[Differences in the degrees of stability of colchicine-resistant clones of murine hepatoma XXIIa].

Cells resistant to colchicine in the parental line of mouse hepatoma XXIIa could be revealed with a frequency of 4-4.5 per 10(5) cells when selected at the drug concentration as high as 0.05 mkg/ml. MNNG as a mutagene was shown to increase the number of resistant cells by 5-6 times. 6 clones of independent origin differed in the level of resistance and in the stability to retain it under non-selective conditions. Multistep selection from the stable clones via 0.25, 1.0, 4.0, 5.0, 10.0 and 20.0 mkg/ml resulted in the appearance of some highly resistant subclones. Stable clones of all the steps of selection appeared to be resistant to ethidium bromide. Genetical polymorphism of colchicine-resistance is suggested in the line of mouse hepatoma XXIIa.