DNA Scission in Hamster Cells and Isolated Nuclei Studied by Low-Voltage Electron Beam Irradiation

• Published in: Radiation research 1974-10, Vol.60 (1), p.1-33
• Main Authors: Cole, Arthur, Cooper, W. Grant, Shonka, Francis, Corry, Peter M., Humphrey, R. M., Ansevin, A. T.
• Format: Article
• Language: English
• Subjects: Animals; Cell nucleus; Cell Nucleus - radiation effects; Centrifugation, Density Gradient; CHO cells; CHO Cells - radiation effects; Cricetinae; Cricetulus; DNA; DNA - radiation effects; DNA Damage; DNA, Single-Stranded - radiation effects; Dose-Response Relationship, Radiation; Electron beams; Electrons; Electrons - adverse effects; Energy; Gamma Rays - adverse effects; Hydrogen-Ion Concentration; Irradiation; Molecules; Nuclear membrane; Radiation dosage; Radiation Tolerance; Relative Biological Effectiveness
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3574002

Low-voltage (0.5-50 keV) electron beam irradiation of hydrated monolayers of Chinese hamster ovary (CHO) cells and isolated CHO nuclei induced single and double strand DNA scission. Gradient sedimentation techniques were used to assay DNA breakage in control populations having a $2\cdot 10^{8}$ number average molecular weight for native DNA and a $2\cdot 10^{7}$ number average for denatured DNA. Beam sensitivity responses, expressed as average cell rads/break, exhibited pronounced minima for beams that penetrated less than one third of the cell thickness and less than 1/20 of the nuclear thickness (i.e., top layer irradiation only). Almost half the total DNA population was degraded by these lower energy beams. A comparison of the breakage efficiency with that for Cs-137 γ-rays yielded estimates of the relative biological effectiveness (RBE) for low energy electrons (