Communication Aphidicolin-induced Endoreduplication in Chinese Hamster Cells1

Aphidicolin, a specific inhibitor of DMA polymerase o, was found to induce high frequencies of endoreduplication in Chinese hamster V79 cells in a dose-dependent manner. The aphidicolin-induced endoreduplication was observed when cells were incubated at 37°but not at 41 °.Since it is known that DMA polymerase AŸis more thermally labile than is DMA polymerase a, the data are consistent with the hypothesis that DNA polymerase AŸ might be responsible for endoreduplication as was reported in mouse trophoblast cells. From the induced diplochromosomes, it was observed that the two unifilarly 5bromodeoxyuridine-substituted chromatids are generally paired and located inside, whereas the two bifilarly 5-bromodeoxyuridine-substituted chromatids are flanking outside re gardless of the presence of sister chromatid exchange or intradiplochromatid interchange.