Effects of DMSO on Vacuole Formation, Contractile Vacuole Function, and Nuclear Division in Tetrahymena Pyriformis GL

1974 ◽  
Vol 16 (1) ◽  
pp. 39-47
Author(s):  
J. R. NILSSON
Keyword(s):  
Cell Division ◽  
Nuclear Division ◽  
Physiological State ◽  
Tetrahymena Pyriformis ◽  
Cell Number ◽  
Contractile Vacuole ◽  
Vacuole Formation ◽  
Control Value ◽  
Dividing Cells

Increasing concentrations of dimethyl sulphoxide (DMSO) affect vacuole formation in Tetrahymena, as measured quantitatively by the uptake of carmine particles. The rate of vacuole formation decreased to about 50% of the control value in 5.0% DMSO (v/v) and to zero in 7.5%. At the latter concentration, the inhibition was expressed immediately; however, the effect of 1-h exposure was reversible after removal of DMSO by washing. In vivo observations revealed abnormal function of the contractile vacuole in 7.5% DMSO, while cell motility and cell division appeared to be unaffected. Although cell division occurred there was little or no increase in cell number, as studied over a cell generation time. Feulgen preparations showed that nuclear division was inhibited and that cell division resulted in one anucleate and one nucleate daughter cell. This effect was also observed in some dividing cells at lower concentrations of DMSO. The effect of DMSO on Tetrahymena was dependent not only on the concentration of the compound but also on the physiological state of the cells.

scholarly journals High-resolution tracking of cell division demonstrates differential effects of TH1 and TH2 cytokines on SCF-dependent human mast cell production in vitro:correlation with apoptosis and Kit expression

Blood ◽  
2005 ◽  
Vol 105 (2) ◽  
pp. 592-599 ◽  
Author(s):  
Marianna Kulka ◽  
Dean D. Metcalfe
Keyword(s):  
Mast Cell ◽  
Cell Division ◽  
Mast Cells ◽  
Cell Number ◽  
Interleukin 4 ◽  
Human Mast Cell ◽  
T Helper 1 ◽  
Cell Production ◽  
Ifn Γ

Abstract T-helper 1 (TH1) (interferon-γ [IFN-γ]) and TH2 (interleukin-4 [IL-4] and IL-5) cytokines have been variably reported to alter human mast cell numbers in complex culture systems. The effects of these cytokines on the kinetics of cell division and cell death are unknown, and their effect on mast cell behavior is relevant to anticipate the consequences of in vivo strategies that alter cytokine levels. To determine the effect of these cytokines on stem cell factor (SCF)–dependent human mast cell production, we used highresolution tracking of cell division and correlated the results with cell apoptosis, expression of Kit, and mast cell degranulation. When IFN-γ, IL-5, or IL-4 was administered over 8 weeks, we found each cytokine decreased the mast number through a different mechanism. IFN-γ inhibited early progenitor cell division, IL-4 down-regulated early Kit expression, and IL-5 blocked later cell division. Further, IL-4 and IFN-γ had the greatest suppressive effect on degranulation and FcϵRI expression. When these cytokines were administered to mature mast cells, IFN-γ and IL-5 had no effect on degranulation and cell division, but IL-4 induced division and potentiated FcϵRI-mediated degranulation. Thus, exposure of human mast cells to IL-4, IL-5, and IFN-γ during growth and differentiation generally down-regulated mast cell number and function, whereas IL-4 increased mature mast cell division and degranulation.

scholarly journals Probing the Catalytic Activity of a Cell Division-Specific Transpeptidase In Vivo with β-Lactams

2003 ◽  
Vol 185 (13) ◽  
pp. 3726-3734 ◽  
Author(s):  
Christian Eberhardt ◽  
Lars Kuerschner ◽  
David S. Weiss
Keyword(s):  
Catalytic Activity ◽  
Cell Division ◽  
Penicillin Binding Protein ◽  
In Vitro System ◽  
New Findings ◽  
Peptidoglycan Cell Wall ◽  
Dividing Cells ◽  
A Cell

ABSTRACT Penicillin-binding protein 3 (PBP3; also called FtsI) is a transpeptidase that catalyzes cross-linking of the peptidoglycan cell wall in the division septum of Escherichia coli. To determine whether the catalytic activity of PBP3 is activated during division, we assayed acylation of PBP3 with three β-lactams (cephalexin, aztreonam, and piperacillin) in growing cells. Acylation of PBP3 with cephalexin, but not aztreonam or piperacillin, appeared to be stimulated by cell division. Specifically, cephalexin acylated PBP3 about 50% faster in a population of dividing cells than in a population of filamentous cells in which division was inhibited by inactivation or depletion of FtsZ, FtsA, FtsQ, FtsW, or FtsN. However, in a simpler in vitro system using isolated membranes, acylation with cephalexin was not impaired by depletion of FtsW or FtsN. A conflicting previous report that the ftsA3(Ts) allele interferes with acylation of PBP3 was found to be due to the presence of a thermolabile PBP3 in the strain used in that study. The new findings presented here are discussed in light of the hypothesis that the catalytic activity of PBP3 is stimulated by interaction(s) with other division proteins. We suggest that there might be allosteric activation of substrate binding.

scholarly journals SYNCHRONIZED CELL DIVISION IN TETRAHYMENA PYRIFORMIS FOLLOWING INHIBITION WITH VINBLASTINE

1968 ◽  
Vol 39 (3) ◽  
pp. 556-563 ◽  
Author(s):  
G. E. Stone
Keyword(s):  
Cell Division ◽  
Tetrahymena Pyriformis ◽  
Cell Number ◽  
Fresh Medium ◽  
Generation Times ◽  
Nuclear Cytology

The ability of Tetrahymena pyriformis to undergo synchronous division following release of inhibition with vinblastine was examined. The degree of synchrony was shown to be correlated with the period of time spent under the influence of vinblastine. Cells were inhibited for different periods of time with vinblastine and then washed free of the inhibitor with fresh medium. The increase in cell number and division index was followed subsequent to release of inhibition. Inhibition for a period of time equal to about two generation times was required to produce a complete doubling of the population during the first division. Inhibition for longer periods of time resulted in the population's increasing by more than a factor of two during the first division burst. The nuclear cytology indicates that the micronucleus is probably blocked in mitosis.

scholarly journals Apical PAR complex proteins protect against epithelial assaults to create a continuous and functional intestinal lumen

2020 ◽  
Author(s):  
Maria D. Sallee ◽  
Melissa A. Pickett ◽  
Jessica L. Feldman
Keyword(s):  
Cell Division ◽  
Epithelial Cells ◽  
Intestinal Lumen ◽  
Microtubule Organizing Center ◽  
Intestinal Tube ◽  
C Elegans ◽  
Junctional Proteins ◽  
Organizing Center ◽  
Dividing Cells

ABSTRACTSustained polarity and adhesion of epithelial cells is essential for the protection of our organs and bodies, and this epithelial integrity emerges during organ development amidst numerous morphogenetic assaults. Using the developing C. elegans intestine as an in vivo model, we investigated how epithelial cells maintain integrity through cell division and elongation to build a functional tube. Live-imaging revealed that apical PAR complex proteins PAR-6/Par6 and PKC-3/aPkc remained apical during mitosis while apical microtubules and microtubule-organizing center (MTOC) proteins were transiently removed. Intestine-specific depletion of PAR-6, PKC-3, and the aPkc regulator CDC-42/Cdc42 caused persistent gaps in the apical MTOC as well as in other apical and junctional proteins after cell division and in non-dividing cells that elongated. Upon hatching, gaps coincided with luminal constrictions that blocked food, and larvae arrested and died. Thus, the apical PAR complex maintains apical and junctional continuity to construct a functional intestinal tube.

scholarly journals Regulation of Fruit Growth and Fruit Size in Apple

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1097A-1097
Author(s):  
Anish Malladi ◽  
Peter Goldsbrough ◽  
Peter Hirst
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Division ◽  
Fruit Development ◽  
Fruit Size ◽  
Cell Number ◽  
Rt Pcr ◽  
Cell Production ◽  
Golden Delicious ◽  
Dividing Cells

Fruit development in apple cultivars varying in their ultimate fruit size was analyzed using cytology, flow cytometry (FCM), and semi-quantitative RT-PCR. Fruit size variation across cultivars was largely explained by variation in cell number. The cell division phase lasted for less than 30 days in all varieties, less than previously believed. A distinct overlap between the cell division and cell expansion phases was present. Analysis of the relative cell production rate (rCPR) showed a major peak about 10 days after full bloom (DAFB) after which it declined. Comparison of the rCPR across varieties suggested distinct patterns of cell production with `Gala' having a low but sustained rCPR, `Pixy Crunch' a short but high rCPR, and `Golden Delicious' having a high and sustained rCPR. FCM analysis also showed similar patterns with a peak in the proportion of dividing cells about 10 DAFB followed by a decline. To further understand regulation of cell number, four cell cycle related genes were cloned from `Gala'. Cyclin Dependent Kinase B (CDK B) and Cyclin B were found to be highly cell division phase specific in their expression. Analysis of gene expression by semi-quantitative RT-PCR indicated peak expression of these two genes at 5-10 DAFB, consistent with the peaks in rCPR and proportion of dividing cells. Comparison of gene expression across the varieties showed higher peak expression of the above genes in the larger-fruited `Golden Delicious' than in the smaller-fruited `Gala.' This study provides novel insight into the regulation of fruit development in apple and also suggests a role for the cell cycle genes in fruit size regulation.

scholarly journals MACROMOLECULAR EVENTS LEADING TO CELL DIVISION IN TETRAHYMENA PYRIFORMIS AFTER REMOVAL AND REPLACEMENT OF REQUIRED PYRIMIDINES

1965 ◽  
Vol 25 (2) ◽  
pp. 9-19 ◽  
Author(s):  
Ivan L. Cameron
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Early Period ◽  
Tetrahymena Pyriformis ◽  
Cell Number ◽  
Cellular Protein ◽  
Cellular Content ◽  
Endogenous Protein

Tetrahymena pyriformis were brought to a non-growing state by removal of pyrimidines from their growth medium. During pyrimidine deprivation cell number increased 3- to 4 fold, and this increase was accompanied by one or more complete cycles of macronuclear DNA replication. Autoradiographic studies show that endogenous protein and RNA were turning over throughout starvation and that RNA breakdown products were used to support the DNA synthesis that occurred during the early period of starvation. However, after 72 hours of starvation all DNA synthesis and cell division had ceased. Feulgen microspectrophotometry shows the macronuclei of these cells to have been stopped at a point prior to DNA replication (G1 stage). After pyrimidine replacement the incorporation of H3-uridine, H3-adenosine, and H3-leucine was measured by the autoradiographic grain counting method. The results indicate that RNA synthesis began to increase almost immediately, but that there was a lag of almost an hour before an increase in protein synthesis. In agreement with the autoradiographic data, chemical data also show that cellular content of RNA began to increase shortly after pyrimidine replacement but that cellular protein content did not increase until about one hour later. Pulse labeling of the cells with H3-thymidine at intervals after pyrimidine replacement shows that labeled macronuclei first began to appear at 150 minutes; that 98 per cent of the macronuclei were in DNA synthesis at 240 to 270 minutes; and that the percentage then began to decrease from 300 to 390 minutes, at which time only 25 per cent of the macronuclei were labeled. Cellular content of DNA did not increase for at least 135 minutes after pyrimidine replacement; however, just before the first cells divided (360 minutes) the DNA content had doubled. After pyrimidine replacement the cells first began to divide at 360 minutes, and 50 per cent had divided at 420 minutes; however, all cells had not divided until 573 minutes. This technique of chemical synchronization of cells in mass cultures makes feasible detailed biochemical analysis of events leading to nuclear DNA replication and cell division.

scholarly journals Specific polar subpopulations of astral microtubules control spindle orientation and symmetric neural stem cell division

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Felipe Mora-Bermúdez ◽  
Fumio Matsuzaki ◽  
Wieland B Huttner
Keyword(s):  
Cell Division ◽  
Basal Cell ◽  
Mitotic Spindle ◽  
Asymmetric Cell Division ◽  
Spindle Cell ◽  
Spindle Orientation ◽  
Cell Cortex ◽  
Dividing Cells ◽  
Stem Cell Division

Mitotic spindle orientation is crucial for symmetric vs asymmetric cell division and depends on astral microtubules. Here, we show that distinct subpopulations of astral microtubules exist, which have differential functions in regulating spindle orientation and division symmetry. Specifically, in polarized stem cells of developing mouse neocortex, astral microtubules reaching the apical and basal cell cortex, but not those reaching the central cell cortex, are more abundant in symmetrically than asymmetrically dividing cells and reduce spindle orientation variability. This promotes symmetric divisions by maintaining an apico-basal cleavage plane. The greater abundance of apical/basal astrals depends on a higher concentration, at the basal cell cortex, of LGN, a known spindle-cell cortex linker. Furthermore, newly developed specific microtubule perturbations that selectively decrease apical/basal astrals recapitulate the symmetric-to-asymmetric division switch and suffice to increase neurogenesis in vivo. Thus, our study identifies a novel link between cell polarity, astral microtubules, and spindle orientation in morphogenesis.

scholarly journals Apical PAR complex proteins protect against programmed epithelial assaults to create a continuous and functional intestinal lumen

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Maria Danielle Sallee ◽  
Melissa A Pickett ◽  
Jessica L Feldman
Keyword(s):  
Cell Division ◽  
Epithelial Cells ◽  
Intestinal Lumen ◽  
Microtubule Organizing Center ◽  
Intestinal Tube ◽  
C Elegans ◽  
Junctional Proteins ◽  
Organizing Center ◽  
Dividing Cells

Sustained polarity and adhesion of epithelial cells is essential for the protection of our organs and bodies, and this epithelial integrity emerges during organ development amidst numerous programmed morphogenetic assaults. Using the developing C. elegans intestine as an in vivo model, we investigated how epithelia maintain their integrity through cell division and elongation to build a functional tube. Live-imaging revealed that apical PAR complex proteins PAR-6/Par6 and PKC-3/aPkc remained apical during mitosis while apical microtubules and microtubule-organizing center (MTOC) proteins were transiently removed. Intestine-specific depletion of PAR-6, PKC-3, and the aPkc regulator CDC-42/Cdc42 caused persistent gaps in the apical MTOC as well as in other apical and junctional proteins after cell division and in non-dividing cells that elongated. Upon hatching, gaps coincided with luminal constrictions that blocked food, and larvae arrested and died. Thus, the apical PAR complex maintains apical and junctional continuity to construct a functional intestinal tube.

scholarly journals SIMULTANEOUS SYNTHESIS OF HISTONE AND DNA IN SYNCHRONOUSLY DIVIDING TETRAHYMENA PYRIFORMIS

1967 ◽  
Vol 32 (3) ◽  
pp. 709-717 ◽  
Author(s):  
John A. Hardin ◽  
Gerald E. Einem ◽  
David T. Lindsay
Keyword(s):  
Heat Treatment ◽  
Cell Division ◽  
Dna Content ◽  
Regulatory Mechanism ◽  
Tetrahymena Pyriformis ◽  
S Phase ◽  
Second Step ◽  
Partial Duplication ◽  
Dividing Cells ◽  
Simultaneous Synthesis

Histone and DNA syntheses have been studied in synchronously dividing Tetrahymena pyriformis GL. During the heat treatment necessary to synchronize cultures of this amicronucleate protozoan, the DNA content of the already polyploid macronucleus increases. When the cells begin synchronous division, their DNA content is reduced in a stepwise process which is closely paralleled by reduction of macronuclear histone content. During cell division, the contents of DNA and histone decrease by slightly more than twofold, and in the subsequent S phase, DNA and histone increase simultaneously to 85% of the values expected if all chromosomes were to double. The first step in the process of reduction of DNA and histone contents is their decrease in excess of twofold, and this is accomplished by removal of extrusion bodies from the nuclei of dividing cells. The second step is a mechanism which allows, in effect, only 70% of the chromatin in the average nucleus to duplicate. Such partial duplication suggests that both histone and DNA syntheses in synchronous Tetrahymena depend upon a regulatory mechanism, the mediating elements of which are localized in only certain chromosomes.

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