CHROMOSOME-ABERRATIONS IN BONE-MARROW GELS OF C3H HE MICE AT AN EARLY-STAGE AFTER WHOLE-BODY IRRADIATION/

Murine acute myeloid leukemia is characterized by chromosome 2 aberrat ions, and genesis of the marker chromosome 2 by radiation is suspected to be an initiating event of radiation leukemogenesis. A detailed ana lysis of the type and frequency of chromosome 2 aberrations in murine bone marrow cells at an early stage after irradiation is provided here . A total of 40 male C3H/He mice was exposed to Cs-137 gamma-ray at a dose of 1, 2 or 3 Gy, and sacrificed 24 hours after irradiation. Metap hase samples prepared from bone marrow cells were Q-banded for karyoty ping or painted with DNA probes specific to chromosome 2. In 5 mice an alyzed by karyotyping, one mouse showed high frequency of the marker a berrations as well as other chromosome 2 aberrations. Chromosome paint ing analysis for the rest of the mice also detected 3 animals showing significantly high frequencies of chromosome 2 aberrations. Dose-depen dence of the frequencies was observed even among those mice that tende d to be sensitive. The results indicated that there was a subgroup of mice carrying hypersensitive chromosome 2. The subgroup could be leuke mia-sensitive if radiation-induced chromosome aberrations are responsi ble for an early change in myeloid leukemogenesis.