scholarly journals The effect of CO2 on the timing of cell cycle events in fission yeast Schizosaccharomyces pombe

1988 ◽  
Vol 89 (3) ◽  
pp. 433-439
Author(s):  
B. NOVÁK ◽  
J. HALBAUER ◽  
E. LÁSZLÓ
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Co2 Production ◽  
Complete Medium ◽  
Co2 Removal ◽  
Wild Type ◽  
In The Wild ◽  
G2 Phase

The effect of CO2 removal on the cell cycle phases of Schizosaccharomyces pombe has been examinedin minimal, aspartate-containing and complete medium. The removal of CO2 shortened the G2 phase of the cell cycle and arrested the cells in G1 phase in minimal medium. The G1 block caused by CO2 deprivation was demonstrated by transition-point and flow-cytometry analyses. The slow-down of anapleurotic CO2 fixation might be responsible for this effect, as aspartic acid could abolish the G1 block. The shortening of G2 phase in the wild-type cells was observed in every medium irrespective of whether the growth rate was changed or not. The experiments in which growth rate was not changed by CO2 shift-down suggest that this CO2 effect can be independent from its action on CO2-fixing steps in metabolism. Therefore we propose that CO2 inhibits mitosis infission yeast and we explain the proportionality between growth rate and cell size at mitosis found by Fantes & Nurse by this CO2 inhibition. The larger CO2 production in fast-growing cells leads to a higher CO2 concentration, which could exerta stronger inhibition of mitosis. A wee mutant, which has lost its mitotic size control, also shows the G1 block after CO2 deprivation, but its mitosis is insensitive to CO2. Comparing the respiration of wee and wild-type cells we conclude that CO2 inhibits the citric acid cycle in the wild type. The consequence of these results in the regulation of fission yeast cell cycle is discussed.

Pattern of end growth of the fission yeast Schizosaccharomyces pombe

1990 ◽  
Vol 36 (6) ◽  
pp. 390-394 ◽  
Author(s):  
Hisao Miyata ◽  
Machiko Miyata ◽  
Byron F. Johnson
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Schizosaccharomyces Pombe ◽  
Key Words ◽  
Fission Yeast ◽  
Doubling Time ◽  
Time Lapse ◽  
Critical Value ◽  
Wild Type ◽  
Time Lapse Photomicrography

The patterns of end growth of individual cells of Schizosaccharomyces pombe, wild-type cells (strain 972 h−), cells exposed to 8 mM hydroxyurea, and cdc mutants (cdc11-123 and cdc2-33), were investigated by time-lapse photomicrography. It was reconfirmed that there are three patterns of end growth: cells growing at the old end, at the new end, and at both ends from the beginning of the cell cycle. Cells that initiated growth at the old (new) end increased their growth rate at the new (old) end and became constant in their growth rate at the old (new) end when cells had their growth rate higher than a critical value: 0.08, 0.09, 0.08, and 0.11 μm/min in wild-type cells, cells exposed to hydroxyurea, cdc11-123 cells, and cdc2-33 cells, respectively. The critical value is proportional to the doubling time in length. Key words: extension, growth, fission yeast.

Changes in the rate of oxygen consumption in synchronous cultures of the fission yeast Schizosaccharomyces pombe

1990 ◽  
Vol 96 (3) ◽  
pp. 429-433
Author(s):  
B. Novak ◽  
J.M. Mitchison
Keyword(s):  
Cell Cycle ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Oxygen Electrode ◽  
Co2 Production ◽  
Synchronous Cultures ◽  
Rate Of Oxygen Consumption

Oxygen consumption was measured with an oxygen electrode in synchronous cultures of S. pombe. There were changes during the cell cycle in the rate of oxygen uptake, which are most clearly shown as oscillations in acceleration curves (rate of the rate of uptake). Under various conditions of selection and induction synchrony the acceleration curves are similar to those found earlier for CO2 production. As with CO2 production, the oscillations continued after a block to the DNA-division cycle. There were, however, two differences between oxygen uptake and CO2 production. The oxygen oscillations were more marked and also were out of phase by half a cycle. The respiratory coefficient therefore changes through the cycle.

Carbon dioxide evolution during the cell cycle of the fission yeast Schizosaccharomyces pombe

1978 ◽  
Vol 33 (1) ◽  
pp. 385-397
Author(s):  
J. Creanor
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Nuclear Division ◽  
Complete Medium ◽  
Co2 Evolution ◽  
Carbon Dioxide Evolution ◽  
Synchronous Cultures ◽  
Constant Addition

The rate of CO2 evolution was measured in synchronous cultures of the fission yeast Schizosaccharomyces pombe growing in a minimal medium. The rate of CO2 evolution was found to double sharply at about the time of nuclear division (0.75 of the way through the cell cycle). For the remainder of the cell cycle the rate remained constant. Addition of inhibitors of DNA synthesis or nuclear division did not affect the pattern of CO2 evolution in synchronous cultures. Similarly, in an induced synchronous culture, in which DNA synthesis, nuclear division and cell division—but not growth, were synchronized, CO2 evolution showed a continuous pattern and not the step-wise increase associated with the normal synchronous cultures. When S. pombe was grown in a complete medium, the evolution of CO2 in a synchronous cultures was shown to increase in a continuous manner but at a rate faster than the growth of the culture.

Nucleoside diphosphokinase and cell cycle control in the fission yeast Schizosaccharomyces pombe

1983 ◽  
Vol 60 (1) ◽  
pp. 355-365
Author(s):  
J.R. Dickinson
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Dna Replication ◽  
Schizosaccharomyces Pombe ◽  
S Phase ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Synchronous Cultures ◽  
In The Wild

Centrifugal elutriation was used to prepare synchronous cultures of Schizosaccharomyces pombe. Nucleoside diphosphokinase activity was measured throughout the cell cycle. In the wild-type strain (972) nucleoside diphosphokinase activity doubled in a stepwise fashion. The midpoint of the rise in enzyme activity was at 0.65 of a cycle, 0.29 of a cycle before the next S phase. Synchronous cultures of the mutant wee 1–6 were also prepared. In this strain S phase is delayed, occurring about 0.3 cycle later than in the wild-type. In wee 1–6 the midpoint of the stepwise doubling in nucleoside diphosphokinase activity occurred at 0.084; showing that the rise in enzyme activity is also delayed. Addition of cycloheximide to an exponentially growing culture caused an immediate inhibition of protein synthesis, yet nucleoside diphosphokinase activity continued to increase exponentially for a further 300 min. This indicates that the stepwise doubling of nucleoside diphosphokinase activity during the cell cycle is not achieved by a simple control on protein synthesis. Two temperature-sensitive cdc- mutants were also used: cdc2-33, a mutant whose single genetic lesion results in the twin defects of a loss of mitotic control and a loss of commitment to the cell cycle; and cdc 10–129, which has a defect in DNA replication. In both mutants a temperature shift-up of an asynchronously growing culture from the permissive (25 degrees C) to the restrictive temperature (36.5 degrees C) results in a rapid inhibition of DNA replication. In both mutants nucleoside diphosphokinase continues to increase exponentially. Therefore, although nucleoside diphosphokinase is required for DNA replication, apparently DNA replication is not required for an increase in nucleoside diphosphokinase activity.

RtoA links initial cell type choice to the cell cycle in Dictyostelium

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3677-3685 ◽  
Author(s):  
S.A. Wood ◽  
R.R. Ammann ◽  
D.A. Brock ◽  
L. Li ◽  
T. Spann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Wild Type ◽  
Cell Type ◽  
Initial Cell ◽  
M Phase ◽  
In The Wild ◽  
G2 Phase ◽  
Novel Protein

In Dictyostelium, initial cell type choice is correlated with the cell-cycle phase of the cell at the time of starvation. We have isolated a mutant, ratioA (rtoA), with a defect in this mechanism that results in an abnormally high percentage of prestalk cells. The rtoA gene has been cloned and sequenced and codes for a novel protein. The cell cycle is normal in rtoA. In the wild type, prestalk cells differentiate from those cells in S or early G2 phase at starvation and prespore cells from cells in late G2 or M phase at starvation. In rtoA mutants, both prestalk and prespore cells originate randomly from cells in any phase of the cell cycle at starvation.

scholarly journals The Constitutive Centromere Component CENP-50 Is Required for Recovery from Spindle Damage

2005 ◽  
Vol 25 (23) ◽  
pp. 10315-10328 ◽  
Author(s):  
Yukinori Minoshima ◽  
Tetsuya Hori ◽  
Masahiro Okada ◽  
Hiroshi Kimura ◽  
Tokuko Haraguchi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Mitotic Checkpoint ◽  
Loss Of Function ◽  
Wild Type ◽  
Centromere Function ◽  
Dt40 Cells ◽  
Precise Role ◽  
Chicken Dt40 Cell

ABSTRACT We identified CENP-50 as a novel kinetochore component. We found that CENP-50 is a constitutive component of the centromere that colocalizes with CENP-A and CENP-H throughout the cell cycle in vertebrate cells. To determine the precise role of CENP-50, we examined its role in centromere function by generating a loss-of-function mutant in the chicken DT40 cell line. The CENP-50 knockout was not lethal; however, the growth rate of cells with this mutation was slower than that of wild-type cells. We observed that the time for CENP-50-deficient cells to complete mitosis was longer than that for wild-type cells. Centromeric localization of CENP-50 was abolished in both CENP-H- and CENP-I-deficient cells. Coimmunoprecipitation experiments revealed that CENP-50 interacted with the CENP-H/CENP-I complex in chicken DT40 cells. We also observed severe mitotic defects in CENP-50-deficient cells with apparent premature sister chromatid separation when the mitotic checkpoint was activated, indicating that CENP-50 is required for recovery from spindle damage.

Overexpression Phenotypes of Plk1 and Ndrg2 in Schizosaccharomyces Pombe: Fission Yeast System for Mammalian Gene Study

2005 ◽  
Vol 277-279 ◽  
pp. 1-6 ◽  
Author(s):  
Young Joo Jang ◽  
Young Sook Kil ◽  
Jee Hee Ahn ◽  
Jae Hoon Ji ◽  
Jong Seok Lim ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Rna Splicing ◽  
Mammalian Cells ◽  
Protein Modification ◽  
Genetic System ◽  
Functional Study ◽  
Mammalian Genes

The fission yeast, Schizosaccharomyces pombe is a single-celled free-living fungus that shares many features with cells of more complicated eukaryotes. Many of the genes required for the cell-cycle control, proteolysis, protein modification, and RNA splicing are highly conserved with those of higher eukaryotes. Moreover, fission yeast has the merit of genetics and its genetic system is already well characterized. As such, the current study evaluated the use of a fission yeast system as a tool for the functional study of mammalian genes and attempted to set up an assay system for novel genes. Since the phenotypes of a deletion mutant and the overexpression of a gene are generally analyzed for a functional study of specific genes in yeast, the present study used overexpression phenotypes to study the functions of mammalian genes. Therefore, based on using a thiamine-repressive promoter, two mammalian genes were expressed in fission yeast, and their overexpressed phenotypes compared with those in mammalian cells. The phenotypes resulting from overexpression were analyzed using a FACS, which analyzes the DNA contents, and a microscope. One of the selected genes was the mammalian Polo-like kinase 1 (Plk1), which is activated and plays a role in the mitotic phase of the cell division cycle. The overexpression of various constructs of Plk1 in the HeLa cells caused cell cycle defects, suggesting that the ectopic Plk1s blocked the endogenous Plk1 in the cells. As expected, when the constructs were overexpressed in the fission yeast system, the cells were arrested in mitosis and defected at the end of mitosis. As such, this data suggests that the Plk1-overexpressed phenotypes were similar in the mammalian cells and the fission yeast, thereby enabling the mammalian Plk1 functions to be approximated in the fission yeast. The other selected gene was the N-Myc downstream-regulated gene 2 (ndrg2), which is upregulated during cell differentiation, yet still not well characterized. When the ndrg2 gene was overexpressed in the fission yeast, the cells contained multi-septa. The septa were positioned well, yet their number increased per cell. Therefore, this gene was speculated to block cell division in the last stage of the cell cycle, making the phenotype potentially useful for explaining cell growth and differentiation in mammalian cells. Accordingly, fission yeast is demonstrated to be an appropriate species for the functional study of mammalian genes.

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