Gene mutations in mammalian cells.
{"Image DocumentName": "Gene mutations in mammalian cells.", "Image ImageDescription": "Gene mutations are routinely measured in mammalian cells after the mutant cells\u2019 acquisition of the capability of growth in the presence of a selective agent, an otherwise toxic drug that can no longer be used by the mutated cell. As for the bacterial assays, a large number of cells is examined to demonstrate significant increases over spontaneous mutation frequencies. However, in mammalian cell gene mutation assays, the chemical exposure step must be followed by an expression period, during which mutant (and nonmutant) cells increase in number and the nonmutant protein (enzyme) present in the mutated cells and the RNA coding for that protein are depleted. Only then can the selective agent be added to permit only the mutated cells to grow and form colonies.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}