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Inhibition of DNA replication by ozone in Chinese hamster V79 cells
Abstract:
DNA replication in Chinese hamster lung fibroblasts, line V79, was depressed in a dose-dependent manner over an ozone concentration range of 1-10 ppm. When the cells were exposed for 1 h at concentrations up to 6 ppm, the rate of DNA replication, as measured by [3H]thymidine incorporation, declined further during a 3-h period immediately following exposure. At higher ozone concentrations, at which more than 99.9% of the cells were killed, no further decline in DNA replication was seen beyond that immediately following exposure. Cultures exposed for 1 h to 10 mM ethyl methanesulfonate or to 10 J/m2 of ultraviolet (UV) light showed a similar progressive decline in the rate of DNA replication. The inhibition of DNA replication by ozone resembled that seen after exposure of cells to chemical mutagens or radiation and did not resemble the inhibition produced by metabolic poisons. The results may indicate that ozone or its reaction products interact directly with DNA in a way that inhibits replication.
Insights
Ozone exposure significantly depresses DNA replication in V79 cells, similar to chemical mutagens or UV radiation. This suggests ozone or its byproducts may directly damage DNA, impacting cellular repair mechanisms.
Area of Science:
- Cell Biology
- Toxicology
- Molecular Biology
Background:
- Ozone is a reactive gas with known toxic effects.
- The impact of ozone on DNA replication is not fully understood.
Purpose of the Study:
- To investigate the effect of ozone exposure on DNA replication in Chinese hamster lung fibroblasts (V79 cells).
- To compare the effects of ozone with known DNA-damaging agents and metabolic inhibitors.
Main Methods:
- V79 cells were exposed to varying concentrations of ozone (1-10 ppm) for 1 hour.
- DNA replication rates were measured using [3H]thymidine incorporation.
- Comparative exposures included ethyl methanesulfonate (EMS) and ultraviolet (UV) light.
Main Results:
- Ozone exposure caused a dose-dependent depression of DNA replication.
- A delayed decline in DNA replication was observed following ozone exposure up to 6 ppm.
- Inhibition patterns by ozone resembled those of chemical mutagens (EMS) and UV radiation, not metabolic poisons.
Conclusions:
- Ozone exposure inhibits DNA replication in V79 cells.
- The mechanism of inhibition appears to involve direct interaction with DNA, similar to mutagens and radiation.
- Further research is warranted to elucidate the specific DNA-damaging pathways involved.