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Chadha Y, Khurana A, Schmoller KM. Eukaryotic cell size regulation and its implications for cellular function and dysfunction. Physiol Rev 2024; 104:1679-1717. [PMID: 38900644 DOI: 10.1152/physrev.00046.2023] [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: 12/26/2023] [Revised: 05/24/2024] [Accepted: 06/19/2024] [Indexed: 06/22/2024] Open
Abstract
Depending on cell type, environmental inputs, and disease, the cells in the human body can have widely different sizes. In recent years, it has become clear that cell size is a major regulator of cell function. However, we are only beginning to understand how the optimization of cell function determines a given cell's optimal size. Here, we review currently known size control strategies of eukaryotic cells and the intricate link of cell size to intracellular biomolecular scaling, organelle homeostasis, and cell cycle progression. We detail the cell size-dependent regulation of early development and the impact of cell size on cell differentiation. Given the importance of cell size for normal cellular physiology, cell size control must account for changing environmental conditions. We describe how cells sense environmental stimuli, such as nutrient availability, and accordingly adapt their size by regulating cell growth and cell cycle progression. Moreover, we discuss the correlation of pathological states with misregulation of cell size and how for a long time this was considered a downstream consequence of cellular dysfunction. We review newer studies that reveal a reversed causality, with misregulated cell size leading to pathophysiological phenotypes such as senescence and aging. In summary, we highlight the important roles of cell size in cellular function and dysfunction, which could have major implications for both diagnostics and treatment in the clinic.
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Affiliation(s)
- Yagya Chadha
- Institute of Functional Epigenetics, Molecular Targets and Therapeutics Center, Helmholtz Zentrum München, Neuherberg, Germany
| | - Arohi Khurana
- Institute of Functional Epigenetics, Molecular Targets and Therapeutics Center, Helmholtz Zentrum München, Neuherberg, Germany
| | - Kurt M Schmoller
- Institute of Functional Epigenetics, Molecular Targets and Therapeutics Center, Helmholtz Zentrum München, Neuherberg, Germany
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2
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Luxmi R, King SM. Cilia Provide a Platform for the Generation, Regulated Secretion, and Reception of Peptidergic Signals. Cells 2024; 13:303. [PMID: 38391915 PMCID: PMC10886904 DOI: 10.3390/cells13040303] [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: 01/15/2024] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 02/24/2024] Open
Abstract
Cilia are microtubule-based cellular projections that act as motile, sensory, and secretory organelles. These structures receive information from the environment and transmit downstream signals to the cell body. Cilia also release vesicular ectosomes that bud from the ciliary membrane and carry an array of bioactive enzymes and peptide products. Peptidergic signals represent an ancient mode of intercellular communication, and in metazoans are involved in the maintenance of cellular homeostasis and various other physiological processes and responses. Numerous peptide receptors, subtilisin-like proteases, the peptide-amidating enzyme, and bioactive amidated peptide products have been localized to these organelles. In this review, we detail how cilia serve as specialized signaling organelles and act as a platform for the regulated processing and secretion of peptidergic signals. We especially focus on the processing and trafficking pathways by which a peptide precursor from the green alga Chlamydomonas reinhardtii is converted into an amidated bioactive product-a chemotactic modulator-and released from cilia in ectosomes. Biochemical dissection of this complex ciliary secretory pathway provides a paradigm for understanding cilia-based peptidergic signaling in mammals and other eukaryotes.
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Affiliation(s)
| | - Stephen M. King
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3305, USA;
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3
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Schmollinger S, Chen S, Merchant SS. Quantitative elemental imaging in eukaryotic algae. Metallomics 2023; 15:mfad025. [PMID: 37186252 PMCID: PMC10209819 DOI: 10.1093/mtomcs/mfad025] [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: 08/30/2022] [Accepted: 03/03/2023] [Indexed: 05/17/2023]
Abstract
All organisms, fundamentally, are made from the same raw material, namely the elements of the periodic table. Biochemical diversity is achieved by how these elements are utilized, for what purpose, and in which physical location. Determining elemental distributions, especially those of trace elements that facilitate metabolism as cofactors in the active centers of essential enzymes, can determine the state of metabolism, the nutritional status, or the developmental stage of an organism. Photosynthetic eukaryotes, especially algae, are excellent subjects for quantitative analysis of elemental distribution. These microbes utilize unique metabolic pathways that require various trace nutrients at their core to enable their operation. Photosynthetic microbes also have important environmental roles as primary producers in habitats with limited nutrient supplies or toxin contaminations. Accordingly, photosynthetic eukaryotes are of great interest for biotechnological exploitation, carbon sequestration, and bioremediation, with many of the applications involving various trace elements and consequently affecting their quota and intracellular distribution. A number of diverse applications were developed for elemental imaging, allowing subcellular resolution, with X-ray fluorescence microscopy (XFM, XRF) being at the forefront, enabling quantitative descriptions of intact cells in a non-destructive method. This Tutorial Review summarizes the workflow of a quantitative, single-cell elemental distribution analysis of a eukaryotic alga using XFM.
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Affiliation(s)
- Stefan Schmollinger
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
- Departments of Molecular and Cell Biology and Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Si Chen
- X-ray Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Sabeeha S Merchant
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
- Departments of Molecular and Cell Biology and Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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4
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Chowdhary AK, Kishi M, Toda T. A novel process for the production of Chromochloris zofingiensis through dark-induced multi-nuclei formation. ALGAL RES 2023. [DOI: 10.1016/j.algal.2023.103053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
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5
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Schoeters F, Spit J, Azizah RN, Van Miert S. Pilot-Scale Cultivation of the Snow Alga Chloromonas typhlos in a Photobioreactor. Front Bioeng Biotechnol 2022; 10:896261. [PMID: 35757813 PMCID: PMC9218667 DOI: 10.3389/fbioe.2022.896261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
The most studied and cultivated microalgae have a temperature optimum between 20 and 35°C. This temperature range hampers sustainable microalgae growth in countries with colder periods. To overcome this problem, psychrotolerant microalgae, such as the snow alga Chloromonas typhlos, can be cultivated during these colder periods. However, most of the research work has been carried out in the laboratory. The step between laboratory-scale and large-scale cultivation is difficult, making pilot-scale tests crucial to gather more information. Here, we presented a successful pilot-scale growth test of C. typhlos. Seven batch mode growth periods were compared during two longer growth tests in a photobioreactor of 350 L. We demonstrated the potential of this alga to be cultivated at colder ambient temperatures. The tests were performed during winter and springtime to compare ambient temperature and sunlight influences. The growth and CO2 usage were continuously monitored to calculate the productivity and CO2 fixation efficiency. A maximum dry weight of 1.082 g L-1 was achieved while a maximum growth rate and maximum daily volumetric and areal productivities of 0.105 d-1, 0.110 g L-1 d-1, and 2.746 g m-2 d-1, respectively, were measured. Future tests to optimize the cultivation of C. typhlos and production of astaxanthin, for example, will be crucial to explore the potential of biomass production of C. typhlos on a commercial scale.
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Affiliation(s)
- Floris Schoeters
- Radius, Thomas More University of Applied Sciences, Geel, Belgium
| | - Jornt Spit
- Radius, Thomas More University of Applied Sciences, Geel, Belgium
| | - Rahmasari Nur Azizah
- Radius, Thomas More University of Applied Sciences, Geel, Belgium.,I-BioStat, Data Science Institute, Hasselt University, Hasselt, Belgium
| | - Sabine Van Miert
- Radius, Thomas More University of Applied Sciences, Geel, Belgium
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6
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Takeuchi T, Lin YT, Fekaris N, Umen J, Sears BB, Benning C. Modulation of CHT7 Complexes during Light/Dark- and Nitrogen-Mediated Life Cycle Transitions of Chlamydomonas. PLANT PHYSIOLOGY 2020; 184:1762-1774. [PMID: 33004613 PMCID: PMC7723089 DOI: 10.1104/pp.20.00864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/21/2020] [Indexed: 06/11/2023]
Abstract
The Chlamydomonas reinhardtii Compromised Hydrolysis of Triacylglycerols7 (CHT7) protein has been previously implicated in the regulation of DNA metabolism and cell-cycle-related gene expression during nitrogen (N) deprivation, and its predicted protein interaction domains are necessary for function. Here, we examined impacts of the cht7 mutation during the cell division cycle under nutrient deficiency in light-dark synchronized cultures. We explored the potential mechanisms affecting CHT7 complex activities during the cell cycle and N starvation, with a focus on the possible interaction between CHT7 and the C. reinhardtii retinoblastoma tumor suppressor (RB) protein homolog MAT3. Notably, the absence of CHT7 did not negatively impact the synchrony of cell division and cell cycle progression during diel growth. Although the majority of CHT7 and MAT3/RB proteins were observed in separate complexes by blue native-PAGE, the two proteins coimmunoprecipitated both during synchronized growth and following N deprivation, suggesting the presence of low abundance subcomplexes containing CHT7 and MAT3/RB. Furthermore, we observed several phosphorylated isoforms of CHT7 under these conditions. To test the potential role of phosphorylation on the structure and function of CHT7, we performed site-directed mutagenesis of previously identified phosphorylated amino acids within CHT7. These phosphorylated residues were dispensable for CHT7 function, but phosphorylated variants of CHT7 persisted, indicating that yet-unidentified residues within CHT7 are also likely phosphorylated. Based on the interaction of CHT7 and MAT3/RB, we postulate the presence of a low-abundance or transient regulatory complex in C. reinhardtii that may be similar to DREAM-like complexes in other organisms.
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Affiliation(s)
- Tomomi Takeuchi
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - Yang-Tsung Lin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - Nicholas Fekaris
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - James Umen
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
| | - Barbara B Sears
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
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7
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Takeuchi T, Sears BB, Lindeboom C, Lin YT, Fekaris N, Zienkiewicz K, Zienkiewicz A, Poliner E, Benning C. Chlamydomonas CHT7 Is Required for an Effective Quiescent State by Regulating Nutrient-Responsive Cell Cycle Gene Expression. THE PLANT CELL 2020; 32:1240-1269. [PMID: 32001503 PMCID: PMC7145468 DOI: 10.1105/tpc.19.00628] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/07/2020] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
COMPROMISED HYDROLYSIS OF TRIACYLGLYCEROLS7 (CHT7) in Chlamydomonas (Chlamydomonas reinhardtii) was previously shown to affect the transcription of a subset of genes during nitrogen (N)-replete growth and following N refeeding. Here, we show that an extensive derepression of genes involved in DNA metabolism and cell cycle-related processes, as well as downregulation of genes encoding oxidoreductases and nutrient transporters, occurs in the cht7 mutant during N deprivation. Cellular mutant phenotypes are consistent with the observed transcriptome misregulation, as cht7 cells fail to properly arrest growth, nuclear replication, and cell division following N deprivation. Reduction in cht7 colony formation following N refeeding is explained by its compromised viability during N deprivation and by the occurrence of abortive divisions during N refeeding. Surprisingly, the largely unstructured C-terminal half of CHT7 with predicted protein binding domains, but not the canonical CXC DNA binding domain, is essential for the ability of CHT7 to form stable complexes and reverse the cellular phenotypes and transcription levels in the cht7 mutant. Hence, although lacking the presumed DNA binding domain, CHT7 modulates the expression of cell cycle genes in response to N availability, which is essential for establishing an effective quiescent state and the coordinated resumption of growth following N refeeding.
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Affiliation(s)
- Tomomi Takeuchi
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - Barbara B Sears
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Chase Lindeboom
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - Yang-Tsung Lin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - Nicholas Fekaris
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - Krzysztof Zienkiewicz
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Centre of Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland
| | - Agnieszka Zienkiewicz
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Centre of Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan 48824
| | - Eric Poliner
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan 48824
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8
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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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9
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Luxmi R, Kumar D, Mains RE, King SM, Eipper BA. Cilia-based peptidergic signaling. PLoS Biol 2019; 17:e3000566. [PMID: 31809498 PMCID: PMC6919629 DOI: 10.1371/journal.pbio.3000566] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/18/2019] [Accepted: 11/15/2019] [Indexed: 01/05/2023] Open
Abstract
Peptide-based intercellular communication is a ubiquitous and ancient process that predates evolution of the nervous system. Cilia are essential signaling centers that both receive information from the environment and secrete bioactive extracellular vesicles (ectosomes). However, the nature of these secreted signals and their biological functions remain poorly understood. Here, we report the developmentally regulated release of the peptide amidating enzyme, peptidylglycine α-amidating monooxygenase (PAM), and the presence of peptidergic signaling machinery (including propeptide precursors, subtilisin-like prohormone convertases, amidated products, and receptors) in ciliary ectosomes from the green alga Chlamydomonas. One identified amidated PAM product serves as a chemoattractant for mating-type minus gametes but repels plus gametes. Thus, cilia provide a previously unappreciated route for the secretion of amidated signaling peptides. Our study in Chlamydomonas and the presence of PAM in mammalian cilia suggest that ciliary ectosome-mediated peptidergic signaling dates to the early eukaryotes and plays key roles in metazoan physiology.
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Affiliation(s)
- Raj Luxmi
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Dhivya Kumar
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Richard E. Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Stephen M. King
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- Electron Microscopy Facility, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Betty A. Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
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10
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Ferrari C, Proost S, Ruprecht C, Mutwil M. PhytoNet: comparative co-expression network analyses across phytoplankton and land plants. Nucleic Acids Res 2019; 46:W76-W83. [PMID: 29718316 PMCID: PMC6030924 DOI: 10.1093/nar/gky298] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/11/2018] [Indexed: 11/15/2022] Open
Abstract
Phytoplankton consists of autotrophic, photosynthesizing microorganisms that are a crucial component of freshwater and ocean ecosystems. However, despite being the major primary producers of organic compounds, accounting for half of the photosynthetic activity worldwide and serving as the entry point to the food chain, functions of most of the genes of the model phytoplankton organisms remain unknown. To remedy this, we have gathered publicly available expression data for one chlorophyte, one rhodophyte, one haptophyte, two heterokonts and four cyanobacteria and integrated it into our PlaNet (Plant Networks) database, which now allows mining gene expression profiles and identification of co-expressed genes of 19 species. We exemplify how the co-expressed gene networks can be used to reveal functionally related genes and how the comparative features of PhytoNet allow detection of conserved transcriptional programs between cyanobacteria, green algae, and land plants. Additionally, we illustrate how the database allows detection of duplicated transcriptional programs within an organism, as exemplified by two putative DNA repair programs within Chlamydomonas reinhardtii. PhytoNet is available from www.gene2function.de.
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Affiliation(s)
- Camilla Ferrari
- Max-Planck Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam, Germany
| | - Sebastian Proost
- Max-Planck Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam, Germany
| | - Colin Ruprecht
- Max-Planck Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476 Potsdam, Germany
| | - Marek Mutwil
- Max-Planck Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam, Germany.,School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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11
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Ivanov IN, Vítová M, Bišová K. Growth and the cell cycle in green algae dividing by multiple fission. Folia Microbiol (Praha) 2019; 64:663-672. [PMID: 31347103 DOI: 10.1007/s12223-019-00741-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/15/2019] [Indexed: 11/24/2022]
Abstract
Most cells divide into two daughter cells; however, some green algae can have different division patterns in which a single mother cell can sometimes give rise to up to thousands of daughter cells. Although such cell cycle patterns can be very complex, they are governed by the same general concepts as the most common binary fission. Moreover, cell cycle progression appears to be connected with size, since cells need to ensure that their size after division will not drop below the limit required for survival. Although the exact mechanism that lets cells measure cell size remains largely unknown, there have been several prominent hypotheses that try to explain it.
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Affiliation(s)
- Ivan Nedyalkov Ivanov
- Institute of Microbiology, Centre Algatech, Laboratory of Cell Cycles of Algae, Opatovický mlýn, Czech Academy of Sciences, 379 81, Třeboň, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Milada Vítová
- Institute of Microbiology, Centre Algatech, Laboratory of Cell Cycles of Algae, Opatovický mlýn, Czech Academy of Sciences, 379 81, Třeboň, Czech Republic
| | - Kateřina Bišová
- Institute of Microbiology, Centre Algatech, Laboratory of Cell Cycles of Algae, Opatovický mlýn, Czech Academy of Sciences, 379 81, Třeboň, Czech Republic.
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12
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Response of the Green Alga Chlamydomonas reinhardtii to the DNA Damaging Agent Zeocin. Cells 2019; 8:cells8070735. [PMID: 31319624 PMCID: PMC6678277 DOI: 10.3390/cells8070735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/14/2019] [Accepted: 07/15/2019] [Indexed: 12/21/2022] Open
Abstract
DNA damage is a ubiquitous threat endangering DNA integrity in all living organisms. Responses to DNA damage include, among others, induction of DNA repair and blocking of cell cycle progression in order to prevent transmission of damaged DNA to daughter cells. Here, we tested the effect of the antibiotic zeocin, inducing double stranded DNA breaks, on the cell cycle of synchronized cultures of the green alga Chlamydomonas reinhardtii. After zeocin application, DNA replication partially occurred but nuclear and cellular divisions were completely blocked. Application of zeocin combined with caffeine, known to alleviate DNA checkpoints, decreased cell viability significantly. This was probably caused by a partial overcoming of the cell cycle progression block in such cells, leading to aberrant cell divisions. The cell cycle block was accompanied by high steady state levels of mitotic cyclin-dependent kinase activity. The data indicate that DNA damage response in C. reinhardtii is connected to the cell cycle block, accompanied by increased and stabilized mitotic cyclin-dependent kinase activity.
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13
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Takeuchi T, Benning C. Nitrogen-dependent coordination of cell cycle, quiescence and TAG accumulation in Chlamydomonas. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:292. [PMID: 31890020 PMCID: PMC6927116 DOI: 10.1186/s13068-019-1635-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 12/12/2019] [Indexed: 05/07/2023]
Abstract
Microalgae hold great promises as sustainable cellular factories for the production of alternative fuels, feeds, and biopharmaceuticals for human health. While the biorefinery approach for fuels along with the coproduction of high-value compounds with industrial, therapeutic, or nutraceutical applications have the potential to make algal biofuels more economically viable, a number of challenges continue to hamper algal production systems at all levels. One such hurdle includes the metabolic trade-off often observed between the increased yields of desired products, such as triacylglycerols (TAG), and the growth of an organism. Initial genetic engineering strategies to improve lipid productivity in microalgae, which focused on overproducing the enzymes involved in fatty acid and TAG biosynthesis or inactivating competing carbon (C) metabolism, have seen some successes albeit at the cost of often greatly reduced biomass. Emergent approaches that aim at modifying the dynamics of entire metabolic pathways by engineering of pertinent transcription factors or signaling networks appear to have successfully achieved a balance between growth and neutral lipid accumulation. However, the biological knowledge of key signaling networks and molecular components linking these two processes is still incomplete in photosynthetic eukaryotes, making it difficult to optimize metabolic engineering strategies for microalgae. Here, we focus on nitrogen (N) starvation of the model green microalga, Chlamydomonas reinhardtii, to present the current understanding of the nutrient-dependent switch between proliferation and quiescence, and the drastic reprogramming of metabolism that results in the storage of C compounds following N starvation. We discuss the potential components mediating the transcriptional repression of cell cycle genes and the establishment of quiescence in Chlamydomonas, and highlight the importance of signaling pathways such as those governed by the target of rapamycin (TOR) and sucrose nonfermenting-related (SnRK) kinases in the coordination of metabolic status with cellular growth. A better understanding of how the cell division cycle is regulated in response to nutrient scarcity and of the signaling pathways linking cellular growth to energy and lipid homeostasis, is essential to improve the prospects of biofuels and biomass production in microalgae.
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Affiliation(s)
- Tomomi Takeuchi
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
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14
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Ji N, Lin L, Li L, Yu L, Zhang Y, Luo H, Li M, Shi X, Wang DZ, Lin S. Metatranscriptome analysis reveals environmental and diel regulation of a Heterosigma akashiwo
(raphidophyceae) bloom. Environ Microbiol 2018; 20:1078-1094. [DOI: 10.1111/1462-2920.14045] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 01/09/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Nanjing Ji
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
- Department of Marine Sciences; University of Connecticut; Groton CT 06340 USA
| | - Lingxiao Lin
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Ling Li
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Liying Yu
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Yaqun Zhang
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Hao Luo
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Meizhen Li
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Xinguo Shi
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
| | - Senjie Lin
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences; Xiamen University; Xiamen Fujian 361102 China
- Department of Marine Sciences; University of Connecticut; Groton CT 06340 USA
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15
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Leslie MP, Shelton DE, Michod RE. Generation time and fitness tradeoffs during the evolution of multicellularity. J Theor Biol 2017; 430:92-102. [PMID: 28709942 DOI: 10.1016/j.jtbi.2017.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Revised: 05/31/2017] [Accepted: 07/10/2017] [Indexed: 11/18/2022]
Abstract
The evolution of multicellular organisms from their unicellular ancestors is an example of an evolutionary transition in individuality (ETI), i.e. a change in the units of selection and adaptation. The theory of ETIs poses particular challenges because, by definition, key theoretical constructs such as fitness are shifting during an ETI. Past work emphasized the importance of life history tradeoffs during ETIs in which lower level units form groups and become individuals at a higher level. In particular, it has been hypothesized that the convexity of the lower-level tradeoff between viability and fecundity changes with group size and determines the optimality of lower-level specialization in the fitness components of the group. This is important because lower-level specialization is a key indicator of higher-level individuality. Here we show that increasing generation time can increase the convexity of the lower-level viability-fecundity tradeoff. This effect is a novel hypothesis for the positive association between cell-group size and cellular specialization in a major model system for ETIs, the volvocine algae. The pattern in this clade is thought to be an example of a more general size-complexity rule. Our hypothesis is that larger groups have longer generation times and longer generation times lead to more convex lower-level viability-fecundity tradeoffs, which could account for specialization being optimal only in larger cell groups (colonies). We discuss the robustness of this effect to various changes in the assumptions of our model. Our work is important for the study of ETIs in general because viability and fecundity are fundamental components of fitness in all systems and because generation time is expected to be changing during many ETIs.
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Affiliation(s)
- Martin P Leslie
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA .
| | - Deborah E Shelton
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Richard E Michod
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
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16
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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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17
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JONG LW, FUJIWARA T, NOZAKI H, MIYAGISHIMA SY. Cell size for commitment to cell division and number of successive cell divisions in multicellular volvocine green algae Tetrabaena socialis and Gonium pectorale. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2017; 93:832-840. [PMID: 29225309 PMCID: PMC5790760 DOI: 10.2183/pjab.93.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/20/2017] [Indexed: 06/07/2023]
Abstract
Volvocine algae constitute a green algal lineage comprising unicellular Chlamydomonas, four-celled Tetrabaena, eight to 32-celled Gonium, and others up to Volvox spp., which consist of up to 50,000 cells. These algae proliferate by multiple fissions with cellular growth up to several fold in size and subsequent successive cell divisions. Chlamydomonas reinhardtii cells produce two to 32 daughter cells by one to five divisions, depending on cellular growth in the G1 phase. By contrast, in this study, we found that Tetrabaena socialis and Gonium pectorale cells mostly produced four and eight daughter cells by two and three successive divisions, respectively. In contrast to C. reinhardtii, which is committed to cell division when the cell has grown two-fold, T. socialis and G. pectorale are committed only when the cells have grown four- and eight-fold, respectively. Thus, our results suggest that evolutionary changes in cellular size for commitment largely contributes to the emergence and evolution of multicellularity in volvocine algae.
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Affiliation(s)
- Lin Wei JONG
- Department of Cell Genetics, National Institute of Genetics, Shizuoka, Japan
- Department of Genetics, Graduate University of Advanced Studies (SOKENDAI), Shizuoka, Japan
| | - Takayuki FUJIWARA
- Department of Cell Genetics, National Institute of Genetics, Shizuoka, Japan
- Department of Genetics, Graduate University of Advanced Studies (SOKENDAI), Shizuoka, Japan
| | - Hisayoshi NOZAKI
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Tokyo, Japan
| | - Shin-ya MIYAGISHIMA
- Department of Cell Genetics, National Institute of Genetics, Shizuoka, Japan
- Department of Genetics, Graduate University of Advanced Studies (SOKENDAI), Shizuoka, Japan
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18
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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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19
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Li Y, Liu D, López-Paz C, Olson BJ, Umen JG. A new class of cyclin dependent kinase in Chlamydomonas is required for coupling cell size to cell division. eLife 2016; 5:e10767. [PMID: 27015111 PMCID: PMC4841777 DOI: 10.7554/elife.10767] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 03/24/2016] [Indexed: 01/04/2023] Open
Abstract
Proliferating cells actively control their size by mechanisms that are poorly understood. The unicellular green alga Chlamydomonas reinhardtii divides by multiple fission, wherein a ‘counting’ mechanism couples mother cell-size to cell division number allowing production of uniform-sized daughters. We identified a sizer protein, CDKG1, that acts through the retinoblastoma (RB) tumor suppressor pathway as a D-cyclin-dependent RB kinase to regulate mitotic counting. Loss of CDKG1 leads to fewer mitotic divisions and large daughters, while mis-expression of CDKG1 causes supernumerous mitotic divisions and small daughters. The concentration of nuclear-localized CDKG1 in pre-mitotic cells is set by mother cell size, and its progressive dilution and degradation with each round of cell division may provide a link between mother cell-size and mitotic division number. Cell-size-dependent accumulation of limiting cell cycle regulators such as CDKG1 is a potentially general mechanism for size control. DOI:http://dx.doi.org/10.7554/eLife.10767.001 Most cells are programmed to maintain a certain size. This property, known as size control, is achieved by balancing growth and division, such that a cell will only divide after it reaches a certain size. However, and despite years of research, it is largely unknown how cells sense their size (or growth) to be able to divide accordingly. One theory proposes that there is a “sizer” protein inside cells, and that cells measure the abundance of this protein and use it to link cell size to the process of division. However, the existence of such a protein remained unproven. Li, Liu et al. have now used the cells of the green alga Chlamydomonas to identify a candidate sizer protein. Chlamydomonas cells, like many other algae, can grow to become very large mother cells that then divide one or more times in succession to produce many daughter cells. Larger mother cells undergo more divisions than smaller mother cells in order to produce daughter cells of a correct size. Using a range of genetic and biochemical techniques, Li, Liu et al. identified a protein that is produced in Chlamydomonas cells just before they begin to divide. Larger mother cells contain more of this protein than smaller cells and the protein encourages cells to divide. For example, mutant cells that lack this protein divided too few times, while cells that produce too much of it divided too many times. The protein, called CDKG1, belongs to a family of proteins that regulate cell division in many organisms. CDKG1 is a kinase – an enzyme that alters the activity of other proteins by adding a phosphate group on to them. In Chlamydomonas, CDKG1 couples cell size to cell division by altering the activity of an important protein called the retinoblastoma-related protein that controls cell division in numerous organisms. This protein is also frequently disrupted in cancers in humans. These findings shed new light on a molecular pathway for size control. Future work will need to determine how the accumulation of CDKG1 links to the size of a mother cell and how it is inactivated once daughter cells reach the appropriate size. DOI:http://dx.doi.org/10.7554/eLife.10767.002
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Affiliation(s)
- Yubing Li
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Plant Molecular and Cell Biology Program, the Horticultural and Plant Science Department, University of Florida, Gainesville, United States
| | - Dianyi Liu
- Donald Danforth Plant Science Center, St. Louis, United States
| | - Cristina López-Paz
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Donald Danforth Plant Science Center, St. Louis, United States
| | - Bradley Jsc Olson
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - James G Umen
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Donald Danforth Plant Science Center, St. Louis, United States
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20
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Bonnefond H, Moelants N, Talec A, Bernard O, Sciandra A. Concomitant effects of light and temperature diel variations on the growth rate and lipid production of Dunaliella salina. ALGAL RES 2016. [DOI: 10.1016/j.algal.2015.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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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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22
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Damodaran SP, Eberhard S, Boitard L, Rodriguez JG, Wang Y, Bremond N, Baudry J, Bibette J, Wollman FA. A millifluidic study of cell-to-cell heterogeneity in growth-rate and cell-division capability in populations of isogenic cells of Chlamydomonas reinhardtii. PLoS One 2015; 10:e0118987. [PMID: 25760649 PMCID: PMC4356620 DOI: 10.1371/journal.pone.0118987] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 01/08/2015] [Indexed: 12/31/2022] Open
Abstract
To address possible cell-to-cell heterogeneity in growth dynamics of isogenic cell populations of Chlamydomonas reinhardtii, we developed a millifluidic drop-based device that not only allows the analysis of populations grown from single cells over periods of a week, but is also able to sort and collect drops of interest, containing viable and healthy cells, which can be used for further experimentation. In this study, we used isogenic algal cells that were first synchronized in mixotrophic growth conditions. We show that these synchronized cells, when placed in droplets and kept in mixotrophic growth conditions, exhibit mostly homogeneous growth statistics, but with two distinct subpopulations: a major population with a short doubling-time (fast-growers) and a significant subpopulation of slowly dividing cells (slow-growers). These observations suggest that algal cells from an isogenic population may be present in either of two states, a state of restricted division and a state of active division. When isogenic cells were allowed to propagate for about 1000 generations on solid agar plates, they displayed an increased heterogeneity in their growth dynamics. Although we could still identify the original populations of slow- and fast-growers, drops inoculated with a single progenitor cell now displayed a wider diversity of doubling-times. Moreover, populations dividing with the same growth-rate often reached different cell numbers in stationary phase, suggesting that the progenitor cells differed in the number of cell divisions they could undertake. We discuss possible explanations for these cell-to-cell heterogeneities in growth dynamics, such as mutations, differential aging or stochastic variations in metabolites and macromolecules yielding molecular switches, in the light of single-cell heterogeneities that have been reported among isogenic populations of other eu- and prokaryotes.
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Affiliation(s)
- Shima P. Damodaran
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
| | - Stephan Eberhard
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste, Institut de Biologie Physico-Chimique, UMR CNRS/UPMC 7141, Paris, France
| | - Laurent Boitard
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
| | - Jairo Garnica Rodriguez
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
| | - Yuxing Wang
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
- Optical Science & Engineering Research Center, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Nicolas Bremond
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
| | - Jean Baudry
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
| | - Jérôme Bibette
- Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France
- * E-mail: (JB); (FAW)
| | - Francis-André Wollman
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste, Institut de Biologie Physico-Chimique, UMR CNRS/UPMC 7141, Paris, France
- * E-mail: (JB); (FAW)
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23
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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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24
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Tulin F, Cross FR. A microbial avenue to cell cycle control in the plant superkingdom. THE PLANT CELL 2014; 26:4019-38. [PMID: 25336509 PMCID: PMC4247570 DOI: 10.1105/tpc.114.129312] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/11/2014] [Accepted: 09/25/2014] [Indexed: 05/22/2023]
Abstract
Research in yeast and animals has resulted in a well-supported consensus model for eukaryotic cell cycle control. The fit of this model to early diverging eukaryotes, such as the plant kingdom, remains unclear. Using the green alga Chlamydomonas reinhardtii, we developed an efficient pipeline, incorporating robotics, semiautomated image analysis, and deep sequencing, to molecularly identify >50 genes, mostly conserved in higher plants, specifically required for cell division but not cell growth. Mutated genes include the cyclin-dependent kinases CDKA (resembling yeast and animal Cdk1) and the plant-specific CDKB. The Chlamydomonas cell cycle consists of a long G1 during which cells can grow >10-fold, followed by multiple rapid cycles of DNA replication and segregation. CDKA and CDKB execute nonoverlapping functions: CDKA promotes transition between G1 and entry into the division cycle, while CDKB is essential specifically for spindle formation and nuclear division, but not for DNA replication, once CDKA-dependent initiation has occurred. The anaphase-promoting complex is required for similar steps in the Chlamydomonas cell cycle as in Opisthokonts; however, the spindle assembly checkpoint, which targets the APC in Opisthokonts, appears severely attenuated in Chlamydomonas, based on analysis of mutants affecting microtubule function. This approach allows unbiased integration of the consensus cell cycle control model with innovations specific to the plant lineage.
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Affiliation(s)
- Frej Tulin
- The Rockefeller University, New York, New York 10065
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25
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Kuwano K, Abe N, Nishi Y, Seno H, Nishihara GN, Iima M, Zachleder V. Growth and cell cycle of Ulva compressa (Ulvophyceae) under LED illumination. JOURNAL OF PHYCOLOGY 2014; 50:744-752. [PMID: 26988458 DOI: 10.1111/jpy.12207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/07/2014] [Indexed: 06/05/2023]
Abstract
The cell-cycle progression of Ulva compressa is diurnally gated at the G1 phase in accordance with light-dark cycles. The present study was designed to examine the spectral sensitivity of the G1 gating system. When blue, red, and green light-emitting diodes (LEDs) were used for illumination either alone or in combination, the cells divided under all illumination conditions, suggesting that all colors of light were able to open the G1 gate. Although blue light was most effective to open the G1 gate, red light alone or green light alone was also able to open the G1 gate even at irradiance levels lower than the light compensation point of each color. Occurrence of a period of no cell division in the course of a day suggested that the G1 gating system normally functioned as under ordinary illumination by cool-white fluorescent lamps. The rise of the proportion of blue light to green light resulted in increased growth rate. On the other hand, the growth rates did not vary regardless of the proportion of blue light to red light. These results indicate that the difference in growth rate due to light color resulted from the difference in photosynthetic efficiency of the colors of light. However, the growth rates significantly decreased under conditions without blue light. This result suggests that blue light mediates cell elongation and because the spectral sensitivity of the cell elongation regulating system was different from that of the G1 gating system, distinct photoreceptors are likely to mediate the two systems.
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Affiliation(s)
- Kazuyoshi Kuwano
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Naoko Abe
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Yukari Nishi
- Faculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Hiromi Seno
- Faculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Gregory N Nishihara
- Institute for East China Sea Research, Nagasaki University, Taira-machi, Nagasaki, 851-2213, Japan
| | - Masafumi Iima
- Faculty of Environmental Studies, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic (ASCR), Opatovický mlýn, 37981, Třeboň, Czech Republic
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26
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Bišová K, Zachleder V. Cell-cycle regulation in green algae dividing by multiple fission. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2585-602. [PMID: 24441762 DOI: 10.1093/jxb/ert466] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Green algae dividing by multiple fission comprise unrelated genera but are connected by one common feature: under optimal growth conditions, they can divide into more than two daughter cells. The number of daughter cells, also known as the division number, is relatively stable for most species and usually ranges from 4 to 16. The number of daughter cells is dictated by growth rate and is modulated by light and temperature. Green algae dividing by multiple fission can thus be used to study coordination of growth and progression of the cell cycle. Algal cultures can be synchronized naturally by alternating light/dark periods so that growth occurs in the light and DNA replication(s) and nuclear and cellular division(s) occur in the dark; synchrony in such cultures is almost 100% and can be maintained indefinitely. Moreover, the pattern of cell-cycle progression can be easily altered by differing growth conditions, allowing for detailed studies of coordination between individual cell-cycle events. Since the 1950s, green algae dividing by multiple fission have been studied as a unique model for cell-cycle regulation. Future sequencing of algal genomes will provide additional, high precision tools for physiological, taxonomic, structural, and molecular studies in these organisms.
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Affiliation(s)
- Kateřina Bišová
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81 Třeboň, Czech Republic
| | - Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81 Třeboň, Czech Republic
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27
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Liu L, Qu J, Zhou X, Liu X, Zhang Z, Wang X, Liu T, Liu G. Discovery of a strongly-interrelated gene network in corals under constant darkness by correlation analysis after wavelet transform on complex network model. PLoS One 2014; 9:e92434. [PMID: 24651851 PMCID: PMC3961355 DOI: 10.1371/journal.pone.0092434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/22/2014] [Indexed: 11/18/2022] Open
Abstract
Coral reefs occupy a relatively small portion of sea area, yet serve as a crucial source of biodiversity by establishing harmonious ecosystems with marine plants and animals. Previous researches mainly focused on screening several key genes induced by stress. Here we proposed a novel method--correlation analysis after wavelet transform of complex network model, to explore the effect of light on gene expression in the coral Acropora millepora based on microarray data. In this method, wavelet transform and the conception of complex network were adopted, and 50 key genes with large differences were finally captured, including both annotated genes and novel genes without accurate annotation. These results shed light on our understanding of coral's response toward light changes and the genome-wide interaction among genes under the control of biorhythm, and hence help us to better protect the coral reef ecosystems. Further studies are needed to explore how functional connections are related to structural connections, and how connectivity arises from the interactions within and between different systems. The method introduced in this study for analyzing microarray data will allow researchers to explore genome-wide interaction network with their own dataset and understand the relevant biological processes.
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Affiliation(s)
- Longlong Liu
- Ocean University of China, Qingdao, Shandong, People's Republic of China
| | - Jieqiong Qu
- Ocean University of China, Qingdao, Shandong, People's Republic of China
| | - Xilong Zhou
- Ocean University of China, Qingdao, Shandong, People's Republic of China
| | - Xuefeng Liu
- Ocean University of China, Qingdao, Shandong, People's Republic of China
| | - Zhaobao Zhang
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan, People's Republic of China
| | - Xumin Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Tao Liu
- Ocean University of China, Qingdao, Shandong, People's Republic of China
| | - Guiming Liu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- * E-mail:
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Nishihama R, Kohchi T. Evolutionary insights into photoregulation of the cell cycle in the green lineage. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:630-7. [PMID: 23978389 DOI: 10.1016/j.pbi.2013.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/25/2013] [Accepted: 07/29/2013] [Indexed: 05/18/2023]
Abstract
Plant growth depends solely on light energy, which drives photosynthesis. Thus, linking growth control to light signals during certain developmental events, such as seed or spore germination and organ formation, is a crucial feature that plants evolved to use energy efficiently. How light controls the cell cycle depends on growth habitats, body plans (unicellular vs. multicellular), and photosensors. For example, the photosensors mediating light signaling to promote cell division appear to differ between green algae and land plants. In this review, we focus on cell-cycle regulation by light and discuss the transition of its molecular mechanisms during evolution. Recent advances show that light-dependent cell-cycle control involves global changes in transcription of cell-cycle genes, and is mediated by auxin and cytokinin.
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Affiliation(s)
- Ryuichi Nishihama
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
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Mocquet C, Sciandra A, Talec A, Bernard O. Cell cycle implication on nitrogen acquisition and synchronization in Thalassiosira weissflogii (Bacillariophyceae). JOURNAL OF PHYCOLOGY 2013; 49:371-380. [PMID: 27008523 DOI: 10.1111/jpy.12045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 05/13/2012] [Indexed: 06/05/2023]
Abstract
The Michaelis-Menten model of nitrogen (N) acquisition, originally used to represent the effect of nutrient concentration on the phytoplankton uptake rate, is inadequate when other factors show temporal variations. Literature generally links diurnal oscillations of N acquisition to a response of the physiological status of microalgae to photon flux density (PFD) and substrate availability. This work describes how the cell cycle also constitutes a significant determinant of N acquisition and, when appropriate, assesses the impact of this property at the macroscopic level. For this purpose, we carried out continuous culture experiments with the diatom Thalassiosira weissflogii (Grunow) G. Fryxell & Hasle exposed to various conditions of light and N supply. The results revealed that a decrease in N acquisition occurred when a significant proportion of the population was in mitosis. This observation suggests that N acquisition is incompatible with mitosis and therefore that its acquisition rate is not constant during the cell cycle. In addition, environmental conditions, such as light and nutrient supply disrupt the cell cycle at the level of the individual cell, which impacts synchrony of the population.
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Affiliation(s)
- Christophe Mocquet
- UPMC, Univ Paris 06, UMR 7093, LOV, Observatoire Océanologique, F-06234, Villefranche/mer, France
- CNRS, UMR 7093, LOV, Observatoire Océanologique, F-06234, Villefranche/mer, France
| | - Antoine Sciandra
- UPMC, Univ Paris 06, UMR 7093, LOV, Observatoire Océanologique, F-06234, Villefranche/mer, France
- CNRS, UMR 7093, LOV, Observatoire Océanologique, F-06234, Villefranche/mer, France
| | - Amélie Talec
- UPMC, Univ Paris 06, UMR 7093, LOV, Observatoire Océanologique, F-06234, Villefranche/mer, France
- CNRS, UMR 7093, LOV, Observatoire Océanologique, F-06234, Villefranche/mer, France
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Nishio K, Hashimoto K, Watanabe K. Light/electricity conversion by defined cocultures of Chlamydomonas and Geobacter. J Biosci Bioeng 2013; 115:412-7. [DOI: 10.1016/j.jbiosc.2012.10.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 10/16/2012] [Accepted: 10/16/2012] [Indexed: 10/27/2022]
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Central carbon metabolism and electron transport in Chlamydomonas reinhardtii: metabolic constraints for carbon partitioning between oil and starch. EUKARYOTIC CELL 2013; 12:776-93. [PMID: 23543671 DOI: 10.1128/ec.00318-12] [Citation(s) in RCA: 221] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The metabolism of microalgae is so flexible that it is not an easy task to give a comprehensive description of the interplay between the various metabolic pathways. There are, however, constraints that govern central carbon metabolism in Chlamydomonas reinhardtii that are revealed by the compartmentalization and regulation of the pathways and their relation to key cellular processes such as cell motility, division, carbon uptake and partitioning, external and internal rhythms, and nutrient stress. Both photosynthetic and mitochondrial electron transfer provide energy for metabolic processes and how energy transfer impacts metabolism and vice versa is a means of exploring the regulation and function of these pathways. A key example is the specific chloroplast localization of glycolysis/gluconeogenesis and how it impacts the redox poise and ATP budget of the plastid in the dark. To compare starch and lipids as carbon reserves, their value can be calculated in terms of NAD(P)H and ATP. As microalgae are now considered a potential renewable feedstock, we examine current work on the subject and also explore the possibility of rerouting metabolism toward lipid production.
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Didur O, Dewez D, Popovic R. Alteration of chromium effect on photosystem II activity in Chlamydomonas reinhardtii cultures under different synchronized state of the cell cycle. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:1870-1875. [PMID: 23238598 DOI: 10.1007/s11356-012-1389-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Accepted: 11/30/2012] [Indexed: 06/01/2023]
Abstract
The inhibitory effect of chromium (Cr) on photosystem II (PSII) activity was investigated in the green alga Chlamydomonas reinhardtii during different phases of the cell cycle. Algae were cultivated in continuous light or a light/dark cycle (16:8 h) to obtain a synchronously dividing cell culture. The cell division phases were determined with the DNA-specific fluorescent probe SYBR green using flow cytometry. The effect of Cr on PSII activity was investigated after a 24-h treatment with algal cultures having different proportions of newly divided cells (G(0)/G(1)), dividing cells at the DNA replication phase (S), and dividing cells at the mitosis phase (G(2)/M). Using chlorophyll a fluorescence parameters based on PSII electron transport capacity in dark- (Φ(M)II) and light-adapted (Φ'(M)II) equilibrium state, we found that the effect of Cr differs depending on the stage of the cell cycle. When algal cultures had a high proportion of cells actively dividing (M phase), the toxic effect of Cr on PSII activity appeared to be much higher and PSII quantum yield was decreased by 80 % compared to algal cultures mainly in the G(0)/G(1) phase. Therefore, the inhibitory effect of Cr on photosynthesis appears to be different according to the cell cycle state of the algal population.
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Affiliation(s)
- Olivier Didur
- Department of Chemistry, University of Quebec in Montreal, C.P. 8888, Succ. Centre-Ville, Montreal, Quebec, H3C 3P8, Canada
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Huysman MJJ, Fortunato AE, Matthijs M, Costa BS, Vanderhaeghen R, Van den Daele H, Sachse M, Inzé D, Bowler C, Kroth PG, Wilhelm C, Falciatore A, Vyverman W, De Veylder L. AUREOCHROME1a-mediated induction of the diatom-specific cyclin dsCYC2 controls the onset of cell division in diatoms (Phaeodactylum tricornutum). THE PLANT CELL 2013; 25:215-28. [PMID: 23292736 PMCID: PMC3584536 DOI: 10.1105/tpc.112.106377] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Cell division in photosynthetic organisms is tightly regulated by light. Although the light dependency of the onset of the cell cycle has been well characterized in various phototrophs, little is known about the cellular signaling cascades connecting light perception to cell cycle activation and progression. Here, we demonstrate that diatom-specific cyclin 2 (dsCYC2) in Phaeodactylum tricornutum displays a transcriptional peak within 15 min after light exposure, long before the onset of cell division. The product of dsCYC2 binds to the cyclin-dependent kinase CDKA1 and can complement G1 cyclin-deficient yeast. Consistent with the role of dsCYC2 in controlling a G1-to-S light-dependent cell cycle checkpoint, dsCYC2 silencing decreases the rate of cell division in diatoms exposed to light-dark cycles but not to constant light. Transcriptional induction of dsCYC2 is triggered by blue light in a fluence rate-dependent manner. Consistent with this, dsCYC2 is a transcriptional target of the blue light sensor AUREOCHROME1a, which functions synergistically with the basic leucine zipper (bZIP) transcription factor bZIP10 to induce dsCYC2 transcription. The functional characterization of a cyclin whose transcription is controlled by light and whose activity connects light signaling to cell cycle progression contributes significantly to our understanding of the molecular mechanisms underlying light-dependent cell cycle onset in diatoms.
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Affiliation(s)
- Marie J J Huysman
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, B-9000 Gent, Belgium
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Sumiya N, Owari S, Watanabe K, Kawano S. ROLE OF MULTIPLE FTSZ RINGS IN CHLOROPLAST DIVISION UNDER OLIGOTROPHIC AND EUTROPHIC CONDITIONS IN THE UNICELLULAR GREEN ALGA NANNOCHLORIS BACILLARIS (CHLOROPHYTA, TREBOUXIOPHYCEAE)(1). JOURNAL OF PHYCOLOGY 2012; 48:1187-1196. [PMID: 27011278 DOI: 10.1111/j.1529-8817.2012.01204.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Chloroplasts of the unicellular green alga Nannochloris bacillaris Naumann cultured under nutrient-enriched conditions have multiple rings of FtsZ, a prokaryote-derived chloroplast division protein. We previously reported that synthesis of excess chloroplast DNA and formation of multiple FtsZ rings occur simultaneously. To clarify the role of multiple FtsZ rings in chloroplast division, we investigated chloroplast DNA synthesis and ring formation in cells cultured under various culture conditions. Cells transferred from a nutrient-enriched medium to an inorganic medium in the light showed a drop in cell division rate, a reduction in chloroplast DNA content, and changes in the shape of chloroplast nucleoids as cells divided. We then examined DNA synthesis by immunodetecting BrdU incorporated into DNA strands using the anti-BrdU antibody. BrdU-labeled nuclei were clearly observed in cells 48 h after transfer into the inorganic medium, while only weak punctate signals were visible in the chloroplasts. In parallel, the number of FtsZ rings decreased from 6 to only 1. When the cells were transferred from an inorganic medium to a nutrient-enriched medium, the number of cells increased only slightly in the first 12 h after transfer; after this time, however, they started to divide more quickly and increased exponentially. Chloroplast nucleoids changed from punctate to rod-like structures, and active chloroplast DNA synthesis and FtsZ ring formation were observed. On the basis of our results, we conclude that multiple FtsZ ring assembly and chloroplast DNA duplication under nutrient-rich conditions facilitate chloroplast division after transfer to oligotrophic conditions without further duplication of chloroplast DNA and formation of new FtsZ rings.
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Affiliation(s)
- Nobuko Sumiya
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Building FSB-601, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Satomi Owari
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Building FSB-601, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Koichi Watanabe
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Building FSB-601, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Shigeyuki Kawano
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Building FSB-601, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
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Swirsky Whitney LA, Novi G, Perata P, Loreti E. Distinct mechanisms regulating gene expression coexist within the fermentative pathways in Chlamydomonas reinhardtii. ScientificWorldJournal 2012; 2012:565047. [PMID: 22792045 PMCID: PMC3385630 DOI: 10.1100/2012/565047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 03/21/2012] [Indexed: 12/12/2022] Open
Abstract
Under dark anoxia, the unicellular green algae Chlamydomonas reinhardtii may produce hydrogen by means of its hydrogenase enzymes, in particular HYD1, using reductants derived from the degradation of intercellular carbon stores. Other enzymes belonging to the fermentative pathways compete for the same reductants. A complete understanding of the mechanisms determining the activation of one pathway rather than another will help us engineer Chlamydomonas for fermentative metabolite production, including hydrogen. We examined the expression pattern of the fermentative genes PDC3, LDH1, ADH2, PFL1, and PFR1 in response to day-night cycles, continuous light, continuous darkness, and low or high oxygen availability, which are all conditions that vary on a regular basis in Chlamydomonas' natural environment. We found that all genes except PFL1 show daily fluctuations in expression, and that PFR1 differentiated itself from the others in that it is clearly responsive to low oxygen, where as PDC3, LDH1, and ADH2 are primarily under diurnal regulation. Our results provide evidence that there exist at least three different regulatory mechanisms within the fermentative pathways and suggest that the fermentative pathways are not redundant but rather that availability of a variety of pathways allows for a differential metabolic response to different environmental conditions.
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36
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Shiratsuchi G, Kamiya R, Hirono M. Scaffolding function of the Chlamydomonas procentriole protein CRC70, a member of the conserved Cep70 family. J Cell Sci 2012; 124:2964-75. [PMID: 21878503 DOI: 10.1242/jcs.084715] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Centriole duplication occurs once per cell cycle through the assembly of daughter centrioles on the side wall of pre-existing centrioles. Little is known about the molecules involved in the assembly of new centrioles. Here, we identify CRC70 as a Chlamydomonas protein with an important role in the accumulation of centriole proteins at the site of assembly. CRC70 contains a highly conserved ~50-amino-acid sequence shared by mammalian Cep70 and preferentially localizes to immature centrioles (the procentrioles). This localization is maintained in the mutant bld10, in which centriole formation is blocked before the assembly of centriolar microtubules. RNA interference (RNAi)-mediated knockdown of CRC70 produces flagella-less cells and inhibits the recruitment of other centriole components, such as SAS-6 and Bld10p to the centriole. Overexpression of CRC70 induces an accumulation of these proteins in discrete spots in the cytoplasm. Overexpression of EGFP-tagged CRC70 in mouse NIH3T3 cells causes the formation of structures apparently related to centrioles. These findings suggest that CRC70 is a member of a conserved protein family and functions as a scaffold for the assembly of the centriole precursor.
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Affiliation(s)
- Gen Shiratsuchi
- Department of Biological Sciences, University of Tokyo, Tokyo 113-0033, Japan
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Target-of-rapamycin complex 1 (Torc1) signaling modulates cilia size and function through protein synthesis regulation. Proc Natl Acad Sci U S A 2012; 109:2021-6. [PMID: 22308353 DOI: 10.1073/pnas.1112834109] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cilium serves as a cellular antenna by coordinating upstream environmental cues with numerous downstream signaling processes that are indispensable for the function of the cell. This role is supported by the revelation that defects of the cilium underlie an emerging class of human disorders, termed "ciliopathies." Although mounting interest in the cilium has demonstrated the essential role that the organelle plays in vertebrate development, homeostasis, and disease pathogenesis, the mechanisms regulating cilia morphology and function remain unclear. Here, we show that the target-of-rapamycin (TOR) growth pathway modulates cilia size and function during zebrafish development. Knockdown of tuberous sclerosis complex 1a (tsc1a), which encodes an upstream inhibitor of TOR complex 1 (Torc1), increases cilia length. In contrast, treatment of embryos with rapamycin, an inhibitor of Torc1, shortens cilia length. Overexpression of ribosomal protein S6 kinase 1 (S6k1), which encodes a downstream substrate of Torc1, lengthens cilia. Furthermore, we provide evidence that TOR-mediated cilia assembly is evolutionarily conserved and that protein synthesis is essential for this regulation. Finally, we demonstrate that TOR signaling and cilia length are pivotal for a variety of downstream ciliary functions, such as cilia motility, fluid flow generation, and the establishment of left-right body asymmetry. Our findings reveal a unique role for the TOR pathway in regulating cilia size through protein synthesis and suggest that appropriate and defined lengths are necessary for proper function of the cilium.
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Llabrés M, Agustí S, Herndl GJ. DIEL IN SITU PICOPHYTOPLANKTON CELL DEATH CYCLES COUPLED WITH CELL DIVISION(1). JOURNAL OF PHYCOLOGY 2011; 47:1247-1257. [PMID: 27020348 DOI: 10.1111/j.1529-8817.2011.01072.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The diel variability in picophytoplankton cell death was analyzed by quantifying the proportion of dead cyanobacteria Prochlorococcus and Synechococcus cells along several in situ diel cycles in the open Mediterranean Sea. During the diel cycle, total cell abundance varied on average 2.8 ± 0.6 and 2.6 ± 0.4 times for Synechococcus and Prochlorococcus populations, respectively. Increasing percentages of dead cells of Prochlorococcus and Synechococcus were observed during the course of the day reaching the highest values around dusk and decreasing as the night progressed, indicating a clear pattern of diel variation in the cell mortality of both cyanobacteria. Diel cycles of cell division were also monitored. The maximum percentage of dead cells (Max % DC) and the G2 + M phase of the cell division occurred within a period of 2 h for Synechoccoccus and 4.5 h for Prochlorococcus, and the lowest fraction of dead cells occurred at early morning, when the maximum number of cells in G1 phase were also observed. The G1 maximum corresponded with the maximal increase in newly divided cells (minimum % dead cells), and the subsequent exposure of healthy daughter cells to environmental stresses during the day resulted in the progressive increase in dying cells, with the loss of these cells from the population when cell division takes place. The discovery of diel patterns in cell death observed revealed the intense dynamics of picocyanobacterial populations in nature.
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Affiliation(s)
- Moira Llabrés
- Department of Global Change Research, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués, 21, 07190 Esporles, Mallorca, SpainDepartment of Global Change Research, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués, 21, 07190 Esporles, Mallorca, Spain The UWA Oceans Institute and School of Plant Biology, University of Western Australia, 35 Striling Highway, Crawley 6009, Perth, AustraliaDepartment of Biological Oceanography, Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
| | - Susana Agustí
- Department of Global Change Research, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués, 21, 07190 Esporles, Mallorca, SpainDepartment of Global Change Research, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués, 21, 07190 Esporles, Mallorca, Spain The UWA Oceans Institute and School of Plant Biology, University of Western Australia, 35 Striling Highway, Crawley 6009, Perth, AustraliaDepartment of Biological Oceanography, Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
| | - Gerhard J Herndl
- Department of Global Change Research, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués, 21, 07190 Esporles, Mallorca, SpainDepartment of Global Change Research, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués, 21, 07190 Esporles, Mallorca, Spain The UWA Oceans Institute and School of Plant Biology, University of Western Australia, 35 Striling Highway, Crawley 6009, Perth, AustraliaDepartment of Biological Oceanography, Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
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Dillard SR, Van K, Spalding MH. Acclimation to low or limiting CO2 in non-synchronous Chlamydomonas causes a transient synchronization of the cell division cycle. PHOTOSYNTHESIS RESEARCH 2011; 109:161-168. [PMID: 21253858 DOI: 10.1007/s11120-010-9618-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 12/30/2010] [Indexed: 05/30/2023]
Abstract
Acclimation of Chlamydomonas reinhardtii (hereafter, Chlamydomonas) to low or limiting CO(2) or inorganic carbon (C(i)) has been studied fairly extensively with regard to the mechanisms underlying the inducible C(i) acquisition systems and the signal transduction pathway involved in recognizing and responding to decreased C(i) availability. Investigation of low C(i )acclimation responses typically is performed with non-synchronous cultures grown in continuous light to avoid any effects of the cell division cycle (CDC) confounding interpretation of acclimation responses. However, little is known about whether acclimation to low C(i) might affect the distribution of cells among the various stages of the CDC. To investigate the effects of a limiting-C(i) challenge on the CDC of Chlamydomonas, flow cytometry was used to monitor the distribution of cells among the CDC stages in both synchronous and non-synchronous cultures during acclimation to low or limiting C(i). When faced with C(i) limitation, non-synchronous cultures of Chlamydomonas undergo transient synchronization as those cells past the Commitment point of the CDC undergo division, while the remainder of the cells pause their growth in early G-phase, with the result that the cells all accumulate in early G-phase, appearing transiently synchronized until acclimated sufficiently to the decreased C(i) for growth to resume. This perturbation of the CDC by a limiting-C(i) challenge has important implications for the interpretation of gene expression and other responses apparently induced by low or limiting C(i).
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Vítová M, Bišová K, Hlavová M, Kawano S, Zachleder V, Cížková M. Chlamydomonas reinhardtii: duration of its cell cycle and phases at growth rates affected by temperature. PLANTA 2011; 234:599-608. [PMID: 21573815 DOI: 10.1007/s00425-011-1427-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 04/28/2011] [Indexed: 05/30/2023]
Abstract
Synchronized cultures of the green alga Chlamydomonas reinhardtii were grown photoautotrophically under a wide range of environmental conditions including temperature (15-37 °C), different mean light intensities (132, 150, 264 μmol m⁻² s⁻¹), different illumination regimes (continuous illumination or alternation of light/dark periods of different durations), and culture methods (batch or continuous culture regimes). These variable experimental approaches were chosen in order to assess the role of temperature in the timing of cell division, the length of the cell cycle and its pre- and post-commitment phases. Analysis of the effect of temperature, from 15 to 37 °C, on synchronized cultures showed that the length of the cell cycle varied markedly from times as short as 14 h to as long as 36 h. We have shown that the length of the cell cycle was proportional to growth rate under any given combination of growth conditions. These findings were supported by the determination of the temperature coefficient (Q₁₀), whose values were above the level expected for temperature-compensated processes. The data presented here show that cell cycle duration in C. reinhardtii is a function of growth rate and is not controlled by a temperature independent endogenous timer or oscillator, including a circadian one.
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Affiliation(s)
- Milada Vítová
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic (ASCR), Opatovický Mlýn, 37981 Třeboň, Czech Republic
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Allahverdiyev AM, Koc RC, Ates SC, Bagirova M, Elcicek S, Oztel ON. Leishmania tropica: the effect of darkness and light on biological activities in vitro. Exp Parasitol 2011; 128:318-23. [PMID: 21510933 DOI: 10.1016/j.exppara.2011.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 04/01/2011] [Accepted: 04/05/2011] [Indexed: 11/27/2022]
Abstract
Leishmania parasites can be exposed to effects of light in their vectors and hosts, at various periods. However, there is no information about the effects of light on Leishmania parasites. The aim of this study is to investigate the effects of light on various cell parameters of Leishmania tropica, in vitro. All experiments were conducted on L. tropica promastigotes and amastigote-macrophage cultures, using flow cytometric analysis, MTT and phenol-sulfuric acid assay, DAPI and Giemsa. The results showed that the morphology of parasites has changed; the cell cycle has been affected and this caused parasites to remain at G0/G1 phase. Furthermore the proliferation, infectivity, glucose consumption and mitochondrial dehydrogenase activities of parasites were decreased. Thus, for the first time, in this study, the effects of light on biological activities of Leishmania parasites were shown. These new information about parasites' biology, would be very important to investigate the effects of light on the parasites in infected vectors and hosts.
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Affiliation(s)
- Adil M Allahverdiyev
- Yildiz Technical University, Department of Bioengineering, 34220 Istanbul, Turkey.
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Whitney LAS, Loreti E, Alpi A, Perata P. Alcohol dehydrogenase and hydrogenase transcript fluctuations during a day-night cycle in Chlamydomonas reinhardtii: the role of anoxia. THE NEW PHYTOLOGIST 2011; 190:488-498. [PMID: 20964692 DOI: 10.1111/j.1469-8137.2010.03503.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
• The unicellular green alga Chlamydomonas reinhardtii contains two iron (Fe)-hydrogenases which are responsible for hydrogen production under anoxia. In the present work the patterns of expression of alcohol dehydrogenase, a typical anaerobic gene in plants, of the hydrogenases genes (HYD1, HYD2) and of the genes responsible for their maturation (HYDEF, HYDG), were analysed. • The expression patterns were analysed by real-time reverse-transcription polymerase chain reaction in Chlamydomonas cultures during the day-night cycle, as well as in response to oxygen availability. • The results indicated that ADH1, HYD1, HYD2, HYDEF and HYDG were expressed following precise day-night fluctuations. ADH1 and HYD2 were modulated by the day-night cycle. Low oxygen plays an important role for the induction of HYD1, HYDEF and HYDG, while ADH1 and HYD2 expression was relatively insensitive to oxygen availability. • The regulation of the anaerobic gene expression in Chlamydomonas is only partly explained by responses to anoxia. The cell cycle and light-dark cycles are equally important elements in the regulatory network modulating the anaerobic response in Chlamydomonas.
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Vítová M, Bišová K, Umysová D, Hlavová M, Kawano S, Zachleder V, Cížková M. Chlamydomonas reinhardtii: duration of its cell cycle and phases at growth rates affected by light intensity. PLANTA 2011; 233:75-86. [PMID: 20922544 DOI: 10.1007/s00425-010-1282-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 09/16/2010] [Indexed: 05/02/2023]
Abstract
In the cultures of the alga Chlamydomonas reinhardtii, division rhythms of any length from 12 to 75 h were found at a range of different growth rates that were set by the intensity of light as the sole source of energy. The responses to light intensity differed in terms of altered duration of the phase from the beginning of the cell cycle to the commitment to divide, and of the phase after commitment to cell division. The duration of the pre-commitment phase was determined by the time required to attain critical cell size and sufficient energy reserves (starch), and thus was inversely proportional to growth rate. If growth was stopped by interposing a period of darkness, the pre-commitment phase was prolonged corresponding to the duration of the dark interval. The duration of the post-commitment phase, during which the processes leading to cell division occurred, was constant and independent of growth rate (light intensity) in the cells of the same division number, or prolonged with increasing division number. It appeared that different regulatory mechanisms operated through these two phases, both of which were inconsistent with gating of cell division at any constant time interval. No evidence was found to support any hypothetical timer, suggested to be triggered at the time of daughter cell release.
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Affiliation(s)
- Milada Vítová
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, Opatovický mlýn, Czech Republic
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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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Matsumura K, Yagi T, Hattori A, Soloviev M, Yasuda K. Using single cell cultivation system for on-chip monitoring of the interdivision timer in Chlamydomonas reinhardtii cell cycle. J Nanobiotechnology 2010; 8:23. [PMID: 20868509 PMCID: PMC2955706 DOI: 10.1186/1477-3155-8-23] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Accepted: 09/25/2010] [Indexed: 01/09/2023] Open
Abstract
Regulation of cell cycle progression in changing environments is vital for cell survival and maintenance, and different regulation mechanisms based on cell size and cell cycle time have been proposed. To determine the mechanism of cell cycle regulation in the unicellular green algae Chlamydomonas reinhardtii, we developed an on-chip single-cell cultivation system that allows for the strict control of the extracellular environment. We divided the Chlamydomonas cell cycle into interdivision and division phases on the basis of changes in cell size and found that, regardless of the amount of photosynthetically active radiation (PAR) and the extent of illumination, the length of the interdivision phase was inversely proportional to the rate of increase of cell volume. Their product remains constant indicating the existence of an 'interdivision timer'. The length of the division phase, in contrast, remained nearly constant. Cells cultivated under light-dark-light conditions did not divide unless they had grown to twice their initial volume during the first light period. This indicates the existence of a 'commitment sizer'. The ratio of the cell volume at the beginning of the division phase to the initial cell volume determined the number of daughter cells, indicating the existence of a 'mitotic sizer'.
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Affiliation(s)
- Kazunori Matsumura
- Kanagawa Academy of Science and Technology, KSP East 310, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan.
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Moulager M, Corellou F, Vergé V, Escande ML, Bouget FY. Integration of light signals by the retinoblastoma pathway in the control of S phase entry in the picophytoplanktonic cell Ostreococcus. PLoS Genet 2010; 6:e1000957. [PMID: 20502677 PMCID: PMC2873908 DOI: 10.1371/journal.pgen.1000957] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 04/20/2010] [Indexed: 01/09/2023] Open
Abstract
Although the decision to proceed through cell division depends largely on the metabolic status or the size of the cell, the timing of cell division is often set by internal clocks such as the circadian clock. Light is a major cue for circadian clock entrainment, and for photosynthetic organisms it is also the main source of energy supporting cell growth prior to cell division. Little is known about how light signals are integrated in the control of S phase entry. Here, we present an integrated study of light-dependent regulation of cell division in the marine green alga Ostreococcus. During early G1, the main genes of cell division were transcribed independently of the amount of light, and the timing of S phase did not occur prior to 6 hours after dawn. In contrast S phase commitment and the translation of a G1 A-type cyclin were dependent on the amount of light in a cAMP–dependent manner. CyclinA was shown to interact with the Retinoblastoma (Rb) protein during S phase. Down-regulating Rb bypassed the requirement for CyclinA and cAMP without altering the timing of S phase. Overexpression of CyclinA overrode the cAMP–dependent control of S phase entry and led to early cell division. Therefore, the Rb pathway appears to integrate light signals in the control of S phase entry in Ostreococcus, though differential transcriptional and posttranscriptional regulations of a G1 A-type cyclin. Furthermore, commitment to S phase depends on a cAMP pathway, which regulates the synthesis of CyclinA. We discuss the relative involvements of the metabolic and time/clock signals in the photoperiodic control of cell division. Microalgae from phytoplankton play an essential role in the biogeochemical cycles through carbon dioxide assimilation in the oceans where they account for more than half of organic carbon production. Photosynthetic cells use light energy for cell growth, but light can also reset the circadian clock, which is involved in the timing of cell division. How light signals are integrated in the control of cell division remains largely unknown in photosynthetic cells. We have used the marine picoeukaryotic alga Ostreococcus to dissect the molecular mechanisms of light-dependent control of cell division. We found that the Retinoblastoma pathway integrates light signals which regulate the synthesis of CyclinA in response to cAMP. Alteration of CyclinA or Rb levels triggers cell division in limiting light conditions and bypasses the need for cAMP. In addition, CyclinA overexpression affects the timing of S phase entry. This first integrated study of light-dependent regulation of cell division in photosynthetic cells provides insight into the underlying molecular mechanisms.
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Affiliation(s)
- Mickael Moulager
- Université Pierre et Marie Curie, Paris 06, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7621, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls-sur-mer, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7621, Université Pierre et Marie Curie, Paris 06, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls-sur-Mer, France
| | - Florence Corellou
- Université Pierre et Marie Curie, Paris 06, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7621, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls-sur-mer, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7621, Université Pierre et Marie Curie, Paris 06, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls-sur-Mer, France
| | - Valérie Vergé
- Université Pierre et Marie Curie, Paris 06, Observatoire Océanologique, Banyuls-sur-mer, France
| | - Marie-Line Escande
- Université Pierre et Marie Curie, Paris 06, Observatoire Océanologique, Banyuls-sur-mer, France
| | - François-Yves Bouget
- Université Pierre et Marie Curie, Paris 06, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7621, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls-sur-mer, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7621, Université Pierre et Marie Curie, Paris 06, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls-sur-Mer, France
- * E-mail:
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Kuwano K, Sakurai R, Motozu Y, Kitade Y, Saga N. DIURNAL CELL DIVISION REGULATED BY GATING THE G1 /S TRANSITION IN ENTEROMORPHA COMPRESSA (CHLOROPHYTA)(1). JOURNAL OF PHYCOLOGY 2008; 44:364-373. [PMID: 27041192 DOI: 10.1111/j.1529-8817.2008.00477.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The cell-cycle progression of Enteromorpha compressa (L.) Nees (=Ulva compressa L.) was diurnally regulated by gating the G1 /S transition. When the gate was open, the cells were able to divide if they had attained a sufficient size. However, the cells were not able to divide while the gate was closed, even if the cells had attained sufficient size. The diurnal rhythm of cell division immediately disappeared when the thalli were transferred to continuous light or darkness. When the thalli were transferred to a shifted photoperiod, the rhythm of cell division immediately and accurately synchronized with the shifted photoperiod. These data support a gating-system model regulated by light:dark (L:D) cycles rather than an endogenous circadian clock. A dark phase of 6 h or longer was essential for gate closing, and a light phase of 14 h was required to renew cell division after a dark phase of >6 h.
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Affiliation(s)
- Kazuyoshi Kuwano
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
| | - Ryousuke Sakurai
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
| | - Yoshitaka Motozu
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
| | - Yukihiro Kitade
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
| | - Naotsune Saga
- Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, JapanFaculty of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
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