The cell cycle during the vegetative stage of Dictyostelium discoideum and its response to temperature change

1978 ◽  
Vol 32 (1) ◽  
pp. 1-20
Author(s):  
I.M. Zada-Hames ◽  
J.M. Ashworth
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Doubling Time ◽  
Nuclear Dna ◽  
Cell Number ◽  
Cell Cycle Time ◽  
Optimum Growth Temperature ◽  
Cell Cycle Phases ◽  
Response To Temperature

The cell cycle in amoebae of Dictyostelium discoideum has been analysed in cells growing asynchronously in axenic medium. For cells growing at the optimum growth temperature of 22 degrees C with a culture doubling time of 8 h the average times for the cell cycle phases are as follows: G1, 1.5 h; S, 2.1 h; G2, 4.4 h; M, 15.2 min. When amoebae are grown at temperatures below 22 degrees C, culture doubling time increases and the cell cycle phases are altered in ways characteristic for each phase. G2 is the most variable period and may occupy up to 70% of the total cell cycle time; S and G1 are the least affected, increasing by only 20% when the cell generation time is doubled. When cells which have reached the stationary phase of growth in liquid medium are washed and reinoculated into fresh medium they divide synchronously after a lag period of 5 h. By following cell number increase and nuclear DNA synthesis in these cultures we have shown that stationary phase cells are arrested in the G2 phase of the cell cycle. Finally, although more than 97% of amoebae grown on a bacterial food source are uninucleate, when grown axenically up to 35% of the cell population may become multinucleate. Our results suggest that these cells probably arise through the failure of cytokinesis to follow karyokinesis. Multinucleate cells appear to have a slightly longer G2 period than mononucleate cells.

Stationary phase and the cell cycle of Dictyostelium discoideum in liquid nutrient medium

1976 ◽  
Vol 20 (3) ◽  
pp. 513-523 ◽  
Author(s):  
D.R. Soll ◽  
J. Yarger ◽  
M. Mirick
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Nutrient Medium ◽  
Nuclear Dna ◽  
Cell Concentration ◽  
Phase Cell ◽  
Cell Multiplication ◽  
Mean Cell Volume ◽  
Liquid Nutrient Medium

Cells of the axenic strain of the cellular slime mould Dictyostelium discoideum, AX-3, multiply in the liquid nutrient medium HL-5 with a doubling time of 12 h. When the cell concentration reaches approximately 1 X10(7) per ml the rate of cell multiplication begins decreasing and after 20–30 h reaches zero, at a stationary phase cell concentration of 2 to 2–5 X 10(7) cells per ml. The intercept of the extrapolated log phase and stationary phase plots has arbitrarily been considered the onset of the stationary phase. We have found that after cells have been in stationary phase for 24–32 h, mean cell volume increases by 25%, average dry weight by 37%, and average protein content by 24%. These values are close to the expected values for a cell population which is blocked at a point late in the cell cycle. Stationary phase cells also contain 25% more nuclear DNA than log phase cells, indicating that the population of cells at stationary phase is blocked after the DNA replication phase. Finally, when stationary phase cells are washed free of stationary phase medium and reinoculated into fresh medium, they reinitiate cell division synchronously. In the light of the demonstrated relationship between stationary phase and the cell cycle, a possible role for the growth inhibitor produced at stationary phase is considered.

Nuclear DNA content and minimum generation time in herbaceous plants

1972 ◽  
Vol 181 (1063) ◽  
pp. 109-135 ◽  
Keyword(s):  
Cell Cycle ◽  
Dna Content ◽  
Cycle Time ◽  
Generation Time ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Annual Species ◽  
Cell Cycle Time ◽  
Developmental Processes ◽  
The Mean

Many components of cell and nuclear size and mass are correlated with nuclear DNA content in plants, as also are the durations and rates of such developmental processes as mitosis and meiosis. It is suggested that the multiple effects of the mass of nuclear DNA which affect all cells and apply throughout the life of the plant can together determine the minimum generation time for each species. The durations of mitosis and of meiosis are both positively correlated with nuclear DNA content and, therefore, species with a short minimum generation time might be expected to have a shorter mean cell cycle time and mean meiotic duration, and a lower mean nuclear DNA content, than species with a long mean minimum generation time. In tests of this hypothesis, using data collated from the literature, it is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species. Furthermore, the mean nuclear DNA content of annual species is significantly lower than for perennial species both in dicotyledons and monocotyledons. Ephemeral species have a significantly lower mean nuclear DNA content than annual species. Among perennial monocotyledons the mean nuclear DNA content of species which can complete a life cycle within one year (facultative perennials) is significantly lower than the mean nuclear DNA content of those which cannot (obligate perennials). However, the mean nuclear DNA content of facultative perennials does not differ significantly from the mean for annual species. It is suggested that the effects of nuclear DNA content on the duration of developmental processes are most obvious during its determinant stages, and that the largest effects of nuclear DNA mass are expressed at times when development is slowest, for instance, during meiosis or at low temperature. It has been suggested that DNA influences development in two ways, directly through its informational content, and indirectly by the physical-mechanical effects of its mass. The term 'nucleotype' is used to describe those conditions of the nucleus which effect the phenotype independently of the informational content of the DNA. It is suggested that cell cycle time, meiotic duration, and minimum generation time are determined by the nucleotype. In addition, it may be that satellite DNA is significant in its nucleotypic effects on developmental processes.

Cell number in relation to primary pattern formation in the embryo of Xenopus laevis

Development ◽  
1979 ◽  
Vol 53 (1) ◽  
pp. 269-289
Author(s):  
Jonathan Cooke
Keyword(s):  
Cell Cycle ◽  
Pattern Formation ◽  
Cell Cycle Control ◽  
Cell Number ◽  
The Body ◽  
Morphological Evidence ◽  
Tail Bud ◽  
Cell Cycle Time ◽  
Mesodermal Cell ◽  
Body Pattern

Morphological evidence is presented that definitive mesoderm formation in Xenopus is best understood as extending to the end of the neurula phase of development. A process of recruitment of cells from the deep neurectoderm layers into mesodermal position and behaviour, strictly comparable with that already agreed to occur around the internal blastoporal ‘lip’ during gastrula stages, can be shown to continue at the posterior end of the presumptive body pattern up to stage 20 (earliest tail bud). Spatial patterns of incidence of mitosis are described for the fifteen hours of development between the late gastrula and stage 20–22. These are related to the onset of new cell behaviours and overt cyto-differentiations characterizing the dorsal axial pattern,which occur in cranio-caudal and then medio-lateral spatial sequence as development proceeds. A relatively abrupt cessation of mitosis, among hitherto asynchronously cycling cells,precedes the other changes at each level in the presumptive axial pattern. The widespread incidence of cells still in DNA synthesis, anterior to the last mitoses in the posterior-to-anteriordevelopmental sequence of axial tissue, strongly suggests that cells of notochord and somites in their prolonged, non-cycling phase are G2-arrested, and thus tetraploid. This is discussed in relation to what is known of cell-cycle control in other situations. Best estimates for cell-cycle time in the still-dividing, posterior mesoderm of the neurula lie between 10 and 15 h. The supposition of continuing recruitment from neurectoderm can resolve an apparent discrepancy whereby total mesodermal cell number nevertheless contrives to double over a period of approximately 12 h during neurulation when most of the cells are leaving the cycle. Because of pre-existing evidence that cells maintain their relative positions (despite distortion)during the movements that form the mesodermal mantle, the patterns presented in this paper can be understood in two ways: as a temporal sequence of developmental events undergone by individual, posteriorly recruited cells as they achieve their final positions in the body pattern, or alternatively as a succession of wavefronts with respect to changes of cellstate, passing obliquely across the presumptive body pattern in antero-posterior direction. These concepts are discussed briefly in relation to recent ideas about pattern formation in growing systems.

The cell cycle and its relationship to development in Acanthamoeba castellanii

1987 ◽  
Vol 88 (5) ◽  
pp. 579-590
Author(s):  
MICHAEL STÖHR ◽  
KURT BOMMERT ◽  
INGRID SCHULZE ◽  
HELGA JANTZEN
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Nuclear Dna ◽  
Acanthamoeba Castellanii ◽  
Nuclear Dna Content ◽  
Defined Medium ◽  
G2 Phase ◽  
D Cells ◽  
High Degree ◽  
The Relationship

The cell cycle and the relationship between particular cell cycle phases and the differentiation of trophozoites into cysts were reinvestigated in Acanthamoeba castellanii using flow fluorometric measurements of nuclear DNA content and synthesis and synchronization of cells by release from the stationary phase. The investigation was performed with cultures growing in non-defined medium (ND cells) showing a high degree of encystation in response to starvation and with subcultures growing in chemically defined nutrient medium (D cells) exhibiting a very low encystation competence. In both cultures the cell cycle starts with a short S phase taking place simultaneously with cytokinesis followed by a long G2 phase. A G1 phase seems to be either absent or very short. Synchronization experiments reveal that in ND cells encystation is initiated from a particular position of late G2. The high encystation competence of stationary phase ND cells seems to be due to arrest of cells at this particular cell cycle position. The lack of encystation competence of stationary phase D cells correlates with the loss of accumulation of cells at this particular stage of the cell cycle. This change of the property of cells is related to the growth condition and not to an irreversible loss of encystation competence of D cells.

scholarly journals Cell cycle phases in the unequal mother/daughter cell cycles of Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (11) ◽  
pp. 2529-2531 ◽  
Author(s):  
B J Brewer ◽  
E Chlebowicz-Sledziewska ◽  
W L Fangman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cycle Phase ◽  
Cell Cycle Time ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Cycles ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Cell Cycle Phases ◽  
Mother Cells

During cell division in the yeast Saccharomyces cerevisiae mother cells produce buds (daughter cells) which are smaller and have longer cell cycles. We performed experiments to compare the lengths of cell cycle phases in mothers and daughters. As anticipated from earlier indirect observations, the longer cell cycle time of daughter cells is accounted for by a longer G1 interval. The S-phase and the G2-phase are of the same duration in mother and daughter cells. An analysis of five isogenic strains shows that cell cycle phase lengths are independent of cell ploidy and mating type.

scholarly journals An automaton model for the cell cycle

2010 ◽  
Vol 1 (1) ◽  
pp. 36-47 ◽  
Author(s):  
Atilla Altinok ◽  
Didier Gonze ◽  
Francis Lévi ◽  
Albert Goldbeter
Keyword(s):  
Cell Cycle ◽  
Steady State ◽  
Deterministic Model ◽  
Initial Conditions ◽  
Cell Number ◽  
Time Step ◽  
M Phase ◽  
Random Manner ◽  
The Mean ◽  
Cell Cycle Phases

We consider an automaton model that progresses spontaneously through the four successive phases of the cell cycle: G1, S (DNA replication), G2 and M (mitosis). Each phase is characterized by a mean duration τ and a variability V . As soon as the prescribed duration of a given phase has passed, the transition to the next phase of the cell cycle occurs. The time at which the transition takes place varies in a random manner according to a distribution of durations of the cell cycle phases. Upon completion of the M phase, the cell divides into two cells, which immediately enter a new cycle in G1. The duration of each phase is reinitialized for the two newborn cells. At each time step in any phase of the cycle, the cell has a certain probability to be marked for exiting the cycle and dying at the nearest G1/S or G2/M transition. To allow for homeostasis, which corresponds to maintenance of the total cell number, we assume that cell death counterbalances cell replication at mitosis. In studying the dynamics of this automaton model, we examine the effect of factors such as the mean durations of the cell cycle phases and their variability, the type of distribution of the durations, the number of cells, the regulation of the cell population size and the independence of steady-state proportions of cells in each phase with respect to initial conditions. We apply the stochastic automaton model for the cell cycle to the progressive desynchronization of cell populations and to their entrainment by the circadian clock. A simple deterministic model leads to the same steady-state proportions of cells in the four phases of the cell cycle.

Expression of a cell surface antigen in Dictyostelium discoideum in relation to the cell cycle

1989 ◽  
Vol 93 (1) ◽  
pp. 199-204
Author(s):  
M. Krefft ◽  
C.J. Weijer
Keyword(s):  
Cell Cycle ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cell Number ◽  
S Phase ◽  
Volume Distribution ◽  
Quantitative Microscopy ◽  
Great Heterogeneity ◽  
A Cell ◽  
The Moment

We have previously shown binding of a monoclonal antibody MUD 9 to the cell surface of Dictyostelium discoideum amoebae and slug cells. In the slug stage the prestalk region was predominantly labelled, while vegetative amoebae showed a great heterogeneity in binding. In the present paper it is shown that the heterogeneous label of vegetative amoebae is due to differences in MUD 9 binding by cells in different cell cycle phases. Cells were synchronized by dilution from stationary phase and the level of MUD 9 binding was determined. Synchrony was determined by investigating increase in cell number and changes in the volume distribution of the cells, and by estimating the number of cells in S phase by monitoring bromodeoxyuridine (BUdR) incorporation. Simultaneously the amount of MUD 9 binding was determined by quantitative microscopy and flow cytometry. The amount of MUD 9 label varies during the cell cycle. The highest amount of label is found on cells early in the cell cycle, i.e. S-phase. These results support the finding that the developmental fate of Dictyostelium discoideum cells depends among other things on the cell cycle position of the cells at the moment of starvation.

Cycle cellulaire et teneurs en ADN nucléaire de cellules en suspension de l’Acer pseudoplatanus en phase exponentielle de croissance. Hétérogénéité de la culture

1974 ◽  
Vol 52 (7) ◽  
pp. 1535-1543 ◽  
Author(s):  
Jacques Rembur
Keyword(s):  
Cell Cycle ◽  
Doubling Time ◽  
Nuclear Dna ◽  
Cell Suspension Cultures ◽  
The Other ◽  
Acer Pseudoplatanus ◽  
Heterogeneous Cell Population ◽  
Constant Rate ◽  
Cell Groups ◽  
The Mean

The mean doubling time of Acer pseudoplatanus L. cell suspension cultures is 66 h during log-phase growth.A constant rate of proliferation and a stable mitotic index show this population to be asynchronous with little variation in the duration of the cell cycle.The results of both continuous and brief labelling show that only 84% of the cells divide. The cell cycle lasts 58 h with G1, S, G2, and M periods of 29, 21, 5.3, and 2.7 h respectively. G1 predominates while G2 is reduced.Microspectrophotometric analysis of nuclear DNA indicates a heterogeneous cell population made up of two proliferating groups, one diploid and the other tetraploid.The formation of tetraploids by endoreduplication and the possible evolution of both cell groups are discussed.

Plastochrone, cycle cellulaire et teneurs en ADN nucléaire du méristème caulinaire de plants de Chrysanthemum segetum soumis à deux conditions lumineuses différentes, sous une photopériode de 16 heures

1990 ◽  
Vol 68 (11) ◽  
pp. 2389-2397 ◽  
Author(s):  
Arlette Nougarède ◽  
Maria Nicola Di Michele ◽  
Pierre Rondet ◽  
Robert Saint-Côme
Keyword(s):  
Cell Cycle ◽  
Doubling Time ◽  
Nuclear Dna ◽  
Cycle Duration ◽  
Axial Zone ◽  
Lateral Zone ◽  
Cell Doubling Time ◽  
Photon Fluence ◽  
The Mean ◽  
Chrysanthemum Segetum

Chrysanthemum segetum plants were grown from seeds under a 16-h photoperiod, at two different photon fluence rates (70 or 200 μmol m−2 s−1. At 200 μmol m−2 s−1, by comparison with 70 μmol m−2 s−1, phyllotaxy was not modified, but the plastochron decreased and the apical diameter increased by extension of the axial zone. The mean cell doubling time decreased 36.2% in the lateral zone, 29% in the axial zone, and only 13% in the rib meristem. In contrast, mitosis duration was constant. Under both light conditions, nuclei with a DNA content within the limits of the 2C range were always predominant, which means that the G1 phase of the cell cycle was the longest. At 200 μmol m−2 s−1, the shortening of the mean cell doubling time is accompanied by a reduction of the percentage of nuclei with DNA levels within the limits of the 2C range. The decrease of the latter was the most important in the axial zone and the least important in the rib meristem, showing that control of cell proliferation was obtained by means of the G1 phase of the cell cycle. Key words: Chrysanthemum segetum, cell cycle, duration of mitosis, plastochron, nuclear DNA levels, zonation.

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