The genotoxicity of N4-aminocytidine in the Drosophila wing spot test

The nucleoside analogue N⁴-aminocytidine is known to inducemutations in bacteria, and was shown to induce somatic mutationsin Drosophila melanogaster after larval administration. Theassay system employed was a wing-hair mutation spot test developedby Würgler and co-workers. The potency of N⁴-aminocytidineto induce somatic mutation is comparable to those of severalfood-pyrolysate mutagens previously reported. The occurrenceof twin spots, i.e. two types of recessive mutant-hair clonesin adjacent positions, suggests that N⁴-aminocytidine inducessomatic recombination in Drosophila. Another feature of themutagenicity of N⁴-aminocytidine is that both the acute andthe chronic larval feedings gave rise to mutant hair formationof similar patterns with respect to the spot-size distributions:small single spots were formed predominantly and the largerthe spotsize, the lower their frequency.