1
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Lynch M, Wei W, Ye Z, Pfrender M. The genome-wide signature of short-term temporal selection. Proc Natl Acad Sci U S A 2024; 121:e2307107121. [PMID: 38959040 DOI: 10.1073/pnas.2307107121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/03/2024] [Indexed: 07/04/2024] Open
Abstract
Despite evolutionary biology's obsession with natural selection, few studies have evaluated multigenerational series of patterns of selection on a genome-wide scale in natural populations. Here, we report on a 10-y population-genomic survey of the microcrustacean Daphnia pulex. The genome sequences of [Formula: see text]800 isolates provide insights into patterns of selection that cannot be obtained from long-term molecular-evolution studies, including the following: the pervasiveness of near quasi-neutrality across the genome (mean net selection coefficients near zero, but with significant temporal variance about the mean, and little evidence of positive covariance of selection across time intervals); the preponderance of weak positive selection operating on minor alleles; and a genome-wide distribution of numerous small linkage islands of observable selection influencing levels of nucleotide diversity. These results suggest that interannual fluctuating selection is a major determinant of standing levels of variation in natural populations, challenge the conventional paradigm for interpreting patterns of nucleotide diversity and divergence, and motivate the need for the further development of theoretical expressions for the interpretation of population-genomic data.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Zhiqiang Ye
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Michael Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556
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2
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Enav H, Paz I, Ley RE. Strain tracking in complex microbiomes using synteny analysis reveals per-species modes of evolution. Nat Biotechnol 2024:10.1038/s41587-024-02276-2. [PMID: 38898177 DOI: 10.1038/s41587-024-02276-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 05/10/2024] [Indexed: 06/21/2024]
Abstract
Microbial species diversify into strains through single-nucleotide mutations and structural changes, such as recombination, insertions and deletions. Most strain-comparison methods quantify differences in single-nucleotide polymorphisms (SNPs) and are insensitive to structural changes. However, recombination is an important driver of phenotypic diversification in many species, including human pathogens. We introduce SynTracker, a tool that compares microbial strains using genome synteny-the order of sequence blocks in homologous genomic regions-in pairs of metagenomic assemblies or genomes. Genome synteny is a rich source of genomic information untapped by current strain-comparison tools. SynTracker has low sensitivity to SNPs, has no database requirement and is robust to sequencing errors. It outperforms existing tools when tracking strains in metagenomic data and is particularly suited for phages, plasmids and other low-data contexts. Applied to single-species datasets and human gut metagenomes, SynTracker, combined with an SNP-based tool, detects strains enriched in either point mutations or structural changes, providing insights into microbial evolution in situ.
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Affiliation(s)
- Hagay Enav
- Department of Microbiome Science, Max Planck Institute for Biology, Tübingen, Germany
| | - Inbal Paz
- Department of Microbiome Science, Max Planck Institute for Biology, Tübingen, Germany
| | - Ruth E Ley
- Department of Microbiome Science, Max Planck Institute for Biology, Tübingen, Germany.
- Cluster of Excellence EXC 2124: Controlling Microbes to Fight Infections (CMFI), University of Tübingen, Tübingen, Germany.
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3
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Zion S, Katz S, Hershberg R. Escherichia coli adaptation under prolonged resource exhaustion is characterized by extreme parallelism and frequent historical contingency. PLoS Genet 2024; 20:e1011333. [PMID: 38885285 PMCID: PMC11213340 DOI: 10.1371/journal.pgen.1011333] [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: 01/10/2024] [Revised: 06/28/2024] [Accepted: 06/05/2024] [Indexed: 06/20/2024] Open
Abstract
Like many other non-sporulating bacterial species, Escherichia coli is able to survive prolonged periods of resource exhaustion, by entering a state of growth called long-term stationary phase (LTSP). In July 2015, we initiated a set of evolutionary experiments aimed at characterizing the dynamics of E. coli adaptation under LTSP. In these experiments populations of E. coli were allowed to initially grow on fresh rich media, but were not provided with any new external growth resources since their establishment. Utilizing whole genome sequencing data obtained for hundreds of clones sampled at 12 time points spanning the first six years of these experiments, we reveal several novel aspects of the dynamics of adaptation. First, we show that E. coli continuously adapts genetically, up to six years under resource exhaustion, through the highly convergent accumulation of mutations. We further show that upon entry into LTSP, long-lasting lineages are established. This lineage structure is in itself convergent, with similar lineages arising across independently evolving populations. The high parallelism with which adaptations occur under LTSP, combined with the LTSP populations' lineage structure, enable us to screen for pairs of loci displaying a significant association in the occurrence of mutations, suggestive of a historical contingency. We find that such associations are highly frequent and that a third of convergently mutated loci are involved in at least one such association. Combined our results demonstrate that LTSP adaptation is characterized by remarkably high parallelism and frequent historical contingency.
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Affiliation(s)
- Shira Zion
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, the Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Sophia Katz
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, the Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ruth Hershberg
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, the Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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4
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Nagy K, Valappil SK, Phan TV, Li S, Dér L, Morris R, Bos J, Winslow S, Galajda P, Ràkhely G, Austin RH. Microfluidic Ecology Unravels the Genetic and Ecological Drivers of T4r Bacteriophage Resistance in E. coli: Insights into Biofilm-Mediated Evolution. RESEARCH SQUARE 2024:rs.3.rs-4356333. [PMID: 38826273 PMCID: PMC11142369 DOI: 10.21203/rs.3.rs-4356333/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
We use a microfluidic ecology which generates non-uniform phage concentration gradients and micro-ecological niches to reveal the importance of time, spatial population structure and collective population dynamics in the de novo evolution of T4r bacteriophage resistant motile E. coli. An insensitive bacterial population against T4r phage occurs within 20 hours in small interconnected population niches created by a gradient of phage virions, driven by evolution in transient biofilm patches. Sequencing of the resistant bacteria reveals mutations at the receptor site of bacteriophage T4r as expected but also in genes associated with biofilm formation and surface adhesion, supporting the hypothesis that evolution within transient biofilms drives de novo phage resistance.
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Affiliation(s)
- Krisztina Nagy
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Hungary
| | | | - Trung V Phan
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Shengkai Li
- Department of Physics, Princeton University, Princeton, NJ, USA
| | - László Dér
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Hungary
| | - Ryan Morris
- School of Physics & Astronomy, University of Edinburgh, Edinburgh, Scotland
| | - Julia Bos
- Institut Pasteur, Université Paris Cité, CNRS UMR 3525, Unité Plasticité du Génome Bactérien, Paris, France
| | | | - Peter Galajda
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Hungary
| | - Gábor Ràkhely
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Hungary
- Department of Biotechnology, University of Szeged, Szeged, Hungary
| | - Robert H Austin
- Department of Physics, Princeton University, Princeton, NJ, USA
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5
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Abs E, Chase AB, Manzoni S, Ciais P, Allison SD. Microbial evolution-An under-appreciated driver of soil carbon cycling. GLOBAL CHANGE BIOLOGY 2024; 30:e17268. [PMID: 38562029 DOI: 10.1111/gcb.17268] [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: 12/20/2023] [Revised: 03/18/2024] [Accepted: 03/18/2024] [Indexed: 04/04/2024]
Abstract
Although substantial advances in predicting the ecological impacts of global change have been made, predictions of the evolutionary impacts have lagged behind. In soil ecosystems, microbes act as the primary energetic drivers of carbon cycling; however, microbes are also capable of evolving on timescales comparable to rates of global change. Given the importance of soil ecosystems in global carbon cycling, we assess the potential impact of microbial evolution on carbon-climate feedbacks in this system. We begin by reviewing the current state of knowledge concerning microbial evolution in response to global change and its specific effect on soil carbon dynamics. Through this integration, we synthesize a roadmap detailing how to integrate microbial evolution into ecosystem biogeochemical models. Specifically, we highlight the importance of microscale mechanistic soil carbon models, including choosing an appropriate evolutionary model (e.g., adaptive dynamics, quantitative genetics), validating model predictions with 'omics' and experimental data, scaling microbial adaptations to ecosystem level processes, and validating with ecosystem-scale measurements. The proposed steps will require significant investment of scientific resources and might require 10-20 years to be fully implemented. However, through the application of multi-scale integrated approaches, we will advance the integration of microbial evolution into predictive understanding of ecosystems, providing clarity on its role and impact within the broader context of environmental change.
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Affiliation(s)
- Elsa Abs
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California, USA
- Laboratoire Des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Alexander B Chase
- Department of Earth Sciences, Southern Methodist University, Dallas, Texas, USA
| | - Stefano Manzoni
- Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
| | - Philippe Ciais
- Laboratoire Des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Steven D Allison
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California, USA
- Department of Earth System Science, University of California, Irvine, Irvine, California, USA
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6
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Shvartzman B, Ram Y. Self-replicating artificial neural networks give rise to universal evolutionary dynamics. PLoS Comput Biol 2024; 20:e1012004. [PMID: 38547320 PMCID: PMC11003675 DOI: 10.1371/journal.pcbi.1012004] [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: 08/01/2023] [Revised: 04/09/2024] [Accepted: 03/17/2024] [Indexed: 04/11/2024] Open
Abstract
In evolutionary models, mutations are exogenously introduced by the modeler, rather than endogenously introduced by the replicator itself. We present a new deep-learning based computational model, the self-replicating artificial neural network (SeRANN). We train it to (i) copy its own genotype, like a biological organism, which introduces endogenous spontaneous mutations; and (ii) simultaneously perform a classification task that determines its fertility. Evolving 1,000 SeRANNs for 6,000 generations, we observed various evolutionary phenomena such as adaptation, clonal interference, epistasis, and evolution of both the mutation rate and the distribution of fitness effects of new mutations. Our results demonstrate that universal evolutionary phenomena can naturally emerge in a self-replicator model when both selection and mutation are implicit and endogenous. We therefore suggest that SeRANN can be applied to explore and test various evolutionary dynamics and hypotheses.
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Affiliation(s)
- Boaz Shvartzman
- School of Zoology, Faculty of Life Sciences, Tel Aviv University; Tel Aviv, Israel
- School of Computer Science, Reichman University; Herzliya, Israel
| | - Yoav Ram
- School of Zoology, Faculty of Life Sciences, Tel Aviv University; Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University; Tel Aviv, Israel
- Edmond J. Safra Center for Bioinformatics, Tel Aviv University; Tel Aviv, Israel
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7
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Nguyen ANT, Gorrell R, Kwok T, Connallon T, McDonald MJ. Horizontal gene transfer facilitates the molecular reverse-evolution of antibiotic sensitivity in experimental populations of H. pylori. Nat Ecol Evol 2024; 8:315-324. [PMID: 38177692 DOI: 10.1038/s41559-023-02269-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Accepted: 11/09/2023] [Indexed: 01/06/2024]
Abstract
Reversing the evolution of traits harmful to humans, such as antimicrobial resistance, is a key ambition of applied evolutionary biology. A major impediment to reverse evolution is the relatively low spontaneous mutation rates that revert evolved genotypes back to their ancestral state. However, the repeated re-introduction of ancestral alleles by horizontal gene transfer (HGT) could make reverse evolution likely. Here we evolve populations of an antibiotic-resistant strain of Helicobacter pylori in growth conditions without antibiotics while introducing an ancestral antibiotic-sensitive allele by HGT. We evaluate reverse evolution using DNA sequencing and find that HGT facilitates the molecular reverse evolution of the antibiotic resistance allele, and that selection for high rates of HGT drives the evolution of increased HGT rates in low-HGT treatment populations. Finally, we use a theoretical model and carry out simulations to infer how the fitness costs of antibiotic resistance, rates of HGT and effects of genetic drift interact to determine the probability and predictability of reverse evolution.
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Affiliation(s)
- An N T Nguyen
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Centre to Impact AMR, Monash University, Clayton, Victoria, Australia
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Rebecca Gorrell
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Terry Kwok
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Biomedical Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Tim Connallon
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.
| | - Michael J McDonald
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.
- Centre to Impact AMR, Monash University, Clayton, Victoria, Australia.
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8
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Al-Tohamy A, Grove A. Targeting bacterial transcription factors for infection control: opportunities and challenges. Transcription 2023:1-28. [PMID: 38126125 DOI: 10.1080/21541264.2023.2293523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023] Open
Abstract
The rising threat of antibiotic resistance in pathogenic bacteria emphasizes the need for new therapeutic strategies. This review focuses on bacterial transcription factors (TFs), which play crucial roles in bacterial pathogenesis. We discuss the regulatory roles of these factors through examples, and we outline potential therapeutic strategies targeting bacterial TFs. Specifically, we discuss the use of small molecules to interfere with TF function and the development of transcription factor decoys, oligonucleotides that compete with promoters for TF binding. We also cover peptides that target the interaction between the bacterial TF and other factors, such as RNA polymerase, and the targeting of sigma factors. These strategies, while promising, come with challenges, from identifying targets to designing interventions, managing side effects, and accounting for changing bacterial resistance patterns. We also delve into how Artificial Intelligence contributes to these efforts and how it may be exploited in the future, and we touch on the roles of multidisciplinary collaboration and policy to advance this research domain.Abbreviations: AI, artificial intelligence; CNN, convolutional neural networks; DTI: drug-target interaction; HTH, helix-turn-helix; IHF, integration host factor; LTTRs, LysR-type transcriptional regulators; MarR, multiple antibiotic resistance regulator; MRSA, methicillin resistant Staphylococcus aureus; MSA: multiple sequence alignment; NAP, nucleoid-associated protein; PROTACs, proteolysis targeting chimeras; RNAP, RNA polymerase; TF, transcription factor; TFD, transcription factor decoying; TFTRs, TetR-family transcriptional regulators; wHTH, winged helix-turn-helix.
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Affiliation(s)
- Ahmed Al-Tohamy
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
- Department of Cell Biology, Biotechnology Research Institute, National Research Centre, Cairo, Egypt
| | - Anne Grove
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
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9
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Olofsson P, Chipkin L, Daileda RC, Azevedo RBR. Mutational meltdown in asexual populations doomed to extinction. J Math Biol 2023; 87:88. [PMID: 37994999 DOI: 10.1007/s00285-023-02019-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 07/03/2023] [Accepted: 10/20/2023] [Indexed: 11/24/2023]
Abstract
Asexual populations are expected to accumulate deleterious mutations through a process known as Muller's ratchet. Lynch and colleagues proposed that the ratchet eventually results in a vicious cycle of mutation accumulation and population decline that drives populations to extinction. They called this phenomenon mutational meltdown. Here, we analyze mutational meltdown using a multi-type branching process model where, in the presence of mutation, populations are doomed to extinction. We analyse the change in size and composition of the population and the time of extinction under this model.
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Affiliation(s)
- Peter Olofsson
- Department of Mathematics, Trinity University, San Antonio, TX, 78212, USA
- Department of Mathematics, Physics and Chemical Engineering, Jönköping University, 551 11, Jönköping, Sweden
| | - Logan Chipkin
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA
| | - Ryan C Daileda
- Department of Mathematics, Trinity University, San Antonio, TX, 78212, USA
| | - Ricardo B R Azevedo
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA.
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10
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Lynch M, Ali F, Lin T, Wang Y, Ni J, Long H. The divergence of mutation rates and spectra across the Tree of Life. EMBO Rep 2023; 24:e57561. [PMID: 37615267 PMCID: PMC10561183 DOI: 10.15252/embr.202357561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/25/2023] Open
Abstract
Owing to advances in genome sequencing, genome stability has become one of the most scrutinized cellular traits across the Tree of Life. Despite its centrality to all things biological, the mutation rate (per nucleotide site per generation) ranges over three orders of magnitude among species and several-fold within individual phylogenetic lineages. Within all major organismal groups, mutation rates scale negatively with the effective population size of a species and with the amount of functional DNA in the genome. This relationship is most parsimoniously explained by the drift-barrier hypothesis, which postulates that natural selection typically operates to reduce mutation rates until further improvement is thwarted by the power of random genetic drift. Despite this constraint, the molecular mechanisms underlying DNA replication fidelity and repair are free to wander, provided the performance of the entire system is maintained at the prevailing level. The evolutionary flexibility of the mutation rate bears on the resolution of several prior conundrums in phylogenetic and population-genetic analysis and raises challenges for future applications in these areas.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of EvolutionArizona State UniversityTempeAZUSA
| | - Farhan Ali
- Biodesign Center for Mechanisms of EvolutionArizona State UniversityTempeAZUSA
| | - Tongtong Lin
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
| | - Yaohai Wang
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
| | - Jiahao Ni
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
| | - Hongan Long
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
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11
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Tuffaha MZ, Varakunan S, Castellano D, Gutenkunst RN, Wahl LM. Shifts in Mutation Bias Promote Mutators by Altering the Distribution of Fitness Effects. Am Nat 2023; 202:503-518. [PMID: 37792927 DOI: 10.1086/726010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
AbstractRecent experimental evidence demonstrates that shifts in mutational biases-for example, increases in transversion frequency-can change the distribution of fitness effects of mutations (DFE). In particular, reducing or reversing a prevailing bias can increase the probability that a de novo mutation is beneficial. It has also been shown that mutator bacteria are more likely to emerge if the beneficial mutations they generate have a larger effect size than observed in the wild type. Here, we connect these two results, demonstrating that mutator strains that reduce or reverse a prevailing bias have a positively shifted DFE, which in turn can dramatically increase their emergence probability. Since changes in mutation rate and bias are often coupled through the gain and loss of DNA repair enzymes, our results predict that the invasion of mutator strains will be facilitated by shifts in mutation bias that offer improved access to previously undersampled beneficial mutations.
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12
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Fronhofer EA, Corenblit D, Deshpande JN, Govaert L, Huneman P, Viard F, Jarne P, Puijalon S. Eco-evolution from deep time to contemporary dynamics: The role of timescales and rate modulators. Ecol Lett 2023; 26 Suppl 1:S91-S108. [PMID: 37840024 DOI: 10.1111/ele.14222] [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: 10/21/2022] [Revised: 03/27/2023] [Accepted: 03/29/2023] [Indexed: 10/17/2023]
Abstract
Eco-evolutionary dynamics, or eco-evolution for short, are often thought to involve rapid demography (ecology) and equally rapid heritable phenotypic changes (evolution) leading to novel, emergent system behaviours. We argue that this focus on contemporary dynamics is too narrow: Eco-evolution should be extended, first, beyond pure demography to include all environmental dimensions and, second, to include slow eco-evolution which unfolds over thousands or millions of years. This extension allows us to conceptualise biological systems as occupying a two-dimensional time space along axes that capture the speed of ecology and evolution. Using Hutchinson's analogy: Time is the 'theatre' in which ecology and evolution are two interacting 'players'. Eco-evolutionary systems are therefore dynamic: We identify modulators of ecological and evolutionary rates, like temperature or sensitivity to mutation, which can change the speed of ecology and evolution, and hence impact eco-evolution. Environmental change may synchronise the speed of ecology and evolution via these rate modulators, increasing the occurrence of eco-evolution and emergent system behaviours. This represents substantial challenges for prediction, especially in the context of global change. Our perspective attempts to integrate ecology and evolution across disciplines, from gene-regulatory networks to geomorphology and across timescales, from today to deep time.
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Affiliation(s)
| | - Dov Corenblit
- GEOLAB, Université Clermont Auvergne, CNRS, Clermont-Ferrand, France
- Laboratoire écologie fonctionnelle et environnement, Université Paul Sabatier, CNRS, INPT, UPS, Toulouse, France
| | | | - Lynn Govaert
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Philippe Huneman
- Institut d'Histoire et de Philosophie des Sciences et des Techniques (CNRS/Université Paris I Sorbonne), Paris, France
| | - Frédérique Viard
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Philippe Jarne
- CEFE, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - IRD - EPHE, Montpellier Cedex 5, France
| | - Sara Puijalon
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne, France
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13
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Campbell RP, Whittington AC, Zorio DAR, Miller BG. Recruitment of a Middling Promiscuous Enzyme Drives Adaptive Metabolic Evolution in Escherichia coli. Mol Biol Evol 2023; 40:msad202. [PMID: 37708398 PMCID: PMC10519446 DOI: 10.1093/molbev/msad202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/29/2023] [Accepted: 09/05/2023] [Indexed: 09/16/2023] Open
Abstract
A key step in metabolic pathway evolution is the recruitment of promiscuous enzymes to perform new functions. Despite the recognition that promiscuity is widespread in biology, factors dictating the preferential recruitment of one promiscuous enzyme over other candidates are unknown. Escherichia coli contains four sugar kinases that are candidates for recruitment when the native glucokinase machinery is deleted-allokinase (AlsK), manno(fructo)kinase (Mak), N-acetylmannosamine kinase (NanK), and N-acetylglucosamine kinase (NagK). The catalytic efficiencies of these enzymes are 103- to 105-fold lower than native glucokinases, ranging from 2,400 M-1 s-1 for the most active candidate, NagK, to 15 M-1 s-1 for the least active candidate, AlsK. To investigate the relationship between catalytic activities of promiscuous enzymes and their recruitment, we performed adaptive evolution of a glucokinase-deficient E. coli strain to restore glycolytic metabolism. We observed preferential recruitment of NanK via a trajectory involving early mutations that facilitate glucose uptake and amplify nanK transcription, followed by nonsynonymous substitutions in NanK that enhance the enzyme's promiscuous glucokinase activity. These substitutions reduced the native activity of NanK and reduced organismal fitness during growth on an N-acetylated carbon source, indicating that enzyme recruitment comes at a cost for growth on other substrates. Notably, the two most active candidates, NagK and Mak, were not recruited, suggesting that catalytic activity alone does not dictate evolutionary outcomes. The results highlight our lack of knowledge regarding biological drivers of enzyme recruitment and emphasize the need for a systems-wide approach to identify factors facilitating or constraining this important adaptive process.
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Affiliation(s)
- Ryan P Campbell
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - A Carl Whittington
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Diego A R Zorio
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Brian G Miller
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
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14
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Lobinska G, Pilpel Y, Ram Y. Phenotype switching of the mutation rate facilitates adaptive evolution. Genetics 2023; 225:iyad111. [PMID: 37293818 PMCID: PMC10471227 DOI: 10.1093/genetics/iyad111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 02/05/2023] [Accepted: 05/25/2023] [Indexed: 06/10/2023] Open
Abstract
The mutation rate plays an important role in adaptive evolution. It can be modified by mutator and anti-mutator alleles. Recent empirical evidence hints that the mutation rate may vary among genetically identical individuals: evidence from bacteria suggests that the mutation rate can be affected by expression noise of a DNA repair protein and potentially also by translation errors in various proteins. Importantly, this non-genetic variation may be heritable via a transgenerational epigenetic mode of inheritance, giving rise to a mutator phenotype that is independent from mutator alleles. Here, we investigate mathematically how the rate of adaptive evolution is affected by the rate of mutation rate phenotype switching. We model an asexual population with two mutation rate phenotypes, non-mutator and mutator. An offspring may switch from its parental phenotype to the other phenotype. We find that switching rates that correspond to so-far empirically described non-genetic systems of inheritance of the mutation rate lead to higher rates of adaptation on both artificial and natural fitness landscapes. These switching rates can maintain within the same individuals both a mutator phenotype and intermediary mutations, a combination that facilitates adaptation. Moreover, non-genetic inheritance increases the proportion of mutators in the population, which in turn increases the probability of hitchhiking of the mutator phenotype with adaptive mutations. This in turns facilitates the acquisition of additional adaptive mutations. Our results rationalize recently observed noise in the expression of proteins that affect the mutation rate and suggest that non-genetic inheritance of this phenotype may facilitate evolutionary adaptive processes.
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Affiliation(s)
- Gabriela Lobinska
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yitzhak Pilpel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Ram
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
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15
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Majic P, Payne JL. Developmental Selection and the Perception of Mutation Bias. Mol Biol Evol 2023; 40:msad179. [PMID: 37556606 PMCID: PMC10443735 DOI: 10.1093/molbev/msad179] [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: 04/05/2023] [Revised: 07/22/2023] [Accepted: 07/26/2023] [Indexed: 08/11/2023] Open
Abstract
The notion that mutations are random relative to their fitness effects is central to the Neo-Darwinian view of evolution. However, a recent interpretation of the patterns of mutation accumulation in the genome of Arabidopsis thaliana has challenged this notion, arguing for the presence of a targeted DNA repair mechanism that causes a nonrandom association of mutation rates and fitness effects. Specifically, this mechanism was suggested to cause a reduction in the rates of mutations on essential genes, thus lowering the rates of deleterious mutations. Central to this argument were attempts to rule out selection at the population level. Here, we offer an alternative and parsimonious interpretation of the patterns of mutation accumulation previously attributed to mutation bias, showing how they can instead or additionally be caused by developmental selection, that is selection occurring at the cellular level during the development of a multicellular organism. Thus, the depletion of deleterious mutations in A. thaliana may indeed be the result of a selective process, rather than a bias in mutation. More broadly, our work highlights the importance of considering development in the interpretation of population-genetic analyses of multicellular organisms, and it emphasizes that efforts to identify mechanisms involved in mutational biases should explicitly account for developmental selection.
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Affiliation(s)
- Paco Majic
- Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Joshua L Payne
- Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
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16
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Callens M, Rose CJ, Finnegan M, Gatchitch F, Simon L, Hamet J, Pradier L, Dubois MP, Bedhomme S. Hypermutator emergence in experimental Escherichia coli populations is stress-type dependent. Evol Lett 2023; 7:252-261. [PMID: 37475751 PMCID: PMC10355175 DOI: 10.1093/evlett/qrad019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/04/2023] [Accepted: 04/21/2023] [Indexed: 07/22/2023] Open
Abstract
Genotypes exhibiting an increased mutation rate, called hypermutators, can propagate in microbial populations because they can have an advantage due to the higher supply of beneficial mutations needed for adaptation. Although this is a frequently observed phenomenon in natural and laboratory populations, little is known about the influence of parameters such as the degree of maladaptation, stress intensity, and the genetic architecture for adaptation on the emergence of hypermutators. To address this knowledge gap, we measured the emergence of hypermutators over ~1,000 generations in experimental Escherichia coli populations exposed to different levels of osmotic or antibiotic stress. Our stress types were chosen based on the assumption that the genetic architecture for adaptation differs between them. Indeed, we show that the size of the genetic basis for adaptation is larger for osmotic stress compared to antibiotic stress. During our experiment, we observed an increased emergence of hypermutators in populations exposed to osmotic stress but not in those exposed to antibiotic stress, indicating that hypermutator emergence rates are stress type dependent. These results support our hypothesis that hypermutator emergence is linked to the size of the genetic basis for adaptation. In addition, we identified other parameters that covaried with stress type (stress level and IS transposition rates) that might have contributed to an increased hypermutator provision and selection. Our results provide a first comparison of hypermutator emergence rates under varying stress conditions and point towards complex interactions of multiple stress-related factors on the evolution of mutation rates.
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Affiliation(s)
- Martijn Callens
- CEFE, CNRS, University of Montpellier, EPHE, IRD, Montpellier, France
- Animal Sciences Unit—Aquatic Environment and Quality, Flanders Research Institute for Agriculture, Fisheries and Food, Oostende, Belgium
| | - Caroline J Rose
- CEFE, CNRS, University of Montpellier, EPHE, IRD, Montpellier, France
| | - Michael Finnegan
- CEFE, CNRS, University of Montpellier, EPHE, IRD, Montpellier, France
| | | | - Léna Simon
- CEFE, CNRS, University of Montpellier, EPHE, IRD, Montpellier, France
- Université Clermont Auvergne, VetAgro Sup, Lempdes, France
| | - Jeanne Hamet
- CEFE, CNRS, University of Montpellier, EPHE, IRD, Montpellier, France
| | - Léa Pradier
- CEFE, CNRS, University of Montpellier, EPHE, IRD, Montpellier, France
| | | | - Stéphanie Bedhomme
- Corresponding author: CEFE, 1919 route de Mende, 34293 Montpellier, France.
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17
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Sane M, Diwan GD, Bhat BA, Wahl LM, Agashe D. Shifts in mutation spectra enhance access to beneficial mutations. Proc Natl Acad Sci U S A 2023; 120:e2207355120. [PMID: 37216547 PMCID: PMC10235995 DOI: 10.1073/pnas.2207355120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 03/27/2023] [Indexed: 05/24/2023] Open
Abstract
Biased mutation spectra are pervasive, with wide variation in the magnitude of mutational biases that influence genome evolution and adaptation. How do such diverse biases evolve? Our experiments show that changing the mutation spectrum allows populations to sample previously undersampled mutational space, including beneficial mutations. The resulting shift in the distribution of fitness effects is advantageous: Beneficial mutation supply and beneficial pleiotropy both increase, while deleterious load reduces. More broadly, simulations indicate that reducing or reversing the direction of a long-term bias is always selectively favored. Such changes in mutation bias can occur easily via altered function of DNA repair genes. A phylogenetic analysis shows that these genes are repeatedly gained and lost in bacterial lineages, leading to frequent bias shifts in opposite directions. Thus, shifts in mutation spectra may evolve under selection and can directly alter the outcome of adaptive evolution by facilitating access to beneficial mutations.
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Affiliation(s)
- Mrudula Sane
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
| | - Gaurav D. Diwan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
- Bioquant, University of Heidelberg,69120Heidelberg, Germany
- Heidelberg University Biochemistry Center (BZH), 69120Heidelberg, Germany
| | - Bhoomika A. Bhat
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
- Undergraduate Programme, Indian Institute of Science, Bengaluru 560012, India
| | - Lindi M. Wahl
- Mathematics, Western University, London, ON, N6A 5B7, Canada
| | - Deepa Agashe
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
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18
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Lynch M, Wei W, Ye Z, Pfrender M. The Genome-wide Signature of Short-term Temporal Selection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538790. [PMID: 37162919 PMCID: PMC10168312 DOI: 10.1101/2023.04.28.538790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Despite evolutionary biology's obsession with natural selection, few studies have evaluated multi-generational series of patterns of selection on a genome-wide scale in natural populations. Here, we report on a nine-year population-genomic survey of the microcrustacean Daphnia pulex. The genome-sequences of > 800 isolates provide insights into patterns of selection that cannot be obtained from long-term molecular-evolution studies, including the pervasiveness of near quasi-neutrality across the genome (mean net selection coefficients near zero, but with significant temporal variance about the mean, and little evidence of positive covariance of selection across time intervals), the preponderance of weak negative selection operating on minor alleles, and a genome-wide distribution of numerous small linkage islands of observable selection influencing levels of nucleotide diversity. These results suggest that fluctuating selection is a major determinant of standing levels of variation in natural populations, challenge the conventional paradigm for interpreting patterns of nucleotide diversity and divergence, and motivate the need for the development of new theoretical expressions for the interpretation of population-genomic data.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Zhiqiang Ye
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Michael Pfrender
- Department of Biological Sciences, Notre Dame University, Notre Dame, IN 46556
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Accelerated Adaptive Laboratory Evolution by Automated Repeated Batch Processes in Parallelized Bioreactors. Microorganisms 2023; 11:microorganisms11020275. [PMID: 36838240 PMCID: PMC9965177 DOI: 10.3390/microorganisms11020275] [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: 11/08/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 01/26/2023] Open
Abstract
Adaptive laboratory evolution (ALE) is a valuable complementary tool for modern strain development. Insights from ALE experiments enable the improvement of microbial cell factories regarding the growth rate and substrate utilization, among others. Most ALE experiments are conducted by serial passaging, a method that involves large amounts of repetitive manual labor and comes with inherent experimental design flaws. The acquisition of meaningful and reliable process data is a burdensome task and is often undervalued and neglected, but also unfeasible in shake flask experiments due to technical limitations. Some of these limitations are alleviated by emerging automated ALE methods on the μL and mL scale. A novel approach to conducting ALE experiments is described that is faster and more efficient than previously used methods. The conventional shake flask approach was translated to a parallelized, L scale stirred-tank bioreactor system that runs controlled, automated, repeated batch processes. The method was validated with a growth optimization experiment of E. coli K-12 MG1655 grown with glycerol minimal media as a benchmark. Off-gas analysis enables the continuous estimation of the biomass concentration and growth rate using a black-box model based on first principles (soft sensor). The proposed method led to the same stable growth rates of E. coli with the non-native carbon source glycerol 9.4 times faster than the traditional manual approach with serial passaging in uncontrolled shake flasks and 3.6 times faster than an automated approach on the mL scale. Furthermore, it is shown that the cumulative number of cell divisions (CCD) alone is not a suitable timescale for measuring and comparing evolutionary progress.
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20
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Laurin D, Mercier C, Quansah N, Robert JS, Usson Y, Schneider D, Hindré T, Schaack B. Extracellular Vesicles from 50,000 Generation Clones of the Escherichia coli Long-Term Evolution Experiment. Int J Mol Sci 2022; 23:ijms232314580. [PMID: 36498912 PMCID: PMC9737989 DOI: 10.3390/ijms232314580] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/15/2022] [Accepted: 11/19/2022] [Indexed: 11/24/2022] Open
Abstract
Extracellular vesicles (EVs) are critical elements of cell-cell communication. Here, we characterized the outer membrane vesicles (OMVs) released by specific clones of Escherichia coli isolated from the Long-Term Evolution Experiment after 50,000 generations (50K) of adaptation to glucose minimal medium. Compared with their ancestor, the evolved clones produce small OMVs but also larger ones which display variable amounts of both OmpA and LPS. Tracking ancestral, fluorescently labelled OMVs revealed that they fuse with both ancestral- and 50K-evolved cells, albeit in different proportions. We quantified that less than 2% of the cells from one 50K-evolved clone acquired the fluorescence delivered by OMVs from the ancestral strain but that one cell concomitantly fuses with several OMVs. Globally, our results showed that OMV production in E. coli is a phenotype that varies along bacterial evolution and question the contribution of OMVs-mediated interactions in bacterial adaptation.
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Affiliation(s)
- David Laurin
- Département Scientifique Auvergne Rhône-Alpes, Etablissement Français du Sang, 38000 Grenoble, France
- Institute for Advanced Biosciences, INSERM U1209 & CNRS UMR 5309, Université Grenoble Alpes, 38042 Grenoble, France
| | - Corinne Mercier
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
- Correspondence:
| | - Nyamekye Quansah
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
| | - Julie Suzanne Robert
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
| | - Yves Usson
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
| | - Dominique Schneider
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
| | - Thomas Hindré
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
| | - Béatrice Schaack
- CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, Université Grenoble Alpes, 38000 Grenoble, France
- CEA, CNRS, IBS, Université Grenoble Alpes, 38044 Grenoble, France
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21
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Persson K, Stenberg S, Tamás MJ, Warringer J. Adaptation of the yeast gene knockout collection is near-perfectly predicted by fitness and diminishing return epistasis. G3 (BETHESDA, MD.) 2022; 12:6694849. [PMID: 36083011 PMCID: PMC9635671 DOI: 10.1093/g3journal/jkac240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 08/29/2022] [Indexed: 05/31/2023]
Abstract
Adaptive evolution of clonally dividing cells and microbes is the ultimate cause of cancer and infectious diseases. The possibility of constraining the adaptation of cell populations, by inhibiting proteins enhancing the evolvability, has therefore attracted interest. However, our current understanding of how genes influence adaptation kinetics is limited, partly because accurately measuring adaptation for many cell populations is challenging. We used a high-throughput adaptive laboratory evolution platform to track the adaptation of >18,000 cell populations corresponding to single-gene deletion strains in the haploid yeast deletion collection. We report that the preadaptation fitness of gene knockouts near-perfectly (R2= 0.91) predicts their adaptation to arsenic, leaving at the most a marginal role for dedicated evolvability gene functions. We tracked the adaptation of another >23,000 gene knockout populations to a diverse range of selection pressures and generalized the almost perfect (R2=0.72-0.98) capacity of preadaptation fitness to predict adaptation. We also reconstructed mutations in FPS1, ASK10, and ARR3, which together account for almost all arsenic adaptation in wild-type cells, in gene deletions covering a broad fitness range and show that the predictability of arsenic adaptation can be understood as a by global epistasis, where excluding arsenic is more beneficial to arsenic unfit cells. The paucity of genes with a meaningful evolvability effect on adaptation diminishes the prospects of developing adjuvant drugs aiming to slow antimicrobial and chemotherapy resistance.
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Affiliation(s)
- Karl Persson
- Corresponding author: Department of Biology and Biological Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Simon Stenberg
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Markus J Tamás
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Jonas Warringer
- Corresponding author: Department of Chemistry and Molecular Biology, University of Gothenburg, PO Box 462, 40530 Gothenburg, Sweden.
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22
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Wagner A. Adaptive evolvability through direct selection instead of indirect, second-order selection. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2022; 338:395-404. [PMID: 34254439 PMCID: PMC9786751 DOI: 10.1002/jez.b.23071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/11/2021] [Accepted: 06/04/2021] [Indexed: 12/30/2022]
Abstract
Can evolvability itself be the product of adaptive evolution? To answer this question is challenging, because any DNA mutation that alters only evolvability is subject to indirect, "second order" selection on the future effects of this mutation. Such indirect selection is weaker than "first-order" selection on mutations that alter fitness, in the sense that it can operate only under restrictive conditions. Here I discuss a route to adaptive evolvability that overcomes this challenge. Specifically, a recent evolution experiment showed that some mutations can enhance both fitness and evolvability through a combination of direct and indirect selection. Unrelated evidence from gene duplication and the evolution of gene regulation suggests that mutations with such dual effects may not be rare. Through such mutations, evolvability may increase at least in part because it provides an adaptive advantage. These observations suggest a research program on the adaptive evolution of evolvability, which aims to identify such mutations and to disentangle their direct fitness effects from their indirect effects on evolvability. If evolvability is itself adaptive, Darwinian evolution may have created more than life's diversity. It may also have helped create the very conditions that made the success of Darwinian evolution possible.
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Affiliation(s)
- Andreas Wagner
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland,Swiss Institute of BioinformaticsQuartier Sorge‐Batiment GenopodeLausanneSwitzerland,The Santa Fe InstituteSanta FeNew MexicoUSA,Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch UniversityStellenboschSouth Africa
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23
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Izutsu M, Lenski RE. Experimental test of the contributions of initial variation and new mutations to adaptive evolution in a novel environment. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.958406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Experimental evolution is an approach that allows researchers to study organisms as they evolve in controlled environments. Despite the growing popularity of this approach, there are conceptual gaps among projects that use different experimental designs. One such gap concerns the contributions to adaptation of genetic variation present at the start of an experiment and that of new mutations that arise during an experiment. The primary source of genetic variation has historically depended largely on the study organisms. In the long-term evolution experiment (LTEE) using Escherichia coli, for example, each population started from a single haploid cell, and therefore, adaptation depended entirely on new mutations. Most other microbial evolution experiments have followed the same strategy. By contrast, evolution experiments using multicellular, sexually reproducing organisms typically start with preexisting variation that fuels the response to selection. New mutations may also come into play in later generations of these experiments, but it is generally difficult to quantify their contribution in these studies. Here, we performed an experiment using E. coli to compare the contributions of initial genetic variation and new mutations to adaptation in a new environment. Our experiment had four treatments that varied in their starting diversity, with 18 populations in each treatment. One treatment depended entirely on new mutations, while the other three began with mixtures of clones, whole-population samples, or mixtures of whole-population samples from the LTEE. We tracked a genetic marker associated with different founders in two treatments. These data revealed significant variation in fitness among the founders, and that variation impacted evolution in the early generations of our experiment. However, there were no differences in fitness among the treatments after 500 or 2,000 generations in the new environment, despite the variation in fitness among the founders. These results indicate that new mutations quickly dominated, and eventually they contributed more to adaptation than did the initial variation. Our study thus shows that preexisting genetic variation can have a strong impact on early evolution in a new environment, but new beneficial mutations may contribute more to later evolution and can even drive some initially beneficial variants to extinction.
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24
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Soto W. Emerging Research Topics in the Vibrionaceae and the Squid- Vibrio Symbiosis. Microorganisms 2022; 10:microorganisms10101946. [PMID: 36296224 PMCID: PMC9607633 DOI: 10.3390/microorganisms10101946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
The Vibrionaceae encompasses a cosmopolitan group that is mostly aquatic and possesses tremendous metabolic and genetic diversity. Given the importance of this taxon, it deserves continued and deeper research in a multitude of areas. This review outlines emerging topics of interest within the Vibrionaceae. Moreover, previously understudied research areas are highlighted that merit further exploration, including affiliations with marine plants (seagrasses), microbial predators, intracellular niches, and resistance to heavy metal toxicity. Agarases, phototrophy, phage shock protein response, and microbial experimental evolution are also fields discussed. The squid-Vibrio symbiosis is a stellar model system, which can be a useful guiding light on deeper expeditions and voyages traversing these "seas of interest". Where appropriate, the squid-Vibrio mutualism is mentioned in how it has or could facilitate the illumination of these various subjects. Additional research is warranted on the topics specified herein, since they have critical relevance for biomedical science, pharmaceuticals, and health care. There are also practical applications in agriculture, zymology, food science, and culinary use. The tractability of microbial experimental evolution is explained. Examples are given of how microbial selection studies can be used to examine the roles of chance, contingency, and determinism (natural selection) in shaping Earth's natural history.
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Affiliation(s)
- William Soto
- Integrated Science Center Rm 3035, Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA 23185, USA
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25
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Planet PJ. Adaptation and Evolution of Pathogens in the Cystic Fibrosis Lung. J Pediatric Infect Dis Soc 2022; 11:S23-S31. [PMID: 36069898 PMCID: PMC9451014 DOI: 10.1093/jpids/piac073] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/11/2022] [Indexed: 02/05/2023]
Abstract
As opposed to acute respiratory infections, the persistent bacterial infections of the lung that characterize cystic fibrosis (CF) provide ample time for bacteria to evolve and adapt. The process of adaptation is recorded in mutations that accumulate over time in the genomes of the infecting bacteria. Some of these mutations lead to obvious phenotypic differences such as antibiotic resistance or the well-known mucoid phenotype of Pseudomonas aeruginosa. Other mutations may be just as important but harder to detect such as increased mutation rates, cell surface changes, and shifts in metabolism and nutrient acquisition. Remarkably, many of the adaptations occur again and again in different patients, signaling that bacteria are adapting to solve specific challenges in the CF respiratory tract. This parallel evolution even extends across distinct bacterial species. This review addresses the bacterial systems that are known to change in long-term CF infections with a special emphasis on cross-species comparisons. Consideration is given to how adaptation may impact health in CF, and the possible evolutionary mechanisms that lead to the repeated parallel adaptations.
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Affiliation(s)
- Paul J Planet
- Corresponding Author: Paul J. Planet, MD, PhD, 3615 Civic Center Blvd, Philadelphia, PA 19104. E-mail:
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26
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Whole-Genome Sequencing and Drug-Susceptibility Analysis of Serial Mycobacterium abscessus Isolates from Thai Patients. BIOLOGY 2022; 11:biology11091319. [PMID: 36138798 PMCID: PMC9495349 DOI: 10.3390/biology11091319] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 11/18/2022]
Abstract
Mycobacterium abscessus is an important pathogen that can cause serious human diseases and is difficult to treat due to antibiotic resistance. In this study, we analyzed, using whole-genome sequence (WGS) data, M. abscessus strains serially isolated from patients at various time intervals. We undertook genetic diversity analysis between subspecies, mutation-rate estimation and identification of drug-resistant mutations with minimum inhibitory concentration (MIC) analysis. Clonal isolates of M. abscessus:—subsp. abscessus (MAB) and subsp. massiliense (MMAS)—causing persistent infection through time, differed by 0−7 and 0−14 SNPs, respectively, despite being isolated 1 to 659 days apart. Two cases caused by MMAS differed by ≥102 SNPs at 350 days apart and were regarded as examples of reinfection. Isolates collected ≤7 days apart exhibited a high mutation rate (133.83 ± 0.00 SNPs/genome (5 Mb)/year for MMAS and 127.75 SNPs/genome (5 Mb)/year for MAB). Mutation rates declined in a time-dependent manner in both subspecies. Based on isolates collected > 180 days apart, MMAS had a significantly higher average mutation rate than MAB (2.89 ± 1.02 versus 0.82 ± 0.83 SNPs/genome (5 Mb)/year, (p = 0.01), respectively). All well-known drug-resistance mutations were found to be strongly associated with high MIC levels for clarithromycin and ciprofloxacin. No known mutations were identified for strains resistant to linezolid and amikacin. MAB strains in the study were susceptible to amikacin, while most MMAS strains were susceptible to clarithromycin, amikacin and linezolid. No hetero-resistance was found in the strains analyzed. Our study reports the genetic diversity and mutation rate of M. abscessus between the two major subspecies and confirms the drug resistance-associated mutations. Information about drug-resistance and associated mutations can be applied in diagnosis and patient management.
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27
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Pennings PS, Ogbunugafor CB, Hershberg R. Reversion is most likely under high mutation supply when compensatory mutations do not fully restore fitness costs. G3 (BETHESDA, MD.) 2022; 12:jkac190. [PMID: 35920784 PMCID: PMC9434179 DOI: 10.1093/g3journal/jkac190] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 10/02/2021] [Indexed: 06/15/2023]
Abstract
The dynamics of adaptation, reversion, and compensation have been central topics in microbial evolution, and several studies have attempted to resolve the population genetics underlying how these dynamics occur. However, questions remain regarding how certain features-the evolution of mutators and whether compensatory mutations alleviate costs fully or partially-may influence the evolutionary dynamics of compensation and reversion. In this study, we attempt to explain findings from experimental evolution by utilizing computational and theoretical approaches toward a more refined understanding of how mutation rate and the fitness effects of compensatory mutations influence adaptive dynamics. We find that high mutation rates increase the probability of reversion toward the wild type when compensation is only partial. However, the existence of even a single fully compensatory mutation is associated with a dramatically decreased probability of reversion to the wild type. These findings help to explain specific results from experimental evolution, where compensation was observed in nonmutator strains, but reversion (sometimes with compensation) was observed in mutator strains, indicating that real-world compensatory mutations are often unable to fully alleviate the costs associated with adaptation. Our findings emphasize the potential role of the supply and quality of mutations in crafting the dynamics of adaptation and reversal, with implications for theoretical population genetics and for biomedical contexts like the evolution of antibiotic resistance.
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Affiliation(s)
- Pleuni S Pennings
- Corresponding author: Department of Biology, San Francisco State University, San Francisco, CA 94132, USA.
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Maddamsetti R, Grant NA. Discovery of positive and purifying selection in metagenomic time series of hypermutator microbial populations. PLoS Genet 2022; 18:e1010324. [PMID: 35981004 PMCID: PMC9426924 DOI: 10.1371/journal.pgen.1010324] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/30/2022] [Accepted: 07/04/2022] [Indexed: 11/18/2022] Open
Abstract
A general method to infer both positive and purifying selection during the real-time evolution of hypermutator pathogens would be broadly useful. To this end, we introduce a Simple Test to Infer Mode of Selection (STIMS) from metagenomic time series of evolving microbial populations. We test STIMS on metagenomic data generated by simulations of bacterial evolution, and on metagenomic data spanning 62,750 generations of Lenski’s long-term evolution experiment with Escherichia coli (LTEE). This benchmarking shows that STIMS detects positive selection in both nonmutator and hypermutator populations, and purifying selection in hypermutator populations. Using STIMS, we find strong evidence of ongoing positive selection on key regulators of the E. coli gene regulatory network, even in some hypermutator populations. STIMS also detects positive selection on regulatory genes in hypermutator populations of Pseudomonas aeruginosa that adapted to subinhibitory concentrations of colistin–an antibiotic of last resort–for just twenty-six days of laboratory evolution. Our results show that the fine-tuning of gene regulatory networks is a general mechanism for rapid and ongoing adaptation. The simplicity of STIMS, together with its intuitive visual interpretation, make it a useful test for positive and purifying selection in metagenomic data sets that track microbial evolution in real-time. Organisms often evolve elevated mutation rates as they adapt to new environments. That said, the genomic basis of adaptation in asexual hypermutator populations has been difficult to discern, because the few mutations driving adaptation are often associated with large numbers of non-adaptive “hitchhiker” mutations elsewhere in the genome. To address this research gap, we present a Simple Test to Infer Mode of Selection (STIMS) which aggregates the overall signature of selection seen over hundreds of genes. Using STIMS, we find strong positive selection on key regulators of the E. coli gene regulatory network across nonmutator and hypermutator populations of Lenski’s long-term evolution experiment with Escherichia coli. We also find positive selection on regulatory genes in populations of Pseudomonas aeruginosa that evolved hypermutability as they evolved to resist colistin, an antibiotic of last resort. Our work shows that positive and purifying selection can be resolved in hypermutator populations, given sufficient genomic data, and show that regulatory mutations are a major driver of adaptation in experimental populations of microbes.
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Affiliation(s)
- Rohan Maddamsetti
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
- * E-mail: (RM); (NAG)
| | - Nkrumah A. Grant
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, United States of America
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- * E-mail: (RM); (NAG)
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Rapid evolution of mutation rate and spectrum in response to environmental and population-genetic challenges. Nat Commun 2022; 13:4752. [PMID: 35963846 PMCID: PMC9376063 DOI: 10.1038/s41467-022-32353-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 07/26/2022] [Indexed: 11/15/2022] Open
Abstract
Ecological and demographic factors can significantly shape the evolution of microbial populations both directly and indirectly, as when changes in the effective population size affect the efficiency of natural selection on the mutation rate. However, it remains unclear how rapidly the mutation-rate responds evolutionarily to the entanglement of ecological and population-genetic factors over time. Here, we directly assess the mutation rate and spectrum of Escherichia coli clones isolated from populations evolving in response to 1000 days of different transfer volumes and resource-replenishment intervals. The evolution of mutation rates proceeded rapidly in response to demographic and/or environmental changes, with substantial bidirectional shifts observed as early as 59 generations. These results highlight the remarkable rapidity by which mutation rates are shaped in asexual lineages in response to environmental and population-genetic forces, and are broadly consistent with the drift-barrier hypothesis for the evolution of mutation rates, while also highlighting situations in which mutator genotypes may be promoted by positive selection. How rapidly the mutation rate responds evolutionarily to ecological and population-genetic factors over time is unclear. Here, the authors show that the evolution of mutation rates in E. coli proceeds rapidly in response to these factors with substantial bidirectional shifts.
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Ní Leathlobhair M, Lenski RE. Population genetics of clonally transmissible cancers. Nat Ecol Evol 2022; 6:1077-1089. [PMID: 35879542 DOI: 10.1038/s41559-022-01790-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 05/12/2022] [Indexed: 11/08/2022]
Abstract
Populations of cancer cells are subject to the same core evolutionary processes as asexually reproducing, unicellular organisms. Transmissible cancers are particularly striking examples of these processes. These unusual cancers are clonal lineages that can spread through populations via physical transfer of living cancer cells from one host individual to another, and they have achieved long-term success in the colonization of at least eight different host species. Population genetic theory provides a useful framework for understanding the shift from a multicellular sexual animal into a unicellular asexual clone and its long-term effects on the genomes of these cancers. In this Review, we consider recent findings from transmissible cancer research with the goals of developing an evolutionarily informed perspective on transmissible cancers, examining possible implications for their long-term fate and identifying areas for future research on these exceptional lineages.
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Affiliation(s)
- Máire Ní Leathlobhair
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK.
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland.
| | - Richard E Lenski
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA
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Polymicrobial infections can select against Pseudomonas aeruginosa mutators because of quorum-sensing trade-offs. Nat Ecol Evol 2022; 6:979-988. [PMID: 35618819 DOI: 10.1038/s41559-022-01768-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/13/2022] [Indexed: 11/08/2022]
Abstract
Bacteria with increased mutation rates (mutators) are common in chronic infections and are associated with poorer clinical outcomes, especially in the case of Pseudomonas aeruginosa infecting cystic fibrosis (CF) patients. There is, however, considerable between-patient variation in both P. aeruginosa mutator frequency and the composition of co-infecting pathogen communities. We investigated whether community context might affect selection of mutators. Using an in vitro CF model community, we show that P. aeruginosa mutators were favoured in the absence of other species but not in their presence. This was because there were trade-offs between adaptation to the biotic and abiotic environments (for example, loss of quorum sensing and associated toxin production was beneficial in the latter but not the former in our in vitro model community) limiting the evolvability advantage of an elevated mutation rate. Consistent with a role of co-infecting pathogens selecting against P. aeruginosa mutators in vivo, we show that the mutation frequency of P. aeruginosa population was negatively correlated with the frequency and diversity of co-infecting bacteria in CF infections. Our results suggest that co-infecting taxa can select against P. aeruginosa mutators, which may have potentially beneficial clinical consequences.
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Abstract
Ecotypic diversification and its associated cooperative behaviors are frequently observed in natural microbial populations whose access to resources is often sporadic. However, the extent to which fluctuations in resource availability influence the emergence of cooperative ecotypes is not fully understood. To determine how exposure to repeated resource limitation affects the establishment and long-term maintenance of ecotypes in a structured environment, we followed 32 populations of Escherichia coli evolving to either 1-day or 10-day feast/famine cycles for 900 days. Population-level analysis revealed that compared to populations evolving to 1-day cycles, 10-day populations evolved increased biofilm density, higher parallelism in mutational targets, and increased mutation rates. As previous investigations of evolution in structured environments have identified biofilm formation as the earliest observable phenotype associated with diversification of ecotypes, we revived cultures midway through the evolutionary process and conducted additional genomic, transcriptional, and phenotypic analyses of clones isolated from these evolving populations. We found not only that 10-day feast/famine cycles support multiple ecotypes but also that these ecotypes exhibit cooperative behavior. Consistent with the black queen hypothesis, or evolution of cooperation by gene loss, transcriptomic evidence suggests the evolution of bidirectional cross-feeding behaviors based on essential resources. These results provide insight into how analogous cooperative relationships may emerge in natural microbial communities. IMPORTANCE Despite regular feast and famine conditions representing an environmental pressure that is commonly encountered by microbial communities, the evolutionary outcomes of repeated cycles of feast and famine have been less studied. By experimentally evolving initially isogenic Escherichia coli populations to 10-day feast/famine cycles, we observed rapid diversification into ecotypes with evidence of bidirectional cross-feeding on costly resources and frequency-dependent fitness. Although unidirectional cross-feeding has been repeatedly observed to evolve in laboratory culture, most investigations of bidirectional cooperative behaviors in microbial populations have been conducted in engineered communities. This work demonstrates the de novo evolution of black queen relationships in a microbial population originating from a single ancestor, providing a model for investigation of the eco-evolutionary processes leading to mutualistic cooperation.
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Paul BG, Eren AM. Eco-evolutionary significance of domesticated retroelements in microbial genomes. Mob DNA 2022; 13:6. [PMID: 35197094 PMCID: PMC8867640 DOI: 10.1186/s13100-022-00262-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/03/2022] [Indexed: 01/03/2023] Open
Abstract
Since the first discovery of reverse transcriptase in bacteria, and later in archaea, bacterial and archaeal retroelements have been defined by their common enzyme that coordinates diverse functions. Yet, evolutionary refinement has produced distinct retroelements across the tree of microbial life that are perhaps best described in terms of their programmed RNA—a compact sequence that preserves core information for a sophisticated mechanism. From this perspective, reverse transcriptase has been selected as the modular tool for carrying out nature’s instructions in various RNA templates. Beneficial retroelements—those that can provide a fitness advantage to their host—evolved to their extant forms in a wide array of microorganisms and their viruses, spanning nearly all habitats. Within each specialized retroelement class, several universal features seem to be shared across diverse taxa, while specific functional and mechanistic insights are based on only a few model retroelement systems from clinical isolates. Currently, little is known about the diversity of cellular functions and ecological significance of retroelements across different biomes. With increasing availability of isolate, metagenome-assembled, and single-amplified genomes, the taxonomic and functional breadth of prokaryotic retroelements is coming into clearer view. This review explores the recently characterized classes of beneficial, yet accessory retroelements of bacteria and archaea. We describe how these specialized mechanisms exploit a form of fixed mobility, whereby the retroelements do not appear to proliferate selfishly throughout the genome. Moreover, we discuss computational approaches for systematic identification of retroelements from vast sequence repositories and highlight recent discoveries in terms of their apparent distribution and ecological significance in nature. Lastly, we present a new perspective on the eco-evolutionary significance of these genetic elements in marine bacteria and demonstrate approaches that enable the characterization of their environmental diversity through metagenomics.
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Affiliation(s)
- Blair G Paul
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA.
| | - A Murat Eren
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA. .,Department of Medicine, University of Chicago, Chicago, IL, USA.
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Anatomy promotes neutral coexistence of strains in the human skin microbiome. Cell Host Microbe 2022; 30:171-182.e7. [PMID: 34995483 PMCID: PMC8831475 DOI: 10.1016/j.chom.2021.12.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/18/2021] [Accepted: 12/09/2021] [Indexed: 01/04/2023]
Abstract
What enables strains of the same species to coexist in a microbiome? Here, we investigate whether host anatomy can explain strain co-residence of Cutibacterium acnes, the most abundant species on human skin. We reconstruct on-person evolution and migration using whole-genome sequencing of C. acnes colonies acquired from healthy subjects, including from individual skin pores, and find considerable spatial structure at the level of pores. Although lineages (sets of colonies separated by <100 mutations) with in vitro fitness differences coexist within centimeter-scale regions, each pore is dominated by a single lineage. Moreover, colonies from a pore typically have identical genomes. An absence of adaptive signatures suggests a genotype-independent source of low within-pore diversity. We therefore propose that pore anatomy imposes random single-cell bottlenecks; the resulting population fragmentation reduces competition and promotes coexistence. Our findings suggest that therapeutic interventions involving pore-dwelling species might focus on removing resident populations over optimizing probiotic fitness.
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35
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Loss of mobile genomic islands in metal resistant, hydrogen-oxidizing Cupriavidus metallidurans. Appl Environ Microbiol 2021; 88:e0204821. [PMID: 34910578 DOI: 10.1128/aem.02048-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of the metal resistant, hydrogen-oxidizing bacterium Cupriavidus metallidurans strain CH34 contains horizontally acquired plasmids and genomic islands. Metal-resistance determinants on the two plasmids may exert genetic dominance over other related determinants. To investigate whether these recessive determinants can be activated in the absence of the dominant ones, the transcriptome of the highly zinc-sensitive deletion mutant Δe4 (ΔcadA ΔzntA ΔdmeF ΔfieF) of the plasmid-free parent AE104 was characterized using gene arrays. As a consequence of some unexpected results, close examination by PCR and genomic re-resequencing of strains CH34, AE104, Δe4 and others revealed that the genomic islands CMGIs 2, 3, 4, D, E, but no other islands or recessive determinants, were deleted in some of these strains. Provided CH34 wild type was kept under alternating zinc and nickel selection pressure, no comparable deletions occurred. All current data suggest that genes were actually deleted and were not, as previously surmised, simply absent from the respective strain. As a consequence, a cured database was compiled from the newly generated and previously published gene array data. Analysis of data from this database indicated that some genes of recessive, no longer needed determinants were nevertheless expressed and up-regulated. Their products may interact with those of the dominant determinants to mediate a mosaic phenotype. The ability to contribute to such a mosaic phenotype may prevent deletion of the recessive determinant. The data suggest that the bacterium actively modifies its genome to deal with metal stress and the same time ensures metal homeostasis. Significance In their natural environment, bacteria continually acquire genes by horizontal gene transfer and newly acquired determinants may become dominant over related ones already present in the host genome. When a bacterium is taken into laboratory culture, it is isolated from the horizontal gene transfer network. It can no longer gain genes, but instead may lose them. This was indeed observed in Cupriavidus metallidurans for loss key metal-resistance determinants when no selection pressure was continuously kept. However, some recessive metal-resistance determinants were maintained in the genome. It is proposed that they might contribute some accessory genes to related dominant resistance determinants, for instance periplasmic metal-binding proteins or two-component regulatory systems. Alternatively, they may only remain in the genome because their DNA serves as a scaffold for the nucleoid. Using C. metallidurans as an example, this study sheds light on the fate and function of horizontally acquired genes in bacteria.
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Ho WC, Behringer MG, Miller SF, Gonzales J, Nguyen A, Allahwerdy M, Boyer GF, Lynch M. Evolutionary Dynamics of Asexual Hypermutators Adapting to a Novel Environment. Genome Biol Evol 2021; 13:evab257. [PMID: 34864972 PMCID: PMC8643662 DOI: 10.1093/gbe/evab257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2021] [Indexed: 12/24/2022] Open
Abstract
How microbes adapt to a novel environment is a central question in evolutionary biology. Although adaptive evolution must be fueled by beneficial mutations, whether higher mutation rates facilitate the rate of adaptive evolution remains unclear. To address this question, we cultured Escherichia coli hypermutating populations, in which a defective methyl-directed mismatch repair pathway causes a 140-fold increase in single-nucleotide mutation rates. In parallel with wild-type E. coli, populations were cultured in tubes containing Luria-Bertani broth, a complex medium known to promote the evolution of subpopulation structure. After 900 days of evolution, in three transfer schemes with different population-size bottlenecks, hypermutators always exhibited similar levels of improved fitness as controls. Fluctuation tests revealed that the mutation rates of hypermutator lines converged evolutionarily on those of wild-type populations, which may have contributed to the absence of fitness differences. Further genome-sequence analysis revealed that, although hypermutator populations have higher rates of genomic evolution, this largely reflects strong genetic linkage. Despite these linkage effects, the evolved population exhibits parallelism in fixed mutations, including those potentially related to biofilm formation, transcription regulation, and mutation-rate evolution. Together, these results are generally inconsistent with a hypothesized positive relationship between the mutation rate and the adaptive speed of evolution, and provide insight into how clonal adaptation occurs in novel environments.
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Affiliation(s)
- Wei-Chin Ho
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Megan G Behringer
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Samuel F Miller
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Jadon Gonzales
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Amber Nguyen
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Meriem Allahwerdy
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Gwyneth F Boyer
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Michael Lynch
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
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Epigenetic modifications affect the rate of spontaneous mutations in a pathogenic fungus. Nat Commun 2021; 12:5869. [PMID: 34620872 PMCID: PMC8497519 DOI: 10.1038/s41467-021-26108-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/17/2021] [Indexed: 12/17/2022] Open
Abstract
Mutations are the source of genetic variation and the substrate for evolution. Genome-wide mutation rates appear to be affected by selection and are probably adaptive. Mutation rates are also known to vary along genomes, possibly in response to epigenetic modifications, but causality is only assumed. In this study we determine the direct impact of epigenetic modifications and temperature stress on mitotic mutation rates in a fungal pathogen using a mutation accumulation approach. Deletion mutants lacking epigenetic modifications confirm that histone mark H3K27me3 increases whereas H3K9me3 decreases the mutation rate. Furthermore, cytosine methylation in transposable elements (TE) increases the mutation rate 15-fold resulting in significantly less TE mobilization. Also accessory chromosomes have significantly higher mutation rates. Finally, we find that temperature stress substantially elevates the mutation rate. Taken together, we find that epigenetic modifications and environmental conditions modify the rate and the location of spontaneous mutations in the genome and alter its evolutionary trajectory.
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Antibiotic-Resistant Genes and Bacteria as Evolving Contaminants of Emerging Concerns (e-CEC): Is It Time to Include Evolution in Risk Assessment? Antibiotics (Basel) 2021; 10:antibiotics10091066. [PMID: 34572648 PMCID: PMC8469798 DOI: 10.3390/antibiotics10091066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/27/2021] [Accepted: 08/31/2021] [Indexed: 11/17/2022] Open
Abstract
The pressing issue of the abundance of antibiotic resistance genes and resistant bacteria in the environment (ARGs and ARB, respectively) requires procedures for assessing the risk to health. The chemo-centric environmental risk assessment models identify hazard(s) in a dose–response manner, obtaining exposure, toxicity, risk, impact and policy. However, this risk assessment approach based on ARGs/ARB evaluation from a quantitative viewpoint shows high unpredictability because ARGs/ARB cannot be considered as standard hazardous molecules: ARB duplicate and ARGs evolve within a biological host. ARGs/ARB are currently listed as Contaminants of Emerging Concern (CEC). In light of such characteristics, we propose to define ARGs/ARB within a new category of evolving CEC (or e-CEC). ARGs/ARB, like any other evolving determinants (e.g., viruses, bacteria, genes), escape environmental controls. When they do so, just one molecule left remaining at a control point can form the origin of a new dangerous and selection-responsive population. As a consequence, perhaps it is time to acknowledge this trait and to include evolutionary concepts within modern risk assessment of e-CEC. In this perspective we analyze the evolutionary responses most likely to influence risk assessment, and we speculate on the means by which current methods could measure evolution. Further work is required to implement and exploit such experimental procedures in future risk assessment protocols.
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Castro RAD, Borrell S, Gagneux S. The within-host evolution of antimicrobial resistance in Mycobacterium tuberculosis. FEMS Microbiol Rev 2021; 45:fuaa071. [PMID: 33320947 PMCID: PMC8371278 DOI: 10.1093/femsre/fuaa071] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/11/2020] [Indexed: 12/12/2022] Open
Abstract
Tuberculosis (TB) has been responsible for the greatest number of human deaths due to an infectious disease in general, and due to antimicrobial resistance (AMR) in particular. The etiological agents of human TB are a closely-related group of human-adapted bacteria that belong to the Mycobacterium tuberculosis complex (MTBC). Understanding how MTBC populations evolve within-host may allow for improved TB treatment and control strategies. In this review, we highlight recent works that have shed light on how AMR evolves in MTBC populations within individual patients. We discuss the role of heteroresistance in AMR evolution, and review the bacterial, patient and environmental factors that likely modulate the magnitude of heteroresistance within-host. We further highlight recent works on the dynamics of MTBC genetic diversity within-host, and discuss how spatial substructures in patients' lungs, spatiotemporal heterogeneity in antimicrobial concentrations and phenotypic drug tolerance likely modulates the dynamics of MTBC genetic diversity in patients during treatment. We note the general characteristics that are shared between how the MTBC and other bacterial pathogens evolve in humans, and highlight the characteristics unique to the MTBC.
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Affiliation(s)
- Rhastin A D Castro
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Basel, Switzerland
| | - Sonia Borrell
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Basel, Switzerland
| | - Sebastien Gagneux
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Basel, Switzerland
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40
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Maddamsetti R, Grant NA. Divergent Evolution of Mutation Rates and Biases in the Long-Term Evolution Experiment with Escherichia coli. Genome Biol Evol 2021; 12:1591-1603. [PMID: 32853353 PMCID: PMC7523724 DOI: 10.1093/gbe/evaa178] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2020] [Indexed: 12/20/2022] Open
Abstract
All organisms encode enzymes that replicate, maintain, pack, recombine, and repair their genetic material. For this reason, mutation rates and biases also evolve by mutation, variation, and natural selection. By examining metagenomic time series of the Lenski long-term evolution experiment (LTEE) with Escherichia coli (Good BH, McDonald MJ, Barrick JE, Lenski RE, Desai MM. 2017. The dynamics of molecular evolution over 60,000 generations. Nature 551(7678):45–50.), we find that local mutation rate variation has evolved during the LTEE. Each LTEE population has evolved idiosyncratic differences in their rates of point mutations, indels, and mobile element insertions, due to the fixation of various hypermutator and antimutator alleles. One LTEE population, called Ara+3, shows a strong, symmetric wave pattern in its density of point mutations, radiating from the origin of replication. This pattern is largely missing from the other LTEE populations, most of which evolved missense, indel, or structural mutations in topA, fis, and dusB—loci that all affect DNA topology. The distribution of mutations in those genes over time suggests epistasis and historical contingency in the evolution of DNA topology, which may have in turn affected local mutation rates. Overall, the replicate populations of the LTEE have largely diverged in their mutation rates and biases, even though they have adapted to identical abiotic conditions.
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Affiliation(s)
| | - Nkrumah A Grant
- BEACON Center for the Study of Evolution in Action, Michigan State University.,Department of Microbiology and Molecular Genetics, Michigan State University.,Program in Ecology, Evolutionary Biology and Behavior, Michigan State University
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41
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Raina A, Sahu PK, Laskar RA, Rajora N, Sao R, Khan S, Ganai RA. Mechanisms of Genome Maintenance in Plants: Playing It Safe With Breaks and Bumps. Front Genet 2021; 12:675686. [PMID: 34239541 PMCID: PMC8258418 DOI: 10.3389/fgene.2021.675686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/04/2021] [Indexed: 01/14/2023] Open
Abstract
Maintenance of genomic integrity is critical for the perpetuation of all forms of life including humans. Living organisms are constantly exposed to stress from internal metabolic processes and external environmental sources causing damage to the DNA, thereby promoting genomic instability. To counter the deleterious effects of genomic instability, organisms have evolved general and specific DNA damage repair (DDR) pathways that act either independently or mutually to repair the DNA damage. The mechanisms by which various DNA repair pathways are activated have been fairly investigated in model organisms including bacteria, fungi, and mammals; however, very little is known regarding how plants sense and repair DNA damage. Plants being sessile are innately exposed to a wide range of DNA-damaging agents both from biotic and abiotic sources such as ultraviolet rays or metabolic by-products. To escape their harmful effects, plants also harbor highly conserved DDR pathways that share several components with the DDR machinery of other organisms. Maintenance of genomic integrity is key for plant survival due to lack of reserve germline as the derivation of the new plant occurs from the meristem. Untowardly, the accumulation of mutations in the meristem will result in a wide range of genetic abnormalities in new plants affecting plant growth development and crop yield. In this review, we will discuss various DNA repair pathways in plants and describe how the deficiency of each repair pathway affects plant growth and development.
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Affiliation(s)
- Aamir Raina
- Mutation Breeding Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, India
- Botany Section, Women’s College, Aligarh Muslim University, Aligarh, India
| | - Parmeshwar K. Sahu
- Department of Genetics and Plant Breeding, Indira Gandhi Agriculture University, Raipur, India
| | | | - Nitika Rajora
- National Agri-Food Biotechnology Institute, Mohali, India
| | - Richa Sao
- Department of Genetics and Plant Breeding, Indira Gandhi Agriculture University, Raipur, India
| | - Samiullah Khan
- Mutation Breeding Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, India
| | - Rais A. Ganai
- Watson-Crick Centre for Molecular Medicine, Islamic University of Science and Technology, Awantipora, India
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42
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Grant NA, Maddamsetti R, Lenski RE. Maintenance of Metabolic Plasticity despite Relaxed Selection in a Long-Term Evolution Experiment with Escherichia coli. Am Nat 2021; 198:93-112. [PMID: 34143718 DOI: 10.1086/714530] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractTraits that are unused in a given environment are subject to processes that tend to erode them, leading to reduced fitness in other environments. Although this general tendency is clear, we know much less about why some traits are lost while others are retained and about the roles of mutation and selection in generating different responses. We addressed these issues by examining populations of a facultative anaerobe, Escherichia coli, that have evolved for >30 years in the presence of oxygen, with relaxed selection for anaerobic growth and the associated metabolic plasticity. We asked whether evolution led to the loss, improvement, or maintenance of anaerobic growth, and we analyzed gene expression and mutational data sets to understand the outcomes. We identified genomic signatures of both positive and purifying selection on aerobic-specific genes, while anaerobic-specific genes showed clear evidence of relaxed selection. We also found parallel evolution at two interacting loci that regulate anaerobic growth. We competed the ancestor and evolved clones from each population in an anoxic environment, and we found that anaerobic fitness had not decayed, despite relaxed selection. In summary, relaxed selection does not necessarily reduce an organism's fitness in other environments. Instead, the genetic architecture of the traits under relaxed selection and their correlations with traits under positive and purifying selection may sometimes determine evolutionary outcomes.
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44
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White PS, Arslan D, Kim D, Penley M, Morran L. Host genetic drift and adaptation in the evolution and maintenance of parasite resistance. J Evol Biol 2021; 34:845-851. [PMID: 33783870 DOI: 10.1111/jeb.13785] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 03/22/2021] [Indexed: 01/17/2023]
Abstract
Host-parasite interactions may often be subject to opposing evolutionary forces, which likely influence the evolutionary trajectories of both partners. Natural selection and genetic drift are two major evolutionary forces that act in host and parasite populations. Further, population size is a significant determinant of the relative strengths of these forces. In small populations, drift may undermine the persistence of beneficial alleles, potentially impeding host adaptation to parasites. Here, we investigate two questions: (a) can selection pressure for increased resistance in small, susceptible host populations overcome the effects of drift and (b) can resistance be maintained in small host populations? To answer these questions, we experimentally evolved the host Caenorhabditis elegans against its bacterial parasite, Serratia marcescens, for 13 host generations. We found that strong selection favouring increased host resistance was insufficient to counteract drift in small populations, resulting in persistently high host mortality. Additionally, in small populations of resistant hosts, we found that selection for the maintenance of resistance is not always sufficient to curb the loss of resistance. We compared these results with selection in large host populations. We found that initially resistant, large host populations were able to maintain high levels of resistance. Likewise, initially susceptible, large host populations were able to gain resistance to the parasite. These results show that strong selection pressure for survival is not always sufficient to counteract drift. In consideration of C. elegans natural population dynamics, we suggest that drift may often impede selection in nature.
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Affiliation(s)
- P Signe White
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA, USA.,Population Biology, Ecology, and Evolution Graduate Program, Laney Graduate School, Emory University, Atlanta, GA, USA
| | - Danial Arslan
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA, USA
| | - David Kim
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA, USA
| | - McKenna Penley
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA, USA
| | - Levi Morran
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA, USA
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45
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Grekov I, Thöming JG, Kordes A, Häussler S. Evolution of Pseudomonas aeruginosa toward higher fitness under standard laboratory conditions. THE ISME JOURNAL 2021; 15:1165-1177. [PMID: 33273720 PMCID: PMC8115180 DOI: 10.1038/s41396-020-00841-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/04/2020] [Accepted: 11/11/2020] [Indexed: 01/29/2023]
Abstract
Identifying genetic factors that contribute to the evolution of adaptive phenotypes in pathogenic bacteria is key to understanding the establishment of infectious diseases. In this study, we performed mutation accumulation experiments to record the frequency of mutations and their effect on fitness in hypermutator strains of the environmental bacterium Pseudomonas aeruginosa in comparison to the host-niche-adapted Salmonella enterica. We demonstrate that P. aeruginosa, but not S. enterica, hypermutators evolve toward higher fitness under planktonic conditions. Adaptation to increased growth performance was accompanied by a reversible perturbing of the local genetic context of membrane and cell wall biosynthesis genes. Furthermore, we observed a fine-tuning of complex regulatory circuits involving multiple di-guanylate modulating enzymes that regulate the transition between fast growing planktonic and sessile biofilm-associated lifestyles. The redundancy and local specificity of the di-guanylate signaling pathways seem to allow a convergent shift toward increased growth performance across niche-adapted clonal P. aeruginosa lineages, which is accompanied by a pronounced heterogeneity of their motility, virulence, and biofilm phenotypes.
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Affiliation(s)
- Igor Grekov
- grid.7490.a0000 0001 2238 295XDepartment of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany ,grid.475435.4Department of Clinical Microbiology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
| | - Janne Gesine Thöming
- grid.452370.70000 0004 0408 1805Institute of Molecular Bacteriology, TWINCORE Centre for Experimental and Clinical Infection Research, Hannover, Germany ,grid.475435.4Department of Clinical Microbiology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
| | - Adrian Kordes
- grid.452370.70000 0004 0408 1805Institute of Molecular Bacteriology, TWINCORE Centre for Experimental and Clinical Infection Research, Hannover, Germany ,grid.10423.340000 0000 9529 9877Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Susanne Häussler
- grid.7490.a0000 0001 2238 295XDepartment of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany ,grid.452370.70000 0004 0408 1805Institute of Molecular Bacteriology, TWINCORE Centre for Experimental and Clinical Infection Research, Hannover, Germany ,grid.475435.4Department of Clinical Microbiology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark ,grid.10423.340000 0000 9529 9877Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
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46
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Katz S, Avrani S, Yavneh M, Hilau S, Gross J, Hershberg R. Dynamics of Adaptation During Three Years of Evolution Under Long-Term Stationary Phase. Mol Biol Evol 2021; 38:2778-2790. [PMID: 33734381 PMCID: PMC8233507 DOI: 10.1093/molbev/msab067] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Many bacterial species that cannot sporulate, such as the model bacterium Escherichia coli, can nevertheless survive for years, following exhaustion of external resources, in a state termed long-term stationary phase (LTSP). Here we describe the dynamics of E. coli adaptation during the first three years spent under LTSP. We show that during this time, E. coli continuously adapts genetically through the accumulation of mutations. For nonmutator clones, the majority of mutations accumulated appear to be adaptive under LTSP, reflected in an extremely convergent pattern of mutation accumulation. Despite the rapid and convergent manner in which populations adapt under LTSP, they continue to harbor extensive genetic variation. The dynamics of evolution of mutation rates under LTSP are particularly interesting. The emergence of mutators affects overall mutation accumulation rates as well as the mutational spectra and the ultimate spectrum of adaptive alleles acquired under LTSP. With time, mutators can evolve even higher mutation rates through the acquisition of additional mutation rate-enhancing mutations. Different mutator and nonmutator clones within a single population and time point can display extreme variation in their mutation rates, resulting in differences in both the dynamics of adaptation and their associated deleterious burdens. Despite these differences, clones that vary greatly in their mutation rates tend to coexist within their populations for many years, under LTSP.
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Affiliation(s)
- Sophia Katz
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Sarit Avrani
- Department of Evolutionary and Environmental Biology and the Institute of Evolution, University of Haifa, Haifa, Israel
| | - Meitar Yavneh
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Sabrin Hilau
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Jonathan Gross
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Ruth Hershberg
- Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
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47
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Park HJ, Gokhale CS, Bertels F. How sequence populations persist inside bacterial genomes. Genetics 2021; 217:6151697. [PMID: 33724360 PMCID: PMC8049555 DOI: 10.1093/genetics/iyab027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/04/2021] [Indexed: 01/04/2023] Open
Abstract
Compared to their eukaryotic counterparts, bacterial genomes are small and contain extremely tightly packed genes. Repetitive sequences are rare but not completely absent. One of the most common repeat families is REPINs. REPINs can replicate in the host genome and form populations that persist for millions of years. Here, we model the interactions of these intragenomic sequence populations with the bacterial host. We first confirm well-established results, in the presence and absence of horizontal gene transfer (hgt) sequence populations either expand until they drive the host to extinction or the sequence population gets purged from the genome. We then show that a sequence population can be stably maintained, when each individual sequence provides a benefit that decreases with increasing sequence population size. Maintaining a sequence population of stable size also requires the replication of the sequence population to be costly to the host, otherwise the sequence population size will increase indefinitely. Surprisingly, in regimes with high hgt rates, the benefit conferred by the sequence population does not have to exceed the damage it causes to its host. Our analyses provide a plausible scenario for the persistence of sequence populations in bacterial genomes. We also hypothesize a limited biologically relevant parameter range for the provided benefit, which can be tested in future experiments.
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Affiliation(s)
- Hye Jin Park
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, 24306, Germany.,Asia Pacific Center for Theoretical Physics, Pohang, 37673, Korea.,Department of Physics, POSTECH, Pohang, 37673, Korea
| | - Chaitanya S Gokhale
- Research Group for Theoretical Models of Eco-evolutionary Dynamics, Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, 24306, Germany
| | - Frederic Bertels
- Research Group for Microbial Molecular Evolution, Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, 24306, Germany
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48
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Nourabadi N, Nishiguchi MK. pH Adaptation Drives Diverse Phenotypes in a Beneficial Bacterium-Host Mutualism. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.611411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abiotic variation can influence the evolution of specific phenotypes that contribute to the diversity of bacterial strains observed in the natural environment. Environmentally transmitted symbiotic bacteria are particularly vulnerable to abiotic fluctuations, given that they must accommodate the transition between the free-living state and the host's internal environment. This type of life history strategy can strongly influence the success of a symbiont, and whether adapting to changes outside the host will allow a greater capacity to survive in symbiosis with the host partner. One example of how environmental breadth is advantageous to the symbiosis is the beneficial association between Vibrio fischeri and sepiolid squids (Cephalopoda: Sepiolidae). Since Vibrio bacteria are environmentally transmitted, they are subject to a wide variety of abiotic variables prior to infecting juvenile squids and must be poised to survive in the host light organ. In order to better understand how a changing abiotic factor (e.g., pH) influences the diversification of symbionts and their eventual symbiotic competence, we used an experimental evolution approach to ascertain how pH adaptation affects symbiont fitness. Results show that low pH adapted Vibrio strains have more efficient colonization rates compared to their ancestral strains. In addition, growth rates had significant differences compared to ancestral strains (pH 6.5–6.8, and 7.2). Bioluminescence production (a marker for symbiont competence) of pH evolved strains also improved at pH 6.5–7.2. Results imply that the evolution and diversification of Vibrio strains adapted to low pH outside the squid improves fitness inside the squid by allowing a higher success rate for host colonization and symbiotic competence.
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49
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Insertion-sequence-mediated mutations both promote and constrain evolvability during a long-term experiment with bacteria. Nat Commun 2021; 12:980. [PMID: 33579917 PMCID: PMC7881107 DOI: 10.1038/s41467-021-21210-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 01/08/2021] [Indexed: 01/26/2023] Open
Abstract
Insertion sequences (IS) are ubiquitous bacterial mobile genetic elements, and the mutations they cause can be deleterious, neutral, or beneficial. The long-term dynamics of IS elements and their effects on bacteria are poorly understood, including whether they are primarily genomic parasites or important drivers of adaptation by natural selection. Here, we investigate the dynamics of IS elements and their contribution to genomic evolution and fitness during a long-term experiment with Escherichia coli. IS elements account for ~35% of the mutations that reached high frequency through 50,000 generations in those populations that retained the ancestral point-mutation rate. In mutator populations, IS-mediated mutations are only half as frequent in absolute numbers. In one population, an exceptionally high ~8-fold increase in IS150 copy number is associated with the beneficial effects of early insertion mutations; however, this expansion later slowed down owing to reduced IS150 activity. This population also achieves the lowest fitness, suggesting that some avenues for further adaptation are precluded by the IS150-mediated mutations. More generally, across all populations, we find that higher IS activity becomes detrimental to adaptation over evolutionary time. Therefore, IS-mediated mutations can both promote and constrain evolvability. Insertion sequences (IS) are common mobile genetic elements in bacteria, but their effects on bacterial evolution are not well understood. Here, Consuegra and colleagues investigate the dynamics and fitness consequences of IS elements in E. coli over 50,000 generations.
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50
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Johnson MS, Gopalakrishnan S, Goyal J, Dillingham ME, Bakerlee CW, Humphrey PT, Jagdish T, Jerison ER, Kosheleva K, Lawrence KR, Min J, Moulana A, Phillips AM, Piper JC, Purkanti R, Rego-Costa A, McDonald MJ, Nguyen Ba AN, Desai MM. Phenotypic and molecular evolution across 10,000 generations in laboratory budding yeast populations. eLife 2021; 10:e63910. [PMID: 33464204 PMCID: PMC7815316 DOI: 10.7554/elife.63910] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 12/12/2020] [Indexed: 01/25/2023] Open
Abstract
Laboratory experimental evolution provides a window into the details of the evolutionary process. To investigate the consequences of long-term adaptation, we evolved 205 Saccharomyces cerevisiae populations (124 haploid and 81 diploid) for ~10,000,000 generations in three environments. We measured the dynamics of fitness changes over time, finding repeatable patterns of declining adaptability. Sequencing revealed that this phenotypic adaptation is coupled with a steady accumulation of mutations, widespread genetic parallelism, and historical contingency. In contrast to long-term evolution in E. coli, we do not observe long-term coexistence or populations with highly elevated mutation rates. We find that evolution in diploid populations involves both fixation of heterozygous mutations and frequent loss-of-heterozygosity events. Together, these results help distinguish aspects of evolutionary dynamics that are likely to be general features of adaptation across many systems from those that are specific to individual organisms and environmental conditions.
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Affiliation(s)
- Milo S Johnson
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
| | - Shreyas Gopalakrishnan
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
| | - Juhee Goyal
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- John A Paulson School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
| | - Megan E Dillingham
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- Graduate Program in Systems, Synthetic, and Quantitative Biology, Harvard UniversityCambridgeUnited States
| | - Christopher W Bakerlee
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
| | - Parris T Humphrey
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
| | - Tanush Jagdish
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Graduate Program in Systems, Synthetic, and Quantitative Biology, Harvard UniversityCambridgeUnited States
| | - Elizabeth R Jerison
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Department of Physics, Harvard UniversityCambridgeUnited States
- Department of Applied Physics, Stanford UniversityStanfordUnited States
| | - Katya Kosheleva
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Department of Physics, Harvard UniversityCambridgeUnited States
| | - Katherine R Lawrence
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Department of Physics, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Jiseon Min
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Department of Molecular and Cellular Biology, Harvard UniversityCambridgeUnited States
- John A Paulson School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
| | - Alief Moulana
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
| | - Angela M Phillips
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
| | - Julia C Piper
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- AeroLabs, Aeronaut Brewing CoSomervilleUnited States
| | - Ramya Purkanti
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- The Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
| | - Artur Rego-Costa
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
| | - Michael J McDonald
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- School of Biological Sciences, Monash UniversityVictoria, MonashAustralia
| | - Alex N Nguyen Ba
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Department of Physics, Harvard UniversityCambridgeUnited States
- Department of Cell and Systems Biology, University of TorontoTorontoCanada
| | - Michael M Desai
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridgeUnited States
- Quantitative Biology Initiative, Harvard UniversityCambridgeUnited States
- NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard UniversityCambridgeUnited States
- Department of Physics, Harvard UniversityCambridgeUnited States
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