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Induction of ouabain-resistant mutations in C3H 10T1/2 mouse cells by ultraviolet light
Abstract:
Ouabain-resistant mutants were induced in C3H mouse embryo 10T1/2 fibroblasts by exposure to ultraviolet light, thus making available an in vitro system for studying mutagenesis and oncogenic transformation in parallel. 86Rb uptake studies showed that biochemical mutants at the plasma membrane Na+,K+ transport ATPase (EC 3.6.1.3) locus were being selected for in this system. The optimal expression time for the mutants was found to depend on the dose of ultraviolet light, as was the induced mutation frequency. The ratio of transformation to mutation frequencies was found to be on the order of 10 for four different doses, suggesting that the target size in the cellular genome for transformation may be approximately 10 times the size of the Na+,K+ ATPase gene. We propose that both transformation and mutation induction can now be quantitatively studied in this single system.
Insights
This study developed a new in vitro system to simultaneously investigate mutagenesis and oncogenic transformation in mouse cells. Ultraviolet light exposure induced ouabain-resistant mutants, enabling parallel study of cell mutation and cancer development.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Developing in vitro systems is crucial for studying complex cellular processes like mutagenesis and oncogenic transformation.
- Understanding the relationship between DNA damage, mutation, and cancer development requires parallel investigation of these events.
- The Na+,K+ transport ATPase is a key plasma membrane protein involved in cellular ion balance.
Purpose of the Study:
- To establish and validate an in vitro system for the parallel study of mutagenesis and oncogenic transformation.
- To investigate the relationship between ultraviolet light dose, mutation frequency, and transformation frequency in mouse fibroblasts.
- To estimate the genomic target size for oncogenic transformation relative to the Na+,K+ ATPase gene.
Main Methods:
- Induction of ouabain-resistant mutants in C3H mouse embryo 10T1/2 fibroblasts using ultraviolet light.
- Selection of biochemical mutants affecting the plasma membrane Na+,K+ transport ATPase (EC 3.6.1.3) using 86Rb uptake studies.
- Quantitative analysis of mutation and transformation frequencies at varying ultraviolet light doses.
Main Results:
- An in vitro system was established allowing parallel study of mutagenesis and oncogenic transformation.
- The optimal expression time for mutants and induced mutation frequency were dependent on ultraviolet light dose.
- A consistent ratio of approximately 10 for transformation to mutation frequencies was observed across different doses.
Conclusions:
- The developed system enables quantitative and parallel study of mutagenesis and oncogenic transformation.
- The findings suggest the cellular genome's target size for transformation is roughly 10 times larger than the Na+,K+ ATPase gene.
- This model provides a valuable tool for investigating the mechanisms linking mutation and cancer initiation.