Stationary phase and the cell cycle of Dictyostelium discoideum in liquid nutrient medium

1976 ◽  
Vol 20 (3) ◽  
pp. 513-523 ◽  
Author(s):  
D.R. Soll ◽  
J. Yarger ◽  
M. Mirick
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Nutrient Medium ◽  
Nuclear Dna ◽  
Cell Concentration ◽  
Phase Cell ◽  
Cell Multiplication ◽  
Mean Cell Volume ◽  
Liquid Nutrient Medium

Cells of the axenic strain of the cellular slime mould Dictyostelium discoideum, AX-3, multiply in the liquid nutrient medium HL-5 with a doubling time of 12 h. When the cell concentration reaches approximately 1 X10(7) per ml the rate of cell multiplication begins decreasing and after 20–30 h reaches zero, at a stationary phase cell concentration of 2 to 2–5 X 10(7) cells per ml. The intercept of the extrapolated log phase and stationary phase plots has arbitrarily been considered the onset of the stationary phase. We have found that after cells have been in stationary phase for 24–32 h, mean cell volume increases by 25%, average dry weight by 37%, and average protein content by 24%. These values are close to the expected values for a cell population which is blocked at a point late in the cell cycle. Stationary phase cells also contain 25% more nuclear DNA than log phase cells, indicating that the population of cells at stationary phase is blocked after the DNA replication phase. Finally, when stationary phase cells are washed free of stationary phase medium and reinoculated into fresh medium, they reinitiate cell division synchronously. In the light of the demonstrated relationship between stationary phase and the cell cycle, a possible role for the growth inhibitor produced at stationary phase is considered.

The cell cycle during the vegetative stage of Dictyostelium discoideum and its response to temperature change

1978 ◽  
Vol 32 (1) ◽  
pp. 1-20
Author(s):  
I.M. Zada-Hames ◽  
J.M. Ashworth
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Doubling Time ◽  
Nuclear Dna ◽  
Cell Number ◽  
Cell Cycle Time ◽  
Optimum Growth Temperature ◽  
Cell Cycle Phases ◽  
Response To Temperature

The cell cycle in amoebae of Dictyostelium discoideum has been analysed in cells growing asynchronously in axenic medium. For cells growing at the optimum growth temperature of 22 degrees C with a culture doubling time of 8 h the average times for the cell cycle phases are as follows: G1, 1.5 h; S, 2.1 h; G2, 4.4 h; M, 15.2 min. When amoebae are grown at temperatures below 22 degrees C, culture doubling time increases and the cell cycle phases are altered in ways characteristic for each phase. G2 is the most variable period and may occupy up to 70% of the total cell cycle time; S and G1 are the least affected, increasing by only 20% when the cell generation time is doubled. When cells which have reached the stationary phase of growth in liquid medium are washed and reinoculated into fresh medium they divide synchronously after a lag period of 5 h. By following cell number increase and nuclear DNA synthesis in these cultures we have shown that stationary phase cells are arrested in the G2 phase of the cell cycle. Finally, although more than 97% of amoebae grown on a bacterial food source are uninucleate, when grown axenically up to 35% of the cell population may become multinucleate. Our results suggest that these cells probably arise through the failure of cytokinesis to follow karyokinesis. Multinucleate cells appear to have a slightly longer G2 period than mononucleate cells.

The cell cycle and its relationship to development in Acanthamoeba castellanii

1987 ◽  
Vol 88 (5) ◽  
pp. 579-590
Author(s):  
MICHAEL STÖHR ◽  
KURT BOMMERT ◽  
INGRID SCHULZE ◽  
HELGA JANTZEN
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Nuclear Dna ◽  
Acanthamoeba Castellanii ◽  
Nuclear Dna Content ◽  
Defined Medium ◽  
G2 Phase ◽  
D Cells ◽  
High Degree ◽  
The Relationship

The cell cycle and the relationship between particular cell cycle phases and the differentiation of trophozoites into cysts were reinvestigated in Acanthamoeba castellanii using flow fluorometric measurements of nuclear DNA content and synthesis and synchronization of cells by release from the stationary phase. The investigation was performed with cultures growing in non-defined medium (ND cells) showing a high degree of encystation in response to starvation and with subcultures growing in chemically defined nutrient medium (D cells) exhibiting a very low encystation competence. In both cultures the cell cycle starts with a short S phase taking place simultaneously with cytokinesis followed by a long G2 phase. A G1 phase seems to be either absent or very short. Synchronization experiments reveal that in ND cells encystation is initiated from a particular position of late G2. The high encystation competence of stationary phase ND cells seems to be due to arrest of cells at this particular cell cycle position. The lack of encystation competence of stationary phase D cells correlates with the loss of accumulation of cells at this particular stage of the cell cycle. This change of the property of cells is related to the growth condition and not to an irreversible loss of encystation competence of D cells.

scholarly journals Dependence of cell-type proportioning and sorting on cell cycle phase in Dictyostelium discoideum

1984 ◽  
Vol 70 (1) ◽  
pp. 133-145 ◽  
Author(s):  
C.J. Weijer ◽  
G. Duschl ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Cell Type ◽  
Slime Mould ◽  
Synchronous Cell ◽  
A Cell ◽  
The Relationship

The relationship between the cell cycle phase of vegetative amoebae and prestalk and prespore differentiation in the slug stage were investigated in the slime mould Dictyostelium discoideum. Cells were synchronized by release from the stationary phase. Samples were taken at various times during the course of a synchronous cell doubling, fluorescently labelled and mixed with cells of random cell cycle phase from exponentially growing cultures. The fate of the fluorescently labelled cells was recorded at the slug stage. Cells early in the cycle exhibit strong prestalk sorting; cells taken later in the cycle exhibit strong prespore sorting. The period of prestalk sorting occurs immediately following mitosis and lasts about 1 h in a cell cycle of about 7 h duration. Accompanying the altered sorting behaviour is a marked changed in the prestalk-prespore proportions in slugs formed from synchronized populations of cells. Cells synchronized early in the cycle form slugs with 55% prespore cells; cells synchronized late in the cycle form slugs with 90% prespore. The results are discussed in terms of models for the formation of the prestalk-prespore pattern in slugs.

scholarly journals A revision of the Dictyostelium discoideum cell cycle

1984 ◽  
Vol 70 (1) ◽  
pp. 111-131 ◽  
Author(s):  
C.J. Weijer ◽  
G. Duschl ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Dictyostelium Discoideum ◽  
Nuclear Dna ◽  
Average Length ◽  
Dna Contents ◽  
Total Dna ◽  
G2 Phase ◽  
Almost All ◽  
Nuclear Dna Contents ◽  
Synchronized Cultures

We have investigated the Dictyostelium discoideum cell cycle using fluorometric determinations of cellular and nuclear DNA contents in exponentially growing cultures and in synchronized cultures. Almost all cells are in G2 during both growth and development. There is no G1 period, S phase is less than 0.5 h, and G2 has an average length of 6.5 h in axenically grown cells. Mitochondrial DNA, which constitutes about half of the total DNA, is replicated throughout the cell cycle. There is no difference in the nuclear DNA contents of axenically grown and bacterially grown cells. Thus the long cell cycle in axenically grown cells is due to a lengthening of the G2 phase.

scholarly journals Convergence of Alarmone and Cell Cycle Signaling from Trans-Encoded Sensory Domains

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Stefano Sanselicio ◽  
Patrick H. Viollier
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Cell Cycle Progression ◽  
Caulobacter Crescentus ◽  
Control Cell ◽  
Phase Cell ◽  
Cycle Progression ◽  
Content Type ◽  
Cell Cycle Regulator ◽  
Domain Protein

ABSTRACT Despite the myriad of different sensory domains encoded in bacterial genomes, only a few are known to control the cell cycle. Here, suppressor genetics was used to unveil the regulatory interplay between the PAS (Per-Arnt-Sim) domain protein MopJ and the uncharacterized GAF (cyclic GMP-phosphodiesterase–adenylyl cyclase–FhlA) domain protein PtsP, which resembles an alternative component of the phosphoenolpyruvate (PEP) transferase system. Both of these systems indirectly target the Caulobacter crescentus cell cycle master regulator CtrA, but in different ways. While MopJ acts on CtrA via the cell cycle kinases DivJ and DivL, which control the removal of CtrA at the G1-S transition, our data show that PtsP signals through the conserved alarmone (p)ppGpp, which prevents CtrA cycling under nutritional stress and in stationary phase. We found that PtsP interacts genetically and physically with the (p)ppGpp synthase/hydrolase SpoT and that it modulates several promoters that are directly activated by the cell cycle transcriptional regulator GcrA. Thus, parallel systems integrate nutritional and systemic signals within the cell cycle transcriptional network, converging on the essential alphaproteobacterial regulator CtrA while also affecting global cell cycle transcription in other ways. IMPORTANCE Many alphaproteobacteria divide asymmetrically, and their cell cycle progression is carefully regulated. How these bacteria control the cell cycle in response to nutrient limitation is not well understood. Here, we identify a multicomponent signaling pathway that acts on the cell cycle when nutrients become scarce in stationary phase. We show that efficient accumulation of the master cell cycle regulator CtrA in stationary-phase Caulobacter crescentus cells requires the previously identified stationary-phase/cell cycle regulator MopJ as well as the phosphoenolpyruvate protein phosphotransferase PtsP, which acts via the conserved (p)ppGpp synthase SpoT. We identify cell cycle-regulated promoters that are affected by this pathway, providing an explanation of how (p)ppGpp-signaling might couple starvation to control cell cycle progression in Caulobacter spp. and likely other Alphaproteobacteria. This pathway has the potential to integrate carbon fluctuation into cell cycle control, since in phosphotransferase systems it is the glycolytic product phosphenolpyruvate (PEP) rather than ATP that is used as the phosphor donor for phosphorylation.

Molecular Mechanisms of Thymoquinone as Anticancer agent

2020 ◽  
Vol 23 ◽  
Author(s):  
Fatma Ismail Alhmied ◽  
Ali Hassan Alammar ◽  
Bayan Mohammed Alsultan ◽  
Marooj Alshehri ◽  
Faheem Hyder Pottoo
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Human Breast Cancer ◽  
Phase Cell ◽  
Cycle Phase ◽  
Human Breast ◽  
Cycle Arrest ◽  
Phase Arrest ◽  
Anti Cancer

Abstract:: Thymoquinone (TQ), the bioactive constituent of Nigella Sativa seeds is a well-known natural compound for the management of several types of cancers. The anti-cancer properties of thymoquinone are thought to be operated via intervening with various oncogenic pathways including cell cycle arrest, prevention of inflammation and oxidative stress, induction of invasion, metastasis, inhibition of angiogenesis, and apoptosis. As well as up-regulation and down-regulation of specific tumor suppressor genes and tumor promoting genes, respectively. Proliferation of various tumor cells is inhibited by TQ via induction of cell cycle arrest, disruption of the microtubule organization, and down regulating cell survival protein expression. TQ induces G1 phase cell cycle arrest in human breast cancer, colon cancer and osteosarcoma cells through inhibiting the activation of cyclin E or cyclin D and up-regulating p27and p21 a cyclin dependent kinase (Cdk) inhibitor. TQ concentration is a significant factor in targeting a particular cell cycle phase. While high concentration of TQ induced G2 phase arrest in human breast cancer (MCF-7) cells, low concentration causes S phase arrest. This review article provides mechanistic insights into the anti-cancer properties of thymoquinone.

5-Nitro-Thiophene-Thiosemicarbazone Derivatives Present Antitumor Activity Mediated by Apoptosis and DNA Intercalation

2019 ◽  
Vol 19 (13) ◽  
pp. 1075-1091 ◽  
Author(s):  
Karla Mirella Roque Marques ◽  
Maria Rodrigues do Desterro ◽  
Sandrine Maria de Arruda ◽  
Luiz Nascimento de Araújo Neto ◽  
Maria do Carmo Alves de Lima ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Antitumor Activity ◽  
Cell Line ◽  
Mitochondrial Membrane ◽  
In Vitro Cytotoxicity ◽  
Dna Intercalation ◽  
Phase Cell ◽  
Fluorescence Studies ◽  
In Silico Studies

Background: Considering the need for the development of new antitumor drugs, associated with the great antitumor potential of thiophene and thiosemicarbazonic derivatives, in this work we promote molecular hybridization approach to synthesize new compounds with increased anticancer activity. Objective: Investigate the antitumor activity and their likely mechanisms of action of a series of N-substituted 2-(5-nitro-thiophene)-thiosemicarbazone derivatives. Methods: Methods were performed in vitro (cytotoxicity, cell cycle progression, morphological analysis, mitochondrial membrane potential evaluation and topoisomerase assay), spectroscopic (DNA interaction studies), and in silico studies (docking and molecular modelling). Results: Most of the compounds presented significant inhibitory activity; the NCIH-292 cell line was the most resistant, and the HL-60 cell line was the most sensitive. The most promising compound was LNN-05 with IC50 values ranging from 0.5 to 1.9 µg.mL-1. The in vitro studies revealed that LNN-05 was able to depolarize (dose-dependently) the mitochondrial membrane, induceG1 phase cell cycle arrest noticeably, promote morphological cell changes associated with apoptosis in chronic human myelocytic leukaemia (K-562) cells, and presented no topoisomerase II inhibition. Spectroscopic UV-vis and molecular fluorescence studies showed that LNN compounds interact with ctDNA forming supramolecular complexes. Intercalation between nitrogenous bases was revealed through KI quenching and competitive ethidium bromide assays. Docking and Molecular Dynamics suggested that 5-nitro-thiophene-thiosemicarbazone compounds interact against the larger DNA groove, and corroborating the spectroscopic results, may assume an intercalating interaction mode. Conclusion: Our findings highlight 5-nitro-thiophene-thiosemicarbazone derivatives, especially LNN-05, as a promising new class of compounds for further studies to provide new anticancer therapies.

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