Maleic hydrazide induces sister-chromatid exchanges in mammalian cells in vitro

Maleic hydrazide (MH) in high concentrations (from 8 X 10(-3)M upward) induces SCEs in human blood cultures if it is added either for the entire culture period (72 h) or for the last 24 h. Parallel to the induction of SCEs, there is a delay in the proliferation of the cultures, as can be seen by the distribution of the first, second and third mitoses following the addition of BrdUrd. MH leads to a pronounced induction of SCEs in V79 cells (quadrupeling the control value) if added for 24 h simultaneously with BrdUrd. Treating the cells for 1 or 3 h prior to the addition of BrdUrd has no or little effect on the frequencies of SCEs.