EFFECTS OF FLUORODEOXYURIDINE ON DNA REPLICATION, CHROMOSOME BREAKAGE, AND REUNION

Abstract

FUDR (5-fluorouracil deoxyribo-side), which is a specific inhibitor of the enzyme thymidylate synthetase, will stop DNA replication in the root tips of Vicia faba very quickly when added in concentrations of 10-7 [image] and 10-6 [image]. Cell division will, however, continue for several hours. Up to three hours the anaphases have chromosomes that are normal in appearance. After this time, gaps appear along with a few fragments. Addition of thymidine or BUDR to the cells at least one hour before they reach anaphase will heal the lesions. The effect of thymidylate deficiency on the reunion of chromosomes broken by radiation was studied. When irradiated roots were immersed in solution of thymidine or BUDR, reunion of the chromosome occurred to almost the same extent as in controls.