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Mutation induction by 5-fluorodeoxyuridine in synchronous Chinese hamster cells
Abstract:
Chinese hamster ovary cells synchronized by mitotic detachment were treated with 5-fluorodeoxyuridine (FdUrd), 0.2 micrograms/ml, at various times in the cell cycle. FdUrd treatment in the early S period induced resistance to 6-thioguanine. Treatment of asynchronous cells with FdUrd caused little increase in 6-thioguanine resistance over the spontaneous frequency. Mitotic selection thus enhances the probability of a cell being in the portion of S period receptive to mutation. These observations suggest that FdUrd treatment leads to mutagenesis at the growing points of DNA replication.
Insights
5-fluorodeoxyuridine (FdUrd) treatment during early S phase in synchronized Chinese hamster ovary cells induces resistance to 6-thioguanine. This suggests FdUrd causes mutations at DNA replication forks, enhancing mutagenesis.
Area of Science:
- Cell Biology
- Molecular Genetics
- Toxicology
Background:
- Cell cycle synchronization is crucial for studying specific cellular events.
- 5-fluorodeoxyuridine (FdUrd) is a thymidine analog used to investigate DNA synthesis and repair.
- 6-thioguanine resistance is a marker for mutations in specific genes.
Purpose of the Study:
- To investigate the mutagenic effects of 5-fluorodeoxyuridine (FdUrd) at different stages of the cell cycle.
- To determine if FdUrd treatment induces resistance to 6-thioguanine in Chinese hamster ovary (CHO) cells.
- To elucidate the relationship between DNA replication timing and FdUrd-induced mutagenesis.
Main Methods:
- Synchronization of CHO cells using mitotic detachment.
- Treatment with 5-fluorodeoxyuridine (FdUrd) at specific cell cycle phases.
- Assessment of 6-thioguanine resistance as a measure of induced mutation frequency.
Main Results:
- FdUrd treatment during the early S phase significantly increased resistance to 6-thioguanine.
- Treatment of asynchronous cells with FdUrd showed only a minor increase in 6-thioguanine resistance.
- Mitotic selection enhanced the proportion of cells in the S phase susceptible to FdUrd-induced mutation.
Conclusions:
- FdUrd-induced mutagenesis is cell cycle-dependent, primarily occurring during the early S phase.
- Mutagenesis by FdUrd appears to target actively replicating DNA at replication growing points.
- Cell cycle synchronization is a valuable tool for dissecting the mechanisms of chemical mutagenesis.