Evidence for an increase in X-ray-induced translocation frequency in oocytes of caffeine-treated Drosophila females.

0-8 h old Drosophila females carrying a reversed metacentric X chromosome and a suitably marked Y chromosome were treated or not with 0.2% caffeine and irradiated with 2000 R X-rays. In contrast with the reduction found in translocation frequency following 2000 R irradiation of the male mated with 0.2% caffeine-treated females, the frequency of interchanges in oocytes was significantly higher with caffeine as compared with controls.