Effect of near ultraviolet and visible light on amoeba

1975 ◽  
Vol 19 (1) ◽  
pp. 117-126
Author(s):  
S. Chatterjee ◽  
S.K. Bhattacharjee
Keyword(s):  
Cell Cycle ◽  
Visible Light ◽  
S Phase ◽  
Nuclear Transplantation ◽  
Phase Cell ◽  
Cycle Phase ◽  
Leucine Incorporation ◽  
Repair System ◽  
Near Ultraviolet ◽  
G2 Phase

The near ultraviolet and visible light (VL) impinging at an intensity of 2–5 × 10(2) J s-1 m-2 for 2–5 h kills the mitotic and the early S-phase (0- to 15-min-old) amoebae. At the mid- and late S-period only a fraction of cells are killed by VL and G2 phase cells are quite resistant. Amoebae of all cell cycle stages show a delay in the first mitotic division. DNA synthesis, as measured by [3H]thymidine incorporation, is depressed in the VL-exposed early-S amoebae. A concurrent but temporary inhibition in [3H]leucine incorporation also occurs in these cells. However, no significant change in [3H]uridine incorporation has been found. To localize the site of lethal damage, nuclear transplantation studies were undertaken between the control amoebae and the amoebae treated with VL. The nucleus of a VL-exposed early S-phase cell recovers when transplanted immediately after VL exposure into an enucleate G2 cytoplasm but dies if grafted into an enucleat S-phase cytoplasm. The therapeutic effect of the G2 cytoplasm, although at a lower level, is also evident even when the treated early S-phase nucleus is implanted 20 h later, but not after 48 h, into the G2 cytoplasm. The amoeba cytoplasm shows resistance to VL-irradiation, can accept a control nucleus from any cell cycle stage, and function normally. The G2 nucleus also remains apparently unaffected to VL exposure and can survive when it is transfered to the control cytoplasm of any cell-cycle phase. All these findings are discussed in the light of the possible existence of a repair system against VL-induced damage in the G2-phase amoeba.

scholarly journals HIV-1 Vif promotes the G1- to S-phase cell-cycle transition

Blood ◽  
2011 ◽  
Vol 117 (4) ◽  
pp. 1260-1269 ◽  
Author(s):  
Jiangfang Wang ◽  
Emma L. Reuschel ◽  
Jason M. Shackelford ◽  
Lauren Jeang ◽  
Debra K. Shivers ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Phase Cell ◽  
Small Interfering Rnas ◽  
Cycle Progression ◽  
Viral Infectivity Factor ◽  
G2 Phase ◽  
Regulate Cell Cycle Progression ◽  
Hiv 1

AbstractHIV-1 depends on host-cell resources for replication, access to which may be limited to a particular phase of the cell cycle. The HIV-encoded proteins Vpr (viral protein R) and Vif (viral infectivity factor) arrest cells in the G2 phase; however, alteration of other cell-cycle phases has not been reported. We show that Vif drives cells out of G1 and into the S phase. The effect of Vif on the G1-to-S transition is distinct from its effect on G2, because G2 arrest is Cullin5-dependent, whereas the G1-to-S progression is Cullin5-independent. Using mass spectrometry, we identified 2 novel cellular partners of Vif, Brd4 and Cdk9, both of which are known to regulate cell-cycle progression. We confirmed the interaction of Vif and Cdk9 by immunoprecipitation and Western blot, and showed that small interfering RNAs (siRNAs) specific for Cdk9 inhibit the Vif-mediated G1-to-S transition. These data suggest that Vif regulates early cell-cycle progression, with implications for infection and latency.

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.

Involvement of the p38 MAPK signaling pathway in S-phase cell-cycle arrest induced by Furazolidone in human hepatoma G2 cells

2012 ◽  
Vol 33 (12) ◽  
pp. 1500-1505 ◽  
Author(s):  
Yu Sun ◽  
Shusheng Tang ◽  
Xi Jin ◽  
Chaoming Zhang ◽  
Wenxia Zhao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Signaling Pathway ◽  
P38 Mapk ◽  
Mapk Signaling ◽  
S Phase ◽  
Mapk Signaling Pathway ◽  
Phase Cell ◽  
Human Hepatoma ◽  
Cycle Arrest

scholarly journals S-Phase Cell Cycle Arrest, Apoptosis, and Molecular Mechanisms of Aplasia Ras homolog Member I–Induced Human Ovarian Cancer SKOV3 Cell Lines

2014 ◽  
Vol 24 (4) ◽  
pp. 629-634 ◽  
Author(s):  
Qiaoying Zhu ◽  
Jianming Hu ◽  
Huijuan Meng ◽  
Yufei Shen ◽  
Jinhua Zhou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Molecular Mechanisms ◽  
Significant Inhibition ◽  
S Phase ◽  
Phase Cell ◽  
Cell Cycle Distribution ◽  
Human Ovarian Cancer ◽  
Skov3 Cell ◽  
Skov3 Cells

ObjectiveAplasia Ras homolog member I (ARHI) is associated with human ovarian cancer (HOC) growth and proliferation; however, the mechanisms are unclear. The purpose of this study was to investigateARHIeffects in HOC SKOV3 cells.MethodsWe transfected SKOV3 cells with PIRES2-EGFP-ARHI and measured growth inhibition rates, cell cycle distribution, apoptosis rates, and expression of P-STAT3 (phosphorylated signal transduction and activators of transcription 3) and P-ERK (phosphorylated extracellular signal regulated protein kinase).ResultsOur data showed significant inhibition of growth, significantly increased S-phase arrest and apoptosis rates, and reduction of P-STAT3 and P-ERK1/2 expression levels.ConclusionsWe propose the mechanism may involveARHI-induced phosphorylation of ERK1/2 and STAT3 protein kinases, thereby blocking proliferation signaling pathways, to induce HOC SKOV3 apoptosis.

scholarly journals Cdc5L interacts with ATR and is required for the S‐phase cell‐cycle checkpoint

EMBO Reports ◽  
2009 ◽  
Vol 10 (9) ◽  
pp. 1029-1035 ◽  
Author(s):  
Nianxiang Zhang ◽  
Ramandeep Kaur ◽  
Shamima Akhter ◽  
Randy J Legerski
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Cell Cycle Checkpoint ◽  
Phase Cell ◽  
Cycle Checkpoint

Biochemical and morphological characterization of the nuclear matrix during the synchronous cell cycle of Physarum polycephalum

1993 ◽  
Vol 105 (4) ◽  
pp. 1121-1130 ◽  
Author(s):  
S. Lang ◽  
T. Decristoforo ◽  
W. Waitz ◽  
P. Loidl
Keyword(s):  
Cell Cycle ◽  
Nuclear Matrix ◽  
Physarum Polycephalum ◽  
Nuclear Periphery ◽  
S Phase ◽  
Cycle Phase ◽  
Electron Microscopic ◽  
Nuclear Lamins ◽  
Synchronous Cell ◽  
Matrix Bound

We have investigated biochemical and ultrastructural aspects of the nuclear matrix during the naturally synchronous cell cycle of Physarum polycephalum. The morphology of the in situ nuclear matrix exhibited significant cell cycle changes as revealed by electron microscopic examination, especially during the progression of nuclei through mitosis and S-phase. In mitosis the interchromatin matrix was found to be retracted to the nuclear periphery; during S-phase this interchromatin matrix gradually resembled, concomitant with the reconstruction of a nucleolar remnant structure. During the G2-period no significant changes in matrix morphology were observed. The pattern of nuclear matrix proteins was invariant during the cell cycle; no cycle phase-specific proteins could be detected. In vivo labelling of plasmodia with [35S]methionine/cysteine showed that only a few proteins are synthesized and assembled into nuclear matrix structures in a cell cycle-dependent way; the majority of proteins were synthesized almost continuously. This was also shown for nuclear lamins homologues. In contrast to bulk nuclear histones, those histones that remain tightly bound to the nuclear matrix were synthesized and assembled into nuclear structures in the very first hour of S-phase; assembly was terminated in mid-S-phase, indicating that nuclear matrix-bound chromatin is replicated early in S-phase. Comparison of the acetylation pattern of matrix-bound histone H4 with bulk nuclear H4 revealed a largely elevated acetate content of matrix H4. The percentage of acetylated subspecies was entirely different from that in bulk nuclear H4, indicating that matrix-associated histones represent a subpopulation of nuclear histones with distinct properties, reflecting specific structural requirements of matrix-attached chromatin.

Excision and replication of extrachromosomal DNA of pea (Pisum sativum)

1983 ◽  
Vol 3 (2) ◽  
pp. 172-181
Author(s):  
J Van't Hof ◽  
C A Bjerknes ◽  
N C Delihas
Keyword(s):  
Cell Cycle ◽  
Pisum Sativum ◽  
S Phase ◽  
Velocity Sedimentation ◽  
Extrachromosomal Dna ◽  
Chromosomal Dna ◽  
Root Tips ◽  
Dividing Cells ◽  
G2 Phase ◽  
Pea Roots

Experiments with cultured pea roots were conducted to determine (i) whether extrachromosomal DNA was produced by cells in the late S phase or in the G2 phase of the cell cycle, (ii) whether the maturation of nascent DNA replicated by these cells achieved chromosomal size, (iii) when extrachromosomal DNA was removed from the chromosomal duplex, and (iv) the replication of nascent chains by the extrachromosomal DNA after its release from the chromosomal duplex. Autoradiography and cytophotometry of cells of carbohydrate-starved root tips revealed that extrachromosomal DNA was produced by a small fraction of cells accumulated in the late S phase after they had replicated about 80% of their DNA. Velocity sedimentation of nascent chromosomal DNA in alkaline sucrose gradients indicated that the DNA of cells in the late S phase failed to achieve chromosomal size. After reaching sizes of 70 X 10(6) to 140 X 10(6) daltons, some of the nascent chromosomal molecules were broken, presumably releasing extrachromosomal DNA several hours later. Sedimentation of selectively extracted extrachromosomal DNA either from dividing cells or from those in the late S phase showed that it replicated two nascent chains, one of 3 X 10(6) daltons and another of 7 X 10(6) daltons. Larger molecules of extrachromosomal DNA were detectable after cells were labeled for 24 h. These two observations were compatible with the idea that the extrachromosomal DNA was first replicated as an integral part of the chromosomal duplex, was cut from the duplex, and then, once free of the chromosome, replicated two smaller chains of 3 X 10(6) and 7 X 10(6) daltons.

scholarly journals Xanthohumol Induces Growth Inhibition and Apoptosis in Ca Ski Human Cervical Cancer Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Wai Kuan Yong ◽  
Sri Nurestri Abd Malek
Keyword(s):  
Cell Cycle ◽  
Cervical Cancer ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Morphological Changes ◽  
S Phase ◽  
Phase Cell ◽  
Cervical Cancer Cell Line ◽  
Dependent Manner ◽  
Cervical Cancer Cells

We investigate induction of apoptosis by xanthohumol on Ca Ski cervical cancer cell line. Xanthohumol is a prenylated chalcone naturally found in hop plants, previously reported to be an effective anticancer agent in various cancer cell lines. The present study showed that xanthohumol was effective to inhibit proliferation of Ca Ski cells based on IC50values using sulforhodamine B (SRB) assay. Furthermore, cellular and nuclear morphological changes were observed in the cells using phase contrast microscopy and Hoechst/PI fluorescent staining. In addition, 48-hour long treatment with xanthohumol triggered externalization of phosphatidylserine, changes in mitochondrial membrane potential, and DNA fragmentation in the cells. Additionally, xanthohumol mediated S phase arrest in cell cycle analysis and increased activities of caspase-3, caspase-8, and caspase-9. On the other hand, Western blot analysis showed that the expression levels of cleaved PARP, p53, and AIF increased, while Bcl-2 and XIAP decreased in a dose-dependent manner. Taken together, these findings indicate that xanthohumol-induced cell death might involve intrinsic and extrinsic apoptotic pathways, as well as downregulation of XIAP, upregulation of p53 proteins, and S phase cell cycle arrest in Ca Ski cervical cancer cells. This work suggests that xanthohumol is a potent chemotherapeutic candidate for cervical cancer.

scholarly journals Cell-cycle phase-dependence of drug-induced cycle progression delay.

1979 ◽  
Vol 27 (1) ◽  
pp. 470-473 ◽  
Author(s):  
W Göhde ◽  
M Meistrich ◽  
R Meyn ◽  
J Schumann ◽  
D Johnston ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Chromosomal Abnormalities ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Drug Induced ◽  
Phase Dependence ◽  
Cycle Progression ◽  
G2 Phase ◽  
Phase Progression ◽  
Pulse Cytophotometry

The effect of adriamycin on cell cycle phase progression of CHO cells synchronized into the various phases of the cell cycle by elutriation was investigated by high resolution pulse cytophotometry. Cells treated in all phases of the cell cycle showed delay in their subsequent progression. In addition to the wellknown block of cells in the G2-phase, a delay in passage of cells from G1 to S and a decreased rate of transit through the S-phase were observed. A broadening of the DNA distributions of the treated cells was observed after cell division indicating induction of chromosomal abnormalities.

scholarly journals Enhancement of DNA-mediated gene transfer by high-Mr carrier DNA in synchronized CV-1 cells

1985 ◽  
Vol 225 (2) ◽  
pp. 529-533 ◽  
Author(s):  
A J Strain ◽  
W A H Wallace ◽  
A H Wyllie
Keyword(s):  
Cell Cycle ◽  
Gene Transfer ◽  
Transfection Efficiency ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
S Phase ◽  
Sv40 Virus ◽  
G2 Phase ◽  
Cycle Dependent ◽  
Sv40 Dna

Synchronized CV-1 cells were transfected with SV40 (simian virus 40) DNA-calcium phosphate co-precipitates. In the presence of carrier DNA, the transfection efficiency of SV40 DNA was decreased 5-fold in S-phase cells and was increased 4-fold in preparations of mitotically enriched cells as compared with asynchronous controls. No difference was observed when carrier DNA was omitted, when cells had progressed through S-phase and into G2-phase, or when the infectivity of cells to intact SV40 virus was tested. These results highlight the importance of cell-cycle-dependent factors on DNA-mediated gene transfer.

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