Light regulation of the cell cycle in <i>Euglena gracilis bacillaris</i>

Yee, Muh-ching; Bartholomew, James C.

doi:10.1002/cyto.990090417

Cited by 12 publications

(5 citation statements)

References 15 publications

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“…Synchronisation of eukaryote unicellular algae by light/dark cycles has been known for a long time, both in red (Cyanidioschyzon) and green (Chlamydomonas, Chlorella, Euglena, picoeukaryotes) algae, and most of them divide at the light/ dark transition (Spudich and Sager, 1980;Donnan et al, 1985;McAteer et al, 1985;Yee and Bartholomew, 1988;Suzuki et al, 1994;Jacquet, 2001;Bisova et al, 2005). A similar synchronisation of cell division by light was observed in Ostreococcus tauri.…”

Section: Discussionmentioning

confidence: 55%

Natural Synchronisation for the Study of Cell Division in the Green Unicellular Alga Ostreococcus tauri

et al. 2006

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Ostreococcus tauri (Prasinophyceae) is a marine unicellular green alga which diverged early in the green lineage. The interest of O. tauri as a potential model to study plant cell division is based on its key phylogenetic position, its simple binary division, a very simple cellular organisation and now the availability of the full genome sequence. In addition O. tauri has a minimal yet complete set of cell cycle control genes. Here we show that division can be naturally synchronised by light/dark cycles and that organelles divide before the nucleus. This natural synchronisation, although being only partial, enables the study of the expression of CDKs throughout the cell cycle. The expression patterns of OtCDKA and OtCDKB were determined both at the mRNA and protein levels. The single OtCDKA gene is constantly expressed throughout the cell cycle, whereas OtCDKB is highly regulated and expressed only in S/G2/M phases. More surprisingly, OtCDKA is not phosphorylated at the tyrosine residue, in contrast to OtCDKB which is strongly phosphorylated during cell division. OtCDKA kinase activity appears before the S phase, indicating a possible role of this protein in the G1/S transition. OtCDKB kinase activity occurs later than OtCDKA, and its tyrosine phosphorylation is correlated to G2/M, suggesting a possible control of the mitotic activity. To our knowledge this is the first organism in the green lineage which showed CDKB tyrosine phosphorylation during cell cycle progression.

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Section: Discussionmentioning

confidence: 55%

Natural Synchronisation for the Study of Cell Division in the Green Unicellular Alga Ostreococcus tauri

et al. 2006

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“…(23). Dark-grown Euglena were obtained by inoculating cells from a light-grown, phototrophic culture into organotrophic medium and allowing the culture to grow 10 d in a foil-wrapped flask.…”

mentioning

confidence: 99%

Effects of 3-(3,4-Dichlorophenyl)-1,1-Dimethylurea on the Cell Cycle in Euglena gracilis

Yee¹,

Bartholomew²

1989

Plant Physiol.

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The cell cycle of the photosynthetic unicellular alga Euglena gracilis growing in phototrophic medium is regulated by light. To investigate the relationship of this cell cycle response to light stimulated photosynthesis, we have tested the effect of the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on Euglena cell cycle transit. While DCMU does not block light stimulated cells from entering the S phase of the cell cycle, it does inhibit the transit through G2/M. Triazine herbicides such as DCMU and atrazine have been shown to interrupt photosynthetic electron transfer at the PSII reaction center (6). The specificity of this inhibitor for photosynthesis has been demonstrated both biochemically as well as genetically. Binding studies using labeled atrazine have shown that the herbicides bind specifically to the DI polypeptide of the reaction center core complex (16). Furthermore, a mutant strain of Euglena has been isolated that is resistant to the effects of DCMU on its photosynthetic apparatus (12).The psbA gene encoding the DI protein has been sequenced from this strain (1 1), and has been shown to contain the same single base change found in the DCMU-resistant Chlamydomonas reinhardtii strain DCMU4 (6). The existence of these DCMU-resistant strains of algae and the studies associating resistance to a mutation in a component ofthe photosynthetic reaction center suggested that DCMU's effect on the cell cycle in DCMU-sensitive strains was directly attributable to its effect on photosynthetic electron transport. DCMU has, however, been shown to have many effects on cell metabolism aside from photosynthetic electron transport. Growth of Euglena in phototrophic medium in the presence of DCMU results in a reduction in the number ofchloroplasts per cell and structural changes in the remaining chloroplasts (21). Addition of DCMU to dark-grown resting Euglena exposed to light results in a decrease in ribulose bisphosphate carboxylase (RuBisco) activity (17). Removal of DCMU results in an increase in RuBisco activity even when chloroplast or cytoplasmic translation is inhibited. DCMU also partially inhibits the accumulation ofseveral chloroplast-encoded polypeptides in Euglena including the large subunit of RuBisco (13). The effects of DCMU on nuclear functions has not been well documented.We have found that DCMU at concentrations in the medium used to inhibit photosynthesis causes a decrease in the rate of transit through G2/M, but does not alter the efficiency with which light induced cells to enter the S phase of the cell cycle from Go. (23). Dark-grown Euglena were obtained by inoculating cells from a light-grown, phototrophic culture into organotrophic medium and allowing the culture to grow 10 d in a foil-wrapped flask. Two bleached strains of E. gracillis var bacillaris, W3BUL and W3BSmL, were obtained from Prof. Jerome Schiff, Brandeis University.Samples were prepared and analyzed on the flow cytometer by pelleting at 8000 rpm in an SM24 rotor (Sorvall) for 5 min, followed by tw...

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“…Whereas the connection between cell division and the need for metabolites and photosynthates is obvious, the mechanism of light acting upon cellular DNA synthesis regulation is not so clear (Yee and Bartholomew, 1988). Flow cytometric DNA analysis is a helpful tool in this respect .…”

Section: Cell Cycle Analysismentioning

confidence: 99%

“…Examination of DNA histograms allowed the localization of the effect of silicon deprivation in terms of progress through G1, S, and G2+M phase. Yee and Bartholomew (1988) studied light regulation of the cell cycle in Euglena gracilis bacilaris. Euglena grown under phototrophic conditions are easily synchronized to a 12 h light-12 h dark regime.…”

Section: Cell Cycle Analysismentioning

confidence: 99%

Flow cytometry as a tool for the study of phytoplankton

Dubelaar¹,

Jonker²

2000

Sci. Mar.

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SUMMARY: An overview is presented on flow cytometry as a tool for counting, analysis and identification of phytoplankton species and groups. The paper covers basics on the analysis technique and instrumentation such as the measuring principle, the type of instrument, limitations and pitfalls with phytoplankton samples and sample handling and preprocessing. Possibilities of the measured entities are discussed, roughly divided in light scatter and related parameters, the endogenous fluorescence and exogenous fluorescence, followed by a discussion on the actual applications such as phytoplankton abundance analysis, ecology and physiology research and monitoring of particle size and biomass. In addition to a limited literature review, we tried to assess how flow cytometry is used in routine laboratory practice and monitoring operations. Therefore, a questionnaire was sent out via email to 47 scientists at 43 institutes known to us as involved in flow cytometric analysis of phytoplankton. In total, 19 scientists responded. Specific survey results are included in italic print whereas some more general answers were integrated in the overview.

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Light regulation of the cell cycle in Euglena gracilis bacillaris

Cited by 12 publications

References 15 publications

Natural Synchronisation for the Study of Cell Division in the Green Unicellular Alga Ostreococcus tauri

Natural Synchronisation for the Study of Cell Division in the Green Unicellular Alga Ostreococcus tauri

Effects of 3-(3,4-Dichlorophenyl)-1,1-Dimethylurea on the Cell Cycle in Euglena gracilis

Flow cytometry as a tool for the study of phytoplankton

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