Action of Ypenyl [5-bis-(2-chloroethyl)-aminomethyluracil] on the chromosomes ofVicia faba

An investigation was carried out on ability of Ypenyl, i.e. 5-bis-(2-chloroethyl)-aminomethyluracil to induce structural disturbances of chromosomes and changes of mitotic activity of meristematic cells of Vicia faba . The cytostatic employed induced chromosomal aberrations mostly of the chromatide type, the greater part of which were localized in the group of small chromosomes. The frequency of aberrations was proportional to the concentration of the substance used as well as to the duration of treatment. After a 24 hour treatment with 0·01 mm solution of Ypenyl the maximum incidence of aberrations was found after 8 hour recovery in water. Longer recovery periods resulted in a gradual decrease in the number of aberrant post-metaphases in the cell population studied. Increasing concentration of Ypenyl led to the decrease in mitotic activity. Short recovery periods caused a considerable decrease in the mitotic index, which was compensated as late as 16 hours after treatment with the cytostatic.