Growth, cell cultivation, cell metabolism, and the cell cycle of Candida utilis as explored by continuous phased culture

1985 ◽  
Vol 31 (3) ◽  
pp. 183-189 ◽  
Author(s):  
P. S. S. Dawson
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Doubling Time ◽  
Microbial Growth ◽  
Candida Utilis ◽  
Cell Metabolism ◽  
Growth Theory ◽  
Cell Cultivation ◽  
Phenotypic Changes ◽  
Nitrogen Phosphorus

The problem of microbial growth, centred both on the population and the cell, and studied largely in batch culture, is also accessible by open methods of continuous culture which release such growth studies from restrictions imposed by the traditional methods. Thus, continuous phased (synchrony) culture enables studies of the cell cycle to be conducted systematically under different conditions of nutrient limitation and growth rate, and allows the phenotypic changes of chemostat steady states to be expressed as patterns of "cell cycle" behaviour over the doubling time. Studies conducted with Candida utilis in this way, in carbon-, nitrogen-, phosphorus-, and other nutrient-limited growths, have revealed a variable behaviour in the cell cycle, especially in the G1 period. Such variability in cell cycle behaviour is closely linked to the nutrient control of growth in the culture and generally accords with the Monod growth theory. Such variable behaviours for the cell are examined and assessed in relation to leading contemporary models for the cell cycle.

Stimulation by pH of cell cycle initiation in the yeast Candida utilis

1981 ◽  
Vol 59 (11) ◽  
pp. 2043-2048 ◽  
Author(s):  
K. Chandapillai Thomas
Keyword(s):  
Cell Cycle ◽  
Nitrogen Source ◽  
Growth Medium ◽  
Respiratory Quotient ◽  
Doubling Time ◽  
Candida Utilis ◽  
Cellular Processes ◽  
Ph Shift ◽  
Bud Emergence ◽  
Limiting Nutrient

The effect of shifting pH of the growth medium on cell cycle initiation by the yeast Candida utilis was studied. The yeast was grown by the phased method of cultivation with nitrogen source (ammonium) in growth limiting concentrations and with a phasing period (imposed doubling time) of 6 h. The pH of the culture during the phased growth was maintained between 2.0 and 2.1. The rate of cell cycle initiation as determined by the rate of bud emergence was 24% per hour. If the pH of the culture was shifted to 6.0 at the beginning of the phasing period and maintained at that level for the rest of the phasing period the rate of bud emergence increased to 50% per hour. The increased rate of bud emergence was accompanied by a fast uptake of oxygen and the growth-limiting nutrient and by a reduction in the respiratory quotient. The results suggest that the pH shift accelerated cellular processes necessary for cell cycle initiation.

scholarly journals Coordination between E. coli Cell Size and Cell Cycle Mediated by DnaA

2020 ◽  
Author(s):  
Qing Zhang ◽  
Zhichao Zhang ◽  
Hualin Shi
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Dna Replication ◽  
Cell Size ◽  
Doubling Time ◽  
Cell Mass ◽  
Replication Initiation ◽  
General Relationship ◽  
E Coli ◽  
Regulatory Processes

Sixty years ago, bacterial cell size was found as an exponential function of growth rate. Fifty years ago, a more general relationship was proposed, in which the cell mass was equal to the initiation mass multiplied by the ratio of the total time of the C and D periods to the doubling time. This relationship has recently been experimentally confirmed by perturbing doubling time, C period, D period or the initiation mass. However, the underlying molecular mechanism remains unclear. Here, we developed a mechanistic and kinetic model to describe how the initiator protein DnaA mediates the initiation of DNA replication in E. coli. In the model, we introduced an initiation probability function involving competitive binding of DnaA-ATP (active) and DnaA-ADP (inactive) at replication origin to determine the initiation of replication. In addition, we considered RNAP availability, ppGpp inhibition, DnaA autorepression, DnaA titration by chromosomal sites, hydrolysis of DnaA-ATP along with DNA replication, reactivation of DnaA-ADP and established a kinetic description of these DnaA regulatory processes. We simulated DnaA kinetics and obtained a self-consistent cell size and a regular DnaA oscillation coordinated with the cell cycle at steady state. The relationship between the cell size obtained by the simulation and the growth rate, C period, D period or initiation mass reproduces the results of the experiment. This model also predicts how the number of DnaA and the initiation mass vary with the perturbation parameters (including those reflecting the mutation or interference of DnaA regulatory processes), which is comparable to experimental data. The results suggest that the regulatory mechanisms of DnaA level and activity are associated with the invariance of initiation mass and the cell size general relationship for matching frequencies of replication initiation and cell division. This study may provide clues for concerted control of cell size and cell cycle in synthetic biology.

scholarly journals Growth Rate-Dependent Regulation of Medial FtsZ Ring Formation

2003 ◽  
Vol 185 (9) ◽  
pp. 2826-2834 ◽  
Author(s):  
Richard B. Weart ◽  
Petra Anne Levin
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Transcriptional Control ◽  
Doubling Time ◽  
Ring Formation ◽  
Intracellular Concentration ◽  
Dependent Manner ◽  
Ftsz Ring ◽  
Division Site ◽  
Rate Dependent

ABSTRACT FtsZ is an essential cell division protein conserved throughout the bacteria and archaea. In response to an unknown cell cycle signal, FtsZ polymerizes into a ring that establishes the future division site. We conducted a series of experiments examining the link between growth rate, medial FtsZ ring formation, and the intracellular concentration of FtsZ in the gram-positive bacterium Bacillus subtilis. We found that, although the frequency of cells with FtsZ rings varies as much as threefold in a growth rate-dependent manner, the average intracellular concentration of FtsZ remains constant irrespective of doubling time. Additionally, expressing ftsZ solely from a constitutive promoter, thereby eliminating normal transcriptional control, did not alter the growth rate regulation of medial FtsZ ring formation. Finally, our data indicate that overexpressing FtsZ does not dramatically increase the frequency of cells with medial FtsZ rings, suggesting that the mechanisms governing ring formation are refractile to increases in FtsZ concentration. These results support a model in which the timing of FtsZ assembly is governed primarily through cell cycle-dependent changes in FtsZ polymerization kinetics and not simply via oscillations in the intracellular concentration of FtsZ. Importantly, this model can be extended to the gram-negative bacterium Escherichia coli. Our data show that, like those in B. subtilis, average FtsZ levels in E. coli are constant irrespective of doubling time.

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.

Some comparative observations on the relative contributions of alternate pathways in the metabolism of glucose by Candida utilis

1976 ◽  
Vol 22 (7) ◽  
pp. 996-1001 ◽  
Author(s):  
P. S. S. Dawson ◽  
W. Okada ◽  
L. P. Steinhauer
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Nutrient Limitation ◽  
Cell Population ◽  
Candida Utilis ◽  
Mineral Salts ◽  
Growth Sequence ◽  
Cultivation Techniques ◽  
Unit Performance

Candida utilis was grown in batch, chemostat, and continuously synchronised (phased) culture on a nitrogen-limited glucose mineral salts medium: phosphorus- and carbon-limited phased cultures were also used. The 14CO2 evolved from [G-1-14C] and [G-6-14C] was used, as a simple C1/C6 ratio, to observe the relative changes in EMP and HMP contributions during growth of the cultures. The ratio varied during the cell cycle, and changed with growth rate, and with nutrient limitation. The changes generally indicated that the HMP predominated, most notably in the early part of the batch-growth sequence and early in the cell cycle.The overall results reflected the relative merits of the different cultivation techniques for examining microbial metabolism: the advantage of a greater resolution by the synchronised method, based upon the unit performance rather than the randomised mean performance of the cell population, was demonstrated.

Changing patterns of 32P and 33P utilization in cells of Candida utilis during the cell cycle

1972 ◽  
Vol 18 (11) ◽  
pp. 1691-1693 ◽  
Author(s):  
P. S. S. Dawson ◽  
H. Glättli
Keyword(s):  
Cell Cycle ◽  
Doubling Time ◽  
Candida Utilis ◽  
Cold Water ◽  
Growth Conditions ◽  
Changing Patterns ◽  
Rna And Dna ◽  
Synchronized Cultures ◽  
In Cells

Incorporation of 33P and 32P into different fractions of continuous phased (synchronized) cultures of Candida utilis was studied. Two different growth conditions (on C-limited and N-limited media) were used at a doubling time of 6 h. Incorporation of 33P and 32P into four fractions (lipid, cold-water ex-tractable, RNA and DNA) showed a variable, nonuniform, behavior during the cell cycle. Different patterns of incorporation between cells on the two media were observed.

Cytokinetic Analysis at Various Ages of an Ascites Tumor after Radiation

1978 ◽  
Vol 64 (5) ◽  
pp. 463-470
Author(s):  
Eva Siracká ◽  
Natasa Pappová
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Cycle Time ◽  
Doubling Time ◽  
Cell Loss ◽  
Whole Body ◽  
Ascites Tumor ◽  
Cell Cycle Time ◽  
Slowing Down ◽  
Proliferative Phase

A cytokinetic analysis has been made of 5-day and of 10-day old murine 6C3HED ascites lymphosarcoma (Gardner) by using a growth curve, percentage of labeled mitoses curves, and continuous labeling curves. The doubling time increased from 36 h in the proliferative phase of growth to 252 h in the stationary phase. The slowing down of the growth rate was due to prolongation of the cell cycle time, with greatest extension in G1 and increased cell loss. The measurement of the kinetic parameters made immediately after irradiation with a whole-body single dose of 3 Gy (300 rad) showed an increase in duration of the cell cycle in the 5-day-old tumor, while in the 10-day-old tumor the cell cycle time was decreased due to reduce length in the G1 phase.

The oxygen uptake of phased yeast cultures growing at different doubling times on nitrogen- and energy-limited media

1968 ◽  
Vol 14 (10) ◽  
pp. 1127-1131 ◽  
Author(s):  
J. Müller ◽  
P. S. S. Dawson
Keyword(s):  
Energy Source ◽  
Cell Cycle ◽  
Oxygen Uptake ◽  
Doubling Time ◽  
Candida Utilis ◽  
Limited Growth ◽  
Yeast Cultures ◽  
Limiting Nutrient ◽  
Source Limitation ◽  
Doubling Times

The oxygen uptake of Candida utilis growing in phased culture at doubling times of 4, 6, 8, and 12 hours was measured under conditions of nitrogen and energy source limitation. No abrupt doubling of oxygen uptake was observed at any stage of the cell cycle. The pattern of oxygen uptake was closely related to the assimilation of the growth-limiting nutrient. In nitrogen-limited growth, the specific oxygen uptake (Qo2) was found to decrease as the doubling time increased, but, in glucose-limited growth, no change was observed.

CONTINUOUS PHASED GROWTH, WITH A MODIFIED CHEMOSTAT

1965 ◽  
Vol 11 (6) ◽  
pp. 893-903 ◽  
Author(s):  
P. S. S. Dawson
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Amino Acid ◽  
Candida Utilis ◽  
Chemostat Culture ◽  
Amino Acid Pool ◽  
Acid Pool ◽  
Preliminary Results

A modified chemostat is described which may be used to maintain a continuously phased population in the culture for periods of many months. Preliminary results with Candida utilis show that changes in the amino acid pool occur over the cell cycle, and that these changes alter with growth rate. The significance of the method and its relationship to chemostat culture are outlined.

Changes in patterns of respiration and glucose utilisation in Candida utilis during the cell cycle: some variations with growth rate

1975 ◽  
Vol 21 (7) ◽  
pp. 1013-1019 ◽  
Author(s):  
P. S. S. Dawson ◽  
D. W. S. Westlake
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Oxygen Uptake ◽  
Candida Utilis ◽  
Hexose Monophosphate ◽  
Mineral Salts ◽  
Glucose Utilisation ◽  
Growth Metabolism ◽  
Doubling Times

The release of 14CO2 from 14C-labelled glucose (G-1-14C, G-3,4-14C, G-6-14C) was followed in phased cultures of Candida utilis grown in a glucose – mineral salts medium under altered conditions of carbon:nitrogen limitation at doubling times of 2, 4, and 6 h. Changes in oxygen uptake and CO2 evolution were observed and respirometric studies showed that the relative contributions of the Embden-Meyerhof-Parnas and hexose monophosphate pathways varied over the cell cycle and changed with growth rate. The results are discussed in relation to the growth metabolism of the cells.

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