RELEVANCE OF DSB REPAIR FOR SPLIT DOSE RECOVERY IN EUKARYOTIC CELLS
It is shown that the molecular damage involved in split dose recovery is the radiation induced DNA double- strand break (dsb). It is also shown that two requirements must be met to yield the reappearance of a shoulder in a split dose experiment: 1. Repair during the split dose interval of dsb induced by the first radiation dose. 2. Repair on the nutrient agar plate of dsb which are left in cells after the second irradiation. Repair of dsb during the split dose interval led to the reappearance of a shoulder provided that cells were plated after the second irradiation under conditions allowing further repair of dsb on the nutrient agar; however, an exponential survival curve after the second irradiation was observed when cells were plated under conditions preventing the dsb repair on the nutrient agar. In contrast, when repair of dsb was not allowed during the split dose interval the shoulder did not reappear after second irradiation although cells were allowed the repair dsb on the nutrient agar plate. These results were obtained with the help of a temperature sensitive yeast mutant (rad 54-3/rad 54-3), proficient in the repair of dsb at 23 degrees C, deficient at 36 degrees C. It has been shown in yeast that a dsb represents a potentially lethal lesion (PLL) and that the shoulder of a single dose survival curve is caused by repair of PLL (dsb) in the nutrient agar plate. In the light of these results it is proposed that split dose recovery is based on the repair of PLL (dsb) during the split dose interval and on the nutrient agar plate after the second irradiation.
Bibliographic Reference: 7TH INTERNATIONAL CONFERENCE OF RADIATION RESEARCH, AMSTERDAM (THE NETHERLANDS), JULY 3-8, 1983 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 31194 ORA
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Record Number: 1989122070800 / Last updated on: 1987-01-01
Available languages: en