Lifetime persistence and clonality of chromosome aberrations in the peripheral blood of mice acutely exposed to ionizing radiation.
Spruill MD; Nelson DO; Ramsey MJ; Nath J; Tucker JD
Radiat Res 2000 Jan; 153(1):110-121
As the measurement of chromosomal translocations increases in popularity for quantifying prior radiation exposure, information on the possible decline of these "stable" aberrations over time is urgently needed. We report here information about the persistence of radiation-induced chromosome aberrations in vivo over the life span of a rodent. Female C57BL/6 mice were given a single whole-body acute exposure of 0, 1, 2, 3 or 4 Gy Cs-137 gamma rays at 8 weeks of age. Chromosome aberrations were analyzed from peripheral blood samples at various intervals between 1 day and 21 months after exposure. Aberrations were detected by painting chromosomes 2 and 8, Translocations decreased dramatically during the first 3 months after irradiation, beyond which time the frequencies remained relatively constant out to 1 year, when the effects of aging and clonal expansion became significant. Both reciprocal and nonreciprocal translocations increased with age in the unexposed control animals and were involved in clones. As expected of unstable aberrations, dicentrics decreased rapidly after exposure and reached baseline levels within 3 months. These results indicate that the persistence of translocations induced by ionizing radiation is complicated by aging and clonal expansion and that these factors must be considered when quantifying translocations at long times after exposure. These results have implications for biological dosimetry in human populations.
Radiation; Radiation-effects; Radiation-measurement; Radiation-exposure; Rodents; Age-factors; Sex-factors; Chromosome-disorders; Blood-analysis; Blood-samples; Blood-tests; Biological-effects; Biological-factors; Biological-transport; Dosimetry; Genotoxic-effects; Genetics
James D. Tucker, Biology and Biotechnology Research Program, L-452, P.O. Box 808, Lawrence Livermore National Laboratory, Livermore, California 94551