Affiliation(s)
- Ramiro Logares
- Institute of Marine Sciences (ICM), CSIC, Barcelona, Catalonia, 08003, Spain.
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2
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Piskovsky V, Oliveira NM. Bacterial motility can govern the dynamics of antibiotic resistance evolution. Nat Commun 2023; 14:5584. [PMID: 37696800 PMCID: PMC10495427 DOI: 10.1038/s41467-023-41196-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 08/24/2023] [Indexed: 09/13/2023] Open
Abstract
Spatial heterogeneity in antibiotic concentrations is thought to accelerate the evolution of antibiotic resistance, but current theory and experiments have overlooked the effect of cell motility on bacterial adaptation. Here, we study bacterial evolution in antibiotic landscapes with a quantitative model where bacteria evolve under the stochastic processes of proliferation, death, mutation and migration. Numerical and analytical results show that cell motility can both accelerate and decelerate bacterial adaptation by affecting the degree of genotypic mixing and ecological competition. Moreover, we find that for sufficiently high rates, cell motility can limit bacterial survival, and we derive conditions for all these regimes. Similar patterns are observed in more complex scenarios, namely where bacteria can bias their motion in chemical gradients (chemotaxis) or switch between motility phenotypes either stochastically or in a density-dependent manner. Overall, our work reveals limits to bacterial adaptation in antibiotic landscapes that are set by cell motility.
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Affiliation(s)
- Vit Piskovsky
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, UK
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK
| | - Nuno M Oliveira
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, UK.
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK.
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3
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Li NK, Corander J, Grad YH, Chang HH. Discovering recent selection forces shaping the evolution of dengue viruses based on polymorphism data across geographic scales. Virus Evol 2022; 8:veac108. [PMID: 36601300 PMCID: PMC9789396 DOI: 10.1093/ve/veac108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 09/23/2022] [Accepted: 11/28/2022] [Indexed: 11/30/2022] Open
Abstract
Incomplete selection makes it challenging to infer selection on genes at short time scales, especially for microorganisms, due to stronger linkage between loci. However, in many cases, the selective force changes with environment, time, or other factors, and it is of great interest to understand selective forces at this level to answer relevant biological questions. We developed a new method that uses the change in dN /dS , instead of the absolute value of dN /dS , to infer the dominating selective force based on sequence data across geographical scales. If a gene was under positive selection, dN /dS was expected to increase through time, whereas if a gene was under negative selection, dN /dS was expected to decrease through time. Assuming that the migration rate decreased and the divergence time between samples increased from between-continent, within-continent different-country, to within-country level, dN /dS of a gene dominated by positive selection was expected to increase with increasing geographical scales, and the opposite trend was expected in the case of negative selection. Motivated by the McDonald-Kreitman (MK) test, we developed a pairwise MK test to assess the statistical significance of detected trends in dN /dS . Application of the method to a global sample of dengue virus genomes identified multiple significant signatures of selection in both the structural and non-structural proteins. Because this method does not require allele frequency estimates and uses synonymous mutations for comparison, it is less prone to sampling error, providing a way to infer selection forces within species using publicly available genomic data from locations over broad geographical scales.
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Affiliation(s)
- Nien-Kung Li
- Department of Life Science & Institute of Bioinformatics and Structural Biology, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan
| | - Jukka Corander
- Helsinki Institute for Information Technology, Department of Mathematics and Statistics, University of Helsinki, Yliopistonkatu 3, Helsinki 00014, Finland,Department of Biostatistics, University of Oslo, Domus Medica Gaustad Sognsvannsveien 9, Oslo 0372, Norway,Parasites and Microbes, The Wellcome Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
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4
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Abstract
Horizontal gene transfer (HGT) is arguably the most conspicuous feature of bacterial evolution. Evidence for HGT is found in most bacterial genomes. Although HGT can considerably alter bacterial genomes, not all transfer events may be biologically significant and may instead represent the outcome of an incessant evolutionary process that only occasionally has a beneficial purpose. When adaptive transfers occur, HGT and positive selection may result in specific, detectable signatures in genomes, such as gene-specific sweeps or increased transfer rates for genes that are ecologically relevant. In this Review, we first discuss the various mechanisms whereby HGT occurs, how the genetic signatures shape patterns of genomic variation and the distinct bioinformatic algorithms developed to detect these patterns. We then discuss the evolutionary theory behind HGT and positive selection in bacteria, and discuss the approaches developed over the past decade to detect transferred DNA that may be involved in adaptation to new environments.
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5
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Environmental stress leads to genome streamlining in a widely distributed species of soil bacteria. THE ISME JOURNAL 2022; 16:423-434. [PMID: 34408268 PMCID: PMC8776746 DOI: 10.1038/s41396-021-01082-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 07/14/2021] [Accepted: 07/28/2021] [Indexed: 02/07/2023]
Abstract
Bacteria have highly flexible pangenomes, which are thought to facilitate evolutionary responses to environmental change, but the impacts of environmental stress on pangenome evolution remain unclear. Using a landscape pangenomics approach, I demonstrate that environmental stress leads to consistent, continuous reduction in genome content along four environmental stress gradients (acidity, aridity, heat, salinity) in naturally occurring populations of Bradyrhizobium diazoefficiens (widespread soil-dwelling plant mutualists). Using gene-level network and duplication functional traits to predict accessory gene distributions across environments, genes predicted to be superfluous are more likely lost in high stress, while genes with multi-functional roles are more likely retained. Genes with higher probabilities of being lost with stress contain significantly higher proportions of codons under strong purifying and positive selection. Gene loss is widespread across the entire genome, with high gene-retention hotspots in close spatial proximity to core genes, suggesting Bradyrhizobium has evolved to cluster essential-function genes (accessory genes with multifunctional roles and core genes) in discrete genomic regions, which may stabilise viability during genomic decay. In conclusion, pangenome evolution through genome streamlining are important evolutionary responses to environmental change. This raises questions about impacts of genome streamlining on the adaptive capacity of bacterial populations facing rapid environmental change.
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6
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Aspergillus fumigatus versus Genus Aspergillus: Conservation, Adaptive Evolution and Specific Virulence Genes. Microorganisms 2021; 9:microorganisms9102014. [PMID: 34683335 PMCID: PMC8539515 DOI: 10.3390/microorganisms9102014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/18/2021] [Accepted: 09/20/2021] [Indexed: 12/15/2022] Open
Abstract
Aspergillus is an important fungal genus containing economically important species, as well as pathogenic species of animals and plants. Using eighteen fungal species of the genus Aspergillus, we conducted a comprehensive investigation of conserved genes and their evolution. This also allows us to investigate the selection pressure driving the adaptive evolution in the pathogenic species A. fumigatus. Among single-copy orthologs (SCOs) for A. fumigatus and the closely related species A. fischeri, we identified 122 versus 50 positively selected genes (PSGs), respectively. Moreover, twenty conserved genes of unknown function were established to be positively selected and thus important for adaption. A. fumigatus PSGs interacting with human host proteins show over-representation of adaptive, symbiosis-related, immunomodulatory and virulence-related pathways, such as the TGF-β pathway, insulin receptor signaling, IL1 pathway and interfering with phagosomal GTPase signaling. Additionally, among the virulence factor coding genes, secretory and membrane protein-coding genes in multi-copy gene families, 212 genes underwent positive selection and also suggest increased adaptation, such as fungal immune evasion mechanisms (aspf2), siderophore biosynthesis (sidD), fumarylalanine production (sidE), stress tolerance (atfA) and thermotolerance (sodA). These genes presumably contribute to host adaptation strategies. Genes for the biosynthesis of gliotoxin are shared among all the close relatives of A. fumigatus as an ancient defense mechanism. Positive selection plays a crucial role in the adaptive evolution of A. fumigatus. The genome-wide profile of PSGs provides valuable targets for further research on the mechanisms of immune evasion, antimycotic targeting and understanding fundamental virulence processes.
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7
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D'Aeth JC, van der Linden MPG, McGee L, de Lencastre H, Turner P, Song JH, Lo SW, Gladstone RA, Sá-Leão R, Ko KS, Hanage WP, Breiman RF, Beall B, Bentley SD, Croucher NJ. The role of interspecies recombination in the evolution of antibiotic-resistant pneumococci. eLife 2021; 10:e67113. [PMID: 34259624 PMCID: PMC8321556 DOI: 10.7554/elife.67113] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/16/2021] [Indexed: 12/27/2022] Open
Abstract
Multidrug-resistant Streptococcus pneumoniae emerge through the modification of core genome loci by interspecies homologous recombinations, and acquisition of gene cassettes. Both occurred in the otherwise contrasting histories of the antibiotic-resistant S. pneumoniae lineages PMEN3 and PMEN9. A single PMEN3 clade spread globally, evading vaccine-induced immunity through frequent serotype switching, whereas locally circulating PMEN9 clades independently gained resistance. Both lineages repeatedly integrated Tn916-type and Tn1207.1-type elements, conferring tetracycline and macrolide resistance, respectively, through homologous recombination importing sequences originating in other species. A species-wide dataset found over 100 instances of such interspecific acquisitions of resistance cassettes and flanking homologous arms. Phylodynamic analysis of the most commonly sampled Tn1207.1-type insertion in PMEN9, originating from a commensal and disrupting a competence gene, suggested its expansion across Germany was driven by a high ratio of macrolide-to-β-lactam consumption. Hence, selection from antibiotic consumption was sufficient for these atypically large recombinations to overcome species boundaries across the pneumococcal chromosome.
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Affiliation(s)
- Joshua C D'Aeth
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College LondonLondonUnited Kingdom
| | - Mark PG van der Linden
- Institute for Medical Microbiology, National Reference Center for Streptococci, University Hospital RWTH AachenAachenGermany
| | - Lesley McGee
- Respiratory Diseases Branch, Centers for Disease Control and PreventionAtlantaUnited States
| | - Herminia de Lencastre
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de LisboaOeirasPortugal
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller UniversityNew YorkUnited States
| | - Paul Turner
- Cambodia Oxford Medical Research Unit, Angkor Hospital for ChildrenSiem ReapCambodia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Jae-Hoon Song
- Department of Molecular Cell Biology, Sungkyunkwan University School of MedicineSuwonRepublic of Korea
| | - Stephanie W Lo
- Parasites & Microbes, Wellcome Sanger Institute, Wellcome Genome CampusHinxtonUnited Kingdom
| | - Rebecca A Gladstone
- Parasites & Microbes, Wellcome Sanger Institute, Wellcome Genome CampusHinxtonUnited Kingdom
| | - Raquel Sá-Leão
- Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Química e Biológica, Universidade Nova de LisboaOeirasPortugal
| | - Kwan Soo Ko
- Department of Molecular Cell Biology, Sungkyunkwan University School of MedicineSuwonRepublic of Korea
| | - William P Hanage
- Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public HealthBostonUnited States
| | - Robert F Breiman
- Department of Global Health, Rollins School of Public Health, Emory UniversityAtlantaUnited States
| | - Bernard Beall
- Respiratory Diseases Branch, Centers for Disease Control and PreventionAtlantaUnited States
| | - Stephen D Bentley
- Parasites & Microbes, Wellcome Sanger Institute, Wellcome Genome CampusHinxtonUnited Kingdom
| | - Nicholas J Croucher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College LondonLondonUnited Kingdom
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8
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Harrow GL, Lees JA, Hanage WP, Lipsitch M, Corander J, Colijn C, Croucher NJ. Negative frequency-dependent selection and asymmetrical transformation stabilise multi-strain bacterial population structures. THE ISME JOURNAL 2021; 15:1523-1538. [PMID: 33408365 PMCID: PMC8115253 DOI: 10.1038/s41396-020-00867-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
Streptococcus pneumoniae can be divided into many strains, each a distinct set of isolates sharing similar core and accessory genomes, which co-circulate within the same hosts. Previous analyses suggested the short-term vaccine-associated dynamics of S. pneumoniae strains may be mediated through multi-locus negative frequency-dependent selection (NFDS), which maintains accessory loci at equilibrium frequencies. Long-term simulations demonstrated NFDS stabilised clonally-evolving multi-strain populations through preventing the loss of variation through drift, based on polymorphism frequencies, pairwise genetic distances and phylogenies. However, allowing symmetrical recombination between isolates evolving under multi-locus NFDS generated unstructured populations of diverse genotypes. Replication of the observed data improved when multi-locus NFDS was combined with recombination that was instead asymmetrical, favouring deletion of accessory loci over insertion. This combination separated populations into strains through outbreeding depression, resulting from recombinants with reduced accessory genomes having lower fitness than their parental genotypes. Although simplistic modelling of recombination likely limited these simulations' ability to maintain some properties of genomic data as accurately as those lacking recombination, the combination of asymmetrical recombination and multi-locus NFDS could restore multi-strain population structures from randomised initial populations. As many bacteria inhibit insertions into their chromosomes, this combination may commonly underlie the co-existence of strains within a niche.
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Affiliation(s)
- Gabrielle L Harrow
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - John A Lees
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - William P Hanage
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, 02115, USA
| | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, 02115, USA
| | - Jukka Corander
- Department of Biostatistics, University of Oslo, Oslo, Norway
- Helsinki Institute of Information Technology, Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland
- Parasites & Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Caroline Colijn
- Parasites & Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Department of Mathematics, Simon Fraser University, Burnaby, BC, Canada
| | - Nicholas J Croucher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK.
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9
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Coolen JPM, den Drijver EPM, Verweij JJ, Schildkraut JA, Neveling K, Melchers WJG, Kolwijck E, Wertheim HFL, Kluytmans JAJW, Huynen MA. Genome-wide analysis in Escherichia coli unravels a high level of genetic homoplasy associated with cefotaxime resistance. Microb Genom 2021; 7:000556. [PMID: 33843573 PMCID: PMC8208684 DOI: 10.1099/mgen.0.000556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 03/11/2021] [Indexed: 11/18/2022] Open
Abstract
Cefotaxime (CTX) is a third-generation cephalosporin (3GC) commonly used to treat infections caused by Escherichia coli. Two genetic mechanisms have been associated with 3GC resistance in E. coli. The first is the conjugative transfer of a plasmid harbouring antibiotic-resistance genes. The second is the introduction of mutations in the promoter region of the ampC β-lactamase gene that cause chromosome-encoded β-lactamase hyperproduction. A wide variety of promoter mutations related to AmpC hyperproduction have been described. However, their link to CTX resistance has not been reported. We recultured 172 cefoxitin-resistant E. coli isolates with known CTX minimum inhibitory concentrations and performed genome-wide analysis of homoplastic mutations associated with CTX resistance by comparing Illumina whole-genome sequencing data of all isolates to a PacBio sequenced reference chromosome. We mapped the mutations on the reference chromosome and determined their occurrence in the phylogeny, revealing extreme homoplasy at the -42 position of the ampC promoter. The 24 occurrences of a T at the -42 position rather than the wild-type C, resulted from 18 independent C>T mutations in five phylogroups. The -42 C>T mutation was only observed in E. coli lacking a plasmid-encoded ampC gene. The association of the -42 C>T mutation with CTX resistance was confirmed to be significant (false discovery rate <0.05). To conclude, genome-wide analysis of homoplasy in combination with CTX resistance identifies the -42 C>T mutation of the ampC promotor as significantly associated with CTX resistance and underlines the role of recurrent mutations in the spread of antibiotic resistance.
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Affiliation(s)
- Jordy P. M. Coolen
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Evert P. M. den Drijver
- Department of Infection Control, Amphia Ziekenhuis, Breda, The Netherlands
- Laboratory for Medical Microbiology and Immunology, Elisabeth-Tweesteden Hospital, Tilburg, The Netherlands
| | - Jaco J. Verweij
- Laboratory for Medical Microbiology and Immunology, Elisabeth-Tweesteden Hospital, Tilburg, The Netherlands
| | - Jodie A. Schildkraut
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kornelia Neveling
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Willem J. G. Melchers
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eva Kolwijck
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Heiman F. L. Wertheim
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan A. J. W. Kluytmans
- Department of Infection Control, Amphia Ziekenhuis, Breda, The Netherlands
- Laboratory for Microbiology, Microvida, Breda, The Netherlands
- Julius Center for Health Sciences and Primary Care, UMCU, Utrecht, The Netherlands
| | - Martijn A. Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Center, Nijmegen, The Netherlands
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10
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Weber RE, Fuchs S, Layer F, Sommer A, Bender JK, Thürmer A, Werner G, Strommenger B. Genome-Wide Association Studies for the Detection of Genetic Variants Associated With Daptomycin and Ceftaroline Resistance in Staphylococcus aureus. Front Microbiol 2021; 12:639660. [PMID: 33658988 PMCID: PMC7917082 DOI: 10.3389/fmicb.2021.639660] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/22/2021] [Indexed: 12/29/2022] Open
Abstract
Background As next generation sequencing (NGS) technologies have experienced a rapid development over the last decade, the investigation of the bacterial genetic architecture reveals a high potential to dissect causal loci of antibiotic resistance phenotypes. Although genome-wide association studies (GWAS) have been successfully applied for investigating the basis of resistance traits, complex resistance phenotypes have been omitted so far. For S. aureus this especially refers to antibiotics of last resort like daptomycin and ceftaroline. Therefore, we aimed to perform GWAS for the identification of genetic variants associated with DAP and CPT resistance in clinical S. aureus isolates. Materials/methods To conduct microbial GWAS, we selected cases and controls according to their clonal background, date of isolation, and geographical origin. Association testing was performed with PLINK and SEER analysis. By using in silico analysis, we also searched for rare genetic variants in candidate loci that have previously been described to be involved in the development of corresponding resistance phenotypes. Results GWAS revealed MprF P314L and L826F to be significantly associated with DAP resistance. These mutations were found to be homogenously distributed among clonal lineages suggesting convergent evolution. Additionally, rare and yet undescribed single nucleotide polymorphisms could be identified within mprF and putative candidate genes. Finally, we could show that each DAP resistant isolate exhibited at least one amino acid substitution within the open reading frame of mprF. Due to the presence of strong population stratification, no genetic variants could be associated with CPT resistance. However, the investigation of the staphylococcal cassette chromosome mec (SCCmec) revealed various mecA SNPs to be putatively linked with CPT resistance. Additionally, some CPT resistant isolates revealed no mecA mutations, supporting the hypothesis that further and still unknown resistance determinants are crucial for the development of CPT resistance in S. aureus. Conclusion We hereby confirmed the potential of GWAS to identify genetic variants that are associated with antibiotic resistance traits in S. aureus. However, precautions need to be taken to prevent the detection of spurious associations. In addition, the implementation of different approaches is still essential to detect multiple forms of variations and mutations that occur with a low frequency.
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Affiliation(s)
- Robert E Weber
- Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany.,Methodology and Research Infrastructure, Genome Sequencing, Robert Koch-Institute, Berlin, Germany
| | - Stephan Fuchs
- Methodology and Research Infrastructure, Bioinformatics, Robert Koch-Institute, Berlin, Germany
| | - Franziska Layer
- Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany.,Methodology and Research Infrastructure, Genome Sequencing, Robert Koch-Institute, Berlin, Germany
| | - Anna Sommer
- Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany.,Methodology and Research Infrastructure, Genome Sequencing, Robert Koch-Institute, Berlin, Germany
| | - Jennifer K Bender
- Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany.,Methodology and Research Infrastructure, Genome Sequencing, Robert Koch-Institute, Berlin, Germany
| | - Andrea Thürmer
- Methodology and Research Infrastructure, Bioinformatics, Robert Koch-Institute, Berlin, Germany
| | - Guido Werner
- Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany.,Methodology and Research Infrastructure, Genome Sequencing, Robert Koch-Institute, Berlin, Germany
| | - Birgit Strommenger
- Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany.,Methodology and Research Infrastructure, Genome Sequencing, Robert Koch-Institute, Berlin, Germany
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11
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Abstract
Genome-wide association studies in bacteria have great potential to deliver a better understanding of the genetic basis of many biologically important phenotypes, including antibiotic resistance, pathogenicity, and host adaptation. Such studies need however to account for the specificities of bacterial genomics, especially in terms of population structure, homologous recombination, and genomic plasticity. A powerful way to tackle this challenge is to use a phylogenetic approach, which is based on long-standing methodology for the evolutionary analysis of bacterial genomic data. Here we present both the theoretical and practical aspects involved in the use of phylogenetic methods for bacterial genome-wide association studies.
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Affiliation(s)
- Xavier Didelot
- School of Life Sciences and Department of Statistics, University of Warwick, Coventry, UK.
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12
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Crits-Christoph A, Olm MR, Diamond S, Bouma-Gregson K, Banfield JF. Soil bacterial populations are shaped by recombination and gene-specific selection across a grassland meadow. THE ISME JOURNAL 2020; 14:1834-1846. [PMID: 32327732 PMCID: PMC7305173 DOI: 10.1038/s41396-020-0655-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/22/2020] [Accepted: 04/02/2020] [Indexed: 01/25/2023]
Abstract
Soil microbial diversity is often studied from the perspective of community composition, but less is known about genetic heterogeneity within species. The relative impacts of clonal interference, gene-specific selection, and recombination in many abundant but rarely cultivated soil microbes remain unknown. Here we track genome-wide population genetic variation for 19 highly abundant bacterial species sampled from across a grassland meadow. Genomic inferences about population structure are made using the millions of sequencing reads that are assembled de novo into consensus genomes from metagenomes, as each read pair describes a short genomic sequence from a cell in each population. Genomic nucleotide identity of assembled genomes was significantly associated with local geography for over half of the populations studied, and for a majority of populations within-sample nucleotide diversity could often be as high as meadow-wide nucleotide diversity. Genes involved in metabolite biosynthesis and extracellular transport were characterized by elevated nucleotide diversity in multiple species. Microbial populations displayed varying degrees of homologous recombination and recombinant variants were often detected at 7-36% of loci genome-wide. Within multiple populations we identified genes with unusually high spatial differentiation of alleles, fewer recombinant events, elevated ratios of nonsynonymous to synonymous variants, and lower nucleotide diversity, suggesting recent selective sweeps for gene variants. Taken together, these results indicate that recombination and gene-specific selection commonly shape genetic variation in several understudied soil bacterial lineages.
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Affiliation(s)
| | - Matthew R Olm
- Department of Earth and Planetary Science, University of California, Berkeley, CA, USA
| | - Spencer Diamond
- Department of Earth and Planetary Science, University of California, Berkeley, CA, USA
| | - Keith Bouma-Gregson
- Department of Earth and Planetary Science, University of California, Berkeley, CA, USA
| | - Jillian F Banfield
- Department of Earth and Planetary Science, University of California, Berkeley, CA, USA.
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA.
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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13
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VanInsberghe D, Arevalo P, Chien D, Polz MF. How can microbial population genomics inform community ecology? Philos Trans R Soc Lond B Biol Sci 2020; 375:20190253. [PMID: 32200748 PMCID: PMC7133533 DOI: 10.1098/rstb.2019.0253] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2019] [Indexed: 12/22/2022] Open
Abstract
Populations are fundamental units of ecology and evolution, but can we define them for bacteria and archaea in a biologically meaningful way? Here, we review why population structure is difficult to recognize in microbes and how recent advances in measuring contemporary gene flow allow us to identify clearly delineated populations among collections of closely related genomes. Such structure can arise from preferential gene flow caused by coexistence and genetic similarity, defining populations based on biological mechanisms. We show that such gene flow units are sufficiently genetically isolated for specific adaptations to spread, making them also ecological units that are differentially adapted compared to their closest relatives. We discuss the implications of these observations for measuring bacterial and archaeal diversity in the environment. We show that operational taxonomic units defined by 16S rRNA gene sequencing have woefully poor resolution for ecologically defined populations and propose monophyletic clusters of nearly identical ribosomal protein genes as an alternative measure for population mapping in community ecological studies employing metagenomics. These population-based approaches have the potential to provide much-needed clarity in interpreting the vast microbial diversity in human and environmental microbiomes. This article is part of the theme issue 'Conceptual challenges in microbial community ecology'.
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Affiliation(s)
- David VanInsberghe
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Graduate Program in Microbiology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Philip Arevalo
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Graduate Program in Microbiology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
| | - Diana Chien
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Graduate Program in Microbiology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Martin F. Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
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Arnold B, Sohail M, Wadsworth C, Corander J, Hanage WP, Sunyaev S, Grad YH. Fine-Scale Haplotype Structure Reveals Strong Signatures of Positive Selection in a Recombining Bacterial Pathogen. Mol Biol Evol 2020; 37:417-428. [PMID: 31589312 PMCID: PMC6993868 DOI: 10.1093/molbev/msz225] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Identifying genetic variation in bacteria that has been shaped by ecological differences remains an important challenge. For recombining bacteria, the sign and strength of linkage provide a unique lens into ongoing selection. We show that derived alleles <300 bp apart in Neisseria gonorrhoeae exhibit more coupling linkage than repulsion linkage, a pattern that cannot be explained by limited recombination or neutrality as these couplings are significantly stronger for nonsynonymous alleles than synonymous alleles. This general pattern is driven by a small fraction of highly diverse genes, many of which exhibit evidence of interspecies horizontal gene transfer and an excess of intermediate frequency alleles. Extensive simulations show that two distinct forms of positive selection can create these patterns of genetic variation: directional selection on horizontally transferred alleles or balancing selection that maintains distinct haplotypes in the presence of recombination. Our results establish a framework for identifying patterns of selection in fine-scale haplotype structure that indicate specific ecological processes in species that recombine with distantly related lineages or possess coexisting adaptive haplotypes.
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Affiliation(s)
- Brian Arnold
- Division of Informatics, Faculty of Arts and Sciences, Harvard University, Cambridge, MA
- Center for Communicable Disease Dynamics, Harvard T. H. Chan School of Public Health, Boston, MA
| | - Mashaal Sohail
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA
| | - Crista Wadsworth
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA
| | - Jukka Corander
- Department of Biostatistics, University of Oslo, Oslo, Norway
- Department of Computer Science, Helsinki Institute for Information Technology HIIT, University of Helsinki, Helsinki, Finland
| | - William P Hanage
- Center for Communicable Disease Dynamics, Harvard T. H. Chan School of Public Health, Boston, MA
| | - Shamil Sunyaev
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA
| | - Yonatan H Grad
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA
- Division of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
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15
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Burghardt LT, Epstein B, Tiffin P. Legacy of prior host and soil selection on rhizobial fitness in planta. Evolution 2019; 73:2013-2023. [PMID: 31334838 DOI: 10.1111/evo.13807] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 06/19/2019] [Accepted: 06/20/2019] [Indexed: 01/03/2023]
Abstract
Measuring selection acting on microbial populations in natural or even seminatural environments is challenging because many microbial populations experience variable selection. The majority of rhizobial bacteria are found in the soil. However, they also live symbiotically inside nodules of legume hosts and each nodule can release thousands of daughter cells back into the soil. We tested how past selection (i.e., legacies) by two plant genotypes and by the soil alone affected selection and genetic diversity within a population of 101 strains of Ensifer meliloti. We also identified allelic variants most strongly associated with soil- and host-dependent fitness. In addition to imposing direct selection on rhizobia populations, soil and host environments had lasting effects across host generations. Host presence and genotype during the legacy period explained 22% and 12% of the variance in the strain composition of nodule communities in the second cohort, respectively. Although strains with high host fitness in the legacy cohort tended to be enriched in the second cohort, the diversity of the strain community was greater when the second cohort was preceded by host rather than soil legacies. Our results indicate the potential importance of soil selection driving the evolution of these plant-associated microbes.
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Affiliation(s)
- Liana T Burghardt
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, 55108
| | - Brendan Epstein
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, 55108
| | - Peter Tiffin
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, 55108
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16
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A Reverse Ecology Approach Based on a Biological Definition of Microbial Populations. Cell 2019; 178:820-834.e14. [DOI: 10.1016/j.cell.2019.06.033] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/28/2019] [Accepted: 06/24/2019] [Indexed: 01/30/2023]
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17
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Vieira A, Silva DN, Várzea V, Paulo OS, Batista D. Genome-Wide Signatures of Selection in Colletotrichum kahawae Reveal Candidate Genes Potentially Involved in Pathogenicity and Aggressiveness. Front Microbiol 2019; 10:1374. [PMID: 31275287 PMCID: PMC6593080 DOI: 10.3389/fmicb.2019.01374] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 06/03/2019] [Indexed: 12/26/2022] Open
Abstract
Plants and their pathogens are engaged in continuous evolutionary battles, with pathogens evolving to circumvent plant defense mechanisms and plants responding through enhanced protection to prevent or mitigate damage induced by pathogen attack. Managed ecosystems are composed of genetically identical populations of crop plants with few changes from year to year. These environments are highly conducive to the emergence and dissemination of pathogens and they exert selective pressure for both qualitative virulence factors responsible for fungal pathogenicity, and quantitative traits linked to pathogen fitness, such as aggressiveness. In this study, we used a comparative genome-wide approach to investigate the genomic basis underlying the pathogenicity and aggressiveness of the fungal coffee pathogen Colletotrichum kahawae infecting green coffee berries. The pathogenicity was investigated by comparing genomic variation between C. kahawae and its non-pathogenic sibling species, while the aggressiveness was studied by a genome-wide association approach with groups of isolates with different phenotypic profiles. High genetic differentiation was observed between C. kahawae and the most closely related species with 5,560 diagnostic SNPs identified, in which a significant enrichment of non-synonymous mutations was detected. Functional annotation of these non-synonymous mutations revealed a significant enrichment mainly in two gene ontology categories, “oxidation–reduction process” and “integral component of membrane.” Finally, the annotation of several genes potentially under-selection revealed that C. kahawae’s pathogenicity may be a complex biological process, in which important biological functions, such as, detoxification and transport, regulation of host and pathogen gene expression, and signaling are involved. On the other hand, the genome-wide association analyses for aggressiveness were able to identify 10 SNPs and 15 SNPs of small effect in single and multi-association analysis, respectively, from which 7 were common, giving in total 18 SNPs potentially associated. The annotation of these genomic regions allowed the identification of four candidate genes encoding F-box domain-containing, nitrosoguanidine resistance, Fungal specific transcription factor domain-containing and C6 transcription factor that could be associated with aggressiveness. This study shed light, for the first time, on the genetic mechanisms of C. kahawae host specialization.
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Affiliation(s)
- Ana Vieira
- Centro de Investigação das Ferrugens do Cafeeiro, Instituto Superior de Agronomia, Universidade de Lisboa, Oeiras, Portugal.,Computational Biology and Population Genomics Group, Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.,Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia, Universidade de Lisboa, Lisbon, Portugal
| | - Diogo Nuno Silva
- Centro de Investigação das Ferrugens do Cafeeiro, Instituto Superior de Agronomia, Universidade de Lisboa, Oeiras, Portugal.,Computational Biology and Population Genomics Group, Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.,Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia, Universidade de Lisboa, Lisbon, Portugal
| | - Vitor Várzea
- Centro de Investigação das Ferrugens do Cafeeiro, Instituto Superior de Agronomia, Universidade de Lisboa, Oeiras, Portugal.,Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia, Universidade de Lisboa, Lisbon, Portugal
| | - Octávio Salgueiro Paulo
- Computational Biology and Population Genomics Group, Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Dora Batista
- Centro de Investigação das Ferrugens do Cafeeiro, Instituto Superior de Agronomia, Universidade de Lisboa, Oeiras, Portugal.,Computational Biology and Population Genomics Group, Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.,Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia, Universidade de Lisboa, Lisbon, Portugal
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18
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Kurilung A, Keeratipusana C, Suriyaphol P, Hampson DJ, Prapasarakul N. Genomic analysis of Leptospira interrogans serovar Paidjan and Dadas isolates from carrier dogs and comparative genomic analysis to detect genes under positive selection. BMC Genomics 2019; 20:168. [PMID: 30832578 PMCID: PMC6399948 DOI: 10.1186/s12864-019-5562-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/25/2019] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Leptospirosis is an emerging infectious disease worldwide that can cause high morbidity and mortality rates in humans and animals. The causative spirochetes have reservoirs in mammalian hosts, but there has been limited analysis of the genomes of isolates recovered from animals. The aims of this study were to characterize genomic features of two Leptospira interrogans strains recently isolated from asymptomatic dogs in Thailand (strains CUDO5 and CDUO8), and to perform comparative genome analyses with other strains. Molecular adaptive evolution in L. interrogans as signaled by positive selection also was analyzed. RESULTS Whole genome sequence analysis revealed that strains CUDO5 and CUDO8 had genome sizes of approximately 4.9 Mbp with 35.1% GC contents. Using monoclonal antibodies, strains CUDO5 and CUDO8 were identified as serovars Paidjan and Dadas, respectively. These strains harbored genes known to be associated with acute and chronic infections. Using Single Nucleotide Polymorphisms phylogeny (SNPs) with 97 L. interrogans strains, CUDO5 and CUDO8 had closest genetic relatedness with each other. Nevertheless, the serovar determinant region (rfb locus) showed variations in the genes encoding sugar biosynthesis. Amongst 13 representative L. interrogans strains examined for molecular adaptive evolution through positive selection under the site-model of Phylogenetic Analysis of Maximum Likelihood, genes responsible for iron acquisition (tlyA and hbpA), motility (fliN2, flgK, and flhB) and thermal adaptation (lpxD1) were under increased selective pressure. CONCLUSIONS L. interrogans serovar Paidjan strain CUDO5 and serovar Dadas strain CUDO8 had close genetic relatedness as analyzed by SNPs phylogeny. They contained genes with established roles in acute and chronic leptospirosis. The rfb locus in both serovars showed gene variation associated with sugar biosynthesis. Positive selection analysis indicated that genes encoding factors involved in motility, temperature adaptation, and iron acquisition were under strong positive selection in L. interrogans. These may be associated with adaptation in the early stages of infection.
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Affiliation(s)
- Alongkorn Kurilung
- Department of Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Chantisa Keeratipusana
- Bioinformatics and Data Management for Research Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Prapat Suriyaphol
- Bioinformatics and Data Management for Research Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - David J Hampson
- Department of Infectious Diseases and Public Health, College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR
| | - Nuvee Prapasarakul
- Department of Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand. .,Diagnosis and Monitoring of Animal Pathogens Research Unit, Department of Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
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19
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Rosen MJ, Davison M, Fisher DS, Bhaya D. Probing the ecological and evolutionary history of a thermophilic cyanobacterial population via statistical properties of its microdiversity. PLoS One 2018; 13:e0205396. [PMID: 30427861 PMCID: PMC6235289 DOI: 10.1371/journal.pone.0205396] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 09/25/2018] [Indexed: 12/11/2022] Open
Abstract
Despite extensive DNA sequencing data derived from natural microbial communities, it remains a major challenge to identify the key evolutionary and ecological forces that shape microbial populations. We have focused on the extensive microdiversity of the cyanobacterium Synechococcus sp., which is a dominant member of the dense phototrophic biofilms in the hot springs of Yellowstone National Park. From deep amplicon sequencing of many loci and statistical analyses of these data, we showed previously that the population has undergone an unexpectedly high degree of homologous recombination, unlinking synonymous SNP-pair correlations even on intragenic length scales. Here, we analyze the genic amino acid diversity, which provides new evidence of selection and insights into the evolutionary history of the population. Surprisingly, some features of the data, including the spectrum of distances between genic-alleles, appear consistent with primarily asexual neutral drift. Yet the non-synonymous site frequency spectrum has too large an excess of low-frequency polymorphisms to result from negative selection on deleterious mutations given the distribution of coalescent times that we infer. And our previous analyses showed that the population is not asexual. Taken together, these apparently contradictory data suggest that selection, epistasis, and hitchhiking all play essential roles in generating and stabilizing the diversity. We discuss these as well as potential roles of ecological niches at genomic and genic levels. From quantitative properties of the diversity and comparative genomic data, we infer aspects of the history and inter-spring dispersal of the meta-population since it was established in the Yellowstone Caldera. Our investigations illustrate the need for combining multiple types of sequencing data and quantitative statistical analyses to develop an understanding of microdiversity in natural microbial populations.
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Affiliation(s)
- Michael J. Rosen
- Applied Physics Department, Stanford University, Stanford, CA, United States of America
| | - Michelle Davison
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, United States of America
| | - Daniel S. Fisher
- Applied Physics Department, Stanford University, Stanford, CA, United States of America
| | - Devaki Bhaya
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, United States of America
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20
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Complete genome sequencing of sixteen Francisella noatunensis subsp. orientalis isolates: A genomic approach for molecular characterization and spread dynamics of this clonal population. Genomics 2018; 110:442-449. [PMID: 30367926 DOI: 10.1016/j.ygeno.2018.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/09/2018] [Accepted: 10/19/2018] [Indexed: 11/23/2022]
Abstract
Francisella noatunensis subsp. orientalis (FNO) is an important emerging pathogen associated with disease outbreaks in farm-raised Nile tilapia. FNO genetic diversity using PCR-based typing, no intra-species discrimination was achieved among isolates/strains from different countries, thus demonstrating a clonal behaviour pattern. In this study, we aimed to evaluate the population structure of FNO isolates by comparing whole-genome sequencing data. The analysis of recombination showed that Brazilian isolates group formed a clonal population; whereas other lineages are also supported by this analysis for isolates from foreign countries. The whole-genome multilocus sequence typing (wgMLST) analysis showed varying numbers of dissimilar alleles, suggesting that the Brazilian clonal population are in expansion. Each Brazilian isolate could be identified as a single node by high-resolution gene-by-gene approach, presenting slight genetic differences associated to mutational events. The common ancestry node suggests a single entry into the country before 2012, and the rapid dissemination of this infectious agent may be linked to market sales of infected fingerlings.
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21
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Fan Y, Xiao Y, Momeni B, Liu YY. Horizontal gene transfer can help maintain the equilibrium of microbial communities. J Theor Biol 2018; 454:53-59. [DOI: 10.1016/j.jtbi.2018.05.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/23/2018] [Accepted: 05/29/2018] [Indexed: 01/15/2023]
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22
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Evolution of a Vegetarian Vibrio: Metabolic Specialization of Vibrio breoganii to Macroalgal Substrates. J Bacteriol 2018; 200:JB.00020-18. [PMID: 29632094 DOI: 10.1128/jb.00020-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 04/03/2018] [Indexed: 02/07/2023] Open
Abstract
While most Vibrionaceae are considered generalists that thrive on diverse substrates, including animal-derived material, we show that Vibrio breoganii has specialized for the consumption of marine macroalga-derived substrates. Genomic and physiological comparisons of V. breoganii with other Vibrionaceae isolates revealed the ability to degrade alginate, laminarin, and additional glycans present in algal cell walls. Moreover, the widely conserved ability to hydrolyze animal-derived polymers, including chitin and glycogen, was lost, along with the ability to efficiently grow on a variety of amino acids. Ecological data showing associations with particulate algal material but not zooplankton further support this shift in niche preference, and the loss of motility appears to reflect a sessile macroalga-associated lifestyle. Together, these findings indicate that algal polysaccharides have become a major source of carbon and energy in V. breoganii, and these ecophysiological adaptations may facilitate transient commensal associations with marine invertebrates that feed on algae.IMPORTANCE Vibrios are often considered animal specialists or generalists. Here, we show that Vibrio breoganii has undergone massive genomic changes to become specialized on algal carbohydrates. Accompanying genomic changes include massive gene import and loss. These vibrios may help us better understand how algal biomass is degraded in the environment and may serve as a blueprint on how to optimize the conversion of algae to biofuels.
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23
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A Reverse Ecology Framework for Bacteria and Archaea. POPULATION GENOMICS: MICROORGANISMS 2018. [DOI: 10.1007/13836_2018_46] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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24
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Mortimer TD, Annis DS, O’Neill MB, Bohr LL, Smith TM, Poinar HN, Mosher DF, Pepperell CS. Adaptation in a Fibronectin Binding Autolysin of Staphylococcus saprophyticus. mSphere 2017; 2:e00511-17. [PMID: 29202045 PMCID: PMC5705806 DOI: 10.1128/msphere.00511-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 11/13/2017] [Indexed: 12/18/2022] Open
Abstract
Human-pathogenic bacteria are found in a variety of niches, including free-living, zoonotic, and microbiome environments. Identifying bacterial adaptations that enable invasive disease is an important means of gaining insight into the molecular basis of pathogenesis and understanding pathogen emergence. Staphylococcus saprophyticus, a leading cause of urinary tract infections, can be found in the environment, food, animals, and the human microbiome. We identified a selective sweep in the gene encoding the Aas adhesin, a key virulence factor that binds host fibronectin. We hypothesize that the mutation under selection (aas_2206A>C) facilitates colonization of the urinary tract, an environment where bacteria are subject to strong shearing forces. The mutation appears to have enabled emergence and expansion of a human-pathogenic lineage of S. saprophyticus. These results demonstrate the power of evolutionary genomic approaches in discovering the genetic basis of virulence and emphasize the pleiotropy and adaptability of bacteria occupying diverse niches. IMPORTANCEStaphylococcus saprophyticus is an important cause of urinary tract infections (UTI) in women; such UTI are common, can be severe, and are associated with significant impacts to public health. In addition to being a cause of human UTI, S. saprophyticus can be found in the environment, in food, and associated with animals. After discovering that UTI strains of S. saprophyticus are for the most part closely related to each other, we sought to determine whether these strains are specially adapted to cause disease in humans. We found evidence suggesting that a mutation in the gene aas is advantageous in the context of human infection. We hypothesize that the mutation allows S. saprophyticus to survive better in the human urinary tract. These results show how bacteria found in the environment can evolve to cause disease.
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Affiliation(s)
- Tatum D. Mortimer
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Douglas S. Annis
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Mary B. O’Neill
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Laboratory of Genetics, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Lindsey L. Bohr
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Microbiology Doctoral Training Program, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Tracy M. Smith
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Department of Medicine, Division of Infectious Diseases, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Hendrik N. Poinar
- McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, Ontario, Canada
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
- Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Deane F. Mosher
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Caitlin S. Pepperell
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Department of Medicine, Division of Infectious Diseases, School of Medicine and Public Health, University of Wisconsin—Madison, Madison, Wisconsin, USA
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25
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Ishihara K. New approach for studying mobile genes using metagenomic analysis. Oral Dis 2017; 24:494-496. [PMID: 28083919 DOI: 10.1111/odi.12640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 01/08/2017] [Indexed: 11/30/2022]
Affiliation(s)
- K Ishihara
- Department of Microbiology, Tokyo Dental College, Tokyo, Japan
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26
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Plissonneau C, Benevenuto J, Mohd-Assaad N, Fouché S, Hartmann FE, Croll D. Using Population and Comparative Genomics to Understand the Genetic Basis of Effector-Driven Fungal Pathogen Evolution. FRONTIERS IN PLANT SCIENCE 2017; 8:119. [PMID: 28217138 PMCID: PMC5289978 DOI: 10.3389/fpls.2017.00119] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/20/2017] [Indexed: 05/20/2023]
Abstract
Epidemics caused by fungal plant pathogens pose a major threat to agro-ecosystems and impact global food security. High-throughput sequencing enabled major advances in understanding how pathogens cause disease on crops. Hundreds of fungal genomes are now available and analyzing these genomes highlighted the key role of effector genes in disease. Effectors are small secreted proteins that enhance infection by manipulating host metabolism. Fungal genomes carry 100s of putative effector genes, but the lack of homology among effector genes, even for closely related species, challenges evolutionary and functional analyses. Furthermore, effector genes are often found in rapidly evolving chromosome compartments which are difficult to assemble. We review how population and comparative genomics toolsets can be combined to address these challenges. We highlight studies that associated genome-scale polymorphisms with pathogen lifestyles and adaptation to different environments. We show how genome-wide association studies can be used to identify effectors and other pathogenicity-related genes underlying rapid adaptation. We also discuss how the compartmentalization of fungal genomes into core and accessory regions shapes the evolution of effector genes. We argue that an understanding of genome evolution provides important insight into the trajectory of host-pathogen co-evolution.
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Affiliation(s)
- Clémence Plissonneau
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
- UMR, BIOGER, INRA, AgroParisTech, Université Paris-SaclayThiverval-Grignon, France
| | - Juliana Benevenuto
- College of Agriculture “Luiz de Queiroz”, University of São PauloSão Paulo, Brazil
| | - Norfarhan Mohd-Assaad
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan MalaysiaSelangor, Malaysia
| | - Simone Fouché
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
| | - Fanny E. Hartmann
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
| | - Daniel Croll
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchatelNeuchatel, Switzerland
- *Correspondence: Daniel Croll,
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27
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Bao YJ, Shapiro BJ, Lee SW, Ploplis VA, Castellino FJ. Phenotypic differentiation of Streptococcus pyogenes populations is induced by recombination-driven gene-specific sweeps. Sci Rep 2016; 6:36644. [PMID: 27821851 PMCID: PMC5099688 DOI: 10.1038/srep36644] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 10/13/2016] [Indexed: 01/05/2023] Open
Abstract
Genomic recombination plays an important role in driving adaptive evolution and population differentiation in bacteria. However, controversy exists as to the effects of recombination on population diversity and differentiation, i.e., recombination is frequent enough to sweep through the population at selected gene loci (gene-specific sweeps), or the recombination rate is low without interfering genome-wide selective sweeps. Observations supporting either view are sparse. Pathogenic bacteria causing infectious diseases are promising candidates to provide observations of recombination. However, phenotype-associated differentiations are usually vague among them due to diverse disease manifestations. Here we report a population genomic study of the group A Streptococcus pyogenes (GAS), a human pathogen with highly recombining genomes. By employing a genome-wide association study on single nucleotide polymorphisms (SNPs), we demonstrate a phenotypic differentiation of GAS, represented by separate clustering of two sublineages associated with niche-specific infections, i.e., skin infection and pharyngitis-induced acute rheumatic fever. By quantifying SNPs associated with the differentiation in a statistical and phylogenetic context, we propose that the phenotype-associated differentiation arose through recombination-driven gene-specific sweeps, rather than genome-wide sweeps. Our work provides a novel paradigm of phenotype-associated differentiation induced by gene-specific sweeps in a human pathogen and has implications for understanding of driving forces of bacterial evolution.
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Affiliation(s)
- Yun-Juan Bao
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA
| | - B Jesse Shapiro
- Département de Sciences Biologiques, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Shaun W Lee
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Victoria A Ploplis
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Francis J Castellino
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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Marston MF, Martiny JBH. Genomic diversification of marine cyanophages into stable ecotypes. Environ Microbiol 2016; 18:4240-4253. [DOI: 10.1111/1462-2920.13556] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/12/2016] [Accepted: 09/27/2016] [Indexed: 01/07/2023]
Affiliation(s)
- Marcia F. Marston
- Department of Biology and Marine Biology; Roger Williams University; Bristol RI 02809 USA
| | - Jennifer B. H. Martiny
- Department of Ecology and Evolutionary Biology; University of California; Irvine CA 92697 USA
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Joseph SJ, Cox D, Wolff B, Morrison SS, Kozak-Muiznieks NA, Frace M, Didelot X, Castillo-Ramirez S, Winchell J, Read TD, Dean D. Dynamics of genome change among Legionella species. Sci Rep 2016; 6:33442. [PMID: 27633769 PMCID: PMC5025774 DOI: 10.1038/srep33442] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/26/2016] [Indexed: 11/16/2022] Open
Abstract
Legionella species inhabit freshwater and soil ecosystems where they parasitize protozoa. L. pneumonphila (LP) serogroup-1 (Lp1) is the major cause of Legionnaires' Disease (LD), a life-threatening pulmonary infection that can spread systemically. The increased global frequency of LD caused by Lp and non-Lp species underscores the need to expand our knowledge of evolutionary forces underlying disease pathogenesis. Whole genome analyses of 43 strains, including all known Lp serogroups 1-17 and 17 emergent LD-causing Legionella species (of which 33 were sequenced in this study) in addition to 10 publicly available genomes, resolved the strains into four phylogenetic clades along host virulence demarcations. Clade-specific genes were distinct for genetic exchange and signal-transduction, indicating adaptation to specific cellular and/or environmental niches. CRISPR spacer comparisons hinted at larger pools of accessory DNA sequences in Lp than predicted by the pan-genome analyses. While recombination within Lp was frequent and has been reported previously, population structure analysis identified surprisingly few DNA admixture events between species. In summary, diverse Legionella LD-causing species share a conserved core-genome, are genetically isolated from each other, and selectively acquire genes with potential for enhanced virulence.
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Affiliation(s)
- Sandeep J. Joseph
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Daniel Cox
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Bernard Wolff
- Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Shatavia S. Morrison
- Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | | | - Michael Frace
- Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Xavier Didelot
- Department of Infectious Disease Epidemiology, Imperial College, Norfolk Place, London, United Kingdom
| | - Santiago Castillo-Ramirez
- Programa de Genomica Evolutiva, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Jonas Winchell
- Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Timothy D. Read
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Deborah Dean
- Department of Medicine and University of California, San Francisco, San Francisco, California, USA
- Department of Biomedical Engineering, University of California at San Francisco and Berkeley, San Francisco and Berkeley, California, USA
- Center for Immunobiology and Vaccine Development, UCSF Benioff Children’s Hospital Oakland Research Institute, Oakland, California, USA
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30
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Perez M, Juniper SK. Insights into Symbiont Population Structure among Three Vestimentiferan Tubeworm Host Species at Eastern Pacific Spreading Centers. Appl Environ Microbiol 2016; 82:5197-205. [PMID: 27316954 PMCID: PMC4988177 DOI: 10.1128/aem.00953-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/10/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The symbiotic relationship between vestimentiferan tubeworms and their intracellular chemosynthetic bacteria is one of the more noteworthy examples of adaptation to deep-sea hydrothermal vent environments. The tubeworm symbionts have never been cultured in the laboratory. Nucleotide sequences from the small subunit rRNA gene suggest that the intracellular symbionts of the eastern Pacific vent tubeworms Oasisia alvinae, Riftia pachyptila, Tevnia jerichonana, and Ridgeia piscesae belong to the same phylotype of gammaproteobacteria, "Candidatus Endoriftia persephone." Comparisons of symbiont genomes between the East Pacific Rise tubeworms R. pachyptila and T. jerichonana confirmed that these two hosts share the same symbionts. Two Ridgeia symbiont genomes were assembled from trophosome metagenomes from worms collected from the Juan de Fuca Ridge (one and five individuals, respectively). We compared these assemblies to those of the sequenced Riftia and Tevnia symbionts. Pangenome composition, genome-wide comparisons of the nucleotide sequences, and pairwise comparisons of 2,313 orthologous genes indicated that "Ca Endoriftia persephone" symbionts are structured on large geographical scales but also on smaller scales and possibly through host specificity. IMPORTANCE Remarkably, the intracellular symbionts of four to six species of eastern Pacific vent tubeworms all belong to the same phylotype of gammaproteobacteria, "Candidatus Endoriftia persephone." Understanding the structure, dynamism, and interconnectivity of "Ca Endoriftia persephone" populations is important to advancing our knowledge of the ecology and evolution of their host worms, which are often keystone species in vent communities. In this paper, we present the first genomes for symbionts associated with the species R. piscesae, from the Juan de Fuca Ridge. We then combine these genomes with published symbiont genomes from the East Pacific Rise tubeworms R. pachyptila and T. jerichonana to develop a portrait of the "Ca Endoriftia persephone" pangenome and an initial outline of symbiont population structure in the different host species. Our study is the first to apply genome-wide comparisons of "Ca Endoriftia persephone" assemblies in the context of population genetics and molecular evolution.
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Affiliation(s)
- Maëva Perez
- School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada
| | - S Kim Juniper
- School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada Department of Biology, University of Victoria, Victoria, BC, Canada
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31
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Porter SS, Chang PL, Conow CA, Dunham JP, Friesen ML. Association mapping reveals novel serpentine adaptation gene clusters in a population of symbiotic Mesorhizobium. ISME JOURNAL 2016; 11:248-262. [PMID: 27420027 PMCID: PMC5315480 DOI: 10.1038/ismej.2016.88] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 05/23/2016] [Accepted: 05/25/2016] [Indexed: 01/18/2023]
Abstract
The genetic variants that underlie microbial environmental adaptation are key components of models of microbial diversification. Characterizing adaptive variants and the pangenomic context in which they evolve remains a frontier in understanding how microbial diversity is generated. The genomics of rhizobium adaptation to contrasting soil environments is ecologically and agriculturally important because these bacteria are responsible for half of all current biologically fixed nitrogen, yet they live the majority of their lives in soil. Our study uses whole-genome sequencing to describe the pan-genome of a focal clade of wild mesorhizobia that show contrasting levels of nickel adaptation despite high relatedness (99.8% identity at 16S). We observe ecotypic specialization within an otherwise genomically cohesive population, rather than finding distinct specialized bacterial lineages in contrasting soil types. This finding supports recent reports that heterogeneous environments impose selection that maintains differentiation only at a small fraction of the genome. Our work further uses a genome-wide association study to propose candidate genes for nickel adaptation. Several candidates show homology to genetic systems involved in nickel tolerance and one cluster of candidates correlates perfectly with soil origin, which validates our approach of ascribing genomic variation to adaptive divergence.
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Affiliation(s)
- Stephanie S Porter
- School of Biological Sciences, Washington State University, Vancouver, WA, USA
| | - Peter L Chang
- Section of Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.,Department of Plant Pathology and Nematology, University of California, Davis, CA, USA
| | - Christopher A Conow
- Section of Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Joseph P Dunham
- Section of Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Maren L Friesen
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
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32
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Mobile genes in the human microbiome are structured from global to individual scales. Nature 2016; 535:435-439. [PMID: 27409808 PMCID: PMC4983458 DOI: 10.1038/nature18927] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 06/15/2016] [Indexed: 12/11/2022]
Abstract
Recent work has underscored the importance of the microbiome in human health, largely attributing differences in phenotype to differences in the species present across individuals1,2,3,4,5. But mobile genes can confer profoundly different phenotypes on different strains of the same species. Little is known about the function and distribution of mobile genes in the human microbiome, and in particular whether the gene pool is globally homogenous or constrained by human population structure. Here, we investigate this question by comparing the mobile genes found in the microbiomes of 81 metropolitan North Americans with that of 172 agrarian Fiji islanders using a combination of single-cell genomics and metagenomics. We find large differences in mobile gene content between the Fijian and North American microbiomes, with functional variation that mirrors known dietary differences such as the excess of plant-based starch degradation genes. Remarkably, differences are also observed between the mobile gene pools of proximal Fijian villages, even though microbiome composition across villages is similar. Finally, we observe high rates of recombination leading to individual-specific mobile elements, suggesting that the abundance of some genes may reflect environmental selection rather than dispersal limitation. Together, these data support the hypothesis that human activities and behaviors provide selective pressures that shape mobile gene pools, and that acquisition of mobile genes is important to colonizing specific human populations.
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33
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Andersen KG, Shapiro BJ, Matranga CB, Sealfon R, Lin AE, Moses LM, Folarin OA, Goba A, Odia I, Ehiane PE, Momoh M, England EM, Winnicki S, Branco LM, Gire SK, Phelan E, Tariyal R, Tewhey R, Omoniwa O, Fullah M, Fonnie R, Fonnie M, Kanneh L, Jalloh S, Gbakie M, Saffa S, Karbo K, Gladden AD, Qu J, Stremlau M, Nekoui M, Finucane HK, Tabrizi S, Vitti JJ, Birren B, Fitzgerald M, McCowan C, Ireland A, Berlin AM, Bochicchio J, Tazon-Vega B, Lennon NJ, Ryan EM, Bjornson Z, Milner DA, Lukens AK, Broodie N, Rowland M, Heinrich M, Akdag M, Schieffelin JS, Levy D, Akpan H, Bausch DG, Rubins K, McCormick JB, Lander ES, Günther S, Hensley L, Okogbenin S, Schaffner SF, Okokhere PO, Khan SH, Grant DS, Akpede GO, Asogun DA, Gnirke A, Levin JZ, Happi CT, Garry RF, Sabeti PC. Clinical Sequencing Uncovers Origins and Evolution of Lassa Virus. Cell 2016; 162:738-50. [PMID: 26276630 DOI: 10.1016/j.cell.2015.07.020] [Citation(s) in RCA: 190] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 04/26/2015] [Accepted: 06/12/2015] [Indexed: 12/25/2022]
Abstract
The 2013-2015 West African epidemic of Ebola virus disease (EVD) reminds us of how little is known about biosafety level 4 viruses. Like Ebola virus, Lassa virus (LASV) can cause hemorrhagic fever with high case fatality rates. We generated a genomic catalog of almost 200 LASV sequences from clinical and rodent reservoir samples. We show that whereas the 2013-2015 EVD epidemic is fueled by human-to-human transmissions, LASV infections mainly result from reservoir-to-human infections. We elucidated the spread of LASV across West Africa and show that this migration was accompanied by changes in LASV genome abundance, fatality rates, codon adaptation, and translational efficiency. By investigating intrahost evolution, we found that mutations accumulate in epitopes of viral surface proteins, suggesting selection for immune escape. This catalog will serve as a foundation for the development of vaccines and diagnostics. VIDEO ABSTRACT.
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Affiliation(s)
- Kristian G Andersen
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA; The Scripps Research Institute, Scripps Translational Science Institute, La Jolla, CA 92037, USA.
| | - B Jesse Shapiro
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA; Department of Biological Sciences, University of Montréal, Montréal, QC H2V 2S9, Canada
| | | | - Rachel Sealfon
- Broad Institute, Cambridge, MA 02142, USA; Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Aaron E Lin
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | - Lina M Moses
- Tulane Health Sciences Center, Tulane University, New Orleans, LA 70118, USA
| | - Onikepe A Folarin
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria; Department of Biological Sciences, College of Natural Sciences, Redeemer's University, Redemption City, Osun State, Nigeria
| | - Augustine Goba
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Ikponmwonsa Odia
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | - Philomena E Ehiane
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | - Mambu Momoh
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone; Eastern Polytechnic College, Kenema, Eastern Province, Sierra Leone
| | | | - Sarah Winnicki
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | | | - Stephen K Gire
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | | | | | - Ryan Tewhey
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | - Omowunmi Omoniwa
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | - Mohammed Fullah
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone; Eastern Polytechnic College, Kenema, Eastern Province, Sierra Leone
| | - Richard Fonnie
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Mbalu Fonnie
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Lansana Kanneh
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Simbirie Jalloh
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Michael Gbakie
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Sidiki Saffa
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Kandeh Karbo
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | | | - James Qu
- Broad Institute, Cambridge, MA 02142, USA
| | - Matthew Stremlau
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | - Mahan Nekoui
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | | | - Shervin Tabrizi
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA
| | - Joseph J Vitti
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | | | | | | | | | | | | | | | | | | | - Zach Bjornson
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94304, USA
| | - Danny A Milner
- Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, MA 02115, USA
| | - Amanda K Lukens
- Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, MA 02115, USA
| | - Nisha Broodie
- College of Medicine, Columbia University, New York, NY 10032, USA
| | | | | | | | - John S Schieffelin
- Tulane Health Sciences Center, Tulane University, New Orleans, LA 70118, USA
| | - Danielle Levy
- Tulane Health Sciences Center, Tulane University, New Orleans, LA 70118, USA
| | - Henry Akpan
- Nigerian Federal Ministry of Health, Abuja, Federal Capital Territory, Nigeria
| | - Daniel G Bausch
- Tulane Health Sciences Center, Tulane University, New Orleans, LA 70118, USA
| | - Kathleen Rubins
- The National Aeronautics and Space Administration, Johnson Space Center, Houston, TX 77058, USA
| | - Joseph B McCormick
- The University of Texas School of Public Health, Brownsville, TX 77030, USA
| | | | - Stephan Günther
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, 20259 Hamburg, Germany
| | - Lisa Hensley
- NIAID Integrated Research Facility, Frederick, MD 21702, USA
| | - Sylvanus Okogbenin
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | | | | | - Peter O Okokhere
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | - S Humarr Khan
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - Donald S Grant
- Lassa Fever Laboratory, Kenema Government Hospital, Kenema, Eastern Province, Sierra Leone
| | - George O Akpede
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | - Danny A Asogun
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
| | | | | | - Christian T Happi
- Institute of Lassa Fever Research and Control, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria; Department of Biological Sciences, College of Natural Sciences, Redeemer's University, Redemption City, Osun State, Nigeria.
| | - Robert F Garry
- Tulane Health Sciences Center, Tulane University, New Orleans, LA 70118, USA
| | - Pardis C Sabeti
- FAS Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02142, USA; Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, MA 02115, USA.
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Shapiro BJ. How clonal are bacteria over time? Curr Opin Microbiol 2016; 31:116-123. [PMID: 27057964 DOI: 10.1016/j.mib.2016.03.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/20/2016] [Accepted: 03/22/2016] [Indexed: 11/15/2022]
Abstract
Bacteria and archaea reproduce clonally (vertical descent), but exchange genes by recombination (horizontal transfer). Recombination allows adaptive mutations or genes to spread rapidly within (or even between) species, and reduces the burden of deleterious mutations. Clonality-defined here as the balance between vertical and horizontal inheritance-is therefore a key microbial trait, determining how quickly a population can adapt and the size of its gene pool. Here, I discuss whether clonality varies over time and if it can be considered a stable trait of a given population. I show that, in some cases, clonality is clearly not static. For example, non-clonal (highly recombining) populations can give rise to clonal expansions, often of pathogens. However, an analysis of time-course metagenomic data from a lake suggests that a bacterial population's past clonality (as measured by its genetic diversity) is a good predictor of its future clonality. Clonality therefore appears to be relatively-but not completely-stable over evolutionary time.
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Affiliation(s)
- B Jesse Shapiro
- Département de sciences biologiques, Université de Montréal, Montréal, QC H3C 3J7, Canada.
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35
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Migration and horizontal gene transfer divide microbial genomes into multiple niches. Nat Commun 2015; 6:8924. [PMID: 26592443 PMCID: PMC4673824 DOI: 10.1038/ncomms9924] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 10/16/2015] [Indexed: 02/01/2023] Open
Abstract
Horizontal gene transfer is central to microbial evolution, because it enables genetic regions to spread horizontally through diverse communities. However, how gene transfer exerts such a strong effect is not understood. Here we develop an eco-evolutionary model and show how genetic transfer, even when rare, can transform the evolution and ecology of microbes. We recapitulate existing models, which suggest that asexual reproduction will overpower horizontal transfer and greatly limit its effects. We then show that allowing immigration completely changes these predictions. With migration, the rates and impacts of horizontal transfer are greatly increased, and transfer is most frequent for loci under positive natural selection. Our analysis explains how ecologically important loci can sweep through competing strains and species. In this way, microbial genomes can evolve to become ecologically diverse where different genomic regions encode for partially overlapping, but distinct, ecologies. Under these conditions ecological species do not exist, because genes, not species, inhabit niches. Horizontal gene transfer is central to microbial evolution. Here, the authors develop an eco-evolutionary model and show that migration can greatly promote horizontal gene transfer, which explains how ecologically-important loci can sweep through the species in a microbial community.
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36
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Joseph SJ, Marti H, Didelot X, Castillo-Ramirez S, Read TD, Dean D. Chlamydiaceae Genomics Reveals Interspecies Admixture and the Recent Evolution of Chlamydia abortus Infecting Lower Mammalian Species and Humans. Genome Biol Evol 2015; 7:3070-84. [PMID: 26507799 PMCID: PMC4994753 DOI: 10.1093/gbe/evv201] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Chlamydiaceae are obligate intracellular bacteria that cause a diversity of severe infections among humans and livestock on a global scale. Identification of new species since 1989 and emergence of zoonotic infections, including abortion in women, underscore the need for genome sequencing of multiple strains of each species to advance our knowledge of evolutionary dynamics across Chlamydiaceae. Here, we genome sequenced isolates from avian, lower mammalian and human hosts. Based on core gene phylogeny, five isolates previously classified as Chlamydia abortus were identified as members of Chlamydia psittaci and Chlamydia pecorum. Chlamydia abortus is the most recently emerged species and is a highly monomorphic group that lacks the conserved virulence-associated plasmid. Low-level recombination and evidence for adaptation to the placenta echo evolutionary processes seen in recently emerged, highly virulent niche-restricted pathogens, such as Bacillus anthracis. In contrast, gene flow occurred within C. psittaci and other Chlamydiaceae species. The C. psittaci strain RTH, isolated from a red-tailed hawk (Buteo jamaicensis), is an outlying strain with admixture of C. abortus, C. psittaci, and its own population markers. An average nucleotide identity of less than 94% compared with other Chlamydiaceae species suggests that RTH belongs to a new species intermediary between C. psittaci and C. abortus. Hawks, as scavengers and predators, have extensive opportunities to acquire multiple species in their intestinal tract. This could facilitate transformation and homologous recombination with the potential for new species emergence. Our findings indicate that incubator hosts such as birds-of-prey likely promote Chlamydiaceae evolution resulting in novel pathogenic lineages.
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Affiliation(s)
- Sandeep J Joseph
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine
| | - Hanna Marti
- Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California
| | - Xavier Didelot
- Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Santiago Castillo-Ramirez
- Programa de Genomica Evolutiva, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Timothy D Read
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine Department of Human Genetics, Emory University School of Medicine
| | - Deborah Dean
- Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California Department of Medicine, University of California, San Francisco Joint Graduate Program in Bioengineering, University of California, San Francisco, and University of California, Berkeley
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Abstract
What are species? How do they arise? These questions are not easy to answer and have been particularly controversial in microbiology. Yet, for those microbiologists studying environmental questions or dealing with clinical issues, the ability to name and recognize species, widely considered the fundamental units of ecology, can be practically useful. On a more fundamental level, the speciation problem, the focus here, is more mechanistic and conceptual. What is the origin of microbial species, and what evolutionary and ecological mechanisms keep them separate once they begin to diverge? To what extent are these mechanisms universal across diverse types of microbes, and more broadly across the entire the tree of life? Here, we propose that microbial speciation must be viewed in light of gene flow, which defines units of genetic similarity, and of natural selection, which defines units of phenotype and ecological function. We discuss to what extent ecological and genetic units overlap to form cohesive populations in the wild, based on recent evolutionary modeling and population genomics studies. These studies suggest a continuous "speciation spectrum," which microbial populations traverse in different ways depending on their balance of gene flow and natural selection.
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Affiliation(s)
- B Jesse Shapiro
- Département de Sciences Biologiques, Université de Montréal, Montréal QC H3C 3J7, Canada
| | - Martin F Polz
- Parsons Laboratory for Environmental Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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38
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Udall YC, Deeni Y, Hapca SM, Raikes D, Spiers AJ. The evolution of biofilm-forming Wrinkly Spreaders in static microcosms and drip-fed columns selects for subtle differences in wrinkleality and fitness. FEMS Microbiol Ecol 2015; 91:fiv057. [DOI: 10.1093/femsec/fiv057] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 12/30/2022] Open
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39
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Takeuchi N, Cordero OX, Koonin EV, Kaneko K. Gene-specific selective sweeps in bacteria and archaea caused by negative frequency-dependent selection. BMC Biol 2015; 13:20. [PMID: 25928466 PMCID: PMC4410459 DOI: 10.1186/s12915-015-0131-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 03/13/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Fixation of beneficial genes in bacteria and archaea (collectively, prokaryotes) is often believed to erase pre-existing genomic diversity through the hitchhiking effect, a phenomenon known as genome-wide selective sweep. Recent studies, however, indicate that beneficial genes spread through a prokaryotic population via recombination without causing genome-wide selective sweeps. These gene-specific selective sweeps seem to be at odds with the existing estimates of recombination rates in prokaryotes, which appear far too low to explain such phenomena. RESULTS We use mathematical modeling to investigate potential solutions to this apparent paradox. Most microbes in nature evolve in heterogeneous, dynamic communities, in which ecological interactions can substantially impact evolution. Here, we focus on the effect of negative frequency-dependent selection (NFDS) such as caused by viral predation (kill-the-winner dynamics). The NFDS maintains multiple genotypes within a population, so that a gene beneficial to every individual would have to spread via recombination, hence a gene-specific selective sweep. However, gene loci affected by NFDS often are located in variable regions of microbial genomes that contain genes involved in the mobility of selfish genetic elements, such as integrases or transposases. Thus, the NFDS-affected loci are likely to experience elevated rates of recombination compared with the other loci. Consequently, these loci might be effectively unlinked from the rest of the genome, so that NFDS would be unable to prevent genome-wide selective sweeps. To address this problem, we analyzed population genetic models of selective sweeps in prokaryotes under NFDS. The results indicate that NFDS can cause gene-specific selective sweeps despite the effect of locally elevated recombination rates, provided NFDS affects more than one locus and the basal rate of recombination is sufficiently low. Although these conditions might seem to contradict the intuition that gene-specific selective sweeps require high recombination rates, they actually decrease the effective rate of recombination at loci affected by NFDS relative to the per-locus basal level, so that NFDS can cause gene-specific selective sweeps. CONCLUSION Because many free-living prokaryotes are likely to evolve under NFDS caused by ubiquitous viruses, gene-specific selective sweeps driven by NFDS are expected to be a major, general phenomenon in prokaryotic populations.
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Affiliation(s)
- Nobuto Takeuchi
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
| | - Otto X Cordero
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland.
| | - Eugene V Koonin
- National Institutes of Health, National Library of Medicine, National Center for Biotechnology Information, Bethesda, USA.
| | - Kunihiko Kaneko
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
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40
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The advent of genome-wide association studies for bacteria. Curr Opin Microbiol 2015; 25:17-24. [PMID: 25835153 DOI: 10.1016/j.mib.2015.03.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/28/2015] [Accepted: 03/05/2015] [Indexed: 02/05/2023]
Abstract
Significant advances in sequencing technologies and genome-wide association studies (GWAS) have revealed substantial insight into the genetic architecture of human phenotypes. In recent years, the application of this approach in bacteria has begun to reveal the genetic basis of bacterial host preference, antibiotic resistance, and virulence. Here, we consider relevant differences between bacterial and human genome dynamics, apply GWAS to a global sample of Mycobacterium tuberculosis genomes to highlight the impacts of linkage disequilibrium, population stratification, and natural selection, and finally compare the traditional GWAS against phyC, a contrasting method of mapping genotype to phenotype based upon evolutionary convergence. We discuss strengths and weaknesses of both methods, and make suggestions for factors to be considered in future bacterial GWAS.
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41
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Evolution and population genomics of the Lyme borreliosis pathogen, Borrelia burgdorferi. Trends Genet 2015; 31:201-7. [PMID: 25765920 DOI: 10.1016/j.tig.2015.02.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 02/12/2015] [Accepted: 02/13/2015] [Indexed: 11/22/2022]
Abstract
Population genomic studies have the potential to address many unresolved questions about microbial pathogens by facilitating the identification of genes underlying ecologically important traits, such as novel virulence factors and adaptations to humans or other host species. Additionally, this framework improves estimations of population demography and evolutionary history to accurately reconstruct recent epidemics and identify the molecular and environmental factors that resulted in the outbreak. The Lyme disease bacterium, Borrelia burgdorferi, exemplifies the power and promise of the application of population genomics to microbial pathogens. We discuss here the future of evolutionary studies in B. burgdorferi, focusing on the primary evolutionary forces of horizontal gene transfer, natural selection, and migration, as investigations transition from analyses of single genes to genomes.
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42
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Abstract
Iron sequestration provides an innate defense, termed nutritional immunity, leading pathogens to scavenge iron from hosts. Although the molecular basis of this battle for iron is established, its potential as a force for evolution at host-pathogen interfaces is unknown. We show that the iron transport protein transferrin is engaged in ancient and ongoing evolutionary conflicts with TbpA, a transferrin surface receptor from bacteria. Single substitutions in transferrin at rapidly evolving sites reverse TbpA binding, providing a mechanism to counteract bacterial iron piracy among great apes. Furthermore, the C2 transferrin polymorphism in humans evades TbpA variants from Haemophilus influenzae, revealing a functional basis for standing genetic variation. These findings identify a central role for nutritional immunity in the persistent evolutionary conflicts between primates and bacterial pathogens.
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Affiliation(s)
- Matthew F Barber
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Nels C Elde
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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43
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Read TD, Massey RC. Characterizing the genetic basis of bacterial phenotypes using genome-wide association studies: a new direction for bacteriology. Genome Med 2014; 6:109. [PMID: 25593593 PMCID: PMC4295408 DOI: 10.1186/s13073-014-0109-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Genome-wide association studies (GWASs) have become an increasingly important approach for eukaryotic geneticists, facilitating the identification of hundreds of genetic polymorphisms that are responsible for inherited diseases. Despite the relative simplicity of bacterial genomes, the application of GWASs to identify polymorphisms responsible for important bacterial phenotypes has only recently been made possible through advances in genome sequencing technologies. Bacterial GWASs are now about to come of age thanks to the availability of massive datasets, and because of the potential to bridge genomics and traditional genetic approaches that is provided by improving validation strategies. A small number of pioneering GWASs in bacteria have been published in the past 2 years, examining from 75 to more than 3,000 strains. The experimental designs have been diverse, taking advantage of different processes in bacteria for generating variation. Analysis of data from bacterial GWASs can, to some extent, be performed using software developed for eukaryotic systems, but there are important differences in genome evolution that must be considered. The greatest experimental advantage of bacterial GWASs is the potential to perform downstream validation of causality and dissection of mechanism. We review the recent advances and remaining challenges in this field and propose strategies to improve the validation of bacterial GWASs.
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Affiliation(s)
- Timothy D Read
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, GA 30322 USA ; Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Ruth C Massey
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY UK
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44
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Farhat MR, Shapiro BJ, Sheppard SK, Colijn C, Murray M. A phylogeny-based sampling strategy and power calculator informs genome-wide associations study design for microbial pathogens. Genome Med 2014; 6:101. [PMID: 25484920 PMCID: PMC4256898 DOI: 10.1186/s13073-014-0101-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 10/30/2014] [Indexed: 11/20/2022] Open
Abstract
Whole genome sequencing is increasingly used to study phenotypic variation among infectious pathogens and to evaluate their relative transmissibility, virulence, and immunogenicity. To date, relatively little has been published on how and how many pathogen strains should be selected for studies associating phenotype and genotype. There are specific challenges when identifying genetic associations in bacteria which often comprise highly structured populations. Here we consider general methodological questions related to sampling and analysis focusing on clonal to moderately recombining pathogens. We propose that a matched sampling scheme constitutes an efficient study design, and provide a power calculator based on phylogenetic convergence. We demonstrate this approach by applying it to genomic datasets for two microbial pathogens: Mycobacterium tuberculosis and Campylobacter species.
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Affiliation(s)
- Maha R Farhat
- Department of Pulmonary and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA ; Department of Global Health and Social Medicine, Harvard Medical School, 641 Huntington Avenue Suite 4A, Boston, MA 02115 USA
| | - B Jesse Shapiro
- Département de sciences biologiques, Université de Montréal, Montréal, QC Canada
| | - Samuel K Sheppard
- Institute of Life Science, College of Medicine, Swansea University, Swansea, SA2 8PP UK
| | - Caroline Colijn
- Department of Mathematics, Imperial College London, London, UK
| | - Megan Murray
- Department of Global Health and Social Medicine, Harvard Medical School, 641 Huntington Avenue Suite 4A, Boston, MA 02115 USA ; Department of Epidemiology, Harvard School of Public Health, Boston, MA USA
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45
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Shapiro BJ, Polz MF. Ordering microbial diversity into ecologically and genetically cohesive units. Trends Microbiol 2014; 22:235-47. [PMID: 24630527 DOI: 10.1016/j.tim.2014.02.006] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 02/08/2014] [Accepted: 02/14/2014] [Indexed: 11/16/2022]
Abstract
We propose that microbial diversity must be viewed in light of gene flow and selection, which define units of genetic similarity, and of phenotype and ecological function, respectively. We discuss to what extent ecological and genetic units overlap to form cohesive populations in the wild, based on recent evolutionary modeling and on evidence from some of the first microbial populations studied with genomics. These show that if recombination is frequent and selection moderate, ecologically adaptive mutations or genes can spread within populations independently of their original genomic background (gene-specific sweeps). Alternatively, if the effect of recombination is smaller than selection, genome-wide selective sweeps should occur. In both cases, however, distinct units of overlapping ecological and genotypic similarity will form if microgeographic separation, likely involving ecological tradeoffs, induces barriers to gene flow. These predictions are supported by (meta)genomic data, which suggest that a 'reverse ecology' approach, in which genomic and gene flow information is used to make predictions about the nature of ecological units, is a powerful approach to ordering microbial diversity.
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Affiliation(s)
- B Jesse Shapiro
- Département de Sciences Biologiques, Université de Montréal, Montréal, QC H3C 3J7, Canada.
| | - Martin F Polz
- Parsons Laboratory for Environmental Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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46
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Cordero OX, Polz MF. Explaining microbial genomic diversity in light of evolutionary ecology. Nat Rev Microbiol 2014; 12:263-73. [PMID: 24590245 DOI: 10.1038/nrmicro3218] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Comparisons of closely related microorganisms have shown that individual genomes can be highly diverse in terms of gene content. In this Review, we discuss several studies showing that much of this variation is associated with social and ecological interactions, which have an important role in the population biology of wild populations of bacteria and archaea. These interactions create frequency-dependent selective pressures that can either stabilize gene frequencies at intermediate levels in populations or promote fast gene turnover, which presents as low gene frequencies in genome surveys. Thus, interpretation of gene-content diversity requires the delineation of populations according to cohesive gene flow and ecology, as micro-evolutionary changes arise in response to local selection pressures and population dynamics.
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Affiliation(s)
- Otto X Cordero
- Department of Environmental Systems Science, Swiss Federal Institute of Technology Zurich (ETH-Zürich), CH-8092 Zürich, Switzerland
| | - Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139-4307, USA
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47
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The quest for a unified view of bacterial land colonization. ISME JOURNAL 2014; 8:1358-69. [PMID: 24451209 PMCID: PMC4069389 DOI: 10.1038/ismej.2013.247] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 11/15/2013] [Accepted: 12/12/2013] [Indexed: 12/13/2022]
Abstract
Exploring molecular mechanisms underlying bacterial water-to-land transition represents a critical start toward a better understanding of the functioning and stability of the terrestrial ecosystems. Here, we perform comprehensive analyses based on a large variety of bacteria by integrating taxonomic, phylogenetic and metagenomic data, in the quest for a unified view that elucidates genomic, evolutionary and ecological dynamics of the marine progenitors in adapting to nonaquatic environments. We hypothesize that bacterial land colonization is dominated by a single-gene sweep, that is, the emergence of dnaE2 derived from an early duplication event of the primordial dnaE, followed by a series of niche-specific genomic adaptations, including GC content increase, intensive horizontal gene transfer and constant genome expansion. In addition, early bacterial radiation may be stimulated by an explosion of land-borne hosts (for example, plants and animals) after initial land colonization events.
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48
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Signatures of Natural Selection and Ecological Differentiation in Microbial Genomes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 781:339-59. [DOI: 10.1007/978-94-007-7347-9_17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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49
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Farhat MR, Shapiro BJ, Kieser KJ, Sultana R, Jacobson KR, Victor TC, Warren RM, Streicher EM, Calver A, Sloutsky A, Kaur D, Posey JE, Plikaytis B, Oggioni MR, Gardy JL, Johnston JC, Rodrigues M, Tang PKC, Kato-Maeda M, Borowsky ML, Muddukrishna B, Kreiswirth BN, Kurepina N, Galagan J, Gagneux S, Birren B, Rubin EJ, Lander ES, Sabeti PC, Murray M. Genomic analysis identifies targets of convergent positive selection in drug-resistant Mycobacterium tuberculosis. Nat Genet 2013; 45:1183-9. [PMID: 23995135 PMCID: PMC3887553 DOI: 10.1038/ng.2747] [Citation(s) in RCA: 292] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 08/08/2013] [Indexed: 11/09/2022]
Abstract
M. tuberculosis is evolving antibiotic resistance, threatening attempts at tuberculosis epidemic control. Mechanisms of resistance, including genetic changes favored by selection in resistant isolates, are incompletely understood. Using 116 newly sequenced and 7 previously sequenced M. tuberculosis whole genomes, we identified genome-wide signatures of positive selection specific to the 47 drug-resistant strains. By searching for convergent evolution--the independent fixation of mutations in the same nucleotide position or gene--we recovered 100% of a set of known resistance markers. We also found evidence of positive selection in an additional 39 genomic regions in resistant isolates. These regions encode components in cell wall biosynthesis, transcriptional regulation and DNA repair pathways. Mutations in these regions could directly confer resistance or compensate for fitness costs associated with resistance. Functional genetic analysis of mutations in one gene, ponA1, demonstrated an in vitro growth advantage in the presence of the drug rifampicin.
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Affiliation(s)
- Maha R Farhat
- Pulmonary and Critical Care Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114
| | - B Jesse Shapiro
- The Eli and Edythe L. Broad Institute, Cambridge, MA, 02142
- Department of Organismic and Evolutionary Biology, Faculty of Arts and Sciences, Harvard University, Cambridge, MA 02138
- Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA 02115
- Département de sciences biologiques, Université de Montréal, Montréal, QC, Canada
| | - Karen J Kieser
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115
| | - Razvan Sultana
- Dana Farber Cancer Institute, Department of Bioinformatics and Computational Biology, Boston, MA, 02115
| | - Karen R Jacobson
- Section of Infectious Diseases, Boston University School of Medicine, Boston, MA 02118
- DST/NRF Centre of Excellence for Biomedical TB Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Thomas C Victor
- DST/NRF Centre of Excellence for Biomedical TB Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Robin M Warren
- DST/NRF Centre of Excellence for Biomedical TB Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Elizabeth M Streicher
- DST/NRF Centre of Excellence for Biomedical TB Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Alistair Calver
- Anglogold Ashanti Health West Vaal Hospital, Orkney, North West, South Africa
| | - Alex Sloutsky
- University of Massachusetts Medical School, Massachusetts Supranational TB Reference Laboratory, 305 South St., Boston MA 01230
| | - Devinder Kaur
- University of Massachusetts Medical School, Massachusetts Supranational TB Reference Laboratory, 305 South St., Boston MA 01230
| | - Jamie E Posey
- Division of Tuberculosis Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA, 30333
| | - Bonnie Plikaytis
- Division of Tuberculosis Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA, 30333
| | - Marco R Oggioni
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - Jennifer L Gardy
- Communicable Disease Prevention and Control Services, British Columbia Centre for Disease Control, Vancouver V5Z 4R4, Canada
| | - James C Johnston
- Clinical Prevention Services, British Columbia Centre for Disease Control, Vancouver V5Z 4R4, Canada
| | - Mabel Rodrigues
- Mycobacteriology/TB Laboratory, BCCDC Public Health Microbiology and Reference Laboratory, Provincial Health Services Authority Laboratories, Vancouver V5Z 4R4, Canada
| | - Patrick K C Tang
- Mycobacteriology/TB Laboratory, BCCDC Public Health Microbiology and Reference Laboratory, Provincial Health Services Authority Laboratories, Vancouver V5Z 4R4, Canada
| | - Midori Kato-Maeda
- Division of Pulmonary and Critical Care, University of California, San Francisco, San Francisco CA 94043
| | - Mark L Borowsky
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
- Department of Genetics, Harvard Medical School, Harvard University, Boston MA 02115
| | - Bhavana Muddukrishna
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
- Department of Genetics, Harvard Medical School, Harvard University, Boston MA 02115
| | - Barry N Kreiswirth
- Public Health Research Institute Tuberculosis Center, Rutgers, The State University of NJ, Newark, NJ 07103
| | - Natalia Kurepina
- Public Health Research Institute Tuberculosis Center, Rutgers, The State University of NJ, Newark, NJ 07103
| | - James Galagan
- The Eli and Edythe L. Broad Institute, Cambridge, MA, 02142
- Departments of Biomedical Engineering, Boston University, Boston, MA 02215
- Department of Microbiology, Boston University, Boston, MA 02215
- Bioinformatics Program, Boston University, Boston, MA 02215
| | - Sebastien Gagneux
- Swiss Tropical and Public Health Institute, 4002 Basel, Switzerland
- University of Basel, 4002 Basel, Switzerland
| | - Bruce Birren
- The Eli and Edythe L. Broad Institute, Cambridge, MA, 02142
| | - Eric J Rubin
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115
| | - Eric S Lander
- The Eli and Edythe L. Broad Institute, Cambridge, MA, 02142
| | - Pardis C Sabeti
- The Eli and Edythe L. Broad Institute, Cambridge, MA, 02142
- Department of Organismic and Evolutionary Biology, Faculty of Arts and Sciences, Harvard University, Cambridge, MA 02138
- Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA 02115
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115
| | - Megan Murray
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA 02115
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115
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50
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Polz MF, Alm EJ, Hanage WP. Horizontal gene transfer and the evolution of bacterial and archaeal population structure. Trends Genet 2013; 29:170-5. [PMID: 23332119 PMCID: PMC3760709 DOI: 10.1016/j.tig.2012.12.006] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 11/29/2012] [Accepted: 12/18/2012] [Indexed: 12/28/2022]
Abstract
Many bacterial and archaeal lineages have a history of extensive and ongoing horizontal gene transfer and loss, as evidenced by the large differences in genome content even among otherwise closely related isolates. How ecologically cohesive populations might evolve and be maintained under such conditions of rapid gene turnover has remained controversial. Here we synthesize recent literature demonstrating the importance of habitat and niche in structuring horizontal gene transfer. This leads to a model of ecological speciation via gradual genetic isolation triggered by differential habitat-association of nascent populations. Further, we hypothesize that subpopulations can evolve through local gene-exchange networks by tapping into a gene pool that is adaptive towards local, continuously changing organismic interactions and is, to a large degree, responsible for the observed rapid gene turnover. Overall, these insights help to explain how bacteria and archaea form populations that display both ecological cohesion and high genomic diversity.
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Affiliation(s)
- Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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