1
|
Mridha S, Wechsler T, Kümmerli R. Space and genealogy determine inter-individual differences in siderophore gene expression in bacterial colonies. Cell Rep 2024; 43:114106. [PMID: 38625795 DOI: 10.1016/j.celrep.2024.114106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 02/09/2024] [Accepted: 03/28/2024] [Indexed: 04/18/2024] Open
Abstract
Heterogeneity in gene expression is common among clonal cells in bacteria, although the sources and functions of variation often remain unknown. Here, we track cellular heterogeneity in the bacterium Pseudomonas aeruginosa during colony growth by focusing on siderophore gene expression (pyoverdine versus pyochelin) important for iron nutrition. We find that the spatial position of cells within colonies and non-genetic yet heritable differences between cell lineages are significant sources of cellular heterogeneity, while cell pole age and lifespan have no effect. Regarding functions, our results indicate that cells adjust their siderophore investment strategies along a gradient from the colony center to its edge. Moreover, cell lineages with below-average siderophore investment benefit from lineages with above-average siderophore investment, presumably due to siderophore sharing. Our study highlights that single-cell experiments with dual gene expression reporters can identify sources of gene expression variation of interlinked traits and offer explanations for adaptive benefits in bacteria.
Collapse
Affiliation(s)
- Subham Mridha
- Department of Quantitative Biomedicine, University of Zurich, 8057 Zurich, Switzerland; Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Tobias Wechsler
- Department of Quantitative Biomedicine, University of Zurich, 8057 Zurich, Switzerland
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, 8057 Zurich, Switzerland.
| |
Collapse
|
2
|
Tang S, Liu Y, Zhu J, Cheng X, Liu L, Hammerschmidt K, Zhou J, Cai Z. Bet hedging in a unicellular microalga. Nat Commun 2024; 15:2063. [PMID: 38453919 PMCID: PMC10920660 DOI: 10.1038/s41467-024-46297-6] [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: 09/15/2023] [Accepted: 02/22/2024] [Indexed: 03/09/2024] Open
Abstract
Understanding how organisms have adapted to persist in unpredictable environments is a fundamental goal in biology. Bet hedging, an evolutionary adaptation observed from microbes to humans, facilitates reproduction and population persistence in randomly fluctuating environments. Despite its prevalence, empirical evidence in microalgae, crucial primary producers and carbon sinks, is lacking. Here, we report a bet-hedging strategy in the unicellular microalga Haematococcus pluvialis. We show that isogenic populations reversibly diversify into heterophenotypic mobile and non-mobile cells independently of environmental conditions, likely driven by stochastic gene expression. Mobile cells grow faster but are stress-sensitive, while non-mobile cells prioritise stress resistance over growth. This is due to shifts from growth-promoting activities (cell division, photosynthesis) to resilience-promoting processes (thickened cell wall, cell enlargement, aggregation, accumulation of antioxidant and energy-storing compounds). Our results provide empirical evidence for bet hedging in a microalga, indicating the potential for adaptation to current and future environmental conditions and consequently conservation of ecosystem functions.
Collapse
Affiliation(s)
- Si Tang
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China
| | - Yaqing Liu
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China
| | - Jianming Zhu
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China
| | - Xueyu Cheng
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China
| | - Lu Liu
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China
| | | | - Jin Zhou
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China.
| | - Zhonghua Cai
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China.
- Technology Innovation Center for Marine Ecology and Human Factor Assessment of Natural Resources Ministry, Tsinghua Shenzhen International Graduate School, Shenzhen, 518055, Guangdong Province, PR China.
| |
Collapse
|
3
|
Liu M, West SA, Cooper GA. Relatedness and the evolution of mechanisms to divide labor in microorganisms. Ecol Evol 2021; 11:14475-14489. [PMID: 34765120 PMCID: PMC8571581 DOI: 10.1002/ece3.8067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 08/16/2021] [Indexed: 01/08/2023] Open
Abstract
Division of labor occurs when cooperating individuals specialize to perform different tasks. In bacteria and other microorganisms, some species divide labor by random specialization, where an individual's role is determined by random fluctuations in biochemical reactions within the cell. Other species divide labor by coordinating across individuals to determine which cells will perform which task, using mechanisms such as between-cell signaling. However, previous theory, examining the evolution of mechanisms to divide labor between reproductives and sterile helpers, has only considered clonal populations, where there is no potential for conflict between individuals. We used a mixture of analytical and simulation models to examine nonclonal populations and found that: (a) intermediate levels of coordination can be favored, between the extreme of no coordination (random) and full coordination; (b) as relatedness decreases, coordinated division of labor is less likely to be favored. Our results can help explain why coordinated division of labor is relatively rare in bacteria, where groups may frequently be nonclonal.
Collapse
Affiliation(s)
- Ming Liu
- Department of ZoologyUniversity of OxfordOxfordUK
| | | | | |
Collapse
|
4
|
Steiner UK. Senescence in Bacteria and Its Underlying Mechanisms. Front Cell Dev Biol 2021; 9:668915. [PMID: 34222238 PMCID: PMC8249858 DOI: 10.3389/fcell.2021.668915] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/14/2021] [Indexed: 12/11/2022] Open
Abstract
Bacteria have been thought to flee senescence by dividing into two identical daughter cells, but this notion of immortality has changed over the last two decades. Asymmetry between the resulting daughter cells after binary fission is revealed in physiological function, cell growth, and survival probabilities and is expected from theoretical understanding. Since the discovery of senescence in morphologically identical but physiologically asymmetric dividing bacteria, the mechanisms of bacteria aging have been explored across levels of biological organization. Quantitative investigations are heavily biased toward Escherichia coli and on the role of inclusion bodies—clusters of misfolded proteins. Despite intensive efforts to date, it is not evident if and how inclusion bodies, a phenotype linked to the loss of proteostasis and one of the consequences of a chain of reactions triggered by reactive oxygen species, contribute to senescence in bacteria. Recent findings in bacteria question that inclusion bodies are only deleterious, illustrated by fitness advantages of cells holding inclusion bodies under varying environmental conditions. The contributions of other hallmarks of aging, identified for metazoans, remain elusive. For instance, genomic instability appears to be age independent, epigenetic alterations might be little age specific, and other hallmarks do not play a major role in bacteria systems. What is surprising is that, on the one hand, classical senescence patterns, such as an early exponential increase in mortality followed by late age mortality plateaus, are found, but, on the other hand, identifying mechanisms that link to these patterns is challenging. Senescence patterns are sensitive to environmental conditions and to genetic background, even within species, which suggests diverse evolutionary selective forces on senescence that go beyond generalized expectations of classical evolutionary theories of aging. Given the molecular tool kits available in bacteria, the high control of experimental conditions, the high-throughput data collection using microfluidic systems, and the ease of life cell imaging of fluorescently marked transcription, translation, and proteomic dynamics, in combination with the simple demographics of growth, division, and mortality of bacteria, make the challenges surprising. The diversity of mechanisms and patterns revealed and their environmental dependencies not only present challenges but also open exciting opportunities for the discovery and deeper understanding of aging and its mechanisms, maybe beyond bacteria and aging.
Collapse
Affiliation(s)
- Ulrich Karl Steiner
- Evolutionary Demography Group, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| |
Collapse
|
5
|
Abstract
Damage is an inevitable consequence of life. For unicellular organisms, this leads to a trade-off between allocating resources into damage repair or into growth coupled with segregation of damage upon cell division, i.e., aging and senescence. Few studies considered repair as an alternative to senescence. None considered biofilms, where the majority of unicellular organisms live, although fitness advantages in well-mixed systems often turn into disadvantages in spatially structured systems such as biofilms. We compared the fitness consequences of aging versus an adaptive repair mechanism based on sensing damage, using an individual-based model of a generic unicellular organism growing in biofilms. We found that senescence is not beneficial provided that growth is limited by substrate availability. Instead, it is useful as a stress response to deal with damage that failed to be repaired when (i) extrinsic mortality was high; (ii) a degree of multicellularity was present; and (iii) damage segregation was effective. The extent of senescence due to damage accumulation—or aging—is evidently evolvable as it differs hugely between species and is not universal, suggesting that its fitness advantages depend on life history and environment. In contrast, repair of damage is present in all organisms studied. Despite the fundamental trade-off between investing resources into repair or into growth, repair and segregation of damage have not always been considered alternatives. For unicellular organisms, unrepaired damage could be divided asymmetrically between daughter cells, leading to senescence of one and rejuvenation of the other. Repair of “unicells” has been predicted to be advantageous in well-mixed environments such as chemostats. Most microorganisms, however, live in spatially structured systems, such as biofilms, with gradients of environmental conditions and cellular physiology as well as a clonal population structure. To investigate whether this clonal structure might favor senescence by damage segregation (a division-of-labor strategy akin to the germline-soma division in multicellular organisms), we used an individual-based computational model and developed an adaptive repair strategy where cells respond to their current intracellular damage levels by investing into repair machinery accordingly. Our simulations showed that the new adaptive repair strategy was advantageous provided that growth was limited by substrate availability, which is typical for biofilms. Thus, biofilms do not favor a germline-soma-like division of labor between daughter cells in terms of damage segregation. We suggest that damage segregation is beneficial only when extrinsic mortality is high, a degree of multicellularity is present, and an active mechanism makes segregation effective. IMPORTANCE Damage is an inevitable consequence of life. For unicellular organisms, this leads to a trade-off between allocating resources into damage repair or into growth coupled with segregation of damage upon cell division, i.e., aging and senescence. Few studies considered repair as an alternative to senescence. None considered biofilms, where the majority of unicellular organisms live, although fitness advantages in well-mixed systems often turn into disadvantages in spatially structured systems such as biofilms. We compared the fitness consequences of aging versus an adaptive repair mechanism based on sensing damage, using an individual-based model of a generic unicellular organism growing in biofilms. We found that senescence is not beneficial provided that growth is limited by substrate availability. Instead, it is useful as a stress response to deal with damage that failed to be repaired when (i) extrinsic mortality was high; (ii) a degree of multicellularity was present; and (iii) damage segregation was effective.
Collapse
|
6
|
Zhu C, Sun G, Wang X, Guo J, Li E, Yang Y, Xu M. Variable cell division time and asymmetric division site lead to filament-to-rod cell cycle of Lysinibacillus varians. FEMS Microbiol Lett 2020; 367:5810660. [PMID: 32196075 DOI: 10.1093/femsle/fnaa054] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/19/2020] [Indexed: 12/27/2022] Open
Abstract
All well-established cell size homeostasis paradigms are based on the researches of rod bacteria like B. subtilis and E. coli, suggesting a constant division time (timer model), division size (sizer model) or added size (adder model) before division. However, Lysinibacillus varians, a new species with regular filament-to-rod cell cycle, is inconsistent with existing models. In this study, the cell size parameters of the type strain GY32, were investigated by combing multiple microscopy techniques and single-cell approach. Our results showed that the filaments of strain GY32 were unicellular cells with multiple nucleoids. The division time of GY32 cells was variable and their daughter cells produced by asymmetric binary fission had different birth sizes, which were proportional to their elongation rates, resulting in high heterogeneity among the sister cells. Furthermore, the added size from birth to division was significantly shorter than birth size (p < 0.01) and decreased along generations. The results above revealed that the asymmetric division site and varied cell size parameters resulted in filament-to-rod cell cycle of L. varians and cell size homeostasis could be a more complex and dynamic process than previously assumed. These findings would be helpful in elucidating the open questions in cell division and cell size heterogeneity.
Collapse
Affiliation(s)
- Chunjie Zhu
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,Guangdong Open Laboratory of Applied Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China
| | - Guoping Sun
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,Guangdong Open Laboratory of Applied Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China
| | - Xiaoming Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Panyu District, 510006, Guangzhou, China
| | - Jun Guo
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,Guangdong Open Laboratory of Applied Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China
| | - Enze Li
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,Guangdong Open Laboratory of Applied Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China
| | - Yonggang Yang
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,Guangdong Open Laboratory of Applied Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China
| | - Meiying Xu
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China.,Guangdong Open Laboratory of Applied Microbiology, Central Xianlie 100, Yuexiu, 510070, Guangzhou, China
| |
Collapse
|
7
|
Lee JA, Riazi S, Nemati S, Bazurto JV, Vasdekis AE, Ridenhour BJ, Remien CH, Marx CJ. Microbial phenotypic heterogeneity in response to a metabolic toxin: Continuous, dynamically shifting distribution of formaldehyde tolerance in Methylobacterium extorquens populations. PLoS Genet 2019; 15:e1008458. [PMID: 31710603 PMCID: PMC6858071 DOI: 10.1371/journal.pgen.1008458] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/15/2019] [Accepted: 10/04/2019] [Indexed: 12/31/2022] Open
Abstract
While microbiologists often make the simplifying assumption that genotype determines phenotype in a given environment, it is becoming increasingly apparent that phenotypic heterogeneity (in which one genotype generates multiple phenotypes simultaneously even in a uniform environment) is common in many microbial populations. The importance of phenotypic heterogeneity has been demonstrated in a number of model systems involving binary phenotypic states (e.g., growth/non-growth); however, less is known about systems involving phenotype distributions that are continuous across an environmental gradient, and how those distributions change when the environment changes. Here, we describe a novel instance of phenotypic diversity in tolerance to a metabolic toxin within wild-type populations of Methylobacterium extorquens, a ubiquitous phyllosphere methylotroph capable of growing on the methanol periodically released from plant leaves. The first intermediate in methanol metabolism is formaldehyde, a potent cellular toxin that is lethal in high concentrations. We have found that at moderate concentrations, formaldehyde tolerance in M. extorquens is heterogeneous, with a cell's minimum tolerance level ranging between 0 mM and 8 mM. Tolerant cells have a distinct gene expression profile from non-tolerant cells. This form of heterogeneity is continuous in terms of threshold (the formaldehyde concentration where growth ceases), yet binary in outcome (at a given formaldehyde concentration, cells either grow normally or die, with no intermediate phenotype), and it is not associated with any detectable genetic mutations. Moreover, tolerance distributions within the population are dynamic, changing over time in response to growth conditions. We characterized this phenomenon using bulk liquid culture experiments, colony growth tracking, flow cytometry, single-cell time-lapse microscopy, transcriptomics, and genome resequencing. Finally, we used mathematical modeling to better understand the processes by which cells change phenotype, and found evidence for both stochastic, bidirectional phenotypic diversification and responsive, directed phenotypic shifts, depending on the growth substrate and the presence of toxin. Scientists tend to appreciate microbes for their simplicity and predictability: a population of genetically identical cells inhabiting a uniform environment is expected to behave in a uniform way. However, counter-examples to this assumption are frequently being discovered, forcing a re-examination of the relationship between genotype and phenotype. In most such examples, bacterial cells are found to split into two discrete populations, for instance growing and non-growing. Here, we report the discovery of a novel example of microbial phenotypic heterogeneity in which cells are distributed along a gradient of phenotypes, ranging from low to high tolerance of a toxic chemical. Furthermore, we demonstrate that the distribution of phenotypes changes in different growth conditions, and we use mathematical modeling to show that cells may change their phenotype either randomly or in a particular direction in response to the environment. Our work expands our understanding of how a bacterial cell's genome, family history, and environment all contribute to its behavior, with implications for the diverse situations in which we care to understand the growth of any single-celled populations.
Collapse
Affiliation(s)
- Jessica A. Lee
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Global Viral, San Francisco, California, United States of America
- * E-mail: (JAL); (CJM)
| | - Siavash Riazi
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Bioinformatics and Computational Biology Graduate Program, University of Idaho, Moscow, Idaho, United States of America
| | - Shahla Nemati
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Department of Physics, University of Idaho, Moscow, Idaho, United States of America
| | - Jannell V. Bazurto
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, Minnesota, United States of America
- Microbial and Plant Genomics Institute, University of Minnesota, Twin Cities, Minnesota, United States of America
| | - Andreas E. Vasdekis
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Department of Physics, University of Idaho, Moscow, Idaho, United States of America
| | - Benjamin J. Ridenhour
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Department of Mathematics, University of Idaho, Moscow, Idaho, United States of America
| | - Christopher H. Remien
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Department of Mathematics, University of Idaho, Moscow, Idaho, United States of America
| | - Christopher J. Marx
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Center for Modeling Complex Interactions, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- * E-mail: (JAL); (CJM)
| |
Collapse
|
8
|
Bettenworth V, Steinfeld B, Duin H, Petersen K, Streit WR, Bischofs I, Becker A. Phenotypic Heterogeneity in Bacterial Quorum Sensing Systems. J Mol Biol 2019; 431:4530-4546. [PMID: 31051177 DOI: 10.1016/j.jmb.2019.04.036] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 04/19/2019] [Accepted: 04/22/2019] [Indexed: 12/11/2022]
Abstract
Quorum sensing is usually thought of as a collective behavior in which all members of a population partake. However, over the last decade, several reports of phenotypic heterogeneity in quorum sensing-related gene expression have been put forward, thus challenging this view. In the respective systems, cells of isogenic populations did not contribute equally to autoinducer production or target gene activation, and in some cases, the fraction of contributing cells was modulated by environmental factors. Here, we look into potential origins of these incidences and into how initial cell-to-cell variations might be amplified to establish distinct phenotypic heterogeneity. We furthermore discuss potential functions heterogeneity in bacterial quorum sensing systems could serve: as a preparation for environmental fluctuations (bet hedging), as a more cost-effective way of producing public goods (division of labor), as a loophole for genotypic cooperators when faced with non-contributing mutants (cheat protection), or simply as a means to fine-tune the output of the population as a whole (output modulation). We illustrate certain aspects of these recent developments with the model organisms Sinorhizobium meliloti, Sinorhizobium fredii and Bacillus subtilis, which possess quorum sensing systems of different complexity, but all show phenotypic heterogeneity therein.
Collapse
Affiliation(s)
- Vera Bettenworth
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, 35043 Marburg, Germany; Faculty of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany.
| | - Benedikt Steinfeld
- BioQuant Center of the University of Heidelberg, 69120 Heidelberg, Germany; Center for Molecular Biology (ZMBH), University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck-Institute for Terrestrial Microbiology, 35043 Marburg, Germany.
| | - Hilke Duin
- Department of Microbiology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany.
| | - Katrin Petersen
- Department of Microbiology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany.
| | - Wolfgang R Streit
- Department of Microbiology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany.
| | - Ilka Bischofs
- BioQuant Center of the University of Heidelberg, 69120 Heidelberg, Germany; Center for Molecular Biology (ZMBH), University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck-Institute for Terrestrial Microbiology, 35043 Marburg, Germany.
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, 35043 Marburg, Germany; Faculty of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany.
| |
Collapse
|
9
|
van Vliet S, Dal Co A, Winkler AR, Spriewald S, Stecher B, Ackermann M. Spatially Correlated Gene Expression in Bacterial Groups: The Role of Lineage History, Spatial Gradients, and Cell-Cell Interactions. Cell Syst 2018; 6:496-507.e6. [PMID: 29655705 DOI: 10.1016/j.cels.2018.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 01/24/2018] [Accepted: 03/14/2018] [Indexed: 10/17/2022]
Abstract
Gene expression levels in clonal bacterial groups have been found to be spatially correlated. These correlations can partly be explained by the shared lineage history of nearby cells, although they could also arise from local cell-cell interactions. Here, we present a quantitative framework that allows us to disentangle the contributions of lineage history, long-range spatial gradients, and local cell-cell interactions to spatial correlations in gene expression. We study pathways involved in toxin production, SOS stress response, and metabolism in Escherichia coli microcolonies and find for all pathways that shared lineage history is the main cause of spatial correlations in gene expression levels. However, long-range spatial gradients and local cell-cell interactions also contributed to spatial correlations in SOS response, amino acid biosynthesis, and overall metabolic activity. Together, our data show that the phenotype of a cell is influenced by its lineage history and population context, raising the question of whether bacteria can arrange their activities in space to perform functions they cannot achieve alone.
Collapse
Affiliation(s)
- Simon van Vliet
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland; Department of Environmental Microbiology, Eawag, 8600 Dübendorf, Switzerland.
| | - Alma Dal Co
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland; Department of Environmental Microbiology, Eawag, 8600 Dübendorf, Switzerland
| | - Annina R Winkler
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland; Department of Environmental Microbiology, Eawag, 8600 Dübendorf, Switzerland
| | | | - Bärbel Stecher
- Max-von-Pettenkofer Institute, LMU Munich, 80336 Munich, Germany; German Center for Infection Research (DZIF), Partner Site LMU Munich, 80336 Munich, Germany
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland; Department of Environmental Microbiology, Eawag, 8600 Dübendorf, Switzerland
| |
Collapse
|
10
|
Florea M. Aging and immortality in unicellular species. Mech Ageing Dev 2017; 167:5-15. [PMID: 28844968 DOI: 10.1016/j.mad.2017.08.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 07/21/2017] [Accepted: 08/13/2017] [Indexed: 12/22/2022]
Abstract
It has been historically thought that in conditions that permit growth, most unicellular species do not to age. This was particularly thought to be the case for symmetrically dividing species, as such species lack a clear distinction between the soma and the germline. Despite this, studies of the symmetrically dividing species Escherichia coli and Schizosaccharomyces pombe have recently started to challenge this notion. They indicate that E. coli and S. pombe do age, but only when subjected to environmental stress. If true, this suggests that aging may be widespread among microbial species in general, and that studying aging in microbes may inform other long-standing questions in aging. This review examines the recent evidence for and against replicative aging in symmetrically dividing unicellular organisms, the mechanisms that underlie aging, why aging evolved in these species, and how microbial aging fits into the context of other questions in aging.
Collapse
Affiliation(s)
- Michael Florea
- Graduate School of Arts and Sciences, Harvard Medical School, 25 Shattuck St, Boston, MA 02115, USA.
| |
Collapse
|
11
|
Boehm A, Arnoldini M, Bergmiller T, Röösli T, Bigosch C, Ackermann M. Genetic Manipulation of Glycogen Allocation Affects Replicative Lifespan in E. coli. PLoS Genet 2016; 12:e1005974. [PMID: 27093302 PMCID: PMC4836754 DOI: 10.1371/journal.pgen.1005974] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/13/2016] [Indexed: 11/18/2022] Open
Abstract
In bacteria, replicative aging manifests as a difference in growth or survival between the two cells emerging from division. One cell can be regarded as an aging mother with a decreased potential for future survival and division, the other as a rejuvenated daughter. Here, we aimed at investigating some of the processes involved in aging in the bacterium Escherichia coli, where the two types of cells can be distinguished by the age of their cell poles. We found that certain changes in the regulation of the carbohydrate metabolism can affect aging. A mutation in the carbon storage regulator gene, csrA, leads to a dramatically shorter replicative lifespan; csrA mutants stop dividing once their pole exceeds an age of about five divisions. These old-pole cells accumulate glycogen at their old cell poles; after their last division, they do not contain a chromosome, presumably because of spatial exclusion by the glycogen aggregates. The new-pole daughters produced by these aging mothers are born young; they only express the deleterious phenotype once their pole is old. These results demonstrate how manipulations of nutrient allocation can lead to the exclusion of the chromosome and limit replicative lifespan in E. coli, and illustrate how mutations can have phenotypic effects that are specific for cells with old poles. This raises the question how bacteria can avoid the accumulation of such mutations in their genomes over evolutionary times, and how they can achieve the long replicative lifespans that have recently been reported. Bacteria were often considered to be potentially immortal and free of aging. This expectation was based on the idea that the two cells emerging from bacterial division are identical and thus also equally old. However, a number of recent studies followed individual bacterial cells over consecutive divisions and reported that individuals with old cell poles show reduced survival and growth. This indicates that at least some types of bacteria age. We were interested in how mutations can affect the aging process and replicative lifespan of bacteria. In eukaryotes the aging process is thought to be modulated by mutations with age-specific effects. For example, there are mutations that have no measureable phenotypic effect early in life but are deleterious later in life. Such mutations play a key role in the evolution of eukaryotic aging and are thought to be responsible for lifespan differences between species. Here, we report that mutations can also have age-specific effects in bacteria. We describe a mutation in E. coli with a deleterious effect on growth and division that only manifests in cells whose cell pole is about four to five divisions old. These results illustrate how mutations can act in an age-specific manner in bacteria, and raise questions about how bacterial lifespan is modulated by such mutations.
Collapse
Affiliation(s)
- Alex Boehm
- Biozentrum, University of Basel, Switzerland
- Philipps-Universität Marburg, LOEWE-Zentrum für Synthetische Mikrobiologie, Marburg, Germany
| | - Markus Arnoldini
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Switzerland
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
- Department of Physics, University of California, San Diego, La Jolla, United States of America
| | - Tobias Bergmiller
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Switzerland
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Thomas Röösli
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Switzerland
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
| | - Colette Bigosch
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Switzerland
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Switzerland
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
- * E-mail:
| |
Collapse
|
12
|
|
13
|
Clegg RJ, Dyson RJ, Kreft JU. Repair rather than segregation of damage is the optimal unicellular aging strategy. BMC Biol 2014; 12:52. [PMID: 25184818 PMCID: PMC4243282 DOI: 10.1186/s12915-014-0052-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/24/2014] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND How aging, being unfavourable for the individual, can evolve is one of the fundamental problems of biology. Evidence for aging in unicellular organisms is far from conclusive. Some studies found aging even in symmetrically dividing unicellular species; others did not find aging in the same, or in different, unicellular species, or only under stress. Mathematical models suggested that segregation of non-genetic damage, as an aging strategy, would increase fitness. However, these models failed to consider repair as an alternative strategy or did not properly account for the benefits of repair. We used a new and improved individual-based model to examine rigorously the effect of a range of aging strategies on fitness in various environments. RESULTS Repair of damage emerges as the best strategy despite its fitness costs, since it immediately increases growth rate. There is an optimal investment in repair that outperforms damage segregation in well-mixed, lasting and benign environments over a wide range of parameter values. Damage segregation becomes beneficial, and only in combination with repair, when three factors are combined: (i) the rate of damage accumulation is high, (ii) damage is toxic and (iii) efficiency of repair is low. In contrast to previous models, our model predicts that unicellular organisms should have active mechanisms to repair damage rather than age by segregating damage. Indeed, as predicted, all organisms have evolved active mechanisms of repair whilst aging in unicellular organisms is absent or minimal under benign conditions, apart from microorganisms with a different ecology, inhabiting short-lived environments strongly favouring early reproduction rather than longevity. CONCLUSIONS Aging confers no fitness advantage for unicellular organisms in lasting environments under benign conditions, since repair of non-genetic damage is better than damage segregation.
Collapse
Affiliation(s)
- Robert J Clegg
- />Centre for Systems Biology, University of Birmingham, Birmingham, UK
- />Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
- />School of Biosciences, University of Birmingham, Birmingham, UK
| | - Rosemary J Dyson
- />Centre for Systems Biology, University of Birmingham, Birmingham, UK
- />School of Mathematics, University of Birmingham, Birmingham, UK
| | - Jan-Ulrich Kreft
- />Centre for Systems Biology, University of Birmingham, Birmingham, UK
- />Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
- />School of Biosciences, University of Birmingham, Birmingham, UK
| |
Collapse
|
14
|
Life history analysis of integrative and conjugative element activation in growing microcolonies of Pseudomonas. J Bacteriol 2014; 196:1425-34. [PMID: 24464463 DOI: 10.1128/jb.01333-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Integrative and conjugative elements (ICE) are in some ways parasitic mobile DNA that propagate vertically through replication with the bacterial host chromosome but at low frequencies can excise and invade new recipient cells through conjugation and reintegration (horizontal propagation). The factors that contribute to successful horizontal propagation are not very well understood. Here, we study the influence of host cell life history on the initiation of transfer of a model ICE named ICEclc in bacteria of the genus Pseudomonas. We use time-lapse microscopy of growing and stationary-phase microcolonies of ICEclc bearing cells in combination with physiological staining and gene reporter analysis in stationary-phase suspended cells. We provide evidence that cell age and cell lineage are unlikely to play a role in the decision to initiate the ICEclc transfer program. In contrast, cells activating ICEclc show more often increased levels of reactive oxygen species and membrane damage than nonactivating cells, suggesting that some form of biochemical damage may make cells more prone to ICEclc induction. Finally, we find that ICEclc active cells appear spatially at random in a microcolony, which may have been a selective advantage for maximizing ICEclc horizontal transmission to new recipient species.
Collapse
|
15
|
Gonze D. Modeling the effect of cell division on genetic oscillators. J Theor Biol 2013; 325:22-33. [DOI: 10.1016/j.jtbi.2013.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 01/22/2013] [Accepted: 02/01/2013] [Indexed: 02/07/2023]
|
16
|
The histidine kinase PdhS controls cell cycle progression of the pathogenic alphaproteobacterium Brucella abortus. J Bacteriol 2012; 194:5305-14. [PMID: 22843843 DOI: 10.1128/jb.00699-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial differentiation is often associated with the asymmetric localization of regulatory proteins, such as histidine kinases. PdhS is an essential and polarly localized histidine kinase in the pathogenic alphaproteobacterium Brucella abortus. After cell division, PdhS is asymmetrically segregated between the two sibling cells, highlighting a differentiation event. However, the function(s) of PdhS in the B. abortus cell cycle remains unknown. We used an original approach, the pentapeptide scanning mutagenesis method, to generate a thermosensitive allele of pdhS. We report that a B. abortus strain carrying this pdhS allele displays growth arrest and an altered DivK-yellow fluorescent protein (YFP) polar localization at the restrictive temperature. Moreover, the production of a nonphosphorylatable PdhS protein or truncated PdhS proteins leads to dominant-negative effects by generating morphological defects consistent with the inhibition of cell division. In addition, we have used a domain mapping approach combined with yeast two-hybrid and fluorescence microscopy methods to better characterize the unusual PdhS sensory domain. We have identified a fragment of the PdhS sensory domain required for protein-protein interaction (amino acids [aa] 210 to 434), a fragment sufficient for polar localization (aa 1 to 434), and a fragment (aa 527 to 661) whose production in B. abortus correlates with the generation of cell shape alterations. The data support a model in which PdhS acts as an essential regulator of cell cycle progression in B. abortus and contribute to a better understanding of the differentiation program inherited by the two sibling cells.
Collapse
|