X-Ray Inhibition of DNA Synthesis at Discrete Times during S Phase in Synchronous Human Diploid Fibroblasts

1982 ◽  
Vol 89 (2) ◽  
pp. 424 ◽  
Author(s):  
L. N. Kapp ◽  
R. B. Painter
Keyword(s):  
Dna Synthesis ◽  
S Phase ◽  
X Ray ◽  
Diploid Fibroblasts ◽  
Human Diploid Fibroblasts ◽  
Inhibition Of Dna Synthesis

scholarly journals Cell population heterogeneity in the inducibility of DNA synthesis in human diploid fibroblasts.

1981 ◽  
Vol 89 (2) ◽  
pp. 194-197 ◽  
Author(s):  
M V Rao
Keyword(s):  
Dna Synthesis ◽  
Cytochalasin B ◽  
Nuclear Dna ◽  
S Phase ◽  
Population Heterogeneity ◽  
Diploid Fibroblasts ◽  
Binucleate Cells ◽  
Human Diploid Fibroblasts ◽  
Significant Difference ◽  
Sister Cells

The initiation of nuclear DNA synthesis has been studied in cytochalasin B (CB)-induced binucleate human diploid fibroblasts (WI-38 cells). Mitotic cells from different passage levels were rendered binucleate by a brief pulse of CB. The cells were then washed free of the drug, and DNA synthesis was studied by [3H]thymidine labeling. The results showed that, in a small percentage of binucleate cells, one nucleus was labeled (S phase) and the other nucleus was unlabeled (G1 phase). There was no significant difference in the percentage of these cells with increasing passage levels. The results of this study suggest that some WI-38 cells retire from the cell cycle at different passage levels, and thereby become refractory to inducers of nuclear DNA synthesis generated by sister cells in S phase.

scholarly journals INHIBITION OF CELL GROWTH IN THE G1 PHASE BY ADENOSINE 3',5'-CYCLIC MONOPHOSPHATE

1974 ◽  
Vol 60 (1) ◽  
pp. 249-257 ◽  
Author(s):  
Jeffrey E. Froehlich ◽  
Martin Rachmeler
Keyword(s):  
Cell Growth ◽  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
S Phase ◽  
Fresh Medium ◽  
G1 Phase ◽  
Cyclic Monophosphate ◽  
Diploid Fibroblasts ◽  
Human Diploid Fibroblasts

Incorporation of tritiated thymidine into acid-precipitable material was used to measure the rate of DNA synthesis in secondary cultures of human diploid fibroblasts. Confluent cultures of human diploid fibroblasts, which are synchronized in the G1 phase due to contact inhibition, were released from growth inhibition either by the addition of fresh medium to the cultures or by trypsinization and replating at nonconfluent densities. Either treatment resulted in a synchronous wave of DNA synthesis beginning 10–15 h after treatment and peaking at 20–25 h. In confluent cultures stimulated by fresh medium, either the addition of 0.25 mM N6, O2-dibutyryl-adenosine 3',5'-cyclic monophosphate (db-cAMP) to the medium in the interval 4–8 h after stimulation or the replacement of the fresh medium in that same 4 h interval with the depleted medium present on the cells for the 2 day period before stimulation delayed the synchronous onset of DNA synthesis in the cultures by about 4 h. In nonconfluent cultures freshly seeded from trypsinized confluent cultures, this same depleted medium obtained after a 2 day incubation of fresh medium on confluent cultures is shown to support the progress of the cells into S phase; however, the addition of 0.25 mM db-cAMP to the medium 3½ h after replating still partially prevented the initiation of DNA synthesis in the cultures. The results are discussed in terms of the role of serum and cAMP in the control of cell growth in fibroblast cultures.

scholarly journals The timing of the formation and usage of replicase clusters in S-phase nuclei of human diploid fibroblasts

1991 ◽  
Vol 100 (4) ◽  
pp. 869-876 ◽  
Author(s):  
I.R. Kill ◽  
J.M. Bridger ◽  
K.H. Campbell ◽  
G. Maldonado-Codina ◽  
C.J. Hutchison
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Indirect Immunofluorescence ◽  
Laser Scanning ◽  
S Phase ◽  
Nuclear Antigen ◽  
In Vitro Techniques ◽  
Diploid Fibroblasts ◽  
Human Diploid Fibroblasts

The sites of nascent DNA synthesis were compared with the distribution of the proliferating cell nuclear antigen (PCNA) in S-phase nuclei of human diploid fibroblasts (HDF) by two in vitro techniques. Firstly, proliferating fibroblasts growing in culture that had been synchronised at S-phase were microinjected with the thymidine analogue biotin-11-dUTP. The sites of incorporation of biotin into injected cells were compared with the distribution of PCNA by indirect immunofluorescence microscopy and laser scanning confocal microscopy (LSCM). In common with other studies, a progression of patterns for both biotin incorporation and PCNA localisation was observed. However, we did not always observe coincidence in these patterns, the pattern of biotin incorporation often resembling the expected, preceding distribution of PCNA. In nuclei in which the pattern of biotin incorporation appeared to be identical to the distribution of PCNA, LSCM revealed that not all of the sites of PCNA immunofluorescence were incorporating biotin at the same time. Secondly, nuclei which had been isolated from quiescent cultures of HDF were innoculated into cell-free extracts of Xenopus eggs which support DNA replication in vitro. Following innoculation into these extracts DNA replication was initiated in each nucleus. The sites of DNA synthesis were detected by biotin-11-dUTP incorporation and compared with the distribution of PCNA by indirect immunofluorescence. Only a single pattern of biotin incorporation and PCNA distribution was observed. PCNA accumulated at multiple discrete spots some 15 min before any biotin incorporation was observed. When biotin incorporation did occur, LSCM revealed almost complete coincidence between the sites of DNA synthesis and the sites at which PCNA was localised.

Interferon inhibition of DNA synthesis and cell division

1972 ◽  
Vol 18 (2) ◽  
pp. 145-151 ◽  
Author(s):  
M. V. O'Shaughnessy ◽  
S. H. S. Lee ◽  
K. R. Rozee
Keyword(s):  
Cell Division ◽  
Antiviral Activity ◽  
Dna Synthesis ◽  
S Phase ◽  
Cell Suspensions ◽  
Depression Effect ◽  
Growth Depression ◽  
Synchronized Cells ◽  
Inhibition Of Dna Synthesis ◽  
New Protein

Using monodispersed cell suspensions, interferon preparations were shown to have both a lethal and a growth-depression effect in the same concentration range as that required for antiviral activity. In addition, synchronized cells treated with interferon respond by delaying their normal uptake of thymidine during S phase until after a period during which new protein is synthesized. Puromycin added during this period prevents both the synthesis of this protein and the subsequent synthesis of DNA.

Complement-dependent induction of DNA synthesis and proliferation of human diploid fibroblasts

1980 ◽  
Vol 105 (3) ◽  
pp. 503-512 ◽  
Author(s):  
Terry I. Korotzer ◽  
James A. Clagett ◽  
William P. Kolb ◽  
Roy C. Page
Keyword(s):  
Dna Synthesis ◽  
Diploid Fibroblasts ◽  
Human Diploid Fibroblasts
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