REDUCED INCIDENCE OF PERSISTENT CHROMOSOME ABERRATIONS IN MICE IRRADIATED AT LOW DOSE-RATE
NORTHWESTERN UNIV EVANSTON IL TECHNOLOGICAL INST
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A marked difference in the production of persistent chromosome aberrations in mouse marrow cells by ionizing radiation delivered at a high dose rate 30 radmin versus a low dose rate 1.45 radhour was observed. Clones of cell with chromosome abnormalities were present in the marrow of all the mice previously exposed to the X rays, either a single dose or fractionated, at 30 radmin. The frequency of chromosome aberrations in these mice varied from 14 to 72 of the cells examined. By contrast, none of the 17 mice exposed to the continuous low dose rate gamma radiation 1.45 radhour showed definite clones of abnormal marrow cells, and the frequency of persistent chromosome aberrations varied from zero to 8 in this group. The possible basis for this marked reduction in the production of persistent chromosome changes in marrow cells following exposure to low dose-rate gamma radiation is briefly discussed. If some of the late effects of radiation, particularly leukemia incidence, are related to the frequency of chromosome aberrations, it is possible that low dose-rate gamma radiation may be less leukemogenic than high dose-rate radiation.
- Genetic Engineering and Molecular Biology