Analysis of chromatid segregation in CHO cells at mitosis

Abstract In the present paper the results of an analysis performed at M3 on chromatid segregation that occurred at M2 in CHO cells treated and untreated with K2Cr2O7 are presented. The percentage of light chromosomes (BB × BB chromatid pairs) in a cell at M3 has been estimated and the empirical frequency distributions of light chromosomes in the different experimental groups have been compared with the theoretical ones (sums of binomial distributions with p=0.5) by means of the non-parametric Kolmogorov-Smirnov test. In all cases a significant difference has been found, together with a shift to the “left” (i.e. p<0.5) of the maximal frequency classes. This behaviour has been explained by assuming the existence of a selective mortality factor acting on cells with light chromosomes prevailing. This cellular mortality of light cells has been attributed by some authors to the presence of the younger one of the two parental DNA strands collecting the damages which occurred during the previous generation. On th...