Chromosomal aberrations induced by caffeine in somatic ganglia of Drosophila melanogaster.

Nerve ganglia of third-instar larvae were treated with various doses of caffeine (5 X 10(-4), 10(-3), 5 X 10(-3), 10(-2) and 2 X 10(-2) M) for 2 h at 25 +/- 1 degrees C. The ganglia were fixed at set time intervals after treatment so that the effect of caffeine in different stages of the cell cycle could be observed. Chromatid aberrations were induced only when the caffeine was administered in G2 or approaching mitosis. No aberrations were observed after treatment in S or early G2. In relation to the different doses administered, a threshold effect was evidenced, the number of aberrations increasing in a marked way at doses exceeding 5 X 10(-3) M. These data indicate that the effect observed in Drosophila melanogaster is similar to that described by Kihlman in animals and plants treated with caffeine at temperatures below 30 degrees C. Results obtained in non-cytological tests (non-disjunction, chromosome loss, lethal recessives, dominant lethals) have so far given incomplete indications as to the mutagenicity of caffeine in Drosophila. The results we have obtained with the cytological test seem to contribute to a better definition of the mutagenicity.