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Ziegler KF, Joshi K, Wright CS, Roy S, Caruso W, Biswas RR, Iyer-Biswas S. Scaling of stochastic growth and division dynamics: A comparative study of individual rod-shaped cells in the Mother Machine and SChemostat platforms. Mol Biol Cell 2024; 35:ar78. [PMID: 38598301 PMCID: PMC11238078 DOI: 10.1091/mbc.e23-11-0452] [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: 12/11/2023] [Revised: 03/15/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024] Open
Abstract
Microfluidic platforms enable long-term quantification of stochastic behaviors of individual bacterial cells under precisely controlled growth conditions. Yet, quantitative comparisons of physiological parameters and cell behaviors of different microorganisms in different experimental and device modalities is not available due to experiment-specific details affecting cell physiology. To rigorously assess the effects of mechanical confinement, we designed, engineered, and performed side-by-side experiments under otherwise identical conditions in the Mother Machine (with confinement) and the SChemostat (without confinement), using the latter as the ideal comparator. We established a protocol to cultivate a suitably engineered rod-shaped mutant of Caulobacter crescentus in the Mother Machine and benchmarked the differences in stochastic growth and division dynamics with respect to the SChemostat. While the single-cell growth rate distributions are remarkably similar, the mechanically confined cells in the Mother Machine experience a substantial increase in interdivision times. However, we find that the division ratio distribution precisely compensates for this increase, which in turn reflects identical emergent simplicities governing stochastic intergenerational homeostasis of cell sizes across device and experimental configurations, provided the cell sizes are appropriately mean-rescaled in each condition. Our results provide insights into the nature of the robustness of the bacterial growth and division machinery.
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Affiliation(s)
- Karl F. Ziegler
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health, Sciences, Monash University, Clayton/Melbourne, VIC 3800, Australia
| | - Kunaal Joshi
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
| | - Charles S. Wright
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907
| | - Shaswata Roy
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
| | - Will Caruso
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
| | - Rudro R. Biswas
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
| | - Srividya Iyer-Biswas
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907
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2
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Seidel T, Artmann PJ, Gkekas I, Illies F, Baack AL, Viefhues M. Microfluidic Single-Cell Study on Arabidopsis thaliana Protoplast Fusion-New Insights on Timescales and Reversibilities. PLANTS (BASEL, SWITZERLAND) 2024; 13:295. [PMID: 38256848 PMCID: PMC10820889 DOI: 10.3390/plants13020295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/24/2024]
Abstract
Plant cells are omnipotent and breeding of new varieties can be achieved by protoplast fusion. Such fusions can be achieved by treatment with poly(ethylene glycol) or by applying an electric field. Microfluidic devices allow for controlled conditions and targeted manipulation of small batches of cells down to single-cell analysis. To provide controlled conditions for protoplast fusions and achieve high reproducibility, we developed and characterized a microfluidic device to reliably trap some Arabidopsis thaliana protoplasts and induced cell fusion by controlled addition of poly(ethylene glycol) (PEG, with a molecular weight of 6000). Experiments were conducted to determine the survival rate of isolated protoplasts in our microfluidic system. Afterward, PEG-induced fusion was studied. Our results indicate that the following fusion parameters had a significant impact on the fusion efficiency and duration: PEG concentration, osmolality of solution and flow velocity. A PEG concentration below 10% led to only partial fusion. The osmolality of the PEG fusion solution was found to strongly impact the fusion process; complete fusion of two source cells sufficiently took part in slightly hyper-osmotic solutions, whereas iso-osmotic solutions led to only partial fusion at a 20% PEG concentration. We observed accelerated fusion for higher fluid velocities. Until this study, it was common sense that fusion is one-directional, i.e., once two cells are fused into one cell, they stay fused. Here, we present for the first time the reversible fusion of protoplasts. Our microfluidic device paves the way to a deeper understanding of the kinetics and processes of cell fusion.
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Affiliation(s)
- Thorsten Seidel
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
| | - Philipp Johannes Artmann
- Experimental Biophysics and Applied Nanosciences, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Ioannis Gkekas
- Experimental Biophysics and Applied Nanosciences, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Franziska Illies
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
- Experimental Biophysics and Applied Nanosciences, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Anna-Lena Baack
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany
| | - Martina Viefhues
- Experimental Biophysics and Applied Nanosciences, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
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3
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Täuber S, Grünberger A. Microfluidic single-cell scale-down systems: introduction, application, and future challenges. Curr Opin Biotechnol 2023; 81:102915. [PMID: 36871470 DOI: 10.1016/j.copbio.2023.102915] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 01/17/2023] [Accepted: 02/02/2023] [Indexed: 03/06/2023]
Abstract
Performance losses during the scaling-up of bioprocesses from the laboratory to the production scale are common obstacles caused by the formation of concentration gradients in bioreactors. To overcome these obstacles, so-called scale-down bioreactors are used to analyze selected large-scale conditions and are one of the most important predictive tools for the successful transfer of bioprocesses from the lab to the industrial scale. In this regard, cellular behavior is usually measured as an averaged value, neglecting possible cell-to-cell heterogeneity within the culture. In contrast, microfluidic single-cell cultivation (MSCC) systems offer the possibility of understanding cellular processes on a single-cell level. To date, most MSCC systems have a limited choice of cultivation parameters that are not representative of bioprocess-relevant environmental conditions. Herein, we critically review recent advances in MSCC that allow the cultivation and analysis of cells under dynamic (bioprocess-relevant) environmental conditions. Finally, we discuss what technological advances and efforts are needed to bridge the gap between current MSCC systems and the use of these systems as single-cell scale-down devices.
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Affiliation(s)
- Sarah Täuber
- Multiscale Bioengineering, Technical Faculty, Bielefeld University, Bielefeld, Germany; Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - Alexander Grünberger
- Multiscale Bioengineering, Technical Faculty, Bielefeld University, Bielefeld, Germany; Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany; Microsystems in Bioprocess Engineering, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany.
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4
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Surface characterisation reveals substrate suitability for cyanobacterial phototaxis. Acta Biomater 2023; 155:386-399. [PMID: 36280031 DOI: 10.1016/j.actbio.2022.10.035] [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: 05/18/2022] [Revised: 09/24/2022] [Accepted: 10/17/2022] [Indexed: 02/02/2023]
Abstract
Cyanobacteria respond to light stimulation, activating localised assembly of type IV pili for motility. The resulting phototactic response is highly dependent on the nature of the incoming light stimulus, and the final motility parameters depend on the surface properties. Conventionally, phototaxis studies are carried out on hydrogel surfaces, such as agarose, with surface properties that vary in time due to experimental conditions. This study considers five substrates, widely utilized in microfluidic technology, to identify the most suitable alternative for performing reliable and repeatable phototaxis assays. The surfaces are characterised via a contact angle goniometer to determine the surface energy, white light interferometry for roughness, zeta-potentials and AFM force distance curves for charge patterns, and XPS for surface composition. Cell motility assays showed 1.25 times increment on surfaces with a water contact angle of 80° compared to a reference glass surface. To prove that motility can be enhanced, polydimethylsiloxane (PDMS) surfaces were plasma treated to alter their surface wettability. The motility on the plasma-treated PDMS showed similar performance as for glass surfaces. In contrast, untreated PDMS surfaces displayed close to zero motility. We also describe the force interactions of cells with the test surfaces using DLVO (Derjaguin-Landau-Verwey-Overbeek) and XDLVO (extended DLVO) theories. The computed DLVO/XDLVO force-distance curves are compared with those obtained using atomic force microscopy. Our findings show that twitching motility on tested surfaces can be described mainly from adhesive forces and hydrophobicity/hydrophilicity surface properties. STATEMENT OF SIGNIFICANCE: The current article focuses on unravelling the potential Micro-Electro-Mechanical System (MEMS) compatible surfaces for studying phototactic twitching motility of cyanobacteria. This is the first exhaustive surface characterization study coupled with phototaxis experiments, to understand the forces contributing to twitching motility. The methods shown in this paper can be further extended to study other surfaces and also to other bacteria exhibiting twitching motility.
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5
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Delgado-Campos A, Cuetos A. Influence of homeostatic mechanisms of bacterial growth and division on structural properties of microcolonies: A computer simulation study. Phys Rev E 2022; 106:034402. [PMID: 36266836 DOI: 10.1103/physreve.106.034402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 08/26/2022] [Indexed: 06/16/2023]
Abstract
Bacterial growth and division generally occur by the process known as binary fission, in which the cells grow polarly until they divide into two daughter cells. Although this process is affected by factors that introduce stochastic variability in both growth rate and daughter cell length, the fact is that the size distribution in growing bacteria remains stable over time. This suggests the existence of homeostatic mechanisms that contribute to maintaining a stable size distribution. Those known as sizer and adder stand out among these mechanisms whose relevance is not entirely determined. In this work, computer simulations using an agent-based model are used to study the effect of these homeostatic mechanisms on the geometrical and structural properties of the developing microcolonies, focusing on the early stages of its development. Also, we examine the effect of linear or exponential dependence with the time of cellular growth on these properties. From our study, we deduce that these mechanisms do not have a noticeable impact on the properties studied, which could be due to the importance that stochastic factors play in the cell division and growth process. In addition, we discuss how competition between cell growth and diffusion is a key aspect in explaining the structure and geometry of developing bacterial microcolonies. The results of the study will help to clarify which processes and parameters should be considered relevant when designing simulation models.
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Affiliation(s)
- Andrés Delgado-Campos
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Seville, Spain
| | - Alejandro Cuetos
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Seville, Spain
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6
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Kitaguchi Y, Tei H, Uriu K. Cell size homeostasis under the circadian regulation of cell division in cyanobacteria. J Theor Biol 2022; 553:111260. [PMID: 36057343 DOI: 10.1016/j.jtbi.2022.111260] [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: 12/27/2021] [Revised: 06/10/2022] [Accepted: 08/18/2022] [Indexed: 10/31/2022]
Abstract
Bacterial cells maintain their characteristic cell size over many generations. Several rod-shaped bacteria, such as Escherichia coli and the cyanobacteria Synechococcus elongatus, divide after adding a constant length to their length at birth. Through this division control known as the adder mechanism, perturbation in cell length due to physiological fluctuation decays over generations at a rate of 2-1 per cell division. However, previous experiments have shown that the circadian clock in cyanobacteria reduces cell division frequency at a specific time of day under constant light. This circadian gating should modulate the division control by the adder mechanism, but its significance remains unknown. Here we address how the circadian gating affects cell length, doubling time, and cell length stability in cyanobacteria by using mathematical models. We show that a cell subject to circadian gating grows for a long time, and gives birth to elongated daughter cells. These elongated daughter cells grow faster than the previous generation, as elongation speed is proportional to cell length and divide in a short time before the next gating. Hence, the distributions of doubling time and cell length become bimodal, as observed in experimental data. Interestingly, the average doubling time over the population of cells is independent of gating because the extension of doubling time by gating is compensated by its reduction in the subsequent generation. On the other hand, average cell length is increased by gating, suggesting that the circadian clock controls cell length. We then show that the decay rate of perturbation in cell length depends on the ratio of delay in division by the gating τG to the average doubling time τ0 as [Formula: see text] . We estimated τG≈2.5, τ0≈13.6 hours, and τG/τ0≈0.18 from experimental data, indicating that a long doubling time in cyanobacteria maintains the decay rate similar to that of the adder mechanism. Thus, our analysis suggests that the acquisition of the circadian clock during evolution did not impose a constraint on cell size homeostasis in cyanobacteria.
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Affiliation(s)
- Yuta Kitaguchi
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1129, Japan.
| | - Hajime Tei
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1129, Japan
| | - Koichiro Uriu
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1129, Japan
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7
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Stojanovski K, Großhans H, Towbin BD. Coupling of growth rate and developmental tempo reduces body size heterogeneity in C. elegans. Nat Commun 2022; 13:3132. [PMID: 35668054 PMCID: PMC9170734 DOI: 10.1038/s41467-022-29720-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 03/24/2022] [Indexed: 11/15/2022] Open
Abstract
Animals increase by orders of magnitude in volume during development. Therefore, small variations in growth rates among individuals could amplify to a large heterogeneity in size. By live imaging of C. elegans, we show that amplification of size heterogeneity is prevented by an inverse coupling of the volume growth rate to the duration of larval stages and does not involve strict size thresholds for larval moulting. We perturb this coupling by changing the developmental tempo through manipulation of a transcriptional oscillator that controls the duration of larval development. As predicted by a mathematical model, this perturbation alters the body volume. Model analysis shows that an inverse relation between the period length and the growth rate is an intrinsic property of genetic oscillators and can occur independently of additional complex regulation. This property of genetic oscillators suggests a parsimonious mechanism that counteracts the amplification of size differences among individuals during development. Animals must reach the correct size during development, despite stochastic differences in their growth rate. Here, Stojanovski et al. show that a coupling of growth and development by an oscillatory timer buffers fluctuations in the growth of the nematode C. elegans to ensure its correct size.
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Affiliation(s)
| | - Helge Großhans
- Friedrich Miescher Institute for Biomedical Research (FMI), Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Benjamin D Towbin
- University of Bern, Bern, Switzerland. .,Friedrich Miescher Institute for Biomedical Research (FMI), Basel, Switzerland.
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8
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Anggraini D, Ota N, Shen Y, Tang T, Tanaka Y, Hosokawa Y, Li M, Yalikun Y. Recent advances in microfluidic devices for single-cell cultivation: methods and applications. LAB ON A CHIP 2022; 22:1438-1468. [PMID: 35274649 DOI: 10.1039/d1lc01030a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Single-cell analysis is essential to improve our understanding of cell functionality from cellular and subcellular aspects for diagnosis and therapy. Single-cell cultivation is one of the most important processes in single-cell analysis, which allows the monitoring of actual information of individual cells and provides sufficient single-cell clones and cell-derived products for further analysis. The microfluidic device is a fast-rising system that offers efficient, effective, and sensitive single-cell cultivation and real-time single-cell analysis conducted either on-chip or off-chip. Here, we introduce the importance of single-cell cultivation from the aspects of cellular and subcellular studies. We highlight the materials and structures utilized in microfluidic devices for single-cell cultivation. We further discuss biological applications utilizing single-cell cultivation-based microfluidics, such as cellular phenotyping, cell-cell interactions, and omics profiling. Finally, present limitations and future prospects of microfluidics for single-cell cultivation are also discussed.
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Affiliation(s)
- Dian Anggraini
- Division of Materials Science, Nara Institute of Science and Technology, Nara 630-0192, Japan.
| | - Nobutoshi Ota
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yigang Shen
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Tao Tang
- Division of Materials Science, Nara Institute of Science and Technology, Nara 630-0192, Japan.
| | - Yo Tanaka
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoichiroh Hosokawa
- Division of Materials Science, Nara Institute of Science and Technology, Nara 630-0192, Japan.
| | - Ming Li
- School of Engineering, Macquarie University, Sydney 2122, Australia.
| | - Yaxiaer Yalikun
- Division of Materials Science, Nara Institute of Science and Technology, Nara 630-0192, Japan.
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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9
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Stawsky A, Vashistha H, Salman H, Brenner N. Multiple timescales in bacterial growth homeostasis. iScience 2022; 25:103678. [PMID: 35118352 PMCID: PMC8792075 DOI: 10.1016/j.isci.2021.103678] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/30/2021] [Accepted: 12/21/2021] [Indexed: 01/12/2023] Open
Abstract
In balanced exponential growth, bacteria maintain many properties statistically stable for a long time: cell size, cell cycle time, and more. As these are strongly coupled variables, it is not a-priori obvious which are directly regulated and which are stabilized through interactions. Here, we address this problem by separating timescales in bacterial single-cell dynamics. Disentangling homeostatic set points from fluctuations around them reveals that some variables, such as growth-rate, cell size and cycle time, are "sloppy" with highly volatile set points. Quantifying the relative contribution of environmental and internal sources, we find that sloppiness is primarily driven by the environment. Other variables such as fold-change define "stiff" combinations of coupled variables with robust set points. These results are manifested geometrically as a control manifold in the space of variables: set points span a wide range of values within the manifold, whereas out-of-manifold deviations are constrained. Our work offers a generalizable data-driven approach for identifying control variables in a multidimensional system.
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Affiliation(s)
- Alejandro Stawsky
- Interdisciplinary Program in Applied Mathematics, Technion, Haifa, Israel
- Network Biology Research Laboratories, Technion, Haifa, Israel
| | - Harsh Vashistha
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Hanna Salman
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Naama Brenner
- Network Biology Research Laboratories, Technion, Haifa, Israel
- Department of Chemical Engineering, Technion, Haifa, Israel
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10
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Messelink JJB, Meyer F, Bramkamp M, Broedersz CP. Single-cell growth inference of Corynebacterium glutamicum reveals asymptotically linear growth. eLife 2021; 10:e70106. [PMID: 34605403 PMCID: PMC8594916 DOI: 10.7554/elife.70106] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 10/01/2021] [Indexed: 11/13/2022] Open
Abstract
Regulation of growth and cell size is crucial for the optimization of bacterial cellular function. So far, single bacterial cells have been found to grow predominantly exponentially, which implies the need for tight regulation to maintain cell size homeostasis. Here, we characterize the growth behavior of the apically growing bacterium Corynebacterium glutamicum using a novel broadly applicable inference method for single-cell growth dynamics. Using this approach, we find that C. glutamicum exhibits asymptotically linear single-cell growth. To explain this growth mode, we model elongation as being rate-limited by the apical growth mechanism. Our model accurately reproduces the inferred cell growth dynamics and is validated with elongation measurements on a transglycosylase deficient ΔrodA mutant. Finally, with simulations we show that the distribution of cell lengths is narrower for linear than exponential growth, suggesting that this asymptotically linear growth mode can act as a substitute for tight division length and division symmetry regulation.
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Affiliation(s)
- Joris JB Messelink
- Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Fabian Meyer
- Ludwig-Maximilians-Universität München, Fakultät BiologiePlanegg-MartinsriedGermany
- Christian-Albrechts-Universität zu Kiel, Institut für allgemeine MikrobiologieKielGermany
| | - Marc Bramkamp
- Ludwig-Maximilians-Universität München, Fakultät BiologiePlanegg-MartinsriedGermany
- Christian-Albrechts-Universität zu Kiel, Institut für allgemeine MikrobiologieKielGermany
| | - Chase P Broedersz
- Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität MünchenMunichGermany
- Department of Physics and Astronomy, Vrije Universiteit AmsterdamAmsterdamNetherlands
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11
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Deng T, DePaoli D, Bégin L, Jia N, Torres de Oliveira L, Côté DC, Vincent WF, Greener J. Versatile Microfluidic Platform for Automated Live-Cell Hyperspectral Imaging Applied to Cold Climate Cyanobacterial Biofilms. Anal Chem 2021; 93:8764-8773. [PMID: 34133116 DOI: 10.1021/acs.analchem.0c05446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microfluidic bioanalytical platforms are driving discoveries from synthetic biology to the health sciences. In this work, we present a platform for in vivo live-cell imaging and automated species detection in mixed cyanobacterial biofilms from cold climate environments. Using a multimodal microscope with custom optics applied to a chip with six parallel growth channels, we monitored biofilm dynamics via continuous imaging at natural irradiance levels. Machine learning algorithms were applied to the collected hyperspectral images for automatic segmentation of mixed-species biofilms into individual species of cyanobacteria with similar filamentous morphology. The coupling of microfluidic technology with modern multimodal imaging and computer vision systems provides a versatile platform for the study of cause-and-effect scenarios of cyanobacterial biofilms, which are important elements of many ecosystems, including lakes and rivers of the polar regions.
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Affiliation(s)
- Tianyang Deng
- Département de chimie, Faculté des sciences et de génie, Université Laval, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Damon DePaoli
- Département de Physique, Génie Physique et Optique, Université Laval, Québec, G1V 0A6, Canada
- CERVO Brain Research Center, Québec G1J 2G3, Canada
| | - Ludovick Bégin
- Département de Physique, Génie Physique et Optique, Université Laval, Québec, G1V 0A6, Canada
- CERVO Brain Research Center, Québec G1J 2G3, Canada
| | - Nan Jia
- Département de chimie, Faculté des sciences et de génie, Université Laval, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Leon Torres de Oliveira
- Département de chimie, Faculté des sciences et de génie, Université Laval, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Daniel C Côté
- Département de Physique, Génie Physique et Optique, Université Laval, Québec, G1V 0A6, Canada
- CERVO Brain Research Center, Québec G1J 2G3, Canada
| | - Warwick F Vincent
- Centre d'études nordiques (CEN), Takuvik Joint International Laboratory & Département de biologie, Université Laval, 2405 rue de la Terrasse, Québec, Québec G1V 0A6, Canada
| | - Jesse Greener
- Département de chimie, Faculté des sciences et de génie, Université Laval, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada
- CHU de Québec, Centre de recherche, Université Laval, 10 rue de l'Espinay, Québec, Québec G1L 3L5, Canada
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12
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Nozoe T, Kussell E. Cell Cycle Heritability and Localization Phase Transition in Growing Populations. PHYSICAL REVIEW LETTERS 2020; 125:268103. [PMID: 33449732 PMCID: PMC8528515 DOI: 10.1103/physrevlett.125.268103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
The cell cycle duration is a variable cellular phenotype that underlies long-term population growth and age structures. By analyzing the stationary solutions of a branching process with heritable cell division times, we demonstrate the existence of a phase transition, which can be continuous or first order, by which a nonzero fraction of the population becomes localized at a minimal division time. Just below the transition, we demonstrate the coexistence of localized and delocalized age-structure phases and the power law decay of correlation functions. Above it, we observe the self-synchronization of cell cycles, collective divisions, and the slow "aging" of population growth rates.
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Affiliation(s)
- Takashi Nozoe
- Department of Biology, New York University, 12 Waverly Place, New York, New York 10003, USA
| | - Edo Kussell
- Department of Biology, New York University, 12 Waverly Place, New York, New York 10003, USA
- Department of Physics, New York University, 726 Broadway, New York, New York 10003, USA
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13
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Vasdekis AE, Singh A. Microbial metabolic noise. WIREs Mech Dis 2020; 13:e1512. [PMID: 33225608 DOI: 10.1002/wsbm.1512] [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: 12/31/2019] [Revised: 09/23/2020] [Accepted: 10/26/2020] [Indexed: 11/06/2022]
Abstract
From the time a cell was first placed under the microscope, it became apparent that identifying two clonal cells that "look" identical is extremely challenging. Since then, cell-to-cell differences in shape, size, and protein content have been carefully examined, informing us of the ultimate limits that hinder two cells from occupying an identical phenotypic state. Here, we present recent experimental and computational evidence that similar limits emerge also in cellular metabolism. These limits pertain to stochastic metabolic dynamics and, thus, cell-to-cell metabolic variability, including the resulting adapting benefits. We review these phenomena with a focus on microbial metabolism and conclude with a brief outlook on the potential relationship between metabolic noise and adaptive evolution. This article is categorized under: Metabolic Diseases > Computational Models Metabolic Diseases > Biomedical Engineering.
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Affiliation(s)
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, USA
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14
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Vargas-Garcia CA, Björklund M, Singh A. Modeling homeostasis mechanisms that set the target cell size. Sci Rep 2020; 10:13963. [PMID: 32811891 PMCID: PMC7434900 DOI: 10.1038/s41598-020-70923-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 08/03/2020] [Indexed: 11/09/2022] Open
Abstract
How organisms maintain cell size homeostasis is a long-standing problem that remains unresolved, especially in multicellular organisms. Recent experiments in diverse animal cell types demonstrate that within a cell population, cellular proliferation is low for small and large cells, but high at intermediate sizes. Here we use mathematical models to explore size-control strategies that drive such a non-monotonic profile resulting in the proliferation capacity being maximized at a target cell size. Our analysis reveals that most models of size control yield proliferation capacities that vary monotonically with cell size, and non-monotonicity requires two key mechanisms: (1) the growth rate decreases with increasing size for excessively large cells; and (2) cell division occurs as per the Adder model (division is triggered upon adding a fixed size from birth), or a Sizer-Adder combination. Consistent with theory, Jurkat T cell growth rates increase with size for small cells, but decrease with size for large cells. In summary, our models show that regulation of both growth and cell-division timing is necessary for size control in animal cells, and this joint mechanism leads to a target cell size where cellular proliferation capacity is maximized.
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Affiliation(s)
- Cesar A Vargas-Garcia
- Corporación Colombiana de Investigación Agropecuaria-Agrosavia, Mosquera, Colombia.
- Fundación Universitaria Konrad Lorenz, Bogotá, Colombia.
| | - Mikael Björklund
- Zhejiang University-University of Edinburgh (ZJU-UoE) Institute, 718 East Haizhou Rd., Haining, 314400, Zhejiang, People's Republic of China
- Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, People's Republic of China
| | - Abhyudai Singh
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, USA
- Department of Mathematical Sciences, University of Delaware, Newark, Delaware, USA
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15
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Kizawa A, Osanai T. Overexpression of the response regulator rpaA causes an impaired cell division in the Cyanobacterium Synechocystis sp. PCC 6803. J GEN APPL MICROBIOL 2020; 66:121-128. [PMID: 32173680 DOI: 10.2323/jgam.2020.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In photosynthetic microorganisms, cell cycle progression depends on day and night cycles; however, how cell division is regulated in response to these environmental changes is poorly understood. RpaA has been implicated in the signal output from both circadian clocks and light/dark conditions in the unicellular spherical-celled cyanobacterium Synechocystis sp. PCC 6803. In the present study, we investigated the involvement of a two-component response regulator RpaA in cell division regulation. Firstly, we examined the effects of rpaA overexpression on cell morphology and the expression levels of cell division genes. We observed an increase in the volume of non-dividing cells and a high proportion of dividing cells in rpaA-overexpressing strains by light microscopy. The expression levels of selected cell division-related genes were higher in the rpaA-overexpressing strain than in the wild type, including minD of the Min system; cdv3 and zipN, which encode two divisome components; and murB, murC, and pbp2, which are involved in peptidoglycan (PG) synthesis. Moreover, in the rpaA-overexpressing strain, the outer membrane and cell wall PG layer were not smooth, and the outer membrane was not clearly visible by transmission electron microscopy. These results demonstrated that rpaA overexpression causes an impaired cell division, which is accompanied by transcriptional activation of cell division genes and morphological changes in the PG layer and outer membrane.
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Affiliation(s)
- Ayumi Kizawa
- Department of Agricultural Chemistry, School of Agriculture, Meiji University
| | - Takashi Osanai
- Department of Agricultural Chemistry, School of Agriculture, Meiji University
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16
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Canonico M, Konert G, Kaňa R. Plasticity of Cyanobacterial Thylakoid Microdomains Under Variable Light Conditions. FRONTIERS IN PLANT SCIENCE 2020; 11:586543. [PMID: 33304364 PMCID: PMC7693714 DOI: 10.3389/fpls.2020.586543] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/09/2020] [Indexed: 05/02/2023]
Abstract
Photosynthetic light reactions proceed in thylakoid membranes (TMs) due to the activity of pigment-protein complexes. These complexes are heterogeneously organized into granal/stromal thylakoids (in plants) or into recently identified cyanobacterial microdomains (MDs). MDs are characterized by specific ratios of photosystem I (PSI), photosystem II (PSII), and phycobilisomes (PBS) and they are visible as sub-micrometer sized areas with different fluorescence ratios. In this report, the process of long-term plasticity in cyanobacterial thylakoid MDs has been explored under variable growth light conditions using Synechocystis sp. PCC6803 expressing YFP tagged PSI. TM organization into MDs has been observed for all categorized shapes of cells independently of their stage in cell cycle. The heterogeneous PSI, PSII, and PBS thylakoid areas were also identified under two types of growth conditions: at continuous light (CL) and at light-dark (L-D) cycle. The acclimation from CL to L-D cycle changed spatial distribution of photosystems, in particular PSI became more evenly distributed in thylakoids under L-D cycle. The process of the spatial PSI (and partially also PSII) redistribution required 1 week and was accompanied by temporal appearance of PBS decoupling probably caused by the re-organization of photosystems. The overall acclimation we observed was defined as TM plasticity as it resembles higher plants grana/stroma reorganization at variable growth light conditions. In addition, we observed large cell to cell variability in the actual MDs organization. It leads us to suggest that the plasticity, and cell to cell variability in MDs could be a manifestation of phenotypic heterogeneity, a recently broadly discussed phenomenon for prokaryotes.
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Affiliation(s)
- Myriam Canonico
- Institute of Microbiology, CAS, Centrum Algatech, Třeboň, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Grzegorz Konert
- Institute of Microbiology, CAS, Centrum Algatech, Třeboň, Czechia
| | - Radek Kaňa
- Institute of Microbiology, CAS, Centrum Algatech, Třeboň, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
- *Correspondence: Radek Kaňa, ; orcid.org/0000-0001-5768-6902
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17
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Abstract
Cells are the building blocks of life, from single-celled microbes through to multi-cellular organisms. To understand a multitude of biological processes we need to understand how cells behave, how they interact with each other and how they respond to their environment. The use of new methodologies is changing the way we study cells allowing us to study them on minute scales and in unprecedented detail. These same methods are allowing researchers to begin to sample the vast diversity of microbes that dominate natural environments. The aim of this special issue is to bring together research and perspectives on the application of new approaches to understand the biological properties of cells, including how they interact with other biological entities. This article is part of a discussion meeting issue 'Single cell ecology'.
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Affiliation(s)
- Thomas A Richards
- Biosciences and Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Ramon Massana
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), 08003 Barcelona, Spain
| | - Stefano Pagliara
- Biosciences and Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Neil Hall
- Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, UK.,School of Biological Sciences, University of East Anglia, Norwich, NR4 7TU, UK
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18
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Lee S, Wu LJ, Errington J. Microfluidic time-lapse analysis and reevaluation of the Bacillus subtilis cell cycle. Microbiologyopen 2019; 8:e876. [PMID: 31197963 PMCID: PMC6813450 DOI: 10.1002/mbo3.876] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/03/2019] [Accepted: 05/13/2019] [Indexed: 12/24/2022] Open
Abstract
Recent studies taking advantage of automated single-cell time-lapse analysis have reignited interest in the bacterial cell cycle. Several studies have highlighted alternative models, such as Sizer and Adder, which differ essentially in relation to whether cells can measure their present size or their amount of growth since birth. Most of the recent work has been done with Escherichia coli. We set out to study the well-characterized Gram-positive bacterium, Bacillus subtilis, at the single-cell level, using an accurate fluorescent marker for division as well as a marker for completion of chromosome replication. Our results are consistent with the Adder model in both fast and slow growth conditions tested, and with Sizer but only at the slower growth rate. We also find that cell size variation arises not only from the expected variation in size at division but also that division site offset from mid-cell contributes to a significant degree. Finally, although traditional cell cycle models imply a strong connection between the termination of a round of replication and subsequent division, we find that at the single-cell level these events are largely disconnected.
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Affiliation(s)
- Seoungjun Lee
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical SchoolNewcastle UniversityNewcastle‐upon‐TyneUK
- Present address:
Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical SchoolNewcastle UniversityNewcastle‐upon‐TyneUK
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical SchoolNewcastle UniversityNewcastle‐upon‐TyneUK
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19
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Ota N, Yonamine Y, Asai T, Yalikun Y, Ito T, Ozeki Y, Hoshino Y, Tanaka Y. Isolating Single Euglena gracilis Cells by Glass Microfluidics for Raman Analysis of Paramylon Biogenesis. Anal Chem 2019; 91:9631-9639. [DOI: 10.1021/acs.analchem.9b01007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Nobutoshi Ota
- Center for Biosystems Dynamics Research, RIKEN, Suita, Osaka 565-0871, Japan
| | - Yusuke Yonamine
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
| | - Takuya Asai
- Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo 113-8656, Japan
| | - Yaxiaer Yalikun
- Center for Biosystems Dynamics Research, RIKEN, Suita, Osaka 565-0871, Japan
| | - Takuro Ito
- Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yasuyuki Ozeki
- Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo 113-8656, Japan
| | - Yu Hoshino
- Department of Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Yo Tanaka
- Center for Biosystems Dynamics Research, RIKEN, Suita, Osaka 565-0871, Japan
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20
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Deng B, Wang H, Tan Z, Quan Y. Microfluidic Cell Trapping for Single-Cell Analysis. MICROMACHINES 2019; 10:mi10060409. [PMID: 31248148 PMCID: PMC6632028 DOI: 10.3390/mi10060409] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/10/2019] [Accepted: 06/18/2019] [Indexed: 12/19/2022]
Abstract
The single-cell capture microfluidic chip has many advantages, including low cost, high throughput, easy manufacturing, integration, non-toxicity and good stability. Because of these characteristics, the cell capture microfluidic chip is increasingly becoming an important carrier on the study of life science and pharmaceutical analysis. Important promises of single-cell analysis are the paring, fusion, disruption and analysis of intracellular components for capturing a single cell. The capture, which is based on the fluid dynamics method in the field of micro fluidic chips is an important way to achieve and realize the operations mentioned above. The aim of this study was to compare the ability of three fluid dynamics-based microfluidic chip structures to capture cells. The effects of cell growth and distribution after being captured by different structural chips and the subsequent observation and analysis of single cells on the chip were compared. It can be seen from the experimental results that the microfluidic chip structure most suitable for single-cell capture is a U-shaped structure. It enables single-cell capture as well as long-term continuous culture and the single-cell observation of captured cells. Compared to the U-shaped structure, the cells captured by the microcavity structure easily overlapped during the culture process and affected the subsequent analysis of single cells. The flow shortcut structure can also be used to capture and observe single cells, however, the shearing force of the fluid caused by the chip structure is likely to cause deformation of the cultured cells. By comparing the cell capture efficiency of the three chips, the reagent loss during the culture process and the cell growth state of the captured cells, we are provided with a theoretical support for the design of a single-cell capture microfluidic chip and a reference for the study of single-cell capture in the future.
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Affiliation(s)
- Bing Deng
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou 215000, China.
| | - Heyi Wang
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou 215000, China.
| | - Zhaoyi Tan
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou 215000, China.
| | - Yi Quan
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou 215000, China.
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21
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Norris V. Successive Paradigm Shifts in the Bacterial Cell Cycle and Related Subjects. Life (Basel) 2019; 9:E27. [PMID: 30866455 PMCID: PMC6462897 DOI: 10.3390/life9010027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 02/28/2019] [Accepted: 03/04/2019] [Indexed: 11/26/2022] Open
Abstract
A paradigm shift in one field can trigger paradigm shifts in other fields. This is illustrated by the paradigm shifts that have occurred in bacterial physiology following the discoveries that bacteria are not unstructured, that the bacterial cell cycle is not controlled by the dynamics of peptidoglycan, and that the growth rates of bacteria in the same steady-state population are not at all the same. These paradigm shifts are having an effect on longstanding hypotheses about the regulation of the bacterial cell cycle, which appear increasingly to be inadequate. I argue that, just as one earthquake can trigger others, an imminent paradigm shift in the regulation of the bacterial cell cycle will have repercussions or "paradigm quakes" on hypotheses about the origins of life and about the regulation of the eukaryotic cell cycle.
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Affiliation(s)
- Vic Norris
- Laboratory of Microbiology Signals and Microenvironment, University of Rouen, 76821 Mont Saint Aignan, France.
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22
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Modi S, Singh A. Controlling organism size by regulating constituent cell numbers. PROCEEDINGS OF THE ... IEEE CONFERENCE ON DECISION & CONTROL. IEEE CONFERENCE ON DECISION & CONTROL 2019; 2018:2685-2690. [PMID: 30886453 DOI: 10.1109/cdc.2018.8619546] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
How living cells employ counting mechanisms to regulate their numbers or density is a long-standing problem in developmental biology that ties directly with organism or tissue size. Diverse cells types have been shown to regulate their numbers via secretion of factors in the extracellular space. These factors act as a proxy for the number of cells and function to reduce cellular proliferation rates creating a negative feedback. It is desirable that the production rate of such factors be kept as low as possible to minimize energy costs and detection by predators. Here we formulate a stochastic model of cell proliferation with feedback control via a secreted extracellular factor. Our results show that while low levels of feedback minimizes random fluctuations in cell numbers around a given set point, high levels of feedback amplify Poisson fluctuations in secreted-factor copy numbers. This trade-off results in an optimal feedback strength, and sets a fundamental limit to noise suppression in cell numbers with short-lived factors providing more efficient noise buffering. We further expand the model to consider external disturbances in key physiological parameters, such as, proliferation and factor synthesis rates. Intriguingly, while negative feedback effectively mitigates disturbances in the proliferation rate, it amplifies disturbances in the synthesis rate. In summary, these results provide unique insights into the functioning of feedback-based counting mechanisms, and apply to organisms ranging from unicellular prokaryotes and eukaryotes to human cells.
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Affiliation(s)
- Saurabh Modi
- Department of Biomedical Engineering, University of Delaware, Newark, DE USA 19716.
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, Biomedical Engineering, Mathematical Sciences, Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE USA 19716.
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23
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Chakrabarti S, Paek AL, Reyes J, Lasick KA, Lahav G, Michor F. Hidden heterogeneity and circadian-controlled cell fate inferred from single cell lineages. Nat Commun 2018; 9:5372. [PMID: 30560953 PMCID: PMC6299096 DOI: 10.1038/s41467-018-07788-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 11/23/2018] [Indexed: 11/09/2022] Open
Abstract
The origin of lineage correlations among single cells and the extent of heterogeneity in their intermitotic times (IMT) and apoptosis times (AT) remain incompletely understood. Here we developed single cell lineage-tracking experiments and computational algorithms to uncover correlations and heterogeneity in the IMT and AT of a colon cancer cell line before and during cisplatin treatment. These correlations could not be explained using simple protein production/degradation models. Sister cell fates were similar regardless of whether they divided before or after cisplatin administration and did not arise from proximity-related factors, suggesting fate determination early in a cell's lifetime. Based on these findings, we developed a theoretical model explaining how the observed correlation structure can arise from oscillatory mechanisms underlying cell fate control. Our model recapitulated the data only with very specific oscillation periods that fit measured circadian rhythms, thereby suggesting an important role of the circadian clock in controlling cellular fates.
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Affiliation(s)
- Shaon Chakrabarti
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, 02215, MA, USA.,Department of Biostatistics, Harvard T. H. Chan School of Public Health, Boston, 02115, MA, USA.,Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, 02138, MA, USA
| | - Andrew L Paek
- Department of Systems Biology, Blavatnik Institute, Harvard Medical School, Boston, 02115, MA, USA.,University of Arizona, Tucson, 85721 AZ, USA
| | - Jose Reyes
- Department of Systems Biology, Blavatnik Institute, Harvard Medical School, Boston, 02115, MA, USA
| | | | - Galit Lahav
- Department of Systems Biology, Blavatnik Institute, Harvard Medical School, Boston, 02115, MA, USA. .,Broad Institute of Harvard and MIT, Cambridge, 02139, MA, USA. .,Ludwig Center at Harvard, Boston, 02215, MA, USA.
| | - Franziska Michor
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, 02215, MA, USA. .,Department of Biostatistics, Harvard T. H. Chan School of Public Health, Boston, 02115, MA, USA. .,Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, 02138, MA, USA. .,Broad Institute of Harvard and MIT, Cambridge, 02139, MA, USA. .,Ludwig Center at Harvard, Boston, 02215, MA, USA. .,Center for Cancer Evolution, Dana-Farber Cancer Institute, Boston, 02215, MA, USA.
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24
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Martins BMC, Tooke AK, Thomas P, Locke JCW. Cell size control driven by the circadian clock and environment in cyanobacteria. Proc Natl Acad Sci U S A 2018; 115:E11415-E11424. [PMID: 30409801 PMCID: PMC6275512 DOI: 10.1073/pnas.1811309115] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
How cells maintain their size has been extensively studied under constant conditions. In the wild, however, cells rarely experience constant environments. Here, we examine how the 24-h circadian clock and environmental cycles modulate cell size control and division timings in the cyanobacterium Synechococcus elongatus using single-cell time-lapse microscopy. Under constant light, wild-type cells follow an apparent sizer-like principle. Closer inspection reveals that the clock generates two subpopulations, with cells born in the subjective day following different division rules from cells born in subjective night. A stochastic model explains how this behavior emerges from the interaction of cell size control with the clock. We demonstrate that the clock continuously modulates the probability of cell division throughout day and night, rather than solely applying an on-off gate to division, as previously proposed. Iterating between modeling and experiments, we go on to identify an effective coupling of the division rate to time of day through the combined effects of the environment and the clock on cell division. Under naturally graded light-dark cycles, this coupling narrows the time window of cell divisions and shifts divisions away from when light levels are low and cell growth is reduced. Our analysis allows us to disentangle, and predict the effects of, the complex interactions between the environment, clock, and cell size control.
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Affiliation(s)
- Bruno M C Martins
- Sainsbury Laboratory, University of Cambridge, CB2 1LR Cambridge, United Kingdom
| | - Amy K Tooke
- Sainsbury Laboratory, University of Cambridge, CB2 1LR Cambridge, United Kingdom
| | - Philipp Thomas
- Department of Mathematics, Imperial College London, SW7 2AZ London, United Kingdom
| | - James C W Locke
- Sainsbury Laboratory, University of Cambridge, CB2 1LR Cambridge, United Kingdom;
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25
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Martins BMC, Tooke AK, Thomas P, Locke JCW. Cell size control driven by the circadian clock and environment in cyanobacteria. Proc Natl Acad Sci U S A 2018. [PMID: 30409801 DOI: 10.1002/(sici)1521-1878(200001)22:1¡10::aid-bies4¿3.0.co;2-a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
How cells maintain their size has been extensively studied under constant conditions. In the wild, however, cells rarely experience constant environments. Here, we examine how the 24-h circadian clock and environmental cycles modulate cell size control and division timings in the cyanobacterium Synechococcus elongatus using single-cell time-lapse microscopy. Under constant light, wild-type cells follow an apparent sizer-like principle. Closer inspection reveals that the clock generates two subpopulations, with cells born in the subjective day following different division rules from cells born in subjective night. A stochastic model explains how this behavior emerges from the interaction of cell size control with the clock. We demonstrate that the clock continuously modulates the probability of cell division throughout day and night, rather than solely applying an on-off gate to division, as previously proposed. Iterating between modeling and experiments, we go on to identify an effective coupling of the division rate to time of day through the combined effects of the environment and the clock on cell division. Under naturally graded light-dark cycles, this coupling narrows the time window of cell divisions and shifts divisions away from when light levels are low and cell growth is reduced. Our analysis allows us to disentangle, and predict the effects of, the complex interactions between the environment, clock, and cell size control.
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Affiliation(s)
- Bruno M C Martins
- Sainsbury Laboratory, University of Cambridge, CB2 1LR Cambridge, United Kingdom
| | - Amy K Tooke
- Sainsbury Laboratory, University of Cambridge, CB2 1LR Cambridge, United Kingdom
| | - Philipp Thomas
- Department of Mathematics, Imperial College London, SW7 2AZ London, United Kingdom
| | - James C W Locke
- Sainsbury Laboratory, University of Cambridge, CB2 1LR Cambridge, United Kingdom;
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26
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Cadart C, Monnier S, Grilli J, Sáez PJ, Srivastava N, Attia R, Terriac E, Baum B, Cosentino-Lagomarsino M, Piel M. Size control in mammalian cells involves modulation of both growth rate and cell cycle duration. Nat Commun 2018; 9:3275. [PMID: 30115907 PMCID: PMC6095894 DOI: 10.1038/s41467-018-05393-0] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/30/2018] [Indexed: 02/04/2023] Open
Abstract
Despite decades of research, how mammalian cell size is controlled remains unclear because of the difficulty of directly measuring growth at the single-cell level. Here we report direct measurements of single-cell volumes over entire cell cycles on various mammalian cell lines and primary human cells. We find that, in a majority of cell types, the volume added across the cell cycle shows little or no correlation to cell birth size, a homeostatic behavior called "adder". This behavior involves modulation of G1 or S-G2 duration and modulation of growth rate. The precise combination of these mechanisms depends on the cell type and the growth condition. We have developed a mathematical framework to compare size homeostasis in datasets ranging from bacteria to mammalian cells. This reveals that a near-adder behavior is the most common type of size control and highlights the importance of growth rate modulation to size control in mammalian cells.
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Affiliation(s)
- Clotilde Cadart
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Institut Pierre-Gilles de Gennes, PSL Research University, F-75005, Paris, France
| | - Sylvain Monnier
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Villeurbanne, France
| | - Jacopo Grilli
- Department of Ecology and Evolution, University of Chicago, 1101 E 57th Street, Chicago, IL, 60637, USA
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM, 87501, USA
| | - Pablo J Sáez
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Institut Pierre-Gilles de Gennes, PSL Research University, F-75005, Paris, France
| | - Nishit Srivastava
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Institut Pierre-Gilles de Gennes, PSL Research University, F-75005, Paris, France
| | - Rafaele Attia
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Institut Pierre-Gilles de Gennes, PSL Research University, F-75005, Paris, France
| | - Emmanuel Terriac
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123, Saarbrücken, Germany
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, UCL, London, WC1E 6BT, UK
- Institute of Physics of Living Systems, UCL, London, WC1E 6BT, UK
| | - Marco Cosentino-Lagomarsino
- Sorbonne Universités, Université Pierre et Marie Curie, Paris, F-75005, France.
- CNRS, UMR 7238 Computational and Quantitative Biology, Paris, F-75005, France.
- FIRC Institute of Molecular Oncology (IFOM), Milan, 20139, Italy.
| | - Matthieu Piel
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005, Paris, France.
- Institut Pierre-Gilles de Gennes, PSL Research University, F-75005, Paris, France.
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27
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Abstract
Microbial cells go through repeated cycles of growth and division. These cycles are not perfect: the time and size at division can fluctuate from one cycle to the next. Still, cell size is kept tightly controlled, and fluctuations do not accumulate to large deviations. How this control is implemented in single cells is still not fully understood. We performed experiments that follow individual bacteria in microfluidic traps for hundreds of generations. This enables us to identify distinct individual dynamic properties that are maintained over many cycles of growth and division. Surprisingly, we find that each cell suppresses fluctuations with a different strength; this variability defines an “individual” behavior for each cell, which is inherited along many generations. Microbial growth and division are fundamental processes relevant to many areas of life science. Of particular interest are homeostasis mechanisms, which buffer growth and division from accumulating fluctuations over multiple cycles. These mechanisms operate within single cells, possibly extending over several division cycles. However, all experimental studies to date have relied on measurements pooled from many distinct cells. Here, we disentangle long-term measured traces of individual cells from one another, revealing subtle differences between temporal and pooled statistics. By analyzing correlations along up to hundreds of generations, we find that the parameter describing effective cell size homeostasis strength varies significantly among cells. At the same time, we find an invariant cell size, which acts as an attractor to all individual traces, albeit with different effective attractive forces. Despite the common attractor, each cell maintains a distinct average size over its finite lifetime with suppressed temporal fluctuations around it, and equilibration to the global average size is surprisingly slow (>150 cell cycles). To show a possible source of variable homeostasis strength, we construct a mathematical model relying on intracellular interactions, which integrates measured properties of cell size with those of highly expressed proteins. Effective homeostasis strength is then influenced by interactions and by noise levels and generally varies among cells. A predictable and measurable consequence of variable homeostasis strength appears as distinct oscillatory patterns in cell size and protein content over many generations. We discuss implications of our results to understanding mechanisms controlling division in single cells and their characteristic timescales.
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28
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Ho PY, Lin J, Amir A. Modeling Cell Size Regulation: From Single-Cell-Level Statistics to Molecular Mechanisms and Population-Level Effects. Annu Rev Biophys 2018. [DOI: 10.1146/annurev-biophys-070317-032955] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most microorganisms regulate their cell size. In this article, we review some of the mathematical formulations of the problem of cell size regulation. We focus on coarse-grained stochastic models and the statistics that they generate. We review the biologically relevant insights obtained from these models. We then describe cell cycle regulation and its molecular implementations, protein number regulation, and population growth, all in relation to size regulation. Finally, we discuss several future directions for developing understanding beyond phenomenological models of cell size regulation.
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Affiliation(s)
- Po-Yi Ho
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Jie Lin
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Ariel Amir
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
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29
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Gangwe Nana GY, Ripoll C, Cabin-Flaman A, Gibouin D, Delaune A, Janniere L, Grancher G, Chagny G, Loutelier-Bourhis C, Lentzen E, Grysan P, Audinot JN, Norris V. Division-Based, Growth Rate Diversity in Bacteria. Front Microbiol 2018; 9:849. [PMID: 29867792 PMCID: PMC5958220 DOI: 10.3389/fmicb.2018.00849] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 04/12/2018] [Indexed: 01/19/2023] Open
Abstract
To investigate the nature and origins of growth rate diversity in bacteria, we grew Escherichia coli and Bacillus subtilis in liquid minimal media and, after different periods of 15N-labeling, analyzed and imaged isotope distributions in individual cells with Secondary Ion Mass Spectrometry. We find a striking inter- and intra-cellular diversity, even in steady state growth. This is consistent with the strand-dependent, hyperstructure-based hypothesis that a major function of the cell cycle is to generate coherent, growth rate diversity via the semi-conservative pattern of inheritance of strands of DNA and associated macromolecular assemblies. We also propose quantitative, general, measures of growth rate diversity for studies of cell physiology that include antibiotic resistance.
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Affiliation(s)
- Ghislain Y Gangwe Nana
- Laboratory of Microbiology Signals and Microenvironment, Department of Biology, University of Rouen, Mont Saint Aignan, France
| | - Camille Ripoll
- Department of Biology, University of Rouen, Mont Saint Aignan, France
| | - Armelle Cabin-Flaman
- Groupe de Physique des Matériaux, Centre National de la Recherche Scientifique, Département de Biologie, Université de Rouen Normandie, Saint-Etienne du Rouvray, France
| | - David Gibouin
- Groupe de Physique des Matériaux, Centre National de la Recherche Scientifique, Département de Biologie, Université de Rouen Normandie, Saint-Etienne du Rouvray, France
| | - Anthony Delaune
- Groupe de Physique des Matériaux, Centre National de la Recherche Scientifique, Département de Biologie, Université de Rouen Normandie, Saint-Etienne du Rouvray, France
| | | | - Gerard Grancher
- R. Salem Laboratory of Maths, UMR 6085 Centre National de la Recherche Scientifique-University of Rouen, Saint Etienne du Rouvray, France
| | - Gaelle Chagny
- R. Salem Laboratory of Maths, UMR 6085 Centre National de la Recherche Scientifique-University of Rouen, Saint Etienne du Rouvray, France
| | - Corinne Loutelier-Bourhis
- UMR Centre National de la Recherche Scientifique, 6014 COBRA, University of Rouen, Mont Saint Aignan, France
| | - Esther Lentzen
- Material Research & Technology Department, Luxembourg Institute of Science and Technology, Belvaux, Luxembourg
| | - Patrick Grysan
- Material Research & Technology Department, Luxembourg Institute of Science and Technology, Belvaux, Luxembourg
| | - Jean-Nicolas Audinot
- Material Research & Technology Department, Luxembourg Institute of Science and Technology, Belvaux, Luxembourg
| | - Vic Norris
- Laboratory of Microbiology Signals and Microenvironment, Department of Biology, University of Rouen, Mont Saint Aignan, France
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30
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Abstract
Microfluidic technology overcomes many of the limitations to traditional analytical methods in microbiology. Unlike bulk-culture methods, it offers single-cell resolution and long observation times spanning hundreds of generations; unlike agarose pad-based microscopy, it has uniform growth conditions that can be tightly controlled. Because the continuous flow of growth medium isolates the cells in a microfluidic device from unpredictable variations in the local chemical environment caused by cell growth and metabolism, authentic changes in gene expression and cell growth in response to specific stimuli can be more confidently observed. Bacillus subtilis is used here as a model bacterial species to demonstrate a "mother machine"-type method for cellular analysis. We show how to construct and plumb a microfluidic device, load it with cells, initiate microscopic imaging, and expose cells to a stimulus by switching from one growth medium to another. A stress-responsive reporter is used as an example to reveal the type of data that may be obtained by this method. We also briefly discuss further applications of this method for other types of experiments, such as analysis of bacterial sporulation.
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Affiliation(s)
- Matthew T Cabeen
- Department of Microbiology and Molecular Genetics, Oklahoma State University;
| | - Richard Losick
- Department of Molecular and Cellular Biology, Harvard University;
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31
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Sibbitts J, Sellens KA, Jia S, Klasner SA, Culbertson CT. Cellular Analysis Using Microfluidics. Anal Chem 2017; 90:65-85. [DOI: 10.1021/acs.analchem.7b04519] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jay Sibbitts
- Department
of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
| | - Kathleen A. Sellens
- Department
of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
| | - Shu Jia
- Department
of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
| | - Scott A. Klasner
- 12966
South
State Highway 94, Marthasville, Missouri 63357, United States
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32
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The phenomenology of cell size control. Curr Opin Cell Biol 2017; 49:53-58. [DOI: 10.1016/j.ceb.2017.11.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 11/05/2017] [Accepted: 11/26/2017] [Indexed: 01/27/2023]
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33
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Chen Z, Chen L, Zhang W. Tools for Genomic and Transcriptomic Analysis of Microbes at Single-Cell Level. Front Microbiol 2017; 8:1831. [PMID: 28979258 PMCID: PMC5611438 DOI: 10.3389/fmicb.2017.01831] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 09/06/2017] [Indexed: 12/16/2022] Open
Abstract
Microbiologists traditionally study population rather than individual cells, as it is generally assumed that the status of individual cells will be similar to that observed in the population. However, the recent studies have shown that the individual behavior of each single cell could be quite different from that of the whole population, suggesting the importance of extending traditional microbiology studies to single-cell level. With recent technological advances, such as flow cytometry, next-generation sequencing (NGS), and microspectroscopy, single-cell microbiology has greatly enhanced the understanding of individuality and heterogeneity of microbes in many biological systems. Notably, the application of multiple ‘omics’ in single-cell analysis has shed light on how individual cells perceive, respond, and adapt to the environment, how heterogeneity arises under external stress and finally determines the fate of the whole population, and how microbes survive under natural conditions. As single-cell analysis involves no axenic cultivation of target microorganism, it has also been demonstrated as a valuable tool for dissecting the microbial ‘dark matter.’ In this review, current state-of-the-art tools and methods for genomic and transcriptomic analysis of microbes at single-cell level were critically summarized, including single-cell isolation methods and experimental strategies of single-cell analysis with NGS. In addition, perspectives on the future trends of technology development in the field of single-cell analysis was also presented.
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Affiliation(s)
- Zixi Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin UniversityTianjin, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin UniversityTianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and EngineeringTianjin, China
| | - Lei Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin UniversityTianjin, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin UniversityTianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and EngineeringTianjin, China
| | - Weiwen Zhang
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin UniversityTianjin, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin UniversityTianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and EngineeringTianjin, China.,Center for Biosafety Research and Strategy, Tianjin UniversityTianjin, China
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34
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Modi S, Vargas-Garcia CA, Ghusinga KR, Singh A. Analysis of Noise Mechanisms in Cell-Size Control. Biophys J 2017; 112:2408-2418. [PMID: 28591613 DOI: 10.1016/j.bpj.2017.04.050] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 03/27/2017] [Accepted: 04/24/2017] [Indexed: 11/15/2022] Open
Abstract
At the single-cell level, noise arises from multiple sources, such as inherent stochasticity of biomolecular processes, random partitioning of resources at division, and fluctuations in cellular growth rates. How these diverse noise mechanisms combine to drive variations in cell size within an isoclonal population is not well understood. Here, we investigate the contributions of different noise sources in well-known paradigms of cell-size control, such as adder (division occurs after adding a fixed size from birth), sizer (division occurs after reaching a size threshold), and timer (division occurs after a fixed time from birth). Analysis reveals that variation in cell size is most sensitive to errors in partitioning of volume among daughter cells, and not surprisingly, this process is well regulated among microbes. Moreover, depending on the dominant noise mechanism, different size-control strategies (or a combination of them) provide efficient buffering of size variations. We further explore mixer models of size control, where a timer phase precedes/follows an adder, as has been proposed in Caulobacter crescentus. Although mixing a timer and an adder can sometimes attenuate size variations, it invariably leads to higher-order moments growing unboundedly over time. This results in a power-law distribution for the cell size, with an exponent that depends inversely on the noise in the timer phase. Consistent with theory, we find evidence of power-law statistics in the tail of C. crescentus cell-size distribution, although there is a discrepancy between the observed power-law exponent and that predicted from the noise parameters. The discrepancy, however, is removed after data reveal that the size added by individual newborns in the adder phase itself exhibits power-law statistics. Taken together, this study provides key insights into the role of noise mechanisms in size homeostasis, and suggests an inextricable link between timer-based models of size control and heavy-tailed cell-size distributions.
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Affiliation(s)
- Saurabh Modi
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware
| | | | - Khem Raj Ghusinga
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware
| | - Abhyudai Singh
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware; Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware; Department of Mathematical Sciences, University of Delaware, Newark, Delaware.
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35
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36
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Priestman M, Thomas P, Robertson BD, Shahrezaei V. Mycobacteria Modify Their Cell Size Control under Sub-Optimal Carbon Sources. Front Cell Dev Biol 2017; 5:64. [PMID: 28748182 PMCID: PMC5506092 DOI: 10.3389/fcell.2017.00064] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/22/2017] [Indexed: 01/21/2023] Open
Abstract
The decision to divide is the most important one that any cell must make. Recent single cell studies suggest that most bacteria follow an “adder” model of cell size control, incorporating a fixed amount of cell wall material before dividing. Mycobacteria, including the causative agent of tuberculosis Mycobacterium tuberculosis, are known to divide asymmetrically resulting in heterogeneity in growth rate, doubling time, and other growth characteristics in daughter cells. The interplay between asymmetric cell division and adder size control has not been extensively investigated. Moreover, the impact of changes in the environment on growth rate and cell size control have not been addressed for mycobacteria. Here, we utilize time-lapse microscopy coupled with microfluidics to track live Mycobacterium smegmatis cells as they grow and divide over multiple generations, under a variety of growth conditions. We demonstrate that, under optimal conditions, M. smegmatis cells robustly follow the adder principle, with constant added length per generation independent of birth size, growth rate, and inherited pole age. However, the nature of the carbon source induces deviations from the adder model in a manner that is dependent on pole age. Understanding how mycobacteria maintain cell size homoeostasis may provide crucial targets for the development of drugs for the treatment of tuberculosis, which remains a leading cause of global mortality.
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Affiliation(s)
- Miles Priestman
- Department of Medicine, MRC Centre for Molecular Bacteriology and Infection, Imperial College LondonLondon, United Kingdom
| | - Philipp Thomas
- Department of Mathematics, Imperial College LondonLondon, United Kingdom
| | - Brian D Robertson
- Department of Medicine, MRC Centre for Molecular Bacteriology and Infection, Imperial College LondonLondon, United Kingdom
| | - Vahid Shahrezaei
- Department of Mathematics, Imperial College LondonLondon, United Kingdom
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