Synchronisme des divisions induit dans des cellules HeLa par un excès de thymidine

Firket, H; Mahieu, P.

doi:10.1016/0014-4827(67)90107-3

Cited by 20 publications

(10 citation statements)

References 18 publications

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“…A constant duration of G2 in murine mast cells after treatment with amethopterin for different time periods has previously been reported by Schindler et al (1968). A shortening of S+G2 after synchronizing HeLa cells with excess thymidine has previously been reported by Firket and Mahieu (1966). The shortening of S is compatible with the findings of Darzynkiewicz et al (1979), who reported that the duration of S correlated with the RNA content of the cells, assuming that the RNA content of the thymidinetreated cells also was abnormally large.…”

Section: R@kning Andseglen Discussionsupporting

confidence: 88%

The relation between protein accumulation and cell cycle traverse of human NHIK 3025 cells in unbalanced growth

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1982

Journal Cellular Physiology

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Human NHIK 3025 cells, synchronized by mitotic selection, were given 2 mM thymidine, which inhibited DNA synthesis without reducing the rate of protein accumulation. After removal of the thymidine the cells proceeded towards mitosis and cell division, with an S duration 2 hours shorter than, but a G2 and M duration nearly identical to that of the control cells. If cycloheximide (1.25 muM) was present together with thymidine, no net protein accumulation took place during the treatment, and the subsequent duration of S, G2, and M was similar to that of untreated cells. The shortening of S seen after treatment with thymidine alone would therefore indicate that the rate of DNA synthesis depended on the amount of some preaccumulated protein. The postreplicative period in thymidine-treated cells was lengthened by cycloheximide treatment although the protein content had already been doubled. This suggests that proteins required for the traverse of this part of the cell cycle might have to be synthesized after completion of DNA replication. Shortly after removal of thymidine, the rate of protein accumulation declined markedly, indicating the existence of some mechanism for negative control of cell mass. In addition, the daughters of thymidine-treated cells had their cell cycle shortened by 2 hours. As a result, the cells had returned to balanced growth already in the first cell cycle following the induction of unbalanced growth. In conclusion, our experiments suggest that NHIK 3025 cells might require a minimum time in order to traverse the cell cycle, which is independent of cell mass.

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Section: R@kning Andseglen Discussionsupporting

confidence: 88%

The relation between protein accumulation and cell cycle traverse of human NHIK 3025 cells in unbalanced growth

Rønning

Seglen

1982

Journal Cellular Physiology

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“…We have chosen to use the values for the parameters obtained from Quastler-Sherman curves of per cent labelled mitoses in freely growing cultures to simulate a population synchronized by an excess of thymidine. HeLa cell populations submitted to this treatment had proved in our hands to give remarkably reproducible results (Firket & Mahieu, 1966).…”

Section: Introductionmentioning

confidence: 93%

A Simple Computer Simulation Model for Growing Cell Populations: Analysis of Synchronized Hela Cell Cultures

1969

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A simple simulation model is presented for growing cell populations. It consists of various ‘classes’of cells (usually thirty) with different cell cycle durations. The cells of each class are distributed in ‘compartments’(thirty to fifty) with different ages. A ‘typical cell’of each compartment is chosen at random and its behaviour weighed according to the number of cells of the compartment. When the parameters for cycle phase durations (G2, S, G1 and M) obtained from Quastler‐Sherman curves on HeLa cell cultures are fed into the model and the initial distribution of cells is randomized according to the law of exponential growth, the model behaves as an exponentially growing culture with near stable values for the percentage of cells in the various phases of the cell cycle. The level of noise due to random sampling is not objectionable. The behaviour of the model is compared to that of HeLa cultures synchronized by two successive treatments with 2 mM thymidine. While a complete block of S gives very inadequate results, a slowing down of this phase to 25 or 30% of its original speed is enough to simulate all the modifications produced by the thymidine treatment on the cultures. It is not necessary to postulate any other effect. These biological conclusions are reached in spite of the simplicity of the system. The behaviour of the model stresses the fact that for simulating the actual behaviour of cell populations, some parameters of the cell cycle have to be known with considerable accuracy, others are less critical. The model is compared with other mathematical models of cell populations recently proposed and ways to improve it are discussed.

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“…Metaphase chromosomes were prepared from HeLa-65 cells growing in suspension culture. As cells in the exponential growth phase reached a density of 2 X lo5 cells/ml, they were synchronized by a double thymidine block [35]. Synchronized cultures were arrested at metaphase, with an efficiency of 95-98%, by addition of colcemid, 0.03 pg/ml, for 15 h.…”

Section: Donor Cell Synchronization and Chromosome Isolationmentioning

confidence: 99%

Alteration of human breast tumor cell membrane functions by chromosome‐mediated gene transfer

Muneer

Gray

1979

J Supramol Struct

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BOT-2 cells (human breast tumor origin) have an impaired ability to utilize exogenous thymidine. Previous studies revealed this deficiency to be the permeation event rather than phosphorylation, since the cells have active thymidine kinase. Chromosome-mediated gene transfer was used to transfer genetic information in the form of metaphase chromosomes, from HeLa-65 cells to the BOT-2 cells, correcting the permease deficiency. Poly-L-ornithine or lipochromes were used for facilitation of chromosome uptake. After selection on HAT medium, transferant clones were isolated at a frequency of 4 x 10(-5) and 1 x 10(-5), respectively. Transferants MGP-1 and MGL-1 are stable after 18 months and have been characterized on the bases of purine and pyrimidine nucleoside uptake, relative thymidine kinase activities, alkaline phosphatase activities, and hydrocortisone-induced alkaline phosphatase activity. MGP-1 demonstrates positive thymidine uptake and incorporates radiolabeled thymidine into DNA. MGL-1 remains thymidine transport-deficient and surveys on HAT by increasing endogenous dihydrofolate reductase activity. Alkaline phosphatase activity in MGL-1 is similar to HeLa-65, 2% of that in BOT-2, and in addition, is inducible 25-30-fold by 3 micro M hydrocortisone. We have separated, genetically, a thymidine permease function from phosphorylation in cells of human origin and have transferred genetic information for the regulation of alkaline phosphatase.

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Synchronisme des divisions induit dans des cellules HeLa par un excès de thymidine

Cited by 20 publications

References 18 publications

The relation between protein accumulation and cell cycle traverse of human NHIK 3025 cells in unbalanced growth

The relation between protein accumulation and cell cycle traverse of human NHIK 3025 cells in unbalanced growth

A Simple Computer Simulation Model for Growing Cell Populations: Analysis of Synchronized Hela Cell Cultures

Alteration of human breast tumor cell membrane functions by chromosome‐mediated gene transfer

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