Age-dependence of the x-ray-induced deficiency in DNA synthesis in HeLa S3 cells during generation 1
The radiation-induced deficiency in DNA synthesis in Generation 1 was studied as a function of the age of HeLa S3 cells at the time of exposure to 220 kV x rays in the previous generation (Generation 0). The amount of DNA synthesized is dependent on the stage in the generation cycle at which cells are irradiated. The smallest deficiency (20 to 35 percent after a dose of 500 rad) is observed in cells irradiated in early G1 or early G2, while the greatest deficiency (55 to 70 percent after 500 rad) is found in cells irradiated at mitosis or at the G1/S transition. The high sensitivity of cells at G1/S is also manifested by a steeper dose-response curve. Cells irradiated in late G2, past the point where their progression is temporarily blocked by x rays, synthesize a normal amount of DNA in Generation 1, while cells that are held up in the G2 block exhibit deficient synthesis in the next generation. The extent of the deficiency in early G1 cells can be enhanced by treatment with 1 mM hydroxyurea for several hours immediately following irradiation. The possibility that deficient DNA synthesis is related to cell killing, and the relation between the G2 block and deficient synthesis, are discussed. (auth)
- Research Organization:
- Washington Univ. School of Medicine, St. Louis
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-33-007429
- OSTI ID:
- 4158196
- Journal Information:
- Radiat. Res., v. 63, no. 3, pp. 501-520, Journal Name: Radiat. Res., v. 63, no. 3, pp. 501-520; ISSN RAREA
- Country of Publication:
- United States
- Language:
- English
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AGE DEPENDENCE
DOSE-RESPONSE RELATIONSHIPS
IRRADIATION
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X RADIATION