Differential patterns of mitochondrial, chloroplastic and nuclear DNA synthesis in the synchronous cell cycle of Chlamydomonas reinhardtii

Planta ◽  
1978 ◽  
Vol 141 (3) ◽  
pp. 259-267 ◽  
Author(s):  
David Grant ◽  
David C. Swinton ◽  
Kwen-Sheng Chiang
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Chlamydomonas Reinhardtii ◽  
Nuclear Dna ◽  
Synchronous Cell

scholarly journals SYNCHRONIZATION OF MITOCHONDRIAL DNA SYNTHESIS IN CHINESE HAMSTER CELLS (LINE CHO) DEPRIVED OF ISOLEUCINE

1973 ◽  
Vol 58 (2) ◽  
pp. 340-345 ◽  
Author(s):  
Kenneth D. Ley ◽  
Marilyn M. Murphy
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Time Course ◽  
Nuclear Dna ◽  
Tritiated Thymidine ◽  
Chinese Hamster ◽  
Chinese Hamster Cells ◽  
In Cells

Mitochondrial DNA (mit-DNA) synthesis was compared in suspension cultures of Chinese hamster cells (line CHO) whose cell cycle events had been synchronized by isoleucine deprivation or mitotic selection. At hourly intervals during cell cycle progression, synchronized cells were exposed to tritiated thymidine ([3H]TdR), homogenized, and nuclei and mitochondria isolated by differential centrifugation. Mit-DNA and nuclear DNA were isolated and incorporation of radioisotope measured as counts per minute ([3H]TdR) per microgram DNA. Mit-DNA synthesis in cells synchronized by mitotic selection began after 4 h and continued for approximately 9 h. This time-course pattern resembled that of nuclear DNA synthesis. In contrast, mit-DNA synthesis in cells synchronized by isoleucine deprivation did not begin until 9–12 h after addition of isoleucine and virtually all [3H]TdR was incorporated during a 3-h interval. We have concluded from these results that mit-DNA synthesis is inhibited in CHO cells which are arrested in G1 because of isoleucine deprivation and that addition of isoleucine stimulates synchronous synthesis of mit-DNA. We believe this method of synchronizing mit-DNA synthesis may be of value in studies of factors which regulate synthesis of mit-DNA.

scholarly journals VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

1973 ◽  
Vol 57 (3) ◽  
pp. 668-674 ◽  
Author(s):  
Pamela Leban Johnston ◽  
Edgar F. Carell
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Synthesis ◽  
Vitamin B12 ◽  
Protein Content ◽  
Euglena Gracilis ◽  
Cell Divisions ◽  
Synchronous Cell ◽  
A Minor ◽  
Macromolecular Composition

When vitamin B12 is added to B12-deficient cultures of Euglena gracilis, the cells undergo two relatively synchronous cell divisions within a shorter than usual period of time, apparently as a result of a transitory shortening of the cell cycle. The first cell division pulse, occurring 4.5 h after addition of B12, is preceded by the completion of DNA duplication, but appears to involve no net synthesis of RNA or protein. Before the second round of cell division at about 11 h, a significant amount of DNA synthesis is observed. This time it is accompanied by a minor increase in the RNA and protein content of the culture. The cellular contents of RNA and protein were observed to decrease steadily after the resumption of cell division in B12-depleted cultures receiving the vitamin. Ultimately all three macromolecules returned to their nondeficient, plateau stage levels; by this time, cell division had ceased.

scholarly journals Circadian Clock Core Component Bmal1 Dictates Cell Cycle Rhythm of Proliferating Hepatocytes during Liver Regeneration

2021 ◽  
Author(s):  
Huaizhou Jiang ◽  
Veronica Garcia ◽  
Jennifer Abla Yanum ◽  
Joonyong Lee ◽  
Guoli Dai
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Circadian Clock ◽  
Liver Regeneration ◽  
Nuclear Dna ◽  
Core Component ◽  
Activation Patterns ◽  
Redox Sensor ◽  
M Phase ◽  
Late Stages

Following partial hepatectomy (PH), the majority of remnant hepatocytes synchronously enter and rhythmically progress through the cell cycle for three major rounds to regain lost liver mass. Whether and how the circadian clock core component Bmal1 modulates this process remains elusive. We performed PH on Bmal1+/+ and hepatocyte-specific Bmal1 knockout (Bmal1hep-/-) mice and compared the initiation and progression of the hepatocyte cell cycle. After PH, Bmal1+/+ hepatocytes exhibited three major waves of nuclear DNA synthesis. In contrast, in Bmal1hep-/- hepatocytes, the first wave of nuclear DNA synthesis was delayed by 12 h, and the third such wave was lost. Following PH, Bmal1+/+ hepatocytes underwent three major waves of mitosis, whereas Bmal1hep-/- hepatocytes fully abolished mitotic oscillation. These Bmal1-dependent disruptions in the rhythmicity of hepatocyte cell cycle after PH were accompanied by suppressed expression peaks of a group of cell cycle components and regulators, and dysregulated activation patterns of mitogenic signaling molecules c-Met and EGFR. Moreover, Bmal1+/+ hepatocytes rhythmically accumulated fat as they expanded following PH, whereas this phenomenon was largely inhibited in Bmal1hep-/- hepatocytes. In addition, during late stages of liver regrowth, Bmal1 absence in hepatocytes caused the activation of redox sensor Nrf2, suggesting an oxidative stress state in regenerated liver tissue. Collectively, we demonstrated that during liver regeneration, Bmal1 partially modulates the oscillation of S-phase progression, fully controls the rhythmicity of M-phase advancement, and largely governs fluctuations in fat metabolism in replicating hepatocytes, and eventually determines the redox state of regenerated livers.

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 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.

scholarly journals Relationship between the timing of DNA replication and the developmental competence in Acanthamoeba castellanii

1988 ◽  
Vol 91 (3) ◽  
pp. 389-399
Author(s):  
H. Jantzen ◽  
I. Schulze ◽  
M. Stohr
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Defined Medium ◽  
Reciprocal Relationship ◽  
Developmental Competence ◽  
Replication Phase ◽  
G2 Phase ◽  
D Cells

In Acanthamoeba, two different cell types are known. Trophozoites are generated in the mitotic division cycle, whereas cells committed at late G2 phase of the cell cycle develop into cysts in response to starvation. In this paper we study the role of timing of DNA replication in regulating development. The investigation was performed with cultures growing in a non-defined medium (ND cells) that show a high encystation competence and with cultures that have been growing in a chemically defined medium (D cells) for several years and show a low encystation competence. Bivariate DNA/BrdUrd distributions show that ND cells progress through a cycle in which the short replication phase occurs immediately and exclusively after prior completion of mitosis. These cells arrest at late G2 phase of the cell cycle during the stationary stage. In D cells, DNA replication and mitosis seem to be uncoupled, since replication takes place before as well as after mitosis. These cells arrest within their replication phase during the stationary stage. These findings indicate that D cells do not progress into late G2 phase of the cell cycle and hence do not have the competence for commitment. The alternate timing of DNA replication and the low encystation competence of D cells can be reversed by cultivation of these cells in ND medium. Synchronization experiments reveal that late G2 phase ND cells exhibit a low capacity for BrdUrd incorporation and growth after transfer into D medium, whereas ND cells of earlier phases of the cell cycle show premitotic incorporation of BrdUrd into nuclear DNA and growth. These findings suggest on the one hand that premitotic DNA synthesis is a prerequisite for growth of cells in D medium, and that there is a dependence of the induction of premitotic DNA synthesis on the cell cycle, and on the other hand that a reciprocal relationship exists between the capacity of premitotic DNA synthesis and commitment to differentiation.

Periodic expression of nuclear and mitochondrial DNA replication genes during the trypanosomatid cell cycle

1994 ◽  
Vol 107 (12) ◽  
pp. 3515-3520
Author(s):  
S.G. Pasion ◽  
G.W. Brown ◽  
L.M. Brown ◽  
D.S. Ray
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Nuclear Dna ◽  
Protein A ◽  
Mrna Levels ◽  
Gene Encoding ◽  
Genes Encoding

In trypanosomatids, DNA replication in the nucleus and in the single mitochondrion (or kinetoplast) initiates nearly simultaneously, suggesting that the DNA synthesis (S) phases of the nucleus and the mitochondrion are coordinately regulated. To investigate the basis for the temporal link between nuclear and mitochondrial DNA synthesis phases the expression of the genes encoding DNA ligase I, the 51 and 28 kDa subunits of replication protein A, dihydrofolate reductase and the mitochondrial type II topoisomerase were analyzed during the cell cycle progression of synchronous cultures of Crithidia fasciculata. These DNA replication genes were all expressed periodically, with peak mRNA levels occurring just prior to or at the peak of DNA synthesis in the synchronized cultures. A plasmid clone (pdN-1) in which TOP2, the gene encoding the mitochondrial topoisomerase, was disrupted by the insertion of a NEO drug-resistance cassette was found to express both a truncated TOP2 mRNA and a truncated topoisomerase polypeptide. The truncated mRNA was also expressed periodically coordinate with the expression of the endogenous TOP2 mRNA indicating that cis elements necessary for periodic expression are contained within cloned sequences. The expression of both TOP2 and nuclear DNA replication genes at the G1/S boundary suggests that regulated expression of these genes may play a role in coordinating nuclear and mitochondrial S phases in trypanosomatids.

scholarly journals Circadian Clock Core Component Bmal1 Dictates Cell Cycle Rhythm of Proliferating Hepatocytes during Liver Regeneration

2021 ◽  
Author(s):  
Huaizhou Jiang ◽  
Veronica Garcia ◽  
Jennifer Yanum ◽  
Joonyong Lee ◽  
Guoli Dai
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Circadian Clock ◽  
Liver Regeneration ◽  
Nuclear Dna ◽  
Third Wave ◽  
Wild Type ◽  
Core Component ◽  
Activation Patterns ◽  
M Phase

Following partial hepatectomy (PH), the majority of remnant hepatocytes synchronously enter and rhythmically progress through the cell cycle for three major rounds to regain the lost liver mass. Whether and how the circadian clock core component Bmal1 modulates this process remains elusive. We performed PH on wild-type and hepatocyte-specific Bmal1 knockout (Bmal1hep-/-) mice and compared the initiation and progression of the hepatocyte cell cycle. After PH, wild-type hepatocytes exhibited three major waves of nuclear DNA synthesis. In contrast, in Bmal1hep-/- hepatocytes, the first wave of nuclear DNA synthesis was delayed by 12 hours, the third wave of nuclear DNA synthesis was lost. Following PH, wild-type hepatocytes underwent three major waves of mitosis, whereas Bmal1hep-/- hepatocytes fully abolished the oscillation of mitosis. These Bmal1-dependent disruptions in the rhythmicity of hepatocyte cell cycle after PH were accompanied with prevented expression peaks of a group of the cell cycle components and regulators, dysregulated activation patterns of mitogenic signaling molecules c-Met and EGFR. Moreover, wild-type hepatocytes rhythmically accumulated fat as they expanded following PH, whereas this event was largely prohibited in Bmal1hep-/- hepatocytes. In addition, during the late stage of liver regrowth, Bmal1 absence in hepatocytes caused the activation of redox sensor Nrf2, suggesting an oxidative stress state in regenerated livers. Collectively, we demonstrate that, during liver regeneration, Bmal1 partially modulates the oscillation of S-phase progression, fully controls the rhythmicity of M-phase advance, and largely govern the fluctuation of fat metabolism of replicating hepatocytes, and eventually determines the redox state of regenerated livers.

scholarly journals Strengths and Weaknesses of Cell Synchronization Protocols Based on Inhibition of DNA Synthesis

2021 ◽  
Vol 22 (19) ◽  
pp. 10759
Author(s):  
Anna Ligasová ◽  
Karel Koberna
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Mammalian Cells ◽  
Building Blocks ◽  
Cell Populations ◽  
Advantages And Disadvantages ◽  
Cell Synchronization ◽  
Synchronous Cell ◽  
Inhibition Of Dna Synthesis ◽  
Selection Of

Synchronous cell populations are commonly used for the analysis of various aspects of cellular metabolism at specific stages of the cell cycle. Cell synchronization at a chosen cell cycle stage is most frequently achieved by inhibition of specific metabolic pathway(s). In this respect, various protocols have been developed to synchronize cells in particular cell cycle stages. In this review, we provide an overview of the protocols for cell synchronization of mammalian cells based on the inhibition of synthesis of DNA building blocks—deoxynucleotides and/or inhibition of DNA synthesis. The mechanism of action, examples of their use, and advantages and disadvantages are described with the aim of providing a guide for the selection of suitable protocol for different studied situations.

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