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Urquhart A, Vogan AA, Gluck-Thaler E. Starships: a new frontier for fungal biology. Trends Genet 2024; 40:1060-1073. [PMID: 39299886 DOI: 10.1016/j.tig.2024.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 08/20/2024] [Accepted: 08/20/2024] [Indexed: 09/22/2024]
Abstract
Transposable elements (TEs) are semiautonomous genetic entities that proliferate in genomes. We recently discovered the Starships, a previously hidden superfamily of giant TEs found in a diverse subphylum of filamentous fungi, the Pezizomycotina. Starships are unlike other eukaryotic TEs because they have evolved mechanisms for both mobilizing entire genes, including those encoding conditionally beneficial phenotypes, and for horizontally transferring between individuals. We argue that Starships have unrivaled capacity to engage their fungal hosts as genetic parasites and mutualists, revealing unexplored terrain for investigating the ecoevolutionary dynamics of TE-eukaryote interactions. We build on existing models of fungal genome evolution by conceptualizing Starships as a distinct genomic compartment whose dynamics profoundly shape fungal biology.
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Affiliation(s)
- Andrew Urquhart
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
| | - Aaron A Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
| | - Emile Gluck-Thaler
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI 53706, USA; Wisconsin Institute for Discovery, Madison, WI 53706, USA.
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2
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Vos M, Buckling A, Kuijper B, Eyre-Walker A, Bontemps C, Leblond P, Dimitriu T. Why do mobile genetic elements transfer DNA of their hosts? Trends Genet 2024; 40:927-938. [PMID: 39304387 DOI: 10.1016/j.tig.2024.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 07/23/2024] [Accepted: 07/23/2024] [Indexed: 09/22/2024]
Abstract
The prokaryote world is replete with mobile genetic elements (MGEs) - self-replicating entities that can move within and between their hosts. Many MGEs not only transfer their own DNA to new hosts but also transfer host DNA located elsewhere on the chromosome in the process. This could potentially lead to indirect benefits to the host when the resulting increase in chromosomal variation results in more efficient natural selection. We review the diverse ways in which MGEs promote the transfer of host DNA and explore the benefits and costs to MGEs and hosts. In many cases, MGE-mediated transfer of host DNA might not be selected for because of a sex function, but evidence of MGE domestication suggests that there may be host benefits of MGE-mediated sex.
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Affiliation(s)
- Michiel Vos
- European Centre for Environment and Human Health, University of Exeter Medical School, Environment and Sustainability Institute, Penryn Campus, Penryn TR10 9FE, UK; Environment and Sustainability Institute, University of Exeter, Penryn TR10 9FE, UK.
| | - Angus Buckling
- Environment and Sustainability Institute, University of Exeter, Penryn TR10 9FE, UK
| | - Bram Kuijper
- Centre for Ecology and Conservation, University of Exeter, Penryn TR10 9FE, UK
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Cyril Bontemps
- Université de Lorraine, Institut National de Recherche pour l'Agriculture, l'Alimentation, et l'Environnement (INRAE), DynAMic, F-54000 Nancy, France
| | - Pierre Leblond
- Université de Lorraine, Institut National de Recherche pour l'Agriculture, l'Alimentation, et l'Environnement (INRAE), DynAMic, F-54000 Nancy, France
| | - Tatiana Dimitriu
- Environment and Sustainability Institute, University of Exeter, Penryn TR10 9FE, UK; Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews KY16 9ST, UK
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3
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Gluck-Thaler E, Forsythe A, Puerner C, Stajich JE, Croll D, Cramer RA, Vogan AA. Giant transposons promote strain heterogeneity in a major fungal pathogen. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.601215. [PMID: 38979181 PMCID: PMC11230402 DOI: 10.1101/2024.06.28.601215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Fungal infections are difficult to prevent and treat in large part due to strain heterogeneity. However, the genetic mechanisms driving pathogen variation remain poorly understood. Here, we determined the extent to which Starships-giant transposons capable of mobilizing numerous fungal genes-generate genetic and phenotypic variability in the human pathogen Aspergillus fumigatus. We analyzed 519 diverse strains, including 12 newly sequenced with long-read technology, to reveal 20 distinct Starships that are generating genomic heterogeneity over timescales potentially relevant for experimental reproducibility. Starship-mobilized genes encode diverse functions, including biofilm-related virulence factors and biosynthetic gene clusters, and many are differentially expressed during infection and antifungal exposure in a strain-specific manner. These findings support a new model of fungal evolution wherein Starships help generate variation in gene content and expression among fungal strains. Together, our results demonstrate that Starships are a previously hidden mechanism generating genotypic and, in turn, phenotypic heterogeneity in a major human fungal pathogen.
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Affiliation(s)
- Emile Gluck-Thaler
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Neuchâtel 2000, Switzerland
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Wisconsin Institute for Discovery, Madison, WI 53706, USA
| | - Adrian Forsythe
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
| | - Charles Puerner
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755 USA
| | - Jason E. Stajich
- Department of Microbiology and Plant Pathology, University of California-Riverside, Riverside, CA 92521, USA
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Neuchâtel 2000, Switzerland
| | - Robert A. Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755 USA
| | - Aaron A. Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
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4
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Gluck-Thaler E, Vogan A. Systematic identification of cargo-mobilizing genetic elements reveals new dimensions of eukaryotic diversity. Nucleic Acids Res 2024; 52:5496-5513. [PMID: 38686785 PMCID: PMC11162782 DOI: 10.1093/nar/gkae327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 03/12/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024] Open
Abstract
Cargo-mobilizing mobile elements (CMEs) are genetic entities that faithfully transpose diverse protein coding sequences. Although common in bacteria, we know little about eukaryotic CMEs because no appropriate tools exist for their annotation. For example, Starships are giant fungal CMEs whose functions are largely unknown because they require time-intensive manual curation. To address this knowledge gap, we developed starfish, a computational workflow for high-throughput eukaryotic CME annotation. We applied starfish to 2 899 genomes of 1 649 fungal species and found that starfish recovers known Starships with 95% combined precision and recall while expanding the number of annotated elements ten-fold. Extant Starship diversity is partitioned into 11 families that differ in their enrichment patterns across fungal classes. Starship cargo changes rapidly such that elements from the same family differ substantially in their functional repertoires, which are predicted to contribute to diverse biological processes such as metabolism. Many elements have convergently evolved to insert into 5S rDNA and AT-rich sequence while others integrate into random locations, revealing both specialist and generalist strategies for persistence. Our work establishes a framework for advancing mobile element biology and provides the means to investigate an emerging dimension of eukaryotic genetic diversity, that of genomes within genomes.
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Affiliation(s)
- Emile Gluck-Thaler
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Neuchâtel 2000, Switzerland
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Wisconsin Institute for Discovery, Madison, WI 53706, USA
| | - Aaron A Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
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5
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Guillén-Chable F, Valdez Iuit JO, Avila Castro LA, Rosas C, Merino E, Rodríguez-Escamilla Z, Martínez-Núñez MA. Geographical distribution of mobile genetic elements in microbial communities along the Yucatan coast. PLoS One 2024; 19:e0301642. [PMID: 38683832 PMCID: PMC11057721 DOI: 10.1371/journal.pone.0301642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/19/2024] [Indexed: 05/02/2024] Open
Abstract
Horizontal gene transfer (HGT) is a well-documented strategy used by bacteria to enhance their adaptability to challenging environmental conditions. Through HGT, a group of conserved genetic elements known as mobile genetic elements (MGEs) is disseminated within bacterial communities. MGEs offer numerous advantages to the host, increasing its fitness by acquiring new functions that help bacteria contend with adverse conditions, including exposure to heavy metal and antibiotics. This study explores MGEs within microbial communities along the Yucatan coast using a metatranscriptomics approach. Prior to this research, nothing was known about the coastal Yucatan's microbial environmental mobilome and HGT processes between these bacterial communities. This study reveals a positive correlation between MGEs and antibiotic resistance genes (ARGs) along the Yucatan coast, with higher MGEs abundance in more contaminated sites. The Proteobacteria and Firmicutes groups exhibited the highest number of MGEs. It's important to highlight that the most abundant classes of MGEs might not be the ones most strongly linked to ARGs, as observed for the recombination/repair class. This work presents the first geographical distribution of the environmental mobilome in Yucatan Peninsula mangroves.
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Affiliation(s)
- Francisco Guillén-Chable
- UMDI-Sisal, Facultad de Ciencias, Universidad Nacional Autónoma de México, Sisal, Yucatán, México
| | - Johnny Omar Valdez Iuit
- UMDI-Sisal, Facultad de Ciencias, Universidad Nacional Autónoma de México, Sisal, Yucatán, México
| | | | - Carlos Rosas
- UMDI-Sisal, Facultad de Ciencias, Universidad Nacional Autónoma de México, Sisal, Yucatán, México
| | - Enrique Merino
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Zuemy Rodríguez-Escamilla
- Facultad de Sistemas Biológicos e Innovación Tecnológica, Universidad Autónoma "Benito Juárez" de Oaxaca, Oaxaca de Juárez, Oaxaca, México
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6
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Carscadden KA, Batstone RT, Hauser FE. Origins and evolution of biological novelty. Biol Rev Camb Philos Soc 2023; 98:1472-1491. [PMID: 37056155 DOI: 10.1111/brv.12963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/30/2023] [Accepted: 04/03/2023] [Indexed: 04/15/2023]
Abstract
Understanding the origins and impacts of novel traits has been a perennial interest in many realms of ecology and evolutionary biology. Here, we build on previous evolutionary and philosophical treatments of this subject to encompass novelties across biological scales and eco-evolutionary perspectives. By defining novelties as new features at one biological scale that have emergent effects at other biological scales, we incorporate many forms of novelty that have previously been treated in isolation (such as novelty from genetic mutations, new developmental pathways, new morphological features, and new species). Our perspective is based on the fundamental idea that the emergence of a novelty, at any biological scale, depends on its environmental and genetic context. Through this lens, we outline a broad array of generative mechanisms underlying novelty and highlight how genomic tools are transforming our understanding of the origins of novelty. Lastly, we present several case studies to illustrate how novelties across biological scales and systems can be understood based on common mechanisms of change and their environmental and genetic contexts. Specifically, we highlight how gene duplication contributes to the evolution of new complex structures in visual systems; how genetic exchange in symbiosis alters functions of both host and symbiont, resulting in a novel organism; and how hybridisation between species can generate new species with new niches.
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Affiliation(s)
- Kelly A Carscadden
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, 1900 Pleasant St, Boulder, CO, 80309, USA
| | - Rebecca T Batstone
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL, 61801, USA
| | - Frances E Hauser
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada
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7
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Tang X, Shang J, Ji Y, Sun Y. PLASMe: a tool to identify PLASMid contigs from short-read assemblies using transformer. Nucleic Acids Res 2023; 51:e83. [PMID: 37427782 PMCID: PMC10450166 DOI: 10.1093/nar/gkad578] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 06/19/2023] [Accepted: 06/26/2023] [Indexed: 07/11/2023] Open
Abstract
Plasmids are mobile genetic elements that carry important accessory genes. Cataloging plasmids is a fundamental step to elucidate their roles in promoting horizontal gene transfer between bacteria. Next generation sequencing (NGS) is the main source for discovering new plasmids today. However, NGS assembly programs tend to return contigs, making plasmid detection difficult. This problem is particularly grave for metagenomic assemblies, which contain short contigs of heterogeneous origins. Available tools for plasmid contig detection still suffer from some limitations. In particular, alignment-based tools tend to miss diverged plasmids while learning-based tools often have lower precision. In this work, we develop a plasmid detection tool PLASMe that capitalizes on the strength of alignment and learning-based methods. Closely related plasmids can be easily identified using the alignment component in PLASMe while diverged plasmids can be predicted using order-specific Transformer models. By encoding plasmid sequences as a language defined on the protein cluster-based token set, Transformer can learn the importance of proteins and their correlation through positionally token embedding and the attention mechanism. We compared PLASMe and other tools on detecting complete plasmids, plasmid contigs, and contigs assembled from CAMI2 simulated data. PLASMe achieved the highest F1-score. After validating PLASMe on data with known labels, we also tested it on real metagenomic and plasmidome data. The examination of some commonly used marker genes shows that PLASMe exhibits more reliable performance than other tools.
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Affiliation(s)
- Xubo Tang
- Department of Electrical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
| | - Jiayu Shang
- Department of Electrical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
| | - Yongxin Ji
- Department of Electrical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
| | - Yanni Sun
- Department of Electrical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
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8
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Mayorga-Ramos A, Zúñiga-Miranda J, Carrera-Pacheco SE, Barba-Ostria C, Guamán LP. CRISPR-Cas-Based Antimicrobials: Design, Challenges, and Bacterial Mechanisms of Resistance. ACS Infect Dis 2023; 9:1283-1302. [PMID: 37347230 PMCID: PMC10353011 DOI: 10.1021/acsinfecdis.2c00649] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Indexed: 06/23/2023]
Abstract
The emergence of antibiotic-resistant bacterial strains is a source of public health concern across the globe. As the discovery of new conventional antibiotics has stalled significantly over the past decade, there is an urgency to develop novel approaches to address drug resistance in infectious diseases. The use of a CRISPR-Cas-based system for the precise elimination of targeted bacterial populations holds promise as an innovative approach for new antimicrobial agent design. The CRISPR-Cas targeting system is celebrated for its high versatility and specificity, offering an excellent opportunity to fight antibiotic resistance in pathogens by selectively inactivating genes involved in antibiotic resistance, biofilm formation, pathogenicity, virulence, or bacterial viability. The CRISPR-Cas strategy can enact antimicrobial effects by two approaches: inactivation of chromosomal genes or curing of plasmids encoding antibiotic resistance. In this Review, we provide an overview of the main CRISPR-Cas systems utilized for the creation of these antimicrobials, as well as highlighting promising studies in the field. We also offer a detailed discussion about the most commonly used mechanisms for CRISPR-Cas delivery: bacteriophages, nanoparticles, and conjugative plasmids. Lastly, we address possible mechanisms of interference that should be considered during the intelligent design of these novel approaches.
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Affiliation(s)
- Arianna Mayorga-Ramos
- Centro
de Investigación Biomédica (CENBIO), Facultad de Ciencias
de la Salud Eugenio Espejo, Universidad
UTE, Quito 170527, Ecuador
| | - Johana Zúñiga-Miranda
- Centro
de Investigación Biomédica (CENBIO), Facultad de Ciencias
de la Salud Eugenio Espejo, Universidad
UTE, Quito 170527, Ecuador
| | - Saskya E. Carrera-Pacheco
- Centro
de Investigación Biomédica (CENBIO), Facultad de Ciencias
de la Salud Eugenio Espejo, Universidad
UTE, Quito 170527, Ecuador
| | - Carlos Barba-Ostria
- Escuela
de Medicina, Colegio de Ciencias de la Salud Quito, Universidad San Francisco de Quito USFQ, Quito 170902, Ecuador
| | - Linda P. Guamán
- Centro
de Investigación Biomédica (CENBIO), Facultad de Ciencias
de la Salud Eugenio Espejo, Universidad
UTE, Quito 170527, Ecuador
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Dewan I, Uecker H. A mathematician's guide to plasmids: an introduction to plasmid biology for modellers. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001362. [PMID: 37505810 PMCID: PMC10433428 DOI: 10.1099/mic.0.001362] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 07/03/2023] [Indexed: 07/29/2023]
Abstract
Plasmids, extrachromosomal DNA molecules commonly found in bacterial and archaeal cells, play an important role in bacterial genetics and evolution. Our understanding of plasmid biology has been furthered greatly by the development of mathematical models, and there are many questions about plasmids that models would be useful in answering. In this review, we present an introductory, yet comprehensive, overview of the biology of plasmids suitable for modellers unfamiliar with plasmids who want to get up to speed and to begin working on plasmid-related models. In addition to reviewing the diversity of plasmids and the genes they carry, their key physiological functions, and interactions between plasmid and host, we also highlight selected plasmid topics that may be of particular interest to modellers and areas where there is a particular need for theoretical development. The world of plasmids holds a great variety of subjects that will interest mathematical biologists, and introducing new modellers to the subject will help to expand the existing body of plasmid theory.
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Affiliation(s)
- Ian Dewan
- Research Group Stochastic Evolutionary Dynamics, Department of Theoretical Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Hildegard Uecker
- Research Group Stochastic Evolutionary Dynamics, Department of Theoretical Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
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10
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Pillay S, Calderón-Franco D, Urhan A, Abeel T. Metagenomic-based surveillance systems for antibiotic resistance in non-clinical settings. Front Microbiol 2022; 13:1066995. [PMID: 36532424 PMCID: PMC9755710 DOI: 10.3389/fmicb.2022.1066995] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/09/2022] [Indexed: 08/12/2023] Open
Abstract
The success of antibiotics as a therapeutic agent has led to their ineffectiveness. The continuous use and misuse in clinical and non-clinical areas have led to the emergence and spread of antibiotic-resistant bacteria and its genetic determinants. This is a multi-dimensional problem that has now become a global health crisis. Antibiotic resistance research has primarily focused on the clinical healthcare sectors while overlooking the non-clinical sectors. The increasing antibiotic usage in the environment - including animals, plants, soil, and water - are drivers of antibiotic resistance and function as a transmission route for antibiotic resistant pathogens and is a source for resistance genes. These natural compartments are interconnected with each other and humans, allowing the spread of antibiotic resistance via horizontal gene transfer between commensal and pathogenic bacteria. Identifying and understanding genetic exchange within and between natural compartments can provide insight into the transmission, dissemination, and emergence mechanisms. The development of high-throughput DNA sequencing technologies has made antibiotic resistance research more accessible and feasible. In particular, the combination of metagenomics and powerful bioinformatic tools and platforms have facilitated the identification of microbial communities and has allowed access to genomic data by bypassing the need for isolating and culturing microorganisms. This review aimed to reflect on the different sequencing techniques, metagenomic approaches, and bioinformatics tools and pipelines with their respective advantages and limitations for antibiotic resistance research. These approaches can provide insight into resistance mechanisms, the microbial population, emerging pathogens, resistance genes, and their dissemination. This information can influence policies, develop preventative measures and alleviate the burden caused by antibiotic resistance.
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Affiliation(s)
- Stephanie Pillay
- Delft Bioinformatics Lab, Delft University of Technology, Delft, Netherlands
| | | | - Aysun Urhan
- Delft Bioinformatics Lab, Delft University of Technology, Delft, Netherlands
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - Thomas Abeel
- Delft Bioinformatics Lab, Delft University of Technology, Delft, Netherlands
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, United States
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11
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Kosterlitz O, Muñiz Tirado A, Wate C, Elg C, Bozic I, Top EM, Kerr B. Estimating the transfer rates of bacterial plasmids with an adapted Luria–Delbrück fluctuation analysis. PLoS Biol 2022; 20:e3001732. [PMID: 35877684 PMCID: PMC9352209 DOI: 10.1371/journal.pbio.3001732] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 08/04/2022] [Accepted: 06/29/2022] [Indexed: 11/26/2022] Open
Abstract
To increase our basic understanding of the ecology and evolution of conjugative plasmids, we need reliable estimates of their rate of transfer between bacterial cells. Current assays to measure transfer rate are based on deterministic modeling frameworks. However, some cell numbers in these assays can be very small, making estimates that rely on these numbers prone to noise. Here, we take a different approach to estimate plasmid transfer rate, which explicitly embraces this noise. Inspired by the classic fluctuation analysis of Luria and Delbrück, our method is grounded in a stochastic modeling framework. In addition to capturing the random nature of plasmid conjugation, our new methodology, the Luria–Delbrück method (“LDM”), can be used on a diverse set of bacterial systems, including cases for which current approaches are inaccurate. A notable example involves plasmid transfer between different strains or species where the rate that one type of cell donates the plasmid is not equal to the rate at which the other cell type donates. Asymmetry in these rates has the potential to bias or constrain current transfer estimates, thereby limiting our capabilities for estimating transfer in microbial communities. In contrast, the LDM overcomes obstacles of traditional methods by avoiding restrictive assumptions about growth and transfer rates for each population within the assay. Using stochastic simulations and experiments, we show that the LDM has high accuracy and precision for estimation of transfer rates compared to the most widely used methods, which can produce estimates that differ from the LDM estimate by orders of magnitude. Plasmid transfer can often spread resistance between important clinical pathogens. This study shows that widely used methods can lead to biased estimates of plasmid transfer rate by several orders of magnitude, and presents a new approach, inspired by the classic Luria-Delbrück approach, for accurately assessing this fundamental rate parameter
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Affiliation(s)
- Olivia Kosterlitz
- Biology Department, University of Washington, Seattle, Washington, United States of America
- BEACON Center for the Study of Evolution in Action, East Lansing, Michigan, United States of America
- * E-mail: (OK); (BK)
| | - Adamaris Muñiz Tirado
- Biology Department, University of Washington, Seattle, Washington, United States of America
| | - Claire Wate
- Biology Department, University of Washington, Seattle, Washington, United States of America
| | - Clint Elg
- BEACON Center for the Study of Evolution in Action, East Lansing, Michigan, United States of America
- Department of Biological Sciences and Institute for Interdisciplinary Data Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Ivana Bozic
- Department of Applied Mathematics, University of Washington, Seattle, Washington, United States of America
| | - Eva M. Top
- BEACON Center for the Study of Evolution in Action, East Lansing, Michigan, United States of America
- Department of Biological Sciences and Institute for Interdisciplinary Data Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Benjamin Kerr
- Biology Department, University of Washington, Seattle, Washington, United States of America
- BEACON Center for the Study of Evolution in Action, East Lansing, Michigan, United States of America
- * E-mail: (OK); (BK)
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