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Chromosomal aberrations induction of o-phenylen-diamine in mouse bone marrow cells and in human lymphocytes
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Caffeine post-treatment causes a shift in the chromosome aberration types induced by mitomycin C, suggesting a caffeine-sensitive mechanism of DNA repair in G2
No full textHuman lymphocytes were exposed in G1 to mitomycin C (2.5 microM for 2 h) and harvested at 3-h intervals from 48 to 84 h after stimulation. All cultures were also post-treated in G2 with caffeine (2 mM). Different types of chromosomal aberrations were scored in the first division metaphases. Caffeine increases all chromosome aberration types by promoting a premature mitosis of damaged cells. However, when the frequency of damaged cells is not affected by the caffeine post-treatment, a reduction of the frequency of the exchange-type aberrations was shown. The possibility that caffeine interferes with some mechanism of G2 repair is discussed
Kinetics of chromosomal aberrations and first mitosis division in human lymphocytes exposed to mitomycin C
No full textIn order to understand the relationship between the chromosomal damage detectable at the first mitosis after mutagen treatment and the induced mitotic delay we studied the time pattern of both mitotic indices and chromosomal aberration frequencies in human lymphocytes treated in G1 with mitomycin C (2.5 microM) and cultured in vitro in the presence of 5-bromo-2'-deoxyuridine. Mitotic delay was observed in treated cells cultured for 81 h. At this point an increase in the frequency of chromosomal aberrations is evident and a higher proportion of abnormal cells enters mitosis, the long delay being due to the extensiveness of DNA damage. The importance of cell cycle progression for the detection of the maximal amount of induced chromosomal damage is discussed
Mutations induced by X-rays and UV radiation during the nuclear cell cycle in the yeast Schizosaccharomyces pombe
No full textThe availability of a cell-division-cycle (cdc) mutant in the fission yeast S. pombe, wee 1-50, has made possible the production of a large population of G1 nuclear-stage synchronized cells. During their development, yeast cells from the G1 into the G2 nuclear stages were treated with X-rays and UV radiation at various doses. The DNA pre-replicative and replicative phases were the most sensitive to both cell lethality and mutant induction with either X-rays or UV radiation. The trends of induced biological effects that were obseved suggest that the induction of mutations is dependent on the number of unrepaired DNA lesions that reach the replicating fork or of those that occur at that time. The X-ray-induced mutations were earlier saturated, possibly because of the higher number of lethal lesions so induced
STUDY METHODS FOR IDENTIFICATION OF MUTAGENIC SUBSTANCE .4. INVIVO CHROMOSOME-ABERRATIONS IN BONE-MARROW CELLS OF MICE
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STUDY METHODS FOR IDENTIFICATION OF MUTAGENIC SUBSTANCE .1. SALMONELLA-TYPHIMURIUM AS GENETIC SYSTEM FOR MOLECULAR CHARACTERIZATION OF MUTATION RESULTS
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