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.

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.

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.

scholarly journals Cell cycle parameters of Chinese hamster ovary cells during exponential, polyamine-limited growth.

1981 ◽  
Vol 1 (7) ◽  
pp. 594-599 ◽  
Author(s):  
J J Harada ◽  
D R Morris
Keyword(s):  
Cell Cycle ◽  
Chinese Hamster Ovary ◽  
Doubling Time ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
S Phase ◽  
Limited Growth ◽  
Ovary Cells ◽  
Index Analysis ◽  
Thymidine Autoradiography

We have previously shown that Chinese hamster ovary cells made polyamine deficient by treatment with alpha-methylornithine, an inhibitor of ornithine decarboxylase, grow exponentially in culture at low densities at one-half the rate observed in untreated (control) cultures. In this study, the cell cycle of polyamine-limited cells was examined by using thymidine autoradiography, mitotic index analysis, and fraction labeled mitoses analysis. We found that the longer doubling time of inhibitor-treated cultures was a consequence of increases in the lengths of the G1 and S phases. The expansion of the S phase was proportional to the increase in doubling time (twofold), whereas the G1 phase was lengthened by slightly more than a factor of 2. The lengths of the G2 and M phases were essentially unchanged. Putrescine stimulated the growth of inhibitor-treated cultures and restored the cell cycle parameters to those of untreated cells.

The operational flexibility of the phased culture technique, as observed by changes in the cell cycle of Candida utilis

1968 ◽  
Vol 14 (10) ◽  
pp. 1115-1126 ◽  
Author(s):  
J. Müller ◽  
P. S. S. Dawson
Keyword(s):  
Cycle Time ◽  
Doubling Time ◽  
Candida Utilis ◽  
Dry Mass ◽  
Culture Technique ◽  
Operational Flexibility ◽  
Cycle Times ◽  
Viable Cells ◽  
Cell Doubling Time ◽  
Doubling Times

The operation of a continuous phasing technique was examined with regard to synchrony and growth of Candida utilis at different doubling times. A nitrogen-limited medium and an energy-limited medium were compared. Numbers of viable cells, dry mass, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), various phosphorus-fractions, and protein were measured.In a nitrogen-limited medium the continuous phasing technique provided good synchrony (65%–80%), and permitted control and variation of the doubling time up to 9 h. Dry mass, various P-fractions, and DNA increased linearly during all cycle times. The cell doubling time was adjustable to the cycle time imposed by the technique. The nitrogen source was always assimilated within 4 h, whatever the length of the cycle employed. The associated pattern of changes in the amino acid pool, protein, and RNA contents of the cells, though characteristic, underwent some modifications with change in doubling time.An inverse relationship between the amount of nitrogen available to the cells for their reproduction and the corresponding doubling time was found.In an energy (glucose)-limited medium the technique appeared to be restricted to a doubling time where the energy source in the medium lasted until the end of the cell's life cycle. The degree of synchrony was 70–75%. A variation of the doubling time by the technique did not seem possible in glucose-limited medium since no adjustment of the growth rate to the imposed cycle time could be observed.

Cell cycle and post cycle changes during continuous phased growth of Candida utilis

1970 ◽  
Vol 16 (8) ◽  
pp. 783-795 ◽  
Author(s):  
P. S. S. Dawson
Keyword(s):  
Cell Cycle ◽  
Candida Utilis ◽  
Culture Method ◽  
Limited Growth ◽  
Cell Cycles ◽  
Carbon And Nitrogen ◽  
Primary And Secondary Metabolism ◽  
Cell Components ◽  
Changing Patterns ◽  
Quantitative Changes

A modification of the continuous phased culture method is described. This permits examination of changes taking place during the cell cycle (cell cycle changes) to be extended into the following period (postcycle changes).Candida utilis was grown on a glucose medium under conditions of carbon and nitrogen limitation. In nitrogen-limited growth, the size of the amino acid pool changed between the cell cycle and postcycle, but remained relatively constant for both periods in carbon-limited growth. In carbon-limited growth, the carbohydrate composition of the cells was relatively little changed, but considerable changes occurred in nitrogen-limited cells during cell cycle and postcycle periods. Changing patterns in phospholipid contents were also observed during cell cycles and postcycles of both carbon- and nitrogen-limited growths.Qualitative and quantitative changes in various cell components were related to the nutrient limiting to growth and the pattern of its use by the cells. The results illustrate the influence of environmental change upon the cell and are discussed in relation to aspects of primary and secondary metabolism in the cell.

Relationship between iron-limited growth and energy limitation during phased cultivation of Candida utilis

1978 ◽  
Vol 24 (4) ◽  
pp. 440-447 ◽  
Author(s):  
K. C. Thomas ◽  
P. S. S. Dawson
Keyword(s):  
Ethyl Acetate ◽  
Candida Utilis ◽  
Energy Charge ◽  
Tca Cycle ◽  
Iron Limitation ◽  
Limited Growth ◽  
Acetyl Coa ◽  
Limiting Nutrient ◽  
Energy Limitation

The yeast Candida utilis was continuously synchronized by the phasing technique (6 h doubling time) with either iron or nitrogen as the limiting nutrient. Iron limitation resulted in decreased molar growth yields with respect to the carbon substrates and ammonia and in increased specific rates of oxygen uptake. Relatively low energy-charge values were maintained by the iron-limited culture. All these taken together seemed to indicate that the growth of the yeast under iron limitation was also limited by metabolically available energy.Considerable amounts of ethyl acetate were produced by the yeast under phased cultivation when the growth was limited by iron but not by nitrogen. In vitro studies using cell-free extracts showed that the substrates for ethyl acetate synthesis were acetyl coenzyme A (acetyl CoA) and ethanol. Under iron-limited growth acetyl CoA seemed to be diverted to ethyl acetate formation rather than being oxidized through the tricarboxylic acid (TCA) cycle. The possibility of energy limitation under iron-limited growth being brought about by the reduced capacity of the yeast to oxidize acetyl CoA through the TCA cycle is considered.

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.

Cell cycle parameters of Chinese hamster ovary cells during exponential, polyamine-limited growth

1981 ◽  
Vol 1 (7) ◽  
pp. 594-599
Author(s):  
J J Harada ◽  
D R Morris
Keyword(s):  
Cell Cycle ◽  
Chinese Hamster Ovary ◽  
Doubling Time ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
S Phase ◽  
Limited Growth ◽  
Ovary Cells ◽  
Index Analysis ◽  
Thymidine Autoradiography

We have previously shown that Chinese hamster ovary cells made polyamine deficient by treatment with alpha-methylornithine, an inhibitor of ornithine decarboxylase, grow exponentially in culture at low densities at one-half the rate observed in untreated (control) cultures. In this study, the cell cycle of polyamine-limited cells was examined by using thymidine autoradiography, mitotic index analysis, and fraction labeled mitoses analysis. We found that the longer doubling time of inhibitor-treated cultures was a consequence of increases in the lengths of the G1 and S phases. The expansion of the S phase was proportional to the increase in doubling time (twofold), whereas the G1 phase was lengthened by slightly more than a factor of 2. The lengths of the G2 and M phases were essentially unchanged. Putrescine stimulated the growth of inhibitor-treated cultures and restored the cell cycle parameters to those of untreated cells.

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.

scholarly journals Assessing Early Heterogeneity in Doubling Times of the COVID-19 Epidemic across Prefectures in Mainland China, January–February, 2020

Epidemiologia ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 95-113 ◽  
Author(s):  
Isaac Chun-Hai Fung ◽  
Xiaolu Zhou ◽  
Chi-Ngai Cheung ◽  
Sylvia K. Ofori ◽  
Kamalich Muniz-Rodriguez ◽  
...  
Keyword(s):  
Regression Models ◽  
Doubling Time ◽  
Metropolitan Areas ◽  
Mainland China ◽  
Linear Regression Models ◽  
Case Count ◽  
Daily Time Series ◽  
The Mean ◽  
Doubling Times ◽  
Daily Time

To describe the geographical heterogeneity of COVID-19 across prefectures in mainland China, we estimated doubling times from daily time series of the cumulative case count between 24 January and 24 February 2020. We analyzed the prefecture-level COVID-19 case burden using linear regression models and used the local Moran’s I to test for spatial autocorrelation and clustering. Four hundred prefectures (~98% population) had at least one COVID-19 case and 39 prefectures had zero cases by 24 February 2020. Excluding Wuhan and those prefectures where there was only one case or none, 76 (17.3% of 439) prefectures had an arithmetic mean of the epidemic doubling time <2 d. Low-population prefectures had a higher per capita cumulative incidence than high-population prefectures during the study period. An increase in population size was associated with a very small reduction in the mean doubling time (−0.012, 95% CI, −0.017, −0.006) where the cumulative case count doubled ≥3 times. Spatial analysis revealed high case count clusters in Hubei and Heilongjiang and fast epidemic growth in several metropolitan areas by mid-February 2020. Prefectures in Hubei and neighboring provinces and several metropolitan areas in coastal and northeastern China experienced rapid growth with cumulative case count doubling multiple times with a small mean doubling time.

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