Related Experiment Videos
[Genetic analysis of the resistance of mouse somatic cells to colchicine]
Abstract:
The genetic nature of the resistance of mouse L cells to 0.06 microgram/ml of colchicine (the first step of selection) was studied. Fluctuation tests showed that the generation of drug-resistant variants in the wild type population was random and did not depend on the action of the selective agent. The rate of spontaneous occurrence of this variants was approximately 2 . 10(-5) per cell per generation. Colchicine resistance proved to be relatively unstable: it was 2--3-fold less in all clones propagated in non-selective conditions for 25--33 days. Two mutagens, ethylmethanesulphonate and N-nitroso-N-methylurea, failed to induce colchicine resistance in conditions when they enhanced the frequency of 8-azaguanine-resistant cells 10-fold.
Insights
Mouse L cells spontaneously develop random colchicine resistance at a rate of 2 x 10^-5 per cell. This resistance is unstable, decreasing significantly when cells are not exposed to the drug.
Area of Science:
- Genetics
- Cell Biology
- Molecular Biology
Background:
- Mouse L cells are a common model for studying drug resistance.
- Colchicine is a potent antimitotic agent that inhibits microtubule polymerization.
- Understanding the genetic basis of drug resistance is crucial for cancer therapy and drug development.
Purpose of the Study:
- To investigate the genetic basis of spontaneous colchicine resistance in mouse L cells.
- To determine the rate of spontaneous mutation to colchicine resistance.
- To assess the stability of colchicine resistance and its inducibility by mutagens.
Main Methods:
- Fluctuation tests were employed to measure the spontaneous mutation rate.
- Clones were propagated in non-selective media to assess resistance stability.
- Mutagenic agents (ethylmethanesulphonate and N-nitroso-N-methylurea) were used to test for induced resistance.
Main Results:
- Spontaneous generation of colchicine-resistant variants occurred randomly, independent of the selective agent.
- The spontaneous mutation rate to colchicine resistance was approximately 2 x 10^-5 per cell per generation.
- Colchicine resistance was unstable, decreasing 2-3 fold after 25-33 days in non-selective conditions.
- Mutagens failed to induce colchicine resistance, even when increasing 8-azaguanine resistance frequency 10-fold.
Conclusions:
- Colchicine resistance in mouse L cells arises from spontaneous, random mutations.
- The resistance is genetically unstable and not directly induced by common mutagens.
- These findings suggest a complex genetic mechanism underlying colchicine resistance in these cells.