Chromosomal aberrations in an ionizing radiation-sensitive mouse lymphoma mutant cells exposed to gamma-rays and 4-nitroquinoline-1-oxide.

Abstract

An X-ray-sensitive mutant LX830, isolated from mouse lymphoma L5178Y cells, was examined for chromosomal aberrations induced by γ-rays and 4-nitroquionoline-l-oxide (4NQO), as compared with a methyl methanesulphonate (MMS) and X-ray-sensitive mutant M10 and their parental L5178Y cells. Spontaneous incidence of chromosomal aberrations in LX830 cells was 2.5 times higher than that in L5178Y cells, but lower than that in M10 cells. In the first mitosis of LX830 cells after 1.0 Gy γ-irradiation, the frequencies of chromosome- and chromatid-type aberrations were significantly higher than those in L5178Y cells. In addition, chromatid exchanges, particularly triradials, isochromatid breaks, and chromatid gaps and breaks were markedly enhanced at G1 phase of LX830 cells. These results are very similar to those in M10 cells. After 4NQO treatment (50 ng/ml), chromatid-type aberrations were induced more frequently at late fixation times. The maximal frequency of chromatid-type aberrations in LX830 cells was about 1.7 times higher than that in L5178Y cells, but LX830 cells were less susceptible to 4NQO than M10 cells. These results indicate that there exist some heterogeneity in the response to 4NQO among ionizing radiation-sensitive mouse cell mutants.