[Frequency of genome mutations in progeny of colony-forming bone marrow cells in BALB/c mice]

Spleen colonies of syngenic bone marrow cells were grown in sublethally irradiated BALB/c mice. DNA contents of interphase nuclei of the colony cells have been measured using the Feulgen cytophotometry. The rates of appearance of cells with variations in chromosome number were calculated according to the following equation: (Formula: see text), where No - the total number of colonies, Nm - the number of mutant colonies, and n- the number of cells examined. The rate of genome mutations was found to be 7.7 +/- 0.6X X10(-2) per cell per generation. Binominal distribution of clones according to the number of mutant cells has been noticed. Cells with decreased numbers of chromosomes (hypodiploid mutants) were of a more frequent occurrence than cells with increased chromosome numbers (hyperdiploid mutants). It is concluded that the propagation of colony-forming bone marrow cells in irradiated animals is accompanied by almost the same increase in frequency of genome mutations as in the case of the cultivation of cells in monolayer cultures.