scholarly journals Temporal programming of chloroplast and cytoplasmic ribosomal RNA transcription in the synchronous cell cycle of Chlamydomonas reinhardtii.

1977 ◽  
Vol 72 (2) ◽  
pp. 470-481 ◽  
Author(s):  
R Wilson ◽  
K S Chiang
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Nuclear Dna ◽  
Dark Period ◽  
S Phase ◽  
Light Period ◽  
Rrna Synthesis ◽  
Rrna Species ◽  
32P Incorporation ◽  
Synchronization Regime

Approximately 90% of the Chlamydomonas reinhardtii chloroplast and cytoplasmic rRNAs was transcribed in the nuclear G1 phase, which occurred during the light period under an alternating light-dark synchronization regime of 12 h each. The remaining 10% of chloroplast and cytoplasmic rRNAs was transcribed from its respective DNAs in the dark period, in the midst of an apparent turnover of a transcription appeared to be prokaryotic in sophistication. The transcription was not interrupted during chloroplast DNA synthesis which occurred during the light period. However, transcription of the nuclear DNA was repressed severely during the nuclear S phase in the dark period. The patterns of incorporation of 32P into chloroplast and cytoplasmic rRNA species in the cell cycle were similar to those of the actual rRNA synthesis as measured optically. However, the quantity of 32P incorporation per unit amount of rRNA synthesized varied considerably during the cell cycle, increasing in all rRNA's during the dark period. 32P incorporation data obtained from continuous and pulse 32P-labeling experiments also revealed a turnover of a small amount of both cytoplasmic and chloroplast rRNAs at the end of the S phase. The 32P incorporation into cytoplasmic and chloroplast rRNAs was well matched temporally with the 32P incorporation into their corresponding ribosomes, indicating that the newly synthesized rRNA molecules are utilized without delay throughout the cell cycle in the assembly of ribosomes.

Immunocytochemical studies on the behavior of RuBisCO and LHCP II during the cell cycle of synchronized Euglena gracilis

1990 ◽  
Vol 48 (3) ◽  
pp. 662-663
Author(s):  
Tetsuaki Osafune ◽  
Shuji Sumida ◽  
Tomoko Ehara ◽  
Eiji Hase ◽  
Jerome A. Schiff
Keyword(s):  
Cell Cycle ◽  
Immunoelectron Microscopy ◽  
Growth Phase ◽  
Euglena Gracilis ◽  
Dark Period ◽  
Light Period ◽  
Carboxylase Activity ◽  
Immunocytochemical Studies ◽  
Lhcp Ii

Changes in the morphology of pyrenoid and the distribution of RuBisCO in the chloroplast of Euglena gracilis were followed by immunoelectron microscopy during the cell cycle in a light (14 h)- dark (10 h) synchronized culture under photoautotrophic conditions. The imrnunoreactive proteins wereconcentrated in the pyrenoid, and less densely distributed in the stroma during the light period (growth phase, Fig. 1-2), but the pyrenoid disappeared during the dark period (division phase), and RuBisCO was dispersed throughout the stroma. Toward the end of the division phase, the pyrenoid began to form in the center of the stroma, and RuBisCO is again concentrated in that pyrenoid region. From a comparison of photosynthetic CO2-fixation with the total carboxylase activity of RuBisCO extracted from Euglena cells in the growth phase, it is suggested that the carboxylase in the pyrenoid functions in CO2-fixation in photosynthesis.

Impact of UV-B Radiation on the Lipid and Fatty Acid Composition of Synchronized Ditylum brightwellii (West) Grunow

1994 ◽  
Vol 49 (9-10) ◽  
pp. 607-614 ◽  
Author(s):  
Günter Döhler ◽  
Thomas Biermann
Keyword(s):  
Cell Cycle ◽  
Fatty Acids ◽  
Dark Period ◽  
Inhibitory Effect ◽  
Light Period ◽  
Marine Diatom ◽  
Lag Phase ◽  
Ditylum Brightwellii ◽  
Acyl Lipids ◽  
The Impact

Abstract The marine diatom Ditylum brightwellii (West) Grunow isolated from the Baltic Sea could be synchronized by a light/dark rhythm of 6.5:17.5 h (white light intensity 8 W m-2) at 18 °C and 0.035 vol.% CO2. Content of protein, DNA and RNA increased linearly up to the end of the cell cycle. Pigments (chlorophyll a, chlorophyll c1 + c2, carotenoids) and galactolipids were synthesized in the light period only. A lag phase of 2 h was observed in the biosynthesis of sulphoquinovosyl diacylglycerol and phosphatidylglycerol. Formation of phosphatidylglycerol and phosphatidylcholin continued in the dark period (30% and 28%, respectively). The pattern of major fatty acids (C14:0, C16:1, C16:0, C18:1 and C20:5) varied during the cell cycle of Ditylum.Biosynthesis of acyl lipids was reduced in dependence on the UV-B dose. The most sensitive lipid was digalactosyl diacylglycerol (total inhibition at 585 J m-2), whereas phosphatidylcholin was less affected (20% reduction). UV-B radiation during the dark period had no effect on the lipid and pigment content. Strongest inhibitory effect of UV-B on cell division, synthesis of protein, pigments, sulphoquinovosyl diacylglycerol and phosphatidylglycerol was found after UV-B radiation at the beginning of the cell cycle (0.-2. h). An exposure time at the end of the light period (4.-6. h) led to a marked damage on the synthesis of monogalactosyl diacylglycerol and phosphatidylglycerol. These findings indicate a stage-dependent response of Ditylum to UV-B irradiance. The impact of UV-B resulted in an increase of unsaturated long chained fatty acids (C18, C20) and in a diminution of short chained fatty acids (C14, C16). Content of ATP was not affected by UV-B radiation under the used conditions. The inhibitory effect of UV-B on synthesis of DNA, RNA, protein and acyl lipids was mainly reversible. Results were discussed with reference to UV-B damage on the enzymes involved in the biosynthesis of acyl lipids and by a reduction of available metabolites.

scholarly journals Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red AlgaCyanidioschyzon merolae

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Shin-ya Miyagishima ◽  
Atsuko Era ◽  
Tomohisa Hasunuma ◽  
Mami Matsuda ◽  
Shunsuke Hirooka ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Dna Replication ◽  
Energy Metabolism ◽  
Cell Cycle Progression ◽  
Nuclear Dna ◽  
S Phase ◽  
Cycle Progression ◽  
Content Type

ABSTRACTThe transition from G1to S phase and subsequent nuclear DNA replication in the cells of many species of eukaryotic algae occur predominantly during the evening and night in the absence of photosynthesis; however, little is known about how day/night changes in energy metabolism and cell cycle progression are coordinated and about the advantage conferred by the restriction of S phase to the night. Using a synchronous culture of the unicellular red algaCyanidioschyzon merolae, we found that the levels of photosynthetic and respiratory activities peak during the morning and then decrease toward the evening and night, whereas the pathways for anaerobic consumption of pyruvate, produced by glycolysis, are upregulated during the evening and night as reported recently in the green algaChlamydomonas reinhardtii. Inhibition of photosynthesis by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) largely reduced respiratory activity and the amplitude of the day/night rhythm of respiration, suggesting that the respiratory rhythm depends largely on photosynthetic activity. Even when the timing of G1/S-phase transition was uncoupled from the day/night rhythm by depletion of retinoblastoma-related (RBR) protein, the same patterns of photosynthesis and respiration were observed, suggesting that cell cycle progression and energy metabolism are regulated independently. Progression of the S phase under conditions of photosynthesis elevated the frequency of nuclear DNA double-strand breaks (DSB). These results suggest that the temporal separation of oxygenic energy metabolism, which causes oxidative stress, from nuclear DNA replication reduces the risk of DSB during cell proliferation inC. merolae.IMPORTANCEEukaryotes acquired chloroplasts through an endosymbiotic event in which a cyanobacterium or a unicellular eukaryotic alga was integrated into a previously nonphotosynthetic eukaryotic cell. Photosynthesis by chloroplasts enabled algae to expand their habitats and led to further evolution of land plants. However, photosynthesis causes greater oxidative stress than mitochondrion-based respiration. In seed plants, cell division is restricted to nonphotosynthetic meristematic tissues and populations of photosynthetic cells expand without cell division. Thus, seemingly, photosynthesis is spatially sequestrated from cell proliferation. In contrast, eukaryotic algae possess photosynthetic chloroplasts throughout their life cycle. Here we show that oxygenic energy conversion (daytime) and nuclear DNA replication (night time) are temporally sequestrated inC. merolae. This sequestration enables “safe” proliferation of cells and allows coexistence of chloroplasts and the eukaryotic host cell, as shown in yeast, where mitochondrial respiration and nuclear DNA replication are temporally sequestrated to reduce the mutation rate.

scholarly journals INDEPENDENCE OF CENTRIOLE FORMATION AND DNA SYNTHESIS

1973 ◽  
Vol 57 (2) ◽  
pp. 359-372 ◽  
Author(s):  
J. B. Rattner ◽  
Stephanie G. Phillips
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Temporal Relationship ◽  
Nuclear Dna ◽  
S Phase ◽  
Centriole Duplication ◽  
And Migration ◽  
Cellular Dna ◽  
Arabinosyl Cytosine ◽  
Mitotic Cells

The temporal relationship between cell cycle events and centriole duplication was investigated electron microscopically in L cells synchronized by mechanically selecting mitotic cells. The two mature centrioles which each cell received at telophase migrated together from the side of the telophase nucleus distal to the stem body around to a region of the cytoplasm near the stem body and then into a groovelike indention in the early G1 nucleus, where they were found throughout interphase. Procentrioles appeared in association with each mature centriole at times varying from 4 to 12 h after mitosis. Since S phase was found to begin on the average about 9 h after mitotic selection, it appeared that cells generated procentrioles late in G1 or early in S. During prophase, the two centriolar duplexes migrated to opposite sides of the nucleus and the daughter centrioles elongated to the mature length. To ascertain whether any aspect of centriolar duplication was contingent upon nuclear DNA synthesis, arabinosyl cytosine was added to mitotic cells at a concentration which inhibited cellular DNA synthesis by more than 99%. Though cells were thus prevented from entering S phase, the course of procentriole formation was not detectibly affected. However, cells were inhibited from proceeding to the next mitosis, and the centriolar elongation and migration normally associated with prophase did not occur.

scholarly journals The Complex Cell Cycle of the Dinoflagellate Protoctist Crypthecodinium Cohnii as Studied In Vivo and by Cytofluorimetry

1991 ◽  
Vol 100 (3) ◽  
pp. 675-682 ◽  
Author(s):  
YVONNE BHAUD ◽  
JEAN-MARIE SALMON ◽  
MARIE-ODILE SOYER-GOBILLARD
Keyword(s):  
Cell Cycle ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
S Phase ◽  
Vegetative Cells ◽  
Crypthecodinium Cohnii ◽  
Daughter Cells ◽  
The Times

The complete cell cycle of the dinoflagellate Crypthecodinium cohnii Biecheler 1938 was observed in vivo in a synchronized heterogeneous population, after DAPI staining of DNA. In a given population, the relative nuclear DNA content in each class of cell was measured using a new numerical image-analysis method that takes into account the total fluorescence intensity (FI), area (A) and shape factor (SF). The visible degree of synchronization of the population was determined from the number of cells with a nuclear content of 1C DNA at ‘synchronization’, time 0. One method of synchronization (method 1), based on the adhesiveness of the cysts, gave no better than 50% synchronization of the population; method 2, based on swimming cells released from cysts cultured on solid medium, gave 73% of cells with the same nuclear DNA content. A scatter plot of data for FI versus A in the first few hours after time 0 showed that the actual degree of synchronization of the population was lower. The length of the C. cohnii cell cycle determined in vivo by light microscopy was 10, 16 or 24 h for vegetative cells giving two, four or eight daughter cells, respectively. Histograms based on the FI measurements showed that in an initially synchronized population observed for 20 h, the times for the first cell cycle were: G1 phase, 6 h; S phase, 1 h 30 min; G2+M, 1h 30 min, with the release of vegetative cells occurring 1 or 2h after the end of cytokinesis. The times for the second cell cycle were G1+S, 3h; G2+M, 2h. FI and A taken together, suggested that the S phase is clearly restricted, as in higher eukaryotes. A and SF, taken together, showed that the large nuclear areas were always in cysts with two or four daughter cells. FI and SF, taken together, showed that the second S phase always occurred after completion of the first nuclear division. Our data concerning the course of the cell cycle in C. cohnii are compared with those from earlier studies, and the control of the number of daughter cells is discussed; this does not depend on the ploidy of the mother cell.

Temporal order of gene replication in Chinese hamster ovary cells

1989 ◽  
Vol 9 (7) ◽  
pp. 2881-2889
Author(s):  
J Taljanidisz ◽  
J Popowski ◽  
N Sarkar
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
Chinese Hamster Ovary Cells ◽  
Repetitive Sequences ◽  
Chinese Hamster ◽  
Nuclear Dna Content ◽  
Single Copy ◽  
S Phase ◽  
Specific Gene ◽  
Cell Permeabilization

To investigate the molecular basis of the regulatory mechanisms responsible for the orderly replication of the mammalian genome, we have developed an experimental system by which the replication order of various genes can be defined with relative ease and precision. Exponentially growing CHO-K1 cells were separated into populations representing various stages of the cell cycle by centrifugal elutriation and analyzed for cell cycle status flow cytometry. The replication of specific genes in each elutriated fraction was measured by labeling with 5-mercuri-dCTP and [3H]dTPP under conditions of optimal DNA synthesis after cell permeabilization with lysolecithin. Newly synthesized mercurated DNA from each elutriated fraction was purified by affinity chromatography on thiol-agarose and replicated with the large fragment of Escherichia coli DNA polymerase I by using [alpha-32P]dATP and random primers. The 32P-labeled DNA representative of various stages of the cell cycle was then hybridized with dot blots of plasmid DNA containing specific cloned genes. From these results, it was possible to deduce the nuclear DNA content at the time each specific gene replicated during S phase (C value). The C values of 29 genes, which included single-copy genes, multifamily genes, oncogenes, and repetitive sequences, were determined and found to be distributed over the entire S phase. Of the 28 genes studied, 19 had been examined by others using in vivo labeling techniques, with results which agreed with the replication pattern observed in this study. The replication times of nine other genes are described here for the first time. Our method of analysis is sensitive enough to determine the replication time of single-copy genes. The replication times of various genes and their levels of expression in exponentially growing CHO cells were compared. Although there was a general correlation between transcriptional activity and replication in the first half of S phase, examination of specific genes revealed a number of exceptions. Approximately 25% of total poly(A) RNA was transcribed from the late-replicating DNA.

Circadian variation in the distribution of cells throughout the different phases of the cell cycle in the anterior pituitary gland of adult male rats as analysed by flow cytometry

1991 ◽  
Vol 129 (3) ◽  
pp. 329-333 ◽  
Author(s):  
E. Carbajo-Pérez ◽  
S. Carbajo ◽  
A. Orfao ◽  
J. L. Vicente-Villardón ◽  
R. Vázquez
Keyword(s):  
Cell Cycle ◽  
Pituitary Gland ◽  
Adult Male ◽  
Anterior Pituitary ◽  
Somatic Cells ◽  
S Phase ◽  
Light Period ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
M Phase

ABSTRACT Flow cytometric analysis of nuclei stained with propidium iodide (PI) has been used to study the distribution of cells throughout the different phases of the cell cycle in the anterior pituitary gland of adult male Sprague–Dawley rats at different times of the day. According to PI fluorescence intensity the relative numbers of cells in S phase (cells with a DNA content between that of somatic cells in interphase (2n) and that of somatic cells after duplication of the DNA prior to cell division (4n)) and G2/M phase (4n) were calculated. A significant circadian rhythm was found for cells in both the S phase (P < 0·05) and the G2/M phase (P < 0·01). The wave of cells in S phase with a peak at the middle of the light period (14.00 h) precedes by about 6 h the wave of cells in G2/M phase (peak at 20.00 h). Most of the DNA-replicating cells were found during the early S phase at 11.00 h, advancing further up to the middle of this phase at 14.00 h. Cells were distributed homogeneously throughout the S phase at 17.00 h. These data strongly suggest that the beginning of the light period triggers a wave of cells to leave G0/G1 into S phase. Journal of Endocrinology (1991) 129, 329–333

scholarly journals Temporal order of gene replication in Chinese hamster ovary cells.

1989 ◽  
Vol 9 (7) ◽  
pp. 2881-2889 ◽  
Author(s):  
J Taljanidisz ◽  
J Popowski ◽  
N Sarkar
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
Chinese Hamster Ovary Cells ◽  
Repetitive Sequences ◽  
Chinese Hamster ◽  
Nuclear Dna Content ◽  
Single Copy ◽  
S Phase ◽  
Specific Gene ◽  
Cell Permeabilization

To investigate the molecular basis of the regulatory mechanisms responsible for the orderly replication of the mammalian genome, we have developed an experimental system by which the replication order of various genes can be defined with relative ease and precision. Exponentially growing CHO-K1 cells were separated into populations representing various stages of the cell cycle by centrifugal elutriation and analyzed for cell cycle status flow cytometry. The replication of specific genes in each elutriated fraction was measured by labeling with 5-mercuri-dCTP and [3H]dTPP under conditions of optimal DNA synthesis after cell permeabilization with lysolecithin. Newly synthesized mercurated DNA from each elutriated fraction was purified by affinity chromatography on thiol-agarose and replicated with the large fragment of Escherichia coli DNA polymerase I by using [alpha-32P]dATP and random primers. The 32P-labeled DNA representative of various stages of the cell cycle was then hybridized with dot blots of plasmid DNA containing specific cloned genes. From these results, it was possible to deduce the nuclear DNA content at the time each specific gene replicated during S phase (C value). The C values of 29 genes, which included single-copy genes, multifamily genes, oncogenes, and repetitive sequences, were determined and found to be distributed over the entire S phase. Of the 28 genes studied, 19 had been examined by others using in vivo labeling techniques, with results which agreed with the replication pattern observed in this study. The replication times of nine other genes are described here for the first time. Our method of analysis is sensitive enough to determine the replication time of single-copy genes. The replication times of various genes and their levels of expression in exponentially growing CHO cells were compared. Although there was a general correlation between transcriptional activity and replication in the first half of S phase, examination of specific genes revealed a number of exceptions. Approximately 25% of total poly(A) RNA was transcribed from the late-replicating DNA.

scholarly journals Regulation of genes encoding the large subunit of ribulose-1,5-bisphosphate carboxylase and the photosystem II polypeptides D-1 and D-2 during the cell cycle of Chlamydomonas reinhardtii.

1986 ◽  
Vol 103 (5) ◽  
pp. 1837-1845 ◽  
Author(s):  
D L Herrin ◽  
A S Michaels ◽  
A L Paul
Keyword(s):  
Cell Cycle ◽  
Photosystem Ii ◽  
Dark Period ◽  
Large Subunit ◽  
Light Period ◽  
Mrna Levels ◽  
Bisphosphate Carboxylase ◽  
Polypeptide Synthesis ◽  
Translational Level

Synthesis of the major chloroplast proteins is temporally regulated in light-dark-synchronized Chlamydomonas cells. We have used cloned chloroplast DNA probes, and in vitro and in vivo protein synthesis to examine the cell cycle regulation of photosystem II polypeptides D-1 and D-2, and the large subunit of ribulose-1,5-bisphosphate carboxylase (RuBPCase LS). Synthesis and accumulation of D-1 and D-2 mRNAs occurs during the first half of the light period (G1), correlating with increasing synthesis of the polypeptides. Rifampicin, added immediately before the light period, inhibited the normal increase in D-1, D-2 polypeptide synthesis. During the dark period D-1, D-2 mRNAs persist at high levels despite reduced rates of mRNA synthesis and translation during this period. Cell-free translation analyses indicate that the D-1 mRNA present during the dark period is efficient at directing synthesis of the D-1 precursor in vitro. We conclude that expression of the psbA (D-1) and psbD (D-2) genes are regulated primarily at the transcriptional level during the light-induction period but at the translational level for the remainder of the cell cycle. Transcripts of the RuBPCase LS gene (rbcL) are also found at high levels during the light and dark periods but, unlike D-1 and D-2, LS mRNA levels do not increase until the last half of the light period and measurable synthesis and accumulation of this mRNA occurs during the dark. Furthermore, induction of LS polypeptide synthesis during the light period is insensitive to rifampicin. We conclude that LS production is regulated primarily at the translational level during the cell cycle.

scholarly journals Relationship between nuclear DNA-content of sperm cells and the timing of events in the cell cycle of Brassica campestris L. (Brassicaceae)

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Hua Deng
Keyword(s):  
Cell Cycle ◽  
Quantitative Analysis ◽  
Dna Content ◽  
Nuclear Dna ◽  
Brassica Campestris ◽  
Nuclear Dna Content ◽  
Pollen Grain ◽  
S Phase ◽  
Sperm Cells ◽  
Generative Cells

In this work we conducted a quantitative analysis of the nuclear DNA-content of developing sperm cells of the plant <em>Brassica campestris</em> L. The sperm cells were in young pollen grain, mature pollen grain and pollen tubes. When generative cells, at the pre-anthesis stage, split into two sperm cells, we have established that the newly-formed sperm cells begin to synthesize nuclear DNA in developing pollen grain of <em>B. campestris</em>. We measured this DNA-content during the development of sperm cells. The results indicate that during development, sperm cells of <em>B. campestris</em> have passed the G<sub>1</sub> phase of the cell cycle and entered the S phase, presumably then fusing with egg cells at a level of 2C, as is characteristic of G<sub>2</sub> type fertilization in angiosperms.

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