Chlamydomonas reinhardtii: duration of its cell cycle and phases at growth rates affected by light intensity

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

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Effect of Light Intensity and Quality on Growth Rate and Composition of Chlorella vulgaris

Plants ◽

10.3390/plants9010031 ◽

2019 ◽

Vol 9 (1) ◽

pp. 31 ◽

Cited By ~ 2

Author(s):

Maria N. Metsoviti ◽

George Papapolymerou ◽

Ioannis T. Karapanagiotidis ◽

Nikolaos Katsoulas

Keyword(s):

Growth Rate ◽

Light Intensity ◽

Chlorella Vulgaris ◽

Lipid Content ◽

Growth Rates ◽

Solar Irradiance ◽

White Led ◽

Microalgal Biomass ◽

Nm Range ◽

Effect Of Light

In this research, the effect of solar irradiance on Chlorella vulgaris cultivated in open bioreactors under greenhouse conditions was investigated, as well as of ratio of light intensity in the 420–520 nm range to light in the 580–680 nm range (I420–520/I580–680) and of artificial irradiation provided by red and white LED lamps in a closed flat plate laboratory bioreactor on the growth rate and composition. The increase in solar irradiance led to faster growth rates (μexp) of C. vulgaris under both environmental conditions studied in the greenhouse (in June up to 0.33 d−1 and in September up to 0.29 d−1) and higher lipid content in microalgal biomass (in June up to 25.6% and in September up to 24.7%). In the experiments conducted in the closed bioreactor, as the ratio I420–520/I580–680 increased, the specific growth rate and the biomass, protein and lipid productivities increased as well. Additionally, the increase in light intensity with red and white LED lamps resulted in faster growth rates (the μexp increased up to 0.36 d−1) and higher lipid content (up to 22.2%), while the protein, fiber, ash and moisture content remained relatively constant. Overall, the trend in biomass, lipid, and protein productivities as a function of light intensity was similar in the two systems (greenhouse and bioreactor).

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Evaluation of genomic sequence-based growth rate methods for synchronized Synechococcus cultures

Applied and Environmental Microbiology ◽

10.1128/aem.01743-21 ◽

2021 ◽

Author(s):

Julia Carroll ◽

Nicolas Van Oostende ◽

Bess B. Ward

Keyword(s):

Cell Cycle ◽

Growth Rate ◽

Dna Replication ◽

Growth Rates ◽

Genomic Sequence ◽

Niche Differentiation ◽

Trophic Levels ◽

Individual Species ◽

Cell Counts

Standard methods for calculating microbial growth rates (μ) through the use of proxies, such as in situ fluorescence, cell cycle, or cell counts, are critical for determining the magnitude of the role bacteria play in marine carbon (C) and nitrogen (N) cycles. Taxon-specific growth rates in mixed assemblages would be useful for attributing biogeochemical processes to individual species and understanding niche differentiation among related clades, such as found in Synechococcus and Prochlorococcus . We tested three novel DNA sequencing-based methods (iRep, bPTR, and GRiD) for evaluating growth of light synchronized Synechococcus cultures under different light intensities and temperatures. In vivo fluorescence and cell cycle analysis were used to obtain standard estimates of growth rate for comparison with the sequence-based methods (SBM). None of the SBM values were correlated with growth rates calculated by standard techniques despite the fact that all three SBM were correlated with percentage of cells in S phase (DNA replication) over the diel cycle. Inaccuracy in determining the time of maximum DNA replication is unlikely to account entirely for the absence of relationship between SBM and growth rate, but the fact that most microbes in the surface ocean exhibit some degree of diel cyclicity is a caution for application of these methods. SBM correlate with DNA replication but cannot be interpreted quantitatively in terms of growth rate. Importance Small but abundant, cyanobacterial strains such as the photosynthetic Synechococcus spp. are essential because they contribute significantly to primary productivity in the ocean. These bacteria generate oxygen and provide biologically-available carbon, which is essential for organisms at higher trophic levels. The small size and diversity of natural microbial assemblages means that taxon-specific activities (e.g., growth rate) are difficult to obtain in the field. It has been suggested that sequence-based methods (SBM) may be able to solve this problem. We find, however, that SBM can detect DNA replication and are correlated with phases of the cell cycle but cannot be interpreted in terms of absolute growth rate for Synechococcus cultures growing under a day-night cycle, like that experienced in the ocean.

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The effect of desferrioxamine on transferrin receptors, the cell cycle and growth rates of human leukaemic cells

Biochemical Journal ◽

10.1042/bj2360243 ◽

1986 ◽

Vol 236 (1) ◽

pp. 243-249 ◽

Cited By ~ 42

Author(s):

A Bomford ◽

J Isaac ◽

S Roberts ◽

A Edwards ◽

S Young ◽

...

Keyword(s):

Cell Cycle ◽

Growth Rates ◽

Iron Chelator ◽

Scatchard Analysis ◽

Transferrin Receptors ◽

Dependent Inhibition ◽

Leukaemic Cells ◽

Dose Dependent Inhibition ◽

And Control ◽

Initial Binding

The effect of the iron chelator, desferrioxamine, on transferrin binding, growth rates and the cell cycle was investigated in the human leukaemic cell line, K562. At all concentrations of the chelator (2-50 microM) binding of 125I-transferrin was increased by 24 h and reached a maximum at 72-96 h. Maximum binding (6-8-fold increased) occurred in cells treated with 20 microM-desferrioxamine, in contrast with control cells which, at 96 h, showed a 50% decrease over initial binding. Scatchard analysis at 4 degrees C showed that this increased binding was due to an increase in the number of receptors, as the Kd was similar in induced (1.8 nM) and control (1.5 nM) cells. After 96 h cells, cultured with 20 and 50 microM-desferrioxamine accumulated 59Fe from bovine transferrin at over twice the rate found with control cells, reflecting the increase in transferrin receptors. Although iron uptake was unimpaired by the chelator there was a dose-dependent inhibition of cell growth, with control cells completing three divisions in 96 h and those in 10 microM-desferrioxamine only two divisions. At the highest concentration (50 microM), cell division was abrogated although cell viability was maintained (85%). In contrast, DNA synthesis was not markedly affected, except at 50 microM-desferrioxamine when incorporation of [3H]thymidine was 52% of that in control cells. Flow cytometry revealed that there was a progressive accumulation of the cells in the active phases of their cycle (S, G2 + M). Desferrioxamine may increase transferrin receptors in two ways: by chelating a regulatory pool of iron within the cell, and by arresting cells in S phase when receptors are maximally expressed.

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HU content and dynamics in Escherichia coli during the cell cycle and at different growth rates

FEMS Microbiology Letters ◽

10.1093/femsle/fnx195 ◽

2017 ◽

Vol 364 (19) ◽

Author(s):

Anteneh Hailu Abebe ◽

Alexander Aranovich ◽

Itzhak Fishov

Keyword(s):

Escherichia Coli ◽

Cell Cycle ◽

Growth Rates

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Prochlorococcus in situ growth rates from cell cycle analysis from RV Cape Hatteras cruises CH0409 and CH0510 in the Western Sargasso Sea in 2009 and 2010.

Biological and Chemical Oceanography Data Management Office ◽

10.1575/1912/bco-dmo.717001.1 ◽

2017 ◽

Author(s):

Brian Binder

Keyword(s):

Cell Cycle ◽

Growth Rates ◽

Cell Cycle Analysis ◽

Sargasso Sea ◽

In Situ Growth ◽

Cape Hatteras

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Comprehensive Discovery of Cell-Cycle-Essential Pathways in Chlamydomonas reinhardtii

The Plant Cell ◽

10.1105/tpc.18.00071 ◽

2018 ◽

Vol 30 (6) ◽

pp. 1178-1198 ◽

Cited By ~ 7

Author(s):

Michal Breker ◽

Kristi Lieberman ◽

Frederick R. Cross

Keyword(s):

Cell Cycle ◽

Chlamydomonas Reinhardtii

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Regulation of the start of DNA replication in Schizosaccharomyces pombe

Journal of Cell Science ◽

10.1242/jcs.112.6.939 ◽

1999 ◽

Vol 112 (6) ◽

pp. 939-946 ◽

Cited By ~ 2

Author(s):

C.R. Carlson ◽

B. Grallert ◽

T. Stokke ◽

E. Boye

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Growth Rate ◽

Schizosaccharomyces Pombe ◽

Growth Rates ◽

Cell Separation ◽

Cell Mass ◽

Nitrogen Sources ◽

S Phase ◽

G1 Phase

Cells of Schizosaccharomyces pombe were grown in minimal medium with different nitrogen sources under steady-state conditions, with doubling times ranging from 2.5 to 14 hours. Flow cytometry and fluorescence microscopy confirmed earlier findings that at rapid growth rates, the G1 phase was short and cell separation occurred at the end of S phase. For some nitrogen sources, the growth rate was greatly decreased, the G1 phase occupied 30–50% of the cell cycle, and cell separation occurred in early G1. In contrast, other nitrogen sources supported low growth rates without any significant increase in G1 duration. The method described allows manipulation of the length of G1 and the relative cell cycle position of S phase in wild-type cells. Cell mass was measured by flow cytometry as scattered light and as protein-associated fluorescence. The extensions of G1 were not related to cell mass at entry into S phase. Our data do not support the hypothesis that the cells must reach a certain fixed, critical mass before entry into S. We suggest that cell mass at the G1/S transition point is variable and determined by a set of molecular parameters. In the present experiments, these parameters were influenced by the different nitrogen sources in a way that was independent of the actual growth rate.

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