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Genetic effects of caffeine
194
3rd ANNUAL MEETING, UPPSALA
with disulfiram which suggests that if clinical doses induce aberrations at all, then they do so with a much lower frequency than was found in the workers exposed to ziram. A Medical Research Council Research Grant is acknowledged.
17 LOPRIENO, N., R. BARALEAND S. BARONCELLI,Laboratorio di Mutagenesi Differenziamento C.N.R., Pisa (Italy).
Genetic effects of caffeine 18 MARSTOKK, ANNE, AND PER OFTEDAL, Institute of General Genetics, University of Oslo (Norway).
Caffeine sensitization in radiation-induced degeneration of Drosophila testes The testes of adult Drosophila males are essentially sacs filled with germ cells of different stages of maturity, but all originating from a small number of stem cells in the distal tip. As first shown by Dr. A. J. Bateman, irradiation with doses 5-1o krad kill off the stem cells, which in two weeks' time leads to the testes appearing as thin threads upon dissection, instead of being filled and as somewhat turgid sacs. A single surviving stem cell is apparently able to repopulate the testes, leading to an all-ornone reaction. The two members of a pair of testes react independently. No mating is needed to e m p t y the testes. Groups of virgin Drosophila males, 24 h old, were irradiated with 15o kV X-rays, with no added filtration. Prior to irradiation, groups were fed sugar solution, or sugar solution to which 0.5% or 1% caffeine had been added. Sugar-fed males showed a dose-sterilization curve with a wide but sharply delimited shoulder. In one experiment, the shoulder width De was 6.0 krad, the 50% sterilization dose SDso was 6.8 krad, and the slope Do was 1.5 krad. Caffeine-fed males in this experiment had D e = 4 . 7 krad, SD50=5.5 krad, and Do----I.5 krad. In IO experiments, the increase in sterilization at the 7.5 krad level was from 48.8=E2.2% in sugar-fed males to 62. 9 :k3.2% and 74.2=~2.3% after feeding with 0.5% and 1% caffeine, respectively.
t9 MENDELSON, D., AND F. H. SOBELS,Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden and J. A. Cohen Institute for Radiopathology and Radiation Protection, Leiden (The Netherlands).
The inhibiting effect of caffeine on a maternal repair system in Drosophila The effect of caffeine on the repair or restitution of chromosome breakage effects has been studied by mating males which had been exposed to X-irradiation to females
3rd ANNUAL MEETING, UPPSALA
with disulfiram which suggests that if clinical doses induce aberrations at all, then they do so with a much lower frequency than was found in the workers exposed to ziram. A Medical Research Council Research Grant is acknowledged.
17 LOPRIENO, N., R. BARALEAND S. BARONCELLI,Laboratorio di Mutagenesi Differenziamento C.N.R., Pisa (Italy).
Genetic effects of caffeine 18 MARSTOKK, ANNE, AND PER OFTEDAL, Institute of General Genetics, University of Oslo (Norway).
Caffeine sensitization in radiation-induced degeneration of Drosophila testes The testes of adult Drosophila males are essentially sacs filled with germ cells of different stages of maturity, but all originating from a small number of stem cells in the distal tip. As first shown by Dr. A. J. Bateman, irradiation with doses 5-1o krad kill off the stem cells, which in two weeks' time leads to the testes appearing as thin threads upon dissection, instead of being filled and as somewhat turgid sacs. A single surviving stem cell is apparently able to repopulate the testes, leading to an all-ornone reaction. The two members of a pair of testes react independently. No mating is needed to e m p t y the testes. Groups of virgin Drosophila males, 24 h old, were irradiated with 15o kV X-rays, with no added filtration. Prior to irradiation, groups were fed sugar solution, or sugar solution to which 0.5% or 1% caffeine had been added. Sugar-fed males showed a dose-sterilization curve with a wide but sharply delimited shoulder. In one experiment, the shoulder width De was 6.0 krad, the 50% sterilization dose SDso was 6.8 krad, and the slope Do was 1.5 krad. Caffeine-fed males in this experiment had D e = 4 . 7 krad, SD50=5.5 krad, and Do----I.5 krad. In IO experiments, the increase in sterilization at the 7.5 krad level was from 48.8=E2.2% in sugar-fed males to 62. 9 :k3.2% and 74.2=~2.3% after feeding with 0.5% and 1% caffeine, respectively.
t9 MENDELSON, D., AND F. H. SOBELS,Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden and J. A. Cohen Institute for Radiopathology and Radiation Protection, Leiden (The Netherlands).
The inhibiting effect of caffeine on a maternal repair system in Drosophila The effect of caffeine on the repair or restitution of chromosome breakage effects has been studied by mating males which had been exposed to X-irradiation to females