Induction of SCE by maleic hydrazide throughout the cell cycle

Abstract

In this paper we studied the effectiveness of a treatment with maleic hydraizide to increase the sister-chromatid exchange yield in root-meristem cells of Allium cepa, in relation to the stage of the cell cycle in which the treatment is performed. Roots were grown in 5-bromodeoxyuridine for two cell cycles and pulse-treatments with maleic hydrazide were carried out a different times throughout both cycles. By analyzing the [ 3H]thymidine-labeled metaphases at the second mitosis, we established the position of cells along the cycle when treated with maleic hydrazide. The results demonstrate that (1) there is a differential sensitivity of plant cells to maleic hydrazide throughout the cell cycle, being maximum during the period of DNA replication, (2) the effectiveness of maleic hydrazide in increasing the sister-chromatid exchange yield could be related to the time available for repaid before the lesions are reached by the replicating forks, and (3) maleic hydrazide induces sister-chromatid exchange formation in a similar way that of alkylating agents, even though it is not alkylating per se.