STRUCTURAL-ABERRATIONS OF CHROMOSOMES IND UCED BY GAMMA-RAYS AND CROSS-ADAPTATION IN CREPIS-CAPILLARIS

Pretreatment of meristem cells of germinating Crepis capillaris seeds with a nonmutagenic concentration of mitomycin C (MC) 6 h prior to irr adiation increases the mutation level induced by 5 and 10 Gy of gamma- rays. The effect of sensitization is more evident at final fixation ti mes and is caused by aberrations of chromatid type. The number of aber rations is almost the same at different fixation times; the number-doe s not depend on the duration of the cell cycle and is almost unmodifie d by MC.