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Hall D. Equations describing semi-confluent cell growth (I) Analytical approximations. Biophys Chem 2024; 307:107173. [PMID: 38241828 DOI: 10.1016/j.bpc.2024.107173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/27/2023] [Accepted: 01/05/2024] [Indexed: 01/21/2024]
Abstract
A set of differential equations with analytical solutions are presented that can quantitatively account for variable degrees of contact inhibition on cell growth in two- and three-dimensional cultures. The developed equations can be used for comparative purposes when assessing contribution of higher-order effects, such as culture geometry and nutrient depletion, on mean cell growth rate. These equations also offer experimentalists the opportunity to characterize cell culture experiments using a single reductive parameter.
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Affiliation(s)
- Damien Hall
- WPI Nano Life Science Institute, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa 920-1164, Japan.
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2
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Machado MD, Soares EV. Features of the microalga Raphidocelis subcapitata: physiology and applications. Appl Microbiol Biotechnol 2024; 108:219. [PMID: 38372796 PMCID: PMC10876740 DOI: 10.1007/s00253-024-13038-0] [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: 08/30/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/20/2024]
Abstract
The microalga Raphidocelis subcapitata was isolated from the Nitelva River (Norway) and subsequently deposited in the collection of the Norwegian Institute of Water Research as "Selenastrum capricornutum Printz". This freshwater microalga, also known as Pseudokirchneriella subcapitata, acquired much of its notoriety due to its high sensitivity to different chemical species, which makes it recommended by different international organizations for the assessment of ecotoxicity. However, outside this scope, R. subcapitata continues to be little explored. This review aims to shed light on a microalga that, despite its popularity, continues to be an "illustrious" unknown in many ways. Therefore, R. subcapitata taxonomy, phylogeny, shape, size/biovolume, cell ultra-structure, and reproduction are reviewed. The nutritional and cultural conditions, chronological aging, and maintenance and preservation of the alga are summarized and critically discussed. Applications of R. subcapitata, such as its use in aquatic toxicology (ecotoxicity assessment and elucidation of adverse toxic outcome pathways) are presented. Furthermore, the latest advances in the use of this alga in biotechnology, namely in the bioremediation of effluents and the production of value-added biomolecules and biofuels, are highlighted. To end, a perspective regarding the future exploitation of R. subcapitata potentialities, in a modern concept of biorefinery, is outlined. KEY POINTS: • An overview of alga phylogeny and physiology is critically reviewed. • Advances in alga nutrition, cultural conditions, and chronological aging are presented. • Its use in aquatic toxicology and biotechnology is highlighted.
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Affiliation(s)
- Manuela D Machado
- Bioengineering Laboratory - CIETI, ISEP-School of Engineering, Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4249-015, Porto, Portugal
- CEB - Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
- LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Eduardo V Soares
- Bioengineering Laboratory - CIETI, ISEP-School of Engineering, Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4249-015, Porto, Portugal.
- CEB - Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
- LABBELS - Associate Laboratory, Braga/Guimarães, Portugal.
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3
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Liu D, Vargas-García CA, Singh A, Umen J. A cell-based model for size control in the multiple fission alga Chlamydomonas reinhardtii. Curr Biol 2023; 33:5215-5224.e5. [PMID: 37949064 PMCID: PMC10750806 DOI: 10.1016/j.cub.2023.10.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 08/03/2023] [Accepted: 10/16/2023] [Indexed: 11/12/2023]
Abstract
Understanding how population-size homeostasis emerges from stochastic individual cell behaviors remains a challenge in biology.1,2,3,4,5,6,7 The unicellular green alga Chlamydomonas reinhardtii (Chlamydomonas) proliferates using a multiple fission cell cycle, where a prolonged G1 phase is followed by n rounds of alternating division cycles (S/M) to produce 2n daughters. A "Commitment" sizer in mid-G1 phase ensures sufficient cell growth before completing the cell cycle. A mitotic sizer couples mother-cell size to division number (n) such that daughter size distributions are uniform regardless of mother size distributions. Although daughter size distributions were highly robust to altered growth conditions, ∼40% of daughter cells fell outside of the 2-fold range expected from a "perfect" multiple fission sizer.7,8 A simple intuitive power law model with stochastic noise failed to reproduce individual division behaviors of tracked single cells. Through additional iterative modeling, we identified an alternative modified threshold (MT) model, where cells need to cross a threshold greater than 2-fold their median starting size to become division-competent (i.e., Committed), after which their behaviors followed a power law model. The Commitment versus mitotic size threshold uncoupling in the MT model was likely a key pre-adaptation in the evolution of volvocine algal multicellularity. A similar experimental approach was used in size mutants mat3/rbr and dp1 that are, respectively, missing repressor or activator subunits of the retinoblastoma tumor suppressor complex (RBC). Both mutants showed altered relationships between Commitment and mitotic sizer, suggesting that RBC functions to decouple the two sizers.
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Affiliation(s)
- Dianyi Liu
- Donald Danforth Plant Science Center, 975 N Warson Rd, St. Louis, MO 63132, USA; Department of Biology, University of Missouri - St. Louis, 1 University Blvd, St. Louis, MO 63121, USA
| | | | - Abhyudai Singh
- Department of Electrical and Computer Engineering, Department of Biomedical Engineering, Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE 19716, USA.
| | - James Umen
- Donald Danforth Plant Science Center, 975 N Warson Rd, St. Louis, MO 63132, USA.
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4
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Széles E, Nagy K, Ábrahám Á, Kovács S, Podmaniczki A, Nagy V, Kovács L, Galajda P, Tóth SZ. Microfluidic Platforms Designed for Morphological and Photosynthetic Investigations of Chlamydomonas reinhardtii on a Single-Cell Level. Cells 2022; 11:cells11020285. [PMID: 35053401 PMCID: PMC8774182 DOI: 10.3390/cells11020285] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/07/2022] [Accepted: 01/13/2022] [Indexed: 11/16/2022] Open
Abstract
Chlamydomonas reinhardtii is a model organism of increasing biotechnological importance, yet, the evaluation of its life cycle processes and photosynthesis on a single-cell level is largely unresolved. To facilitate the study of the relationship between morphology and photochemistry, we established microfluidics in combination with chlorophyll a fluorescence induction measurements. We developed two types of microfluidic platforms for single-cell investigations: (i) The traps of the “Tulip” device are suitable for capturing and immobilizing single cells, enabling the assessment of their photosynthesis for several hours without binding to a solid support surface. Using this “Tulip” platform, we performed high-quality non-photochemical quenching measurements and confirmed our earlier results on bulk cultures that non-photochemical quenching is higher in ascorbate-deficient mutants (Crvtc2-1) than in the wild-type. (ii) The traps of the “Pot” device were designed for capturing single cells and allowing the growth of the daughter cells within the traps. Using our most performant “Pot” device, we could demonstrate that the FV/FM parameter, an indicator of photosynthetic efficiency, varies considerably during the cell cycle. Our microfluidic devices, therefore, represent versatile platforms for the simultaneous morphological and photosynthetic investigations of C. reinhardtii on a single-cell level.
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Affiliation(s)
- Eszter Széles
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary; (E.S.); (S.K.); (A.P.); (V.N.); (L.K.)
- Doctoral School of Biology, University of Szeged, H-6722 Szeged, Hungary
| | - Krisztina Nagy
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary; (K.N.); (Á.Á.); (P.G.)
| | - Ágnes Ábrahám
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary; (K.N.); (Á.Á.); (P.G.)
- Doctoral School of Multidisciplinary Medical Sciences, University of Szeged, H-6720 Szeged, Hungary
| | - Sándor Kovács
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary; (E.S.); (S.K.); (A.P.); (V.N.); (L.K.)
| | - Anna Podmaniczki
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary; (E.S.); (S.K.); (A.P.); (V.N.); (L.K.)
- Doctoral School of Biology, University of Szeged, H-6722 Szeged, Hungary
| | - Valéria Nagy
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary; (E.S.); (S.K.); (A.P.); (V.N.); (L.K.)
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary; (E.S.); (S.K.); (A.P.); (V.N.); (L.K.)
| | - Péter Galajda
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary; (K.N.); (Á.Á.); (P.G.)
| | - Szilvia Z. Tóth
- Institute of Plant Biology, Biological Research Centre, H-6726 Szeged, Hungary; (E.S.); (S.K.); (A.P.); (V.N.); (L.K.)
- Correspondence:
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5
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Dominant rule of community effect in synchronized beating behavior of cardiomyocyte networks. Biophys Rev 2020; 12:481-501. [PMID: 32367300 DOI: 10.1007/s12551-020-00688-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 03/03/2020] [Indexed: 10/24/2022] Open
Abstract
Exploiting the combination of latest microfabrication technologies and single cell measurement technologies, we can measure the interactions of single cells, and cell networks from "algebraic" and "geometric" perspectives under the full control of their environments and interactions. However, the experimental constructive single cell-based approach still remains the limitations regarding the quality and condition control of those cells. To overcome these limitations, mathematical modeling is one of the most powerful complementary approaches. In this review, we first explain our on-chip experimental methods for constructive approach, and we introduce the results of the "community effect" of beating cardiomyocyte networks as an example of this approach. On-chip analysis revealed that (1) synchronized interbeat intervals (IBIs) of cell networks were followed to the more stable beating cells even their IBIs were slower than the other cells, which is against the conventional faster firing regulation or "overdrive suppression," and (2) fluctuation of IBIs of cardiomyocyte networks decreased according to the increase of the number of connected cells regardless of their geometry. The mathematical simulation of this synchronous behavior of cardiomyocyte networks also fitted well with the experimental results after incorporating the fluctuation-dissipation theorem into the oscillating stochastic phase model, in which the concept of spatially arranged cardiomyocyte networks was involved. The constructive experiments and mathematical modeling indicated the dominant rule of synchronization behavior of beating cardiomyocyte networks is a kind of stability-oriented synchronization phenomenon as the "community effect" or a fluctuation-dissipation phenomenon. Finally, as a practical application of this approach, the predictive cardiotoxicity is introduced.
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6
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Heldt FS, Tyson JJ, Cross FR, Novák B. A Single Light-Responsive Sizer Can Control Multiple-Fission Cycles in Chlamydomonas. Curr Biol 2020; 30:634-644.e7. [DOI: 10.1016/j.cub.2019.12.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 09/25/2019] [Accepted: 12/09/2019] [Indexed: 12/18/2022]
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7
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Analysis of population structures of the microalga Acutodesmus obliquus during lipid production using multi-dimensional single-cell analysis. Sci Rep 2018; 8:6242. [PMID: 29674634 PMCID: PMC5908859 DOI: 10.1038/s41598-018-24638-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 04/03/2018] [Indexed: 02/08/2023] Open
Abstract
Microalgae bear a great potential to produce lipids for biodiesel, feed, or even food applications. To understand the still not well-known single-cell dynamics during lipid production in microalgae, a novel single-cell analytical technology was applied to study a well-established model experiment. Multidimensional single-cell dynamics were investigated with a non-supervised image analysis technique that utilizes data from epi-fluorescence microscopy. Reliability of this technique was successfully proven via reference analysis. The technique developed was used to determine cell size, chlorophyll amount, neutral lipid amount, and deriving properties on a single-cellular level in cultures of the biotechnologically promising alga Acutodesmus obliquus. The results illustrated a high correlation between cell size and chlorophyll amount, but a very low and dynamic correlation between cell size, lipid amount, and lipid density. During growth conditions under nitrogen starvation, cells with low chlorophyll content tend to start the lipid production first and the cell suspension differentiated in two subpopulations with significantly different lipid contents. Such quantitative characterization of single-cell dynamics of lipid synthesizing algae was done for the first time and the potential of such simple technology is highly relevant to other biotechnological applications and to deeper investigate the process of microalgal lipid accumulation.
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8
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Brennan GL, Colegrave N, Collins S. Evolutionary consequences of multidriver environmental change in an aquatic primary producer. Proc Natl Acad Sci U S A 2017; 114:9930-9935. [PMID: 28847969 PMCID: PMC5604004 DOI: 10.1073/pnas.1703375114] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Climate change is altering aquatic environments in a complex way, and simultaneous shifts in many properties will drive evolutionary responses in primary producers at the base of both freshwater and marine ecosystems. So far, evolutionary studies have shown how changes in environmental drivers, either alone or in pairs, affect the evolution of growth and other traits in primary producers. Here, we evolve a primary producer in 96 unique environments with different combinations of between one and eight environmental drivers to understand how evolutionary responses to environmental change depend on the identity and number of drivers. Even in multidriver environments, only a few dominant drivers explain most of the evolutionary changes in population growth rates. Most populations converge on the same growth rate by the end of the evolution experiment. However, populations adapt more when these dominant drivers occur in the presence of other drivers. This is due to an increase in the intensity of selection in environments with more drivers, which are more likely to include dominant drivers. Concurrently, many of the trait changes that occur during the initial short-term response to both single and multidriver environmental change revert after about 450 generations of evolution. In future aquatic environments, populations will encounter differing combinations of drivers and intensities of selection, which will alter the adaptive potential of primary producers. Accurately gauging the intensity of selection on key primary producers will help in predicting population size and trait evolution at the base of aquatic food webs.
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Affiliation(s)
- Georgina L Brennan
- Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom
- Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Bangor University, Bangor LL57 2UW, United Kingdom
| | - Nick Colegrave
- Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom
| | - Sinéad Collins
- Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom;
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9
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de Winter L, Cabanelas I, Órfão A, Vaessen E, Martens D, Wijffels R, Barbosa M. The influence of day length on circadian rhythms of Neochloris oleoabundans. ALGAL RES 2017. [DOI: 10.1016/j.algal.2016.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Shelton DE, Leslie MP, Michod RE. Models of cell division initiation in Chlamydomonas: A challenge to the consensus view. J Theor Biol 2017; 412:186-197. [PMID: 27816674 DOI: 10.1016/j.jtbi.2016.10.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 09/19/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
We develop and compare two models for division initiation in cells of the unicellular green alga Chlamydomonas reinhardtii, a topic that has remained controversial in spite of years of empirical work. Achieving a better understanding of C. reinhardtii cell cycle regulation is important because this species is used in studies of fundamental eukaryotic cell features and in studies of the evolution of multicellularity. C. reinhardtii proliferates asexually by multiple fission, interspersing rapid rounds of symmetric division with prolonged periods of growth. Our Model 1 reflects major elements of the current consensus view on C. reinhardtii division initiation, with cells first growing to a specific size, then waiting for a particular time prior to division initiation. In Model 2, our proposed alternative, growing cells divide when they have reached a growth-rate-dependent target size. The two models imply a number of different empirical patterns. We highlight these differences alongside published data, which currently fall short of unequivocally distinguishing these differences in predicted cell behavior. Nevertheless, several lines of evidence are suggestive of more Model 2-like behavior than Model 1-like behavior. Our specification of these models adds rigor to issues that have too often been worked out in relation to loose, verbal models and is directly relevant to future development of informative experiments.
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Affiliation(s)
- Deborah E Shelton
- Department of Ecology and Evolutionary Biology, University of Arizona, 1041 E. Lowell St. Tucson, AZ 85721, United States.
| | - Martin P Leslie
- Department of Ecology and Evolutionary Biology, University of Arizona, 1041 E. Lowell St. Tucson, AZ 85721, United States
| | - Richard E Michod
- Department of Ecology and Evolutionary Biology, University of Arizona, 1041 E. Lowell St. Tucson, AZ 85721, United States; Kavli Institute for Theoretical Physics, University of California Santa Barbara, Santa Barbara, CA 93106, United States
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11
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Seed CE, Tomkins JL. Flow Cytometric Methods for Indirect Analysis and Quantification of Gametogenesis in Chlamydomonas reinhardtii (Chlorophyceae). PLoS One 2016; 11:e0161453. [PMID: 27676075 PMCID: PMC5038954 DOI: 10.1371/journal.pone.0161453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/06/2016] [Indexed: 11/30/2022] Open
Abstract
Induction of sexual reproduction in the facultatively sexual Chlamydomonas reinhardtii is cued by depletion of nitrogen. We explore the capacity for indirect monitoring of population variation in the gametogenic process using flow cytometry. We describe a high-throughput method capable of identifying fluorescence, ploidy and scatter profiles that track vegetative cells entering and undergoing gametogenesis. We demonstrate for the first time, that very early and late growth phases reduce the capacity to distinguish putative gametes from vegetative cells based on scatter and fluorescence profiles, and that early/mid-logarithmic cultures show the optimal distinction between vegetative cells and gamete scatter profiles. We argue that early/mid logarithmic cultures are valuable in such high throughput comparative approaches when investigating optimisation or quantification of gametogenesis based on scatter and fluorescence profiles. This approach provides new insights into the impact of culture conditions on gametogenesis, while documenting novel scatter and fluorescence profile shifts which typify the process. This method has potential applications to; enabling quick high-throughput monitoring, uses in increasing efficiency in the quantification of gametogenesis, as a method of comparing the switch between vegetative and gametic states across treatments, and as criteria for enrichment of gametic phenotypes in cell sorting assays.
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Affiliation(s)
- Catherine E. Seed
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, Australia
- * E-mail:
| | - Joseph L. Tomkins
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, Australia
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12
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Yagi T, Yamashita K, Okada N, Isono T, Momose D, Mineki S, Tokunaga E. Hydrogen photoproduction in green algae Chlamydomonas reinhardtii sustainable over 2 weeks with the original cell culture without supply of fresh cells nor exchange of the whole culture medium. JOURNAL OF PLANT RESEARCH 2016; 129:771-779. [PMID: 27083446 DOI: 10.1007/s10265-016-0825-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/14/2016] [Indexed: 06/05/2023]
Abstract
Unicellular green algae Chlamydomonas reinhardtii are known to make hydrogen photoproduction under the anaerobic condition with water molecules as the hydrogen source. Since the hydrogen photoproduction occurs for a cell to circumvent crisis of its survival, it is only temporary. It is a challenge to realize persistent hydrogen production because the cells must withstand stressful conditions to survive with alternation of generations in the cell culture. In this paper, we have found a simple and cost-effective method to sustain the hydrogen production over 14 days in the original culture, without supply of fresh cells nor exchange of the culture medium. This is achieved for the cells under hydrogen production in a sulfur-deprived culture solution on the {anaerobic, intense light} condition in a desiccator, by periodically providing a short period of the recovery time (2 h) with a small amount of TAP(+S) supplied outside of the desiccator. As this operation is repeated, the response time of transition into hydrogen production (preparation time) is shortened and the rate of hydrogen production (build up time) is increased. The optimum states of these properties favorable to the hydrogen production are attained in a few days and stably sustained for more than 10 days. Since generations are alternated during this consecutive hydrogen production experiment, it is suggested that the improved hydrogen production properties are inherited to next generations without genetic mutation. The properties are reset only when the cells are placed on the {sulfur-sufficient, aerobic, moderate light} conditions for a long time (more than 1 day at least).
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Affiliation(s)
- Takafumi Yagi
- Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Kyohei Yamashita
- Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Norihide Okada
- Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Takumi Isono
- Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Daisuke Momose
- Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Shigeru Mineki
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba-ken, 278-8510, Japan
| | - Eiji Tokunaga
- Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
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13
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14
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Cross FR, Umen JG. The Chlamydomonas cell cycle. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 82:370-392. [PMID: 25690512 PMCID: PMC4409525 DOI: 10.1111/tpj.12795] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/03/2015] [Accepted: 02/04/2015] [Indexed: 05/18/2023]
Abstract
The position of Chlamydomonas within the eukaryotic phylogeny makes it a unique model in at least two important ways: as a representative of the critically important, early-diverging lineage leading to plants; and as a microbe retaining important features of the last eukaryotic common ancestor (LECA) that has been lost in the highly studied yeast lineages. Its cell biology has been studied for many decades and it has well-developed experimental genetic tools, both classical (Mendelian) and molecular. Unlike land plants, it is a haploid with very few gene duplicates, making it ideal for loss-of-function genetic studies. The Chlamydomonas cell cycle has a striking temporal and functional separation between cell growth and rapid cell division, probably connected to the interplay between diurnal cycles that drive photosynthetic cell growth and the cell division cycle; it also exhibits a highly choreographed interaction between the cell cycle and its centriole-basal body-flagellar cycle. Here, we review the current status of studies of the Chlamydomonas cell cycle. We begin with an overview of cell-cycle control in the well-studied yeast and animal systems, which has yielded a canonical, well-supported model. We discuss briefly what is known about similarities and differences in plant cell-cycle control, compared with this model. We next review the cytology and cell biology of the multiple-fission cell cycle of Chlamydomonas. Lastly, we review recent genetic approaches and insights into Chlamydomonas cell-cycle regulation that have been enabled by a new generation of genomics-based tools.
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Affiliation(s)
| | - James G Umen
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
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15
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Rading MM, Sandmann M, Steup M, Chiarugi D, Valleriani A. Weak correlation of starch and volume in synchronized photosynthetic cells. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:012711. [PMID: 25679646 DOI: 10.1103/physreve.91.012711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Indexed: 06/04/2023]
Abstract
In cultures of unicellular algae, features of single cells, such as cellular volume and starch content, are thought to be the result of carefully balanced growth and division processes. Single-cell analyses of synchronized photoautotrophic cultures of the unicellular alga Chlamydomonas reinhardtii reveal, however, that the cellular volume and starch content are only weakly correlated. Likewise, other cell parameters, e.g., the chlorophyll content per cell, are only weakly correlated with cell size. We derive the cell size distributions at the beginning of each synchronization cycle considering growth, timing of cell division and daughter cell release, and the uneven division of cell volume. Furthermore, we investigate the link between cell volume growth and starch accumulation. This work presents evidence that, under the experimental conditions of light-dark synchronized cultures, the weak correlation between both cell features is a result of a cumulative process rather than due to asymmetric partition of biomolecules during cell division. This cumulative process necessarily limits cellular similarities within a synchronized cell population.
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Affiliation(s)
- M Michael Rading
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Michael Sandmann
- innoFSPEC, Institut für Chemie, Universität Potsdam, Physikalische Chemie, 14476 Potsdam, Germany
| | - Martin Steup
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Davide Chiarugi
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Angelo Valleriani
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
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16
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Park JW, Na SC, Nguyen TQ, Paik SM, Kang M, Hong D, Choi IS, Lee JH, Jeon NL. Live cell imaging compatible immobilization of Chlamydomonas reinhardtii in microfluidic platform for biodiesel research. Biotechnol Bioeng 2014; 112:494-501. [PMID: 25220860 DOI: 10.1002/bit.25453] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/19/2014] [Accepted: 09/05/2014] [Indexed: 11/06/2022]
Abstract
This paper describes a novel surface immobilization method for live-cell imaging of Chlamydomonas reinhardtii for continuous monitoring of lipid droplet accumulation. Microfluidics allows high-throughput manipulation and analysis of single cells in precisely controlled microenvironment. Fluorescence imaging based quantitative measurement of lipid droplet accumulation in microalgae had been difficult due to their intrinsic motile behavior. We present a simple surface immobilization method using gelatin coating as the "biological glue." We take advantage of hydroxyproline (Hyp)-based non-covalent interaction between gelatin and the outer cell wall of microalgae to anchor the cells inside the microfluidic device. We have continuously monitored single microalgal cells for up to 6 days. The immobilized microalgae remain viable (viability was comparable to bulk suspension cultured controls). When exposed to wall shear stress, most of the cells remain attached up to 0.1 dyne/cm(2) . Surface immobilization allowed high-resolution, live-cell imaging of mitotic process in real time-which followed previously reported stages in mitosis of suspension cultured cells. Use of gelatin coated microfluidics devices can result in better methods for microalgae strain screening and culture condition optimization that will help microalgal biodiesel become more economically viable.
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Affiliation(s)
- Jae Woo Park
- Division of WCU (World Class University) Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Korea
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Machado MD, Soares EV. Modification of cell volume and proliferative capacity of Pseudokirchneriella subcapitata cells exposed to metal stress. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 147:1-6. [PMID: 24342441 DOI: 10.1016/j.aquatox.2013.11.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 11/14/2013] [Accepted: 11/26/2013] [Indexed: 06/03/2023]
Abstract
The impact of metals (Cd, Cr, Cu and Zn) on growth, cell volume and cell division of the freshwater alga Pseudokirchneriella subcapitata exposed over a period of 72 h was investigated. The algal cells were exposed to three nominal concentrations of each metal: low (closed to 72 h-EC10 values), intermediate (closed to 72 h-EC50 values) and high (upper than 72 h-EC90 values). The exposure to low metal concentrations resulted in a decrease of cell volume. On the contrary, for the highest metal concentrations an increase of cell volume was observed; this effect was particularly notorious for Cd and less pronounced for Zn. Two behaviours were found when algal cells were exposed to intermediate concentrations of metals: Cu(II) and Cr(VI) induced a reduction of cell volume, while Cd(II) and Zn(II) provoked an opposite effect. The simultaneous nucleus staining and cell image analysis, allowed distinguishing three phases in P. subcapitata cell cycle: growth of mother cell; cell division, which includes two divisions of the nucleus; and, release of four autospores. The exposure of P. subcapitata cells to the highest metal concentrations resulted in the arrest of cell growth before the first nucleus division [for Cr(VI) and Cu(II)] or after the second nucleus division but before the cytokinesis (release of autospores) when exposed to Cd(II). The different impact of metals on algal cell volume and cell-cycle progression, suggests that different toxicity mechanisms underlie the action of different metals studied. The simultaneous nucleus staining and cell image analysis, used in the present work, can be a useful tool in the analysis of the toxicity of the pollutants, in P. subcapitata, and help in the elucidation of their different modes of action.
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Affiliation(s)
- Manuela D Machado
- Bioengineering Laboratory-CIETI, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4200-072 Porto, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Eduardo V Soares
- Bioengineering Laboratory-CIETI, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4200-072 Porto, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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Yasuda K. On-chip cellomics: Single-cell-based constructive cell-network assay for quasi-in vivo screening of cardiotoxicity. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:2825-8. [PMID: 24110315 DOI: 10.1109/embc.2013.6610128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have developed methods and systems of analyzing epigenetic information in cells, as well as that of genetic information, to expand our understanding of how living systems are determined. A system of analyzing epigenetic information was developed starting from the twin complementary viewpoints of cell regulation as an 'algebraic' system (emphasis on temporal aspects) and as a 'geometric' system (emphasis on spatial aspects). As an example of the 'geometric' system, we have developed an quasi-in vivo hiPS cardiomyocyte network assay and confirmed that it can predict the risk of lethal arrythmia correctly in 22 compounds. The knowlege acquired from this study may lead to the use of cells that fully control practical applications like cell-based drug screening and the regeneration of organs.
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19
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The synchronized cell cycle of Neochloris oleoabundans and its influence on biomass composition under constant light conditions. ALGAL RES 2013. [DOI: 10.1016/j.algal.2013.09.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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20
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Glaesener AG, Merchant SS, Blaby-Haas CE. Iron economy in Chlamydomonas reinhardtii. FRONTIERS IN PLANT SCIENCE 2013; 4:337. [PMID: 24032036 PMCID: PMC3759009 DOI: 10.3389/fpls.2013.00337] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 08/09/2013] [Indexed: 05/05/2023]
Abstract
While research on iron nutrition in plants has largely focused on iron-uptake pathways, photosynthetic microbes such as the unicellular green alga Chlamydomonas reinhardtii provide excellent experimental systems for understanding iron metabolism at the subcellular level. Several paradigms in iron homeostasis have been established in this alga, including photosystem remodeling in the chloroplast and preferential retention of some pathways and key iron-dependent proteins in response to suboptimal iron supply. This review presents our current understanding of iron homeostasis in Chlamydomonas, with specific attention on characterized responses to changes in iron supply, like iron-deficiency. An overview of frequently used methods for the investigation of iron-responsive gene expression, physiology and metabolism is also provided, including preparation of media, the effect of cell size, cell density and strain choice on quantitative measurements and methods for the determination of metal content and assessing the effect of iron supply on photosynthetic performance.
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Affiliation(s)
- Anne G. Glaesener
- Department of Chemistry and Biochemistry, University of California, Los AngelesLos Angeles, CA, USA
| | - Sabeeha S. Merchant
- Department of Chemistry and Biochemistry, University of California, Los AngelesLos Angeles, CA, USA
- Institute of Genomics and Proteomics, David Geffen School of Medicine at the University of CaliforniaLos Angeles, CA, USA
| | - Crysten E. Blaby-Haas
- Department of Chemistry and Biochemistry, University of California, Los AngelesLos Angeles, CA, USA
- *Correspondence: Crysten E. Blaby-Haas, Department of Chemistry and Biochemistry, University of California, Box 951569, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569, USA e-mail:
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On-chip cellomics assay enabling algebraic and geometric understanding of epigenetic information in cellular networks of living systems. 1. Temporal aspects of epigenetic information in bacteria. SENSORS 2012; 12:7169-206. [PMID: 22969343 PMCID: PMC3435972 DOI: 10.3390/s120607169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 05/24/2012] [Accepted: 05/24/2012] [Indexed: 11/16/2022]
Abstract
A series of studies aimed at developing methods and systems of analyzing epigenetic information in cells and in cell networks, as well as that of genetic information, was examined to expand our understanding of how living systems are determined. Because cells are minimum units reflecting epigenetic information, which is considered to map the history of a parallel-processing recurrent network of biochemical reactions, their behaviors cannot be explained by considering only conventional DNA information-processing events. The role of epigenetic information on cells, which complements their genetic information, was inferred by comparing predictions from genetic information with cell behaviour observed under conditions chosen to reveal adaptation processes, population effects and community effects. A system of analyzing epigenetic information was developed starting from the twin complementary viewpoints of cell regulation as an “algebraic” system (emphasis on temporal aspects) and as a “geometric” system (emphasis on spatial aspects). Exploiting the combination of latest microfabrication technology and measurement technologies, which we call on-chip cellomics assay, we can control and re-construct the environments and interaction of cells from “algebraic” and “geometric” viewpoints. In this review, temporal viewpoint of epigenetic information, a part of the series of single-cell-based “algebraic” and “geometric” studies of celluler systems in our research groups, are summerized and reported. The knowlege acquired from this study may lead to the use of cells that fully control practical applications like cell-based drug screening and the regeneration of organs.
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A Short-Term Advantage for Syngamy in the Origin of Eukaryotic Sex: Effects of Cell Fusion on Cell Cycle Duration and Other Effects Related to the Duration of the Cell Cycle-Relationship between Cell Growth Curve and the Optimal Size of the Species, and Circadian Cell Cycle in Photosynthetic Unicellular Organisms. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:746825. [PMID: 22666626 PMCID: PMC3361227 DOI: 10.1155/2012/746825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 12/21/2011] [Accepted: 12/23/2011] [Indexed: 11/24/2022]
Abstract
The origin of sex is becoming a vexatious issue for Evolutionary Biology. Numerous hypotheses have been proposed, based on the genetic effects of sex, on trophic effects or on the formation of cysts and syncytia. Our approach addresses the change in cell cycle duration which would cause cell fusion. Several results are obtained through graphical and mathematical analysis and computer simulations. (1) In poor environments, cell fusion would be an advantageous strategy, as fusion between cells of different size shortens the cycle of the smaller cell (relative to the asexual cycle), and the majority of mergers would occur between cells of different sizes. (2) The easiest-to-evolve regulation of cell proliferation (sexual/asexual) would be by modifying the checkpoints of the cell cycle. (3) A regulation of this kind would have required the existence of the G2 phase, and sex could thus be the cause of the appearance of this phase. Regarding cell cycle, (4) the exponential curve is the only cell growth curve that has no effect on the optimal cell size in unicellular species; (5) the existence of a plateau with no growth at the end of the cell cycle explains the circadian cell cycle observed in unicellular algae.
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Olson BJ, Oberholzer M, Li Y, Zones JM, Kohli HS, Bisova K, Fang SC, Meisenhelder J, Hunter T, Umen JG. Regulation of the Chlamydomonas cell cycle by a stable, chromatin-associated retinoblastoma tumor suppressor complex. THE PLANT CELL 2010; 22:3331-47. [PMID: 20978220 PMCID: PMC2990127 DOI: 10.1105/tpc.110.076067] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 08/31/2010] [Accepted: 10/09/2010] [Indexed: 05/19/2023]
Abstract
We examined the cell cycle dynamics of the retinoblastoma (RB) protein complex in the unicellular alga Chlamydomonas reinhardtii that has single homologs for each subunit-RB, E2F, and DP. We found that Chlamydomonas RB (encoded by MAT3) is a cell cycle-regulated phosphoprotein, that E2F1-DP1 can bind to a consensus E2F site, and that all three proteins interact in vivo to form a complex that can be quantitatively immunopurified. Yeast two-hybrid assays revealed the formation of a ternary complex between MAT3, DP1, and E2F1 that requires a C-terminal motif in E2F1 analogous to the RB binding domain of plant and animal E2Fs. We examined the abundance of MAT3/RB and E2F1-DP1 in highly synchronous cultures and found that they are synthesized and remain stably associated throughout the cell cycle with no detectable fraction of free E2F1-DP1. Consistent with their stable association, MAT3/RB and DP1 are constitutively nuclear, and MAT3/RB does not require DP1-E2F1 for nuclear localization. In the nucleus, MAT3/RB remains bound to chromatin throughout the cell cycle, and its chromatin binding is mediated through E2F1-DP1. Together, our data show that E2F-DP complexes can regulate the cell cycle without dissociation of their RB-related subunit and that other changes may be sufficient to convert RB-E2F-DP from a cell cycle repressor to an activator.
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Affiliation(s)
- Bradley J.S.C. Olson
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Michael Oberholzer
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Yubing Li
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - James M. Zones
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Harjivan S. Kohli
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Katerina Bisova
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Su-Chiung Fang
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Jill Meisenhelder
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - James G. Umen
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
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Algebraic and Geometric Understanding of Cells: Epigenetic Inheritance of Phenotypes Between Generations. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2010; 124:55-81. [DOI: 10.1007/10_2010_97] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Oldenhof H, Zachleder V, Van den Ende H. The cell cycle of Chlamydomonas reinhardtii: the role of the commitment point. Folia Microbiol (Praha) 2007; 52:53-60. [PMID: 17571796 DOI: 10.1007/bf02932138] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Chlamydomonas reinhardtii cells can double their size several times during the light period before they enter the division phase. To explain the role of the commitment point (defined as the moment in the cell cycle after which cells can complete the cell cycle independently of light) and the moment of initiation of cell division we investigated whether the timing of commitment to cell division and cell division itself are dependent upon cell size or if they are under control of a timer mechanism that measures a period of constant duration. The time point at which cells attain commitment to cell division was dependent on the growth rate and coincided with the moment at which cells have approximately doubled in size. The timing of cell division was temperature-dependent and took place after a period of constant duration from the onset of the light period, irrespective of the light intensity and timing of the commitment point. We concluded that at the commitment point all the prerequisites are checked, which is required for progression through the cell cycle; the commitment point is not the moment at which cell division is initiated but it functions as a checkpoint, which ensures that cells have passed the minimum cell size required for the cell division.
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Affiliation(s)
- H Oldenhof
- Laboratory of Plant Physiology, Swammerdam Institute for Life Sciences, University ofAmsterdam, 1098 SM Amsterdam, The Netherlands.
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26
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Fang SC, Reyes CDL, Umen JG. Cell size checkpoint control by the retinoblastoma tumor suppressor pathway. PLoS Genet 2006; 2:e167. [PMID: 17040130 PMCID: PMC1599770 DOI: 10.1371/journal.pgen.0020167] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Accepted: 08/17/2006] [Indexed: 01/15/2023] Open
Abstract
Size control is essential for all proliferating cells, and is thought to be regulated by checkpoints that couple cell size to cell cycle progression. The aberrant cell-size phenotypes caused by mutations in the retinoblastoma (RB) tumor suppressor pathway are consistent with a role in size checkpoint control, but indirect effects on size caused by altered cell cycle kinetics are difficult to rule out. The multiple fission cell cycle of the unicellular alga Chlamydomonas reinhardtii uncouples growth from division, allowing direct assessment of the relationship between size phenotypes and checkpoint function. Mutations in the C. reinhardtii RB homolog encoded by MAT3 cause supernumerous cell divisions and small cells, suggesting a role for MAT3 in size control. We identified suppressors of an mat3 null allele that had recessive mutations in DP1 or dominant mutations in E2F1, loci encoding homologs of a heterodimeric transcription factor that is targeted by RB-related proteins. Significantly, we determined that the dp1 and e2f1 phenotypes were caused by defects in size checkpoint control and were not due to a lengthened cell cycle. Despite their cell division defects, mat3, dp1, and e2f1 mutants showed almost no changes in periodic transcription of genes induced during S phase and mitosis, many of which are conserved targets of the RB pathway. Conversely, we found that regulation of cell size was unaffected when S phase and mitotic transcription were inhibited. Our data provide direct evidence that the RB pathway mediates cell size checkpoint control and suggest that such control is not directly coupled to the magnitude of periodic cell cycle transcription. All cell types have a characteristic size, but the means by which cell size is determined remain mysterious. In proliferating cells, control mechanisms termed checkpoints are thought to prevent cells from dividing until they have reached a minimum size, but the nature of size checkpoints has proved difficult to dissect. The unicellular alga Chlamydomonas reinhardtii divides via an unusual mechanism that uncouples growth from division, and thereby allows a direct assessment of how different genetic pathways contribute to size control. The retinoblastoma (RB) tumor suppressor pathway is a critical regulator of cell cycle control in plants and animals and is thought to act as a transcriptional switch for cell cycle genes, but it had not been directly implicated in cell size checkpoint function. The authors found that mutations in genes that encode key proteins of the RB pathway in Chlamydomonas affect cell size and cell cycle control by altering size checkpoint function. Unexpectedly, the predicted transcriptional targets of the RB pathway were not affected by the mutations, and blocking transcription did not alter cell size control. These data link the RB tumor suppressor pathway directly to size control and suggest the possibility that cell size and cell cycle control by the RB pathway may not be coupled to its transcriptional output.
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Affiliation(s)
- Su-Chiung Fang
- Plant Biology Laboratory, The Salk Institute, La Jolla, California, United States of America
| | - Chris de los Reyes
- Plant Biology Laboratory, The Salk Institute, La Jolla, California, United States of America
| | - James G Umen
- Plant Biology Laboratory, The Salk Institute, La Jolla, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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27
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Wakamoto Y, Ramsden J, Yasuda K. Single-cell growth and division dynamics showing epigenetic correlations. Analyst 2005; 130:311-7. [PMID: 15724159 DOI: 10.1039/b409860a] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The emergence of variation and subsequent inheritance of the emergent characteristics in a clonal population of bacteria is considered as evidence for epigenetic processes in the cell. We report here the results of experiments in which we quantitatively examined variations in single Escherichia coli cells with an identical genetic endowment in order to establish whether certain characteristics of single cells were inherited by their descendants maintained in a uniform environment. Significantly large variations of interdivision time, initial length, and final length were observed from generation to generation. Comparing the generations shows that interdivision time had no correlation with that of the consecutive generations, whereas those of initial length and final length were positively correlated with those of neighbouring generations.
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Affiliation(s)
- Yuichi Wakamoto
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
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28
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Yasuda K. Biotechnology approach to determination of genetic and epigenetic control in cells. J Nanobiotechnology 2004; 2:11. [PMID: 15555071 PMCID: PMC535532 DOI: 10.1186/1477-3155-2-11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2003] [Accepted: 11/22/2004] [Indexed: 11/23/2022] Open
Abstract
A series of studies aimed at developing methods and systems for analyzing epigenetic information in cells are presented. The role of the epigenetic information of cells, which is complementary to their genetic information, was inferred by comparing the predictions of genetic information with the cell behaviour observed under conditions chosen to reveal adaptation processes and community effects. Analysis of epigenetic information was developed starting from the twin complementary viewpoints of cells regulation as an 'algebraic' system (emphasis on the temporal aspect) and as a 'geometric' system (emphasis on the spatial aspect). The knowlege acquired from this study will lead to the use of cells for fully controlled practical applications like cell-based drug screening and the regeneration of organs.
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Affiliation(s)
- Kenji Yasuda
- Department of Life Sciences, Graduate school of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 JAPAN.
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29
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Brehm-Stecher BF, Johnson EA. Single-cell microbiology: tools, technologies, and applications. Microbiol Mol Biol Rev 2004; 68:538-59, table of contents. [PMID: 15353569 PMCID: PMC515252 DOI: 10.1128/mmbr.68.3.538-559.2004] [Citation(s) in RCA: 297] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The field of microbiology has traditionally been concerned with and focused on studies at the population level. Information on how cells respond to their environment, interact with each other, or undergo complex processes such as cellular differentiation or gene expression has been obtained mostly by inference from population-level data. Individual microorganisms, even those in supposedly "clonal" populations, may differ widely from each other in terms of their genetic composition, physiology, biochemistry, or behavior. This genetic and phenotypic heterogeneity has important practical consequences for a number of human interests, including antibiotic or biocide resistance, the productivity and stability of industrial fermentations, the efficacy of food preservatives, and the potential of pathogens to cause disease. New appreciation of the importance of cellular heterogeneity, coupled with recent advances in technology, has driven the development of new tools and techniques for the study of individual microbial cells. Because observations made at the single-cell level are not subject to the "averaging" effects characteristic of bulk-phase, population-level methods, they offer the unique capacity to observe discrete microbiological phenomena unavailable using traditional approaches. As a result, scientists have been able to characterize microorganisms, their activities, and their interactions at unprecedented levels of detail.
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Affiliation(s)
- Byron F Brehm-Stecher
- Department of Food Microbiology and Toxicology, University of Wisconsin-Madison Food Research Institute, 1925 Willow Drive, Madison, WI 53706, USA
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