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.

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.

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.

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.

Stem cell growth and differentiation in Hydra attenuata. I. Regulation of the self-renewal probability in multiclone aggregates

1979 ◽  
Vol 38 (1) ◽  
pp. 155-169
Author(s):  
F. Sproull ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Growth Rate ◽  
Stem Cell ◽  
Cell Density ◽  
Cell Population ◽  
Negative Feedback ◽  
The Self ◽  
Stem Cell Population ◽  
Self Renewal

Interstitial stem cells in Hydra are rapidly proliferating multipotent stem cells which continuously give rise to precursors for nerve and nematocyte differentiation. Growth of the stem cell population is controlled by the cell cycle time of the stem cells and the self-renewal probability, Ps (the fraction of stem cells in each generation which divide to yield more stem cells). In normal Hydra the stem cell generation time is 24 h and Ps = 0.6; under these conditions the stem cell population doubles in 3.5 days. In the present experiments we have systematically investigated the dependence of Ps on stem cell density. We culture stem cells in a feeder layer system consisting of aggregates of nitrogen-mustard (NM)-inactivated Hydra cells. In this system stem cell density can be varied over a wide range by changing the number of clone-forming units (CFU) added to the aggregates. We have measured the growth rate of the stem cell population and the cell cycle of stem cells in NM aggregates after 4–7 days of culture. From these data we calculate the value of Ps. The results indicate that the growth rate decreases 4-fold as the number of CFU seeded per aggregate increases from 10 to 400. Under these same conditions the cell cycle remains constant. The values of Ps calculated from these results indicate the Ps decreases from 0.75 in aggregates seeded with 10–30 CFU to 0.55 in aggregates seeded with 200–400 CFU. These results support a model in which Ps is controlled by negative feedback from neighbouring stem cells. In addition, our experiments indicate that Ps decreases during the growth of stem cell clones. When only a few stem cells are seeded in aggregates, they give rise to isolated clones distributed throughout the aggregate. Ps decreases markedly within such clones as they grow in size presumably due to increasing stem cell content of the clones. Since Ps in such isolated clones declines with growth, we infer that the local stem cell concentration is what controls Ps and that the spatial range of the negative feedback signal is short compared to the dimensions of NM aggregates.

scholarly journals The Consequences of Budding versus Binary Fission on Adaptation and Aging in Primitive Multicellularity

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 661
Author(s):  
Hanna Isaksson ◽  
Peter L. Conlin ◽  
Ben Kerr ◽  
William C. Ratcliff ◽  
Eric Libby
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Cellular Senescence ◽  
Carrying Capacity ◽  
The Other ◽  
Binary Fission ◽  
Fundamental Aspect ◽  
Accumulated Damage ◽  
Cell Age ◽  
Multicellular Organisms

Early multicellular organisms must gain adaptations to outcompete their unicellular ancestors, as well as other multicellular lineages. The tempo and mode of multicellular adaptation is influenced by many factors including the traits of individual cells. We consider how a fundamental aspect of cells, whether they reproduce via binary fission or budding, can affect the rate of adaptation in primitive multicellularity. We use mathematical models to study the spread of beneficial, growth rate mutations in unicellular populations and populations of multicellular filaments reproducing via binary fission or budding. Comparing populations once they reach carrying capacity, we find that the spread of mutations in multicellular budding populations is qualitatively distinct from the other populations and in general slower. Since budding and binary fission distribute age-accumulated damage differently, we consider the effects of cellular senescence. When growth rate decreases with cell age, we find that beneficial mutations can spread significantly faster in a multicellular budding population than its corresponding unicellular population or a population reproducing via binary fission. Our results demonstrate that basic aspects of the cell cycle can give rise to different rates of adaptation in multicellular organisms.

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.

In vitro evidence that LHRH stimulates the recruitment of prolactin mRNA-expressing cells during the postnatal period in the rat

1994 ◽  
Vol 12 (1) ◽  
pp. 107-118 ◽  
Author(s):  
A Van Bael ◽  
R Huygen ◽  
B Himpens ◽  
C Denef
Keyword(s):  
Cell Cycle ◽  
Cell Population ◽  
Blot Hybridization ◽  
Postnatal Period ◽  
S Phase ◽  
Female Rats ◽  
Mrna Levels ◽  
Dot Blot ◽  
Total Cell Population

ABSTRACT We have studied the effect of LHRH and neuropeptide Y (NPY) on prolactin (PRL) mRNA levels in pituitary reaggregate cell cultures from 14-day-old female rats, by means of in situ hybridization and Northern blot analysis. As estimated by computer-image analysis, addition of LHRH on day 5 in culture for 40 h resulted in a 37% increase in the total cytoplasmic areas of cells containing PRL mRNA, visualized using a digoxigenin-labelled PRL cRNA. The size of individual PRL-expressing cells was not influenced, nor was the content of PRL mRNA per cell. A similar effect of LHRH was found by dot blot hybridization of extracted RNA. PRL mRNA levels were not affected by NPY. LHRH induced a 29% increase in the number of PRL mRNA-expressing cells processing through the S phase of the cell cycle, visualized by the incorporation of [3H]thymidine ([3H]T) into DNA over 16 h. The fraction of [3H]T-labelled cells was 10–12% of the total cell population. NPY did not influence the number of [3H]T-positive cells expressing PRL mRNA, but completely blocked the effect of LHRH on the latter population. The present data suggest that LHRH, probably via a paracrine action of gonadotrophs, stimulates the recruitment of new lactotrophs, an action which is negatively modulated by NPY. Since the magnitude of this effect was the same in the total pituitary cell population as in cells processing through the S phase of the cell cycle and presumably mitosis, recruitment of lactotrophs seems to be based on differentiation of progenitor or immature cells into PRL-expressing cells, rather than on a mitogenic action on pre-existing lactotrophs alone.

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