Chromosomal nondisjunction: the action of Colcemid on Chinese hamster cells in vitro

Quantitative study has been carried out of the conditions under which exposure of Chinese hamster cells to Colcemid produces polyploidy, chromosomal aneuploidy and cell killing. Single cell survival curves indicate that survival decreases with increasing exposure time and drug concentration. However, for exposure periods of 24 to 48 hours and drug concentrations in the neighborhood of 0.05 to 0.9 µg/ml, a plateau is reached at 20 to 50% survival. No appreciable change in chromosome counts occurs at or below 0.01 µg/ml. At 0.015 µg/ml, counts indicative of nondisjunction appear and increase, reaching a maximum at 0.02 µg/ml. From 0.03 to 0.07 µg/ml, approximately 80% of the cells are tetraploidized. A variety of clones with additional chromosomes can be obtained which may be useful for genetic-biochemical studies. Chromosome losses are also produced, but under the conditions employed here, these were generally inviable. The system appears to lend itself to screening of various agents for their ability to produce changes in chromosome number in mammalian cells in vitro.