Inhibition of DNA synthesis in synchronized Chinese hamster cells treated in G1 or early S phase with cycloheximide or puromycin

1972 ◽  
Vol 75 (2) ◽  
pp. 314-320 ◽  
Author(s):  
D.P. Highfield ◽  
W.C. Dewey
Keyword(s):  
Dna Synthesis ◽  
Chinese Hamster ◽  
S Phase ◽  
Chinese Hamster Cells ◽  
Inhibition Of Dna Synthesis

scholarly journals CELL KILLING BY ACTINOMYCIN D IN RELATION TO THE GROWTH CYCLE OF CHINESE HAMSTER CELLS

1969 ◽  
Vol 42 (2) ◽  
pp. 366-376 ◽  
Author(s):  
M. M. Elkind ◽  
E. Kano ◽  
H. Sutton-Gilbert
Keyword(s):  
Dna Synthesis ◽  
Functional Capacity ◽  
Response Pattern ◽  
Actinomycin D ◽  
Chinese Hamster ◽  
Growth Cycle ◽  
S Phase ◽  
Chinese Hamster Cells ◽  
X Irradiation ◽  
A Cell

Using Chinese hamster cells in culture, we have measured the effectiveness of actinomycin D to suppress division as a function of the position, or age, of a cell in its growth cycle. Cells were first exposed to millimolar concentrations of hydroxyurea in order to produce a synchronized population just before the onset of DNA synthesis. Thereafter, the survival response after 30 min exposures to actinomycin D was measured. Cells become resistant as they enter the S phase and then sensitive again in the latter part of S. When they reach G2 (or G2-mitosis) they are maximally resistant; at 1.0 µg/ml, for example, the survival in G2 is 30-fold greater than it is in G1. These results, plus measurements reported earlier on the interaction of damage in S cells due to actinomycin D and X-irradiation, suggest that the age-response pattern of the toxic effects of this drug probably reflects both the functional capacity of DNA-actinomycin complexes and the ability of this antibiotic to penetrate chromatin and bind to DNA.

scholarly journals Detection of G1 proteins in Chinese hamster cells synchronized by isoleucine deprivation or mitotic selection.

1975 ◽  
Vol 66 (1) ◽  
pp. 95-101 ◽  
Author(s):  
K D Ley
Keyword(s):  
Time Course ◽  
Sodium Dodecyl ◽  
Chinese Hamster ◽  
Protein S ◽  
S Phase ◽  
Supernatant Fraction ◽  
G1 Phase ◽  
Differential Centrifugation ◽  
Chinese Hamster Cells ◽  
Soluble Supernatant

Examination of labeling patterns of proteins in Chinese hamster cells(line CHO) revealed the presence of a class of protein(s) that is synthesized during G1 phase of the cell cycle. Cells arrested in G1 by isoleucine (Ile) deprivation were prelabeded with [14-C]Ile, induced to traverse G1 by addition of unlabeled Ile, and labeled with [3-H]Ile at hourly intervals. Cells were fractionated into neclear and cytoplasmic portions, and proteins were separated by sodium dodecyl sulfate-polyacrylamide get electrophoresis. Gel profiles of proteins in the 45,000-160,000 mol wt range from the cytoplasm of cells in G1 were similar to those from cells arrested in G1 except for the presence of a mojor peak of [1-H]Ile incorporated into a protein(s) of approximately 80,000 mol wt. Peaks of net [3-H]Ile incorporation were not detected in neclear preparations. Cellular fractionation by differential centrifugation showed the peak I protein was located in the soluble supernatant fraction of the cytoplasm. Time-course studies showed that synthesis of this protein began 1-2 h after initiation of G1 traverse; the protein reached maximum levels in 4-6 h and was reduced to undetectable levels by 9 h. A cytoplasmic protein with similar electrophoretic mobility was found in G1 phase of cells synchronized by mitotic selection. This class of proteins is synthesized by cells before entry into S phase and may be involved in initiation of DNA synthesis.

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