EUROPEAN ENVIRONMENTALMUTAGEN SOCIETY
283
6O OBE, G., B. BEEK AND G. DUDIN, Institut fiir Genetik, Freie Universititt Berlin, I Berlin 33, Amimallee 5-7 (Germany)
Some experiments on the action of lead acetate on human leukocytes in vitro In human two-day leukocyte cultures we found two maxima of DNA synthesis and two mitotic waves. These patterns were influenced b y a lead acetate treatment (Io -5 M) in a constant manner. Each of the two DNA synthesis peaks was split into two sub-peaks. Therefore, in the culture time interval from 24 up to 50 h, four instead of two DNA synthesis peaks were seen. Correlated with this we found four waves of mitoses. With the same concentration of lead acetate few dicentric chromosomes were induced in two-day leukocyte cultures without elevating the frequencies of chromatid aberrations. In three-day cultures treated with lead acetate we found some spiralization defects of chromosomes resembling premature chromosome condensations obtained after the induction of micronuclei.
61 SCHROEDER, T. M.,AND CHR. MAUGE
I nfluence of higher incubation temperature on spontaneous and induced chromosome instability The basic reason for our experiments was to test whether lymphocytes of heterozygotes for the Fanconi anaemia (FA) gene differ in reaction to higher incubation temperature from chromosomes of healthy control individuals. Results from these investigations do not show significant differences in numbers of aberrant cells or in types of chromosomal aberration. Control cultures, incubated at 4 o°, seem to grow even better than parallel cultures at 37°; they exhibit a higher mitotic rate. Since there was no effect of higher temperature on control lymphocyte cultures, we started testing the influence of a change in incubation temperature on the spon taneous chromosome instability in lymphocytes from a patient with untreated Fanconi anaemia. The only constant effect in a series of experiments was a decrease ill the numbers of chromatid interchanges. A possible interpretation of this result is that it m a y be a visible sign of an existing repair enzyme sensitive to temperature. In a second series of experiments, we tested the effect of 4 °0 incubation temperature on chromosomal breakage induced b y Tremmon and mltomycin C. Surprisingly few effects were noted as to numbers of aberrant cells, aberration index and types of aberration with either agent. More experiments are necessary to confirm the primary results. However, one important statement can be made: that incubation of normal lymphocytes treated or controlled at 4 °0 under the laboratory conditions did not greatly influence the amount of chromosomal damage.
283
6O OBE, G., B. BEEK AND G. DUDIN, Institut fiir Genetik, Freie Universititt Berlin, I Berlin 33, Amimallee 5-7 (Germany)
Some experiments on the action of lead acetate on human leukocytes in vitro In human two-day leukocyte cultures we found two maxima of DNA synthesis and two mitotic waves. These patterns were influenced b y a lead acetate treatment (Io -5 M) in a constant manner. Each of the two DNA synthesis peaks was split into two sub-peaks. Therefore, in the culture time interval from 24 up to 50 h, four instead of two DNA synthesis peaks were seen. Correlated with this we found four waves of mitoses. With the same concentration of lead acetate few dicentric chromosomes were induced in two-day leukocyte cultures without elevating the frequencies of chromatid aberrations. In three-day cultures treated with lead acetate we found some spiralization defects of chromosomes resembling premature chromosome condensations obtained after the induction of micronuclei.
61 SCHROEDER, T. M.,AND CHR. MAUGE
I nfluence of higher incubation temperature on spontaneous and induced chromosome instability The basic reason for our experiments was to test whether lymphocytes of heterozygotes for the Fanconi anaemia (FA) gene differ in reaction to higher incubation temperature from chromosomes of healthy control individuals. Results from these investigations do not show significant differences in numbers of aberrant cells or in types of chromosomal aberration. Control cultures, incubated at 4 o°, seem to grow even better than parallel cultures at 37°; they exhibit a higher mitotic rate. Since there was no effect of higher temperature on control lymphocyte cultures, we started testing the influence of a change in incubation temperature on the spon taneous chromosome instability in lymphocytes from a patient with untreated Fanconi anaemia. The only constant effect in a series of experiments was a decrease ill the numbers of chromatid interchanges. A possible interpretation of this result is that it m a y be a visible sign of an existing repair enzyme sensitive to temperature. In a second series of experiments, we tested the effect of 4 °0 incubation temperature on chromosomal breakage induced b y Tremmon and mltomycin C. Surprisingly few effects were noted as to numbers of aberrant cells, aberration index and types of aberration with either agent. More experiments are necessary to confirm the primary results. However, one important statement can be made: that incubation of normal lymphocytes treated or controlled at 4 °0 under the laboratory conditions did not greatly influence the amount of chromosomal damage.
