scholarly journals Sensitivity of the Cell Division Cycle to α-Amanitin In ALLIUM ROOT TIPS

1974 ◽  
Vol 14 (3) ◽  
pp. 461-473
Author(s):  
C. DE LATORRE ◽  
M. E. FERNANDEZ-GOMEZ ◽  
G. GIMENEZ-MARTIN ◽  
A. GONZALEZ-FERNANDEZ
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Normal Structure ◽  
Cell Division Cycle ◽  
The Other ◽  
Root Tips ◽  
Meristematic Cells ◽  
Normal Duration ◽  
S Period ◽  
Nucleolar Rna

The effect of α-amanitin on the cell cycle in Allium cepa meristematic cells was studied: the G1 and G2 periods are prolonged respectively to 1.9 and 1.7 times the normal duration; the S-period is lengthened very little; and the prophase of mitosis is increased to twice the normal duration. It is postulated that real differences in the activity of the non-nucleolar RNA poly-merase might exist in the course of the cell division cycle and that they would account for the higher sensitivities shown by G1, G2 and prophase. On the other hand, the interphase nucleolus responds by segregation in the first few hours of α-amanitin treatment, but recovers its normal structure in continued presence of the drug; and nucleolar reorganization is inhibited in the first few hours in recently formed cells, but the process is subsequently speeded up to attain the same value 4 h after the treatment was begun as in untreated cells.

Periodic segmental anomalies induced by heat shock in the chick embryo are associated with the cell cycle

Development ◽  
1989 ◽  
Vol 105 (1) ◽  
pp. 119-130 ◽  
Author(s):  
D.R. Primmett ◽  
W.E. Norris ◽  
G.J. Carlson ◽  
R.J. Keynes ◽  
C.D. Stern
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Heat Shock ◽  
Simple Model ◽  
Chick Embryo ◽  
Heat Shock Proteins ◽  
Cell Division Cycle ◽  
The Other ◽  
Chick Embryos ◽  
Shock Proteins

This study provides evidence that cells destined to segment together into somites have a degree of cell division synchrony. We have measured the duration of the cell division cycle in somite and segmental plate cells of the chick embryo as 9.5 h using [3H]thymidine pulse- and-chase. Treatment of embryos with any of a variety of inhibitors known to affect the cell division cycle causes discrete periodic segmental anomalies: these anomalies appear about 6–7 somites after treatment and, in some cases, a second anomaly is observed 6 to 7 somites after the first. Since somites take 1.5 h to form, the 6- to 7- somite interval corresponds to about 9–10 h, which is the duration of the cell cycle as determined in these experiments. The anomalies are similar to those seen after heat shock of 2-day chick embryos. Heat shock and some of the other treatments induce the expression of heat-shock proteins (hsp); however, since neither the expression nor the distribution of these proteins relate to the presence or distribution of anomalies seen, we conclude that hsps are not responsible for the pattern of segmental anomalies observed. The production of periodic segmental anomalies appears to be linked to the cell cycle. A simple model is proposed, in which we suggest that the cell division cycle is involved directly in gating cells that will segment together.

Histone H3 transcription in Saccharomyces cerevisiae is controlled by multiple cell cycle activation sites and a constitutive negative regulatory element

1992 ◽  
Vol 12 (12) ◽  
pp. 5455-5463 ◽  
Author(s):  
K B Freeman ◽  
L R Karns ◽  
K A Lutz ◽  
M M Smith
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Division ◽  
Transcriptional Activation ◽  
Regulatory Element ◽  
Histone H3 ◽  
Regulatory Elements ◽  
Cell Division Cycle ◽  
Cell Cycle Activation ◽  
Multiple Cell

The promoters of the Saccharomyces cerevisiae histone H3 and H4 genes were examined for cis-acting DNA sequence elements regulating transcription and cell division cycle control. Deletion and linker disruption mutations identified two classes of regulatory elements: multiple cell cycle activation (CCA) sites and a negative regulatory site (NRS). Duplicate 19-bp CCA sites are present in both the copy I and copy II histone H3-H4 promoters arranged as inverted repeats separated by 45 and 68 bp. The CCA sites are both necessary and sufficient to activate transcription under cell division cycle control. A single CCA site provides cell cycle control but is a weak transcriptional activator, while an inverted repeat comprising two CCA sites provides both strong transcriptional activation and cell division cycle control. The NRS was identified in the copy I histone H3-H4 promoter. Deletion or disruption of the NRS increased the level of the histone H3 promoter activity but did not alter the cell division cycle periodicity of transcription. When the CCA sites were deleted from the histone promoter, the NRS element was unable to confer cell division cycle control on the remaining basal level of transcription. When the NRS element was inserted into the promoter of a foreign reporter gene, transcription was constitutively repressed and did not acquire cell cycle regulation.

scholarly journals p12DOC-1 Is a Novel Cyclin-Dependent Kinase 2-Associated Protein

2000 ◽  
Vol 20 (17) ◽  
pp. 6300-6307 ◽  
Author(s):  
Satoru Shintani ◽  
Hiroe Ohyama ◽  
Xue Zhang ◽  
Jim McBride ◽  
Kou Matsuo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Ectopic Expression ◽  
Cell Division Cycle ◽  
Cyclin Dependent Kinase ◽  
Data Support ◽  
Normal Keratinocytes ◽  
Active Pool ◽  
Growth Suppressor

ABSTRACT Regulated cyclin-dependent kinase (CDK) levels and activities are critical for the proper progression of the cell division cycle. p12DOC-1 is a growth suppressor isolated from normal keratinocytes. We report that p12DOC-1 associates with CDK2. More specifically, p12DOC-1 associates with the monomeric nonphosphorylated form of CDK2 (p33CDK2). Ectopic expression of p12DOC-1 resulted in decreased cellular CDK2 and reduced CDK2-associated kinase activities and was accompanied by a shift in the cell cycle positions of p12DOC-1transfectants (↑ G1 and ↓ S). The p12DOC-1-mediated decrease of CDK2 was prevented if the p12DOC-1 transfectants were grown in the presence of the proteosome inhibitor clasto-lactacystin β-lactone, suggesting that p12DOC-1 may target CDK2 for proteolysis. A CDK2 binding mutant was created and was found to revert p12DOC-1-mediated, CDK2-associated cell cycle phenotypes. These data support p12DOC-1 as a specific CDK2-associated protein that negatively regulates CDK2 activities by sequestering the monomeric pool of CDK2 and/or targets CDK2 for proteolysis, reducing the active pool of CDK2.

Localization of Hematopoietic Stem Cells in Coculture with Mesenchymal Stromal Cells Impacts on Phenotype and Cell Cycle Status

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4774-4774
Author(s):  
Duohui Jing ◽  
Nael Alakel ◽  
Fernando Fierro ◽  
Katrin Mueller ◽  
Martin Bornhaeuser ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Cell Division ◽  
Stromal Cells ◽  
The Other ◽  
Cell Contact ◽  
Adherent Cells ◽  
Hematopoietic Stem ◽  
Cell Fractions

Abstract Hematopoietic stem cells (HSC) are defined by their capacity of self-renewal and differentiation. In recent years it became clear that cell to cell contact mediated communication between mesenchymal stromal cells (MSC) and HSC is important for homeostasis of hematopoiesis. MSC play a crucial role in the so called bone marrow niche giving rise to the majority of marrow stromal cell lineages. In vitro we investigated the impact of MSC on CD34 purified HSC expansion and differentiation demonstrating a promoting impact of MSC on adherent HSC in comparison to non adherent HSC in terms of phenotype, migration capacity and clonogenicity. Performing phase contrast microscopy and confocal microscopy we are able to distinguish HSC which are located on the surface of a MSC monolayer (phase-bright cells) and HSC which are covered by MSC monolayer (phase-dim cells). Both HSC fractions and the non-adherent cells were isolated separately by performing serial washing steps. All three fractions were analyzed at fixed time points during the first week of co-culture in term of cell cycle progression, proliferation, maturation and cell division accompanied differentiation. First we performed propidium iodide (PI) staining for cell cycle analysis revealing that the phase-bright cells contained the highest percentage of G2 cells in comparison to the non adherent cells and the phase-dim cells; 13.9 ±1.0% vs 1.3 ±1.2% vs 2.7 ±2.0%, p<0.001. The data indicate the facilitating impact of MSC on HSC in performing mitosis which is however depending on the location of interaction. When HSC are released into supernatant (non adherent cells) or covered by MSC, G2 phase was significantly down-regulated. Next we studied the proliferation capacity of the separate cell fractions. Consistent with the data of cell cycle, cell number of phase-bright faction increased much faster than the other two fractions during the first 4 days suggesting that the MSC surface in vitro is the predominant location of HSC proliferation. Next we investigated the phenotype of HSC. According to FACS analysis results (CD34+CD38-) phase-dim cells revealed a more immature phenotype in comparison to the non adherent cells and the phase-bright cells. During the first four days 80% of phase-dim cells remained CD34+CD38-, while cells of the phase-bright- and the non adherent fraction exhibited a significant more mature phenotype. Performing cell division tracking using CFSE we were able to show that over time number of divisions of phase-dim cells were significantly diminished in comparison to the other two cell fractions in co-cultures. In addition, phase-dim cells started to lose CD34 at the 7th generation, while non-adherent and phase-bright cells already lost CD34 at the 4th generation. These data suggest that “stemness” of HSC was rather preserved in the cell fraction which was covered by MSC monolayer than in the cell fraction on the surface of MSC. In conclusion we demonstrate HSC in distinct locations in vitro showing different behaviors in terms of phenotype and proliferation. It becomes evident that not only the cell to cell contact matters but also the localization of contact. Further experiments are needed to investigate NOD/SCID repopulation potential of the different cell fractions.

The cell division cycle of Trypanosoma brucei brucei : timing of event markers and cytoskeletal modulations

1989 ◽  
Vol 323 (1218) ◽  
pp. 573-588 ◽  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Trypanosoma Brucei ◽  
Basal Body ◽  
Single Copy ◽  
Cell Division Cycle ◽  
Basal Bodies ◽  
Division Plane ◽  
Transmission Electron ◽  
Single Nucleus

We have analysed the timing and order of events occurring within the cell division cycle of Trypanosoma brucei . Cells in the earliest stages of the cell cycle possess a single copy of three major organelles: the nucleus, the kinetoplast and the flagellum. The first indication of progress through the cell cycle is the elongation of the pro-basal body lying adjacent to the mature basal body subtending the flagellum. This newly elongated basal body occupies a posterior position within the cell when it initiates growth of the new daughter flagellum. Genesis of two new pro-basal bodies occurs only after growth of the new daughter flagellum has been initiated. Extension of the new flagellum, together with the paraflagellar rod, then continues throughout a major portion of the cell cycle. During this period of flagellum elongation, kinetoplast division occurs and the two kinetoplasts, together with the two flagellar basal bodies, then move apart within the cell. Mitosis is then initiated and a complex pattern of organelle positions is achieved whereby a division plane runs longitudinally through the cell such that each daughter ultimately receives a single nucleus, kinetoplast and flagellum. These events have been described from observations of whole cytoskeletons by transmission electron microscopy together with detection of particular organelles by fluorescence microscopy. The order and timing of events within the cell cycle has been derived from analyses of the proportion of a given cell type occurring within an exponentially growing culture.

scholarly journals Classic “broken cell” techniques and newer live cell methods for cell cycle assessment

2013 ◽  
Vol 304 (10) ◽  
pp. C927-C938 ◽  
Author(s):  
Lindsay Henderson ◽  
Dante S. Bortone ◽  
Curtis Lim ◽  
Alexander C. Zambon
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Single Cell ◽  
Living Cells ◽  
Cell Division Cycle ◽  
Live Cell ◽  
Nucleotide Analogs ◽  
Protein Ubiquitination ◽  
Cell Cycle Pathway ◽  
Cell Niche

Many common, important diseases are either caused or exacerbated by hyperactivation (e.g., cancer) or inactivation (e.g., heart failure) of the cell division cycle. A better understanding of the cell cycle is critical for interpreting numerous types of physiological changes in cells. Moreover, new insights into how to control it will facilitate new therapeutics for a variety of diseases and new avenues in regenerative medicine. The progression of cells through the four main phases of their division cycle [G0/G1, S (DNA synthesis), G2, and M (mitosis)] is a highly conserved process orchestrated by several pathways (e.g., transcription, phosphorylation, nuclear import/export, and protein ubiquitination) that coordinate a core cell cycle pathway. This core pathway can also receive inputs that are cell type and cell niche dependent. “Broken cell” methods (e.g., use of labeled nucleotide analogs) to assess for cell cycle activity have revealed important insights regarding the cell cycle but lack the ability to assess living cells in real time (longitudinal studies) and with single-cell resolution. Moreover, such methods often require cell synchronization, which can perturb the pathway under study. Live cell cycle sensors can be used at single-cell resolution in living cells, intact tissue, and whole animals. Use of these more recently available sensors has the potential to reveal physiologically relevant insights regarding the normal and perturbed cell division cycle.

scholarly journals Suspended Animation Extends Survival Limits of Caenorhabditis elegans and Saccharomyces cerevisiae at Low Temperature

2010 ◽  
Vol 21 (13) ◽  
pp. 2161-2171 ◽  
Author(s):  
Kin Chan ◽  
Jesse P. Goldmark ◽  
Mark B. Roth
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Cell Division Cycle ◽  
Wild Type ◽  
Suspended Animation ◽  
C Elegans ◽  
High Viability ◽  
Cold Sensitive

The orderly progression through the cell division cycle is of paramount importance to all organisms, as improper progression through the cycle could result in defects with grave consequences. Previously, our lab has shown that model eukaryotes such as Saccharomyces cerevisiae, Caenorhabditis elegans, and Danio rerio all retain high viability after prolonged arrest in a state of anoxia-induced suspended animation, implying that in such a state, progression through the cell division cycle is reversibly arrested in an orderly manner. Here, we show that S. cerevisiae (both wild-type and several cold-sensitive strains) and C. elegans embryos exhibit a dramatic decrease in viability that is associated with dysregulation of the cell cycle when exposed to low temperatures. Further, we find that when the yeast or worms are first transitioned into a state of anoxia-induced suspended animation before cold exposure, the associated cold-induced viability defects are largely abrogated. We present evidence that by imposing an anoxia-induced reversible arrest of the cell cycle, the cells are prevented from engaging in aberrant cell cycle events in the cold, thus allowing the organisms to avoid the lethality that would have occurred in a cold, oxygenated environment.

scholarly journals Mammalian Orc1 Protein Is Selectively Released from Chromatin and Ubiquitinated during the S-to-M Transition in the Cell Division Cycle

2002 ◽  
Vol 22 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Cong-Jun Li ◽  
Melvin L. DePamphilis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Half Life ◽  
S Phase ◽  
Cell Division Cycle ◽  
26S Proteasome ◽  
Selective Dissociation

ABSTRACT Previous studies have shown that changes in the affinity of the hamster Orc1 protein for chromatin during the M-to-G1 transition correlate with the activity of hamster origin recognition complexes (ORCs) and the appearance of prereplication complexes at specific sites. Here we show that Orc1 is selectively released from chromatin as cells enter S phase, converted into a mono- or diubiquitinated form, and then deubiquitinated and re-bound to chromatin during the M-to-G1 transition. Orc1 is degraded by the 26S proteasome only when released into the cytosol, and peptide additions to Orc1 make it hypersensitive to polyubiquitination. In contrast, Orc2 remains tightly bound to chromatin throughout the cell cycle and is not a substrate for ubiquitination. Since the concentration of Orc1 remains constant throughout the cell cycle, and its half-life in vivo is the same as that of Orc2, ubiquitination of non-chromatin-bound Orc1 presumably facilitates the inactivation of ORCs by sequestering Orc1 during S phase. Thus, in contrast to yeast (Saccharomyces cerevisiae and Schizosaccharomyces pombe), mammalian ORC activity appears to be regulated during each cell cycle through selective dissociation and reassociation of Orc1 from chromatin-bound ORCs.

scholarly journals Gene Expression Changes and Anti-proliferative Effect of Noni (Morinda Citrifolia) Fruit Extract Analysed by Real Time-PCR

Molekul ◽  
2017 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Hermansyah Hermansyah ◽  
Susilawati Susilawati
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Division ◽  
Real Time ◽  
Cell Division Cycle ◽  
Morinda Citrifolia ◽  
Transcriptional Analysis ◽  
Fruit Extract ◽  
Proliferative Effect

To elucidate the anti-proliferative effect of noni (Morinda citrifolia) fruit extract for a Saccharomyces cerevisiae model organism, analysis of gene expression changes related to cell cycle associated with inhibition effect of noni fruit extract was carried out. Anti-proliferative of noni fruit extract was analyzed using gene expression changes of Saccharomyces cerevisiae (strains FY833 and BY4741).  Transcriptional analysis of genes that play a role in cell cycle was conducted by growing cells on YPDAde broth medium containing 1% (w/v) noni fruit extract, and then subjected using quantitative real-time polymerase chain reaction (RT-PCR).  Transcriptional level of genes CDC6 (Cell Division Cycle-6), CDC20 (Cell Division Cycle-20), FAR1 (Factor ARrest-1), FUS3 (FUSsion-3), SIC1 (Substrate/Subunit Inhibitor of Cyclin-dependent protein kinase-1), WHI5 (WHIskey-5), YOX1 (Yeast homeobOX-1) and YHP1 (Yeast Homeo-Protein-1) increased, oppositely genes expression of DBF4 (DumbBell Forming), MCM1 (Mini Chromosome Maintenance-1) and TAH11 (Topo-A Hypersensitive-11) decreased, while the expression level of genes CDC7 (Cell Division Cycle-7), MBP1 (MIul-box Binding Protein-1) and SWI6 (SWItching deficient-6) relatively unchanged. These results indicated that gene expression changes might associate with anti-proliferative effect from noni fruit extract. These gene expressions changes lead to the growth inhibition of S.cerevisiae cell because of cell cycle defect.

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