T. Andoh, T. Ide
Jun 1, 1972
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Influential Citations
36
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Quality indicators
Journal
Cancer research
Abstract
The effect of the carcinogen, 4-nitroquinoline 1-oxide, on cultured mouse fibroblasts, strain L-P3, a substrain of L-929, was studied. Cells were cultured in a protein- and lipid-free synthetic medium, DM-120. Strand breakage and repair of DNA caused by 4-nitroquinoline 1-oxide was examined. 4-Nitroquinoline 1-oxide caused single- and double-strand breaks of DNA as shown by alkaline and neutral sucrose gradient centrifugation, respectively. Breakage increased with increase in the concentration of carcinogen. At a concentration of 1 × 10-5 m 4-nitroquinoline 1-oxide, the DNA in the cells consisted of a heterogeneous population of single-stranded molecules with 40 to 120 S or an apparently homogeneous population of double-strand molecules with an s 20, w of approximately 130 S, presumably containing single-strand breaks. Both the single- and double-strand breaks of DNA were repaired on incubation of treated cells at 37° in medium without the carcinogen (“recovery incubation”). A 24-hr incubation period was required for complete repair of double-strand breaks while a 3-hr period was sufficient for complete repair of single-strand breaks. Concomitantly with repair of double-strand breaks, the treated cells regained the ability to grow at the same rate as untreated cells.