Abstract
The sister chromatid exchange (SCE) in Chinese hamster D-6 cells was induced by treatment with the excess amounts of deoxyribonucleosides such as dA, dG, and dT or their mixtures. The induction of the SCE, however, was suppressed by additions of dC and combinations of the other deoxyribonucleosides with dC. These results suggested that SCEs could be induced by the inhibition of ribonucleotide reductase activity, namely, metabolic perturbation of deoxyribonucleotide synthesis. On the other hand, SCE was induced by hydroxyurea (HU) at about two times of control. SCE inducing by HU, however, was not suppressed by simultaneous addition of deoxyribonucleosides (dA, dG, dT, and dC). This result means that induction of SCE by HU was not due to the depletion of deoxyribonucleotides, but it might be due to any other factor which is unknown at present.
