STUDIES ON THE REVERSAL OF 5-FLUORODEOXYURIDINE-INDUCED MITOTIC INHIBITION BY THYMIDINE AND THYMIDINE ANALOGUES

Abstract

At concentrations of 10−7M and 10−8M, 5-fluorodeoxyuridine (FUDR) completely inhibits cell division in root tips of Vicia faba. Suppression of cell division by 10−8M FUDR is incomplete. In roots treated with 10−4M thymidine (TDR), the level of mitosis is unchanged. In 10−3M TDR, 10−4M 5-bromodeoxyuridine (BUDR), or 10−4M 5-iododeoxyuridine (IUDR), there is some decline in the mitotic index, particularly at later time periods.After a 2.5-hour treatment with 10−0M FUDR, roots do not recover for more than 2 days in water. Recovery is faster in TDR. There is a slight enhancement of recovery in 10−6M TDR and more rapid recovery at higher concentrations. The TDR analogues, BUDR and IUDR, are also somewhat effective in reversing FUDR-induced mitotic inhibition. TDR itself is most effective, followed by BUDR and IUDR, in that order. Renewed cell division, however, is often only temporary.When administered simultaneously with 10−3M FUDR, TDR, at higher concentrations, provides some protection from mitotic inhibition. The protection from 10−6M FUDR offered by simultaneous exposure to IUDR is slight. With simultaneous exposure to 10−6M FUDR and 10−4M BUDR, a decline in the level of mitosis is followed by partially synchronous cell divisions.