Evidence for DNA double-strand breaks as the critical lesions in yeast cells irradiated with sparsely or densely ionizing radiation under oxic or anoxic conditions.
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Cell Survival↗
Biomedical subjects
D Blöcher
Publications and source records attributed to D Blöcher.
The linear relationship between DNA double-strand breaks and radiation dose (30 MeV electrons) is converted into a quadratic function by cellular repair.
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DNA↗
Measurement of the kinetics of DNA double strand break repair in Ehrlich ascites tumour cells using the unwinding method.
Two main components of DNA strand break repair have been found using the unwinding method. The first has a time constant (t37) of some minutes and the second, much slower component, a time constant of several hours. The time constant for the slower component of repair was found to vary with the conditions of incubation and to depend on the quality of the radiation. The t37 values obtained for slow repair under various conditions after X-irradiation and after alpha-irradiation were found to be close to those for repair of double strand breaks as measured by velocity sedimentation. Values for initial breaks, obtained by extrapolation of slow repair data back to time zero, were also close to those obtained for double strand breaks. We therefore propose that the unwinding method can be a useful technique for monitoring the repair of double strand breaks.
Alpha Particles↗
Repair of DNA double-strand breaks in irradiated yeast cells under nongrowth conditions.
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Bacteriological Techniques↗
The influence of oxygen on the survival and yield of DNA double-strand breaks in irradiated yeast cells.
Survival and induction of DNA double-strand breaks were studied in cells of Saccharomyces cerevisiae irradiated under oxic or anoxic conditions with 30 MeV electrons. A linear relationship between DNA double-strand breakage and dose was found in both cases. The o.e.r.-value for colony forming ability was found to be 1.9 +/- 0.2, whereas the o.e.r.-value for DNA double-strand breakage was 3.0 +/- 0.1. These results are not inconsistent with the idea that DNA double-strand breaks are involved in killing of yeast cells. The frequency of induction of DNA double-strand breaks was found to be 0.74 x 10(-11) double-strand breaks per g/mol per Gy when cells were irradiated under oxygen and 0.24 x 10(-11) double-strand breaks per g/mol per Gy under nitrogen.
Cell Survival↗