Preparation of Synchronous Cultures of the Fission yeast, Schizosaccharomyces pombe

Author(s):  
James Creanor
1978 ◽  
Vol 33 (1) ◽  
pp. 399-411
Author(s):  
J. Creanor

Oxygen uptake was measured in synchronous cultures of the fission yeast Schizosaccharomyces pombe. The rate of oxygen uptake was found to increase in a step-wise manner at the beginning of the cycle and again in the middle of the cycle. The increases in rate were such that overall, oxygen uptake doubled in rate once per cell cycle. Addition of inhibitors of DNA synthesis or nuclear division to a synchronous culture did not affect the uptake of oxygen. In an induced synchronous culture, in which DNA synthesis, cell division, and nuclear division, but not ‘growth’ were synchronized, oxygen uptake increased continuously in rate and did not show the step-wise rises which were shown in the selection-synchronized culture. These results were compared with previous measurements of oxygen uptake in yeast and an explanation is suggested for the many different patterns which have been reported.


1984 ◽  
Vol 69 (1) ◽  
pp. 199-210
Author(s):  
J. Creanor ◽  
J.M. Mitchison

The rate of protein synthesis has been measured with pulse labels of [3H]tryptophan in synchronous and asynchronous cultures of cdc mutants of Schizosaccharomyces pombe shifted up to the restrictive temperature. The cell cycle related fluctuations in rate that occur in normal synchronous cultures vanish when nuclear division is blocked in synchronous cultures of cdc2 and cdc10. But they persist in cdc11 where nuclear division continues and cleavage is stopped. We conclude that nuclear division affects the rate of synthesis and that this effect is inhibitory and probably persists for the last 40% of the cycle. When nuclear division has been blocked, the rate of synthesis continues to increase until a plateau is reached where the rate remains constant. Three size mutants of cdc2 reach the plateau at the same average protein content per cell although their initial protein contents vary over a threefold range. Comparison of these results with those from cdc10 leads to the tentative conclusion that the plateau starts when the cells reach a critical protein/DNA ratio.


1980 ◽  
Vol 46 (1) ◽  
pp. 399-431
Author(s):  
T. Benitez ◽  
P. Nurse ◽  
J.M. Mitchison

The induction potentials of 2 enzymes, sucrase and arginase, have been measured in asynchronous and synchronous cultures of the fission yeast Schizosaccharomyces pombe. The effect on potential of inhibiting DNA synthesis is asynchronous cultures has been studied using 2 temperature-sensitive dcd mutants, one blocked in DNA replication and the other blocked in mitosis. The results show that despite inhibition of DNA synthesis, sucrase and arginase potential both continue to increase exponentially for at least a generation of growth after shifting the cdc mutants from the permissive to the restrictive temperature. A second method of inhibiting DNA synthesis, using deoxyadenosine, has also been tested. Cells treated with deoxyadenosine stop the increase in potential for a short period. However, experiments carried out using a cdc mutant together with deoxyadenosine show that the block to the increase in potential is due to a side effect of the inhibitor. It appears that increase in potential is not dependent upon continued DNA replication, and that gene dosage does not control potential in the normal cell cycle. This conclusion is supported by measurements on mutants of different cell sizes. potential is proportional to size (protein content per cell is asynchronous culture) and not to DNA content. Although potential is not gene limited in normal cells, it does appear to be so in the abnormally large cells produced by a cdc block. If cdc mutants of different sizes are grown asynchronously, and DNA synthesis is inhibited by a shift to the restrictive temperature, there is no increase in potential. This critical ratio is different for the 2 enzymes, but for each enzyme it is similar in all the mutants tested. When large cells (produced by a mutant block for 4.5 h) are shifted down in temperature, there are synchronous rounds of DNA synthesis and division and also step doublings in potential. In synchronous cultures of wild type cells, both enzymes show a stepwise doubling of potential at 0.2 of a cycle after DNA replication. In synchronous cultures of cdc mutants blocked either in replication or in mitosis, the potential steps continue with the normal timing observed in wild type cells. This shows that the steps are not dependent on the events of the DNA-division cycle but are controlled by another mechanism. Attainment of a critical size might be part of this mechanism, but tests with size mutants argue against this.


1977 ◽  
Vol 162 (1) ◽  
pp. 39-46 ◽  
Author(s):  
S W Edwards ◽  
D Lloyd

1. Changes in activity of ATPase (adenosine triphosphatase) during the cell cycle of Schizosaccharomyces pombe were analysed in cell-free extracts of cells harvested from different stages of growth of synchronous cultures and also after cell-cycle fractionation. 2. Oligomycin-sensitive ATPase oscillates in both glucose-repressed synchronous cultures and shows four maxima of activity approximately equally spaced through the cell cycle. The amplitude of the oscillations accounts for between 13 and 80% of the total activity at different times in the cell cycle. 3. Oligomycin sensitivity varies over a fourfold range at different stages of the cell cycle. 4. The periodicity of maximum oligomycin sensitivity is one-quarter of a cell cycle. 5. These results were confirmed for the first three-quarters of the cell cycle by cell-cycle fractionation. 6. In cells growing synchronously with glycerol, ATPase activity increases in a stepwise pattern, with two steps per cell cycle; the first of these occurs at 0.54 of the cell cycle and the second at 0.95. 7. These results are discussed in relation to previously obtained data on the development of mitochondrial activities during the cell cycle.


1990 ◽  
Vol 96 (3) ◽  
pp. 429-433
Author(s):  
B. Novak ◽  
J.M. Mitchison

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.


1978 ◽  
Vol 33 (1) ◽  
pp. 385-397
Author(s):  
J. Creanor

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.


2002 ◽  
Vol 3 (3) ◽  
pp. 221-225

In recent months a bumper crop of genomes has been completed, including the fission yeast (Schizosaccharomyces pombe) and rice (Oryza sativa). Two large-scale studies ofSaccharomyces cerevisiaeprotein complexes provided a picture of the eukaryotic proteome as a network of complexes. Amongst the other stories of interest was a demonstration that proteomic analysis of blood samples can be used to detect ovarian cancer, perhaps even as early as stage I.


1986 ◽  
Vol 83 (21) ◽  
pp. 8253-8257 ◽  
Author(s):  
L. Clarke ◽  
H. Amstutz ◽  
B. Fishel ◽  
J. Carbon

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