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Plating efficiency as a function of time postirradiation: evidence for the delayed expression of lethal mutations
M S Mendonca1, W Kurohara, R Antoniono
1Department of Radiological Sciences, University of California, Irvine 92717.
Radiation Research
|August 1, 1989
Summary
Gamma irradiation initially boosts human cell plating efficiency (PE), but it never fully recovers. Delayed expression of lethal mutations may impact radiation transformation frequency estimations.
Area of Science:
- Cellular and Molecular Biology
- Radiation Biology
- Genetics
Background:
- Gamma irradiation is a known mutagenic agent.
- Understanding cellular responses to radiation is crucial for risk assessment.
Purpose of the Study:
- To investigate the long-term effects of gamma irradiation on human cell plating efficiency (PE).
- To explore the potential link between delayed PE changes and lethal mutations.
Main Methods:
- Human cell hybrid line (HeLa X skin fibroblast, CGL1) was exposed to 7 Gy gamma radiation.
- Plating efficiency was measured over time post-irradiation and compared to controls.
- Cell densities and growth conditions were standardized.
Main Results:
- Irradiated cells showed an initial increase in PE, but it remained below control levels.
- A significant decrease in PE was observed 9-10 days post-irradiation (after ~10 cell doublings).
- Unirradiated cells exhibited a PE decrease much later, around Day 15.
Conclusions:
- The delayed decrease in PE suggests a late-onset expression of radiation-induced lethal mutations.
- These findings may necessitate re-evaluation of methods for estimating radiation-induced transformation frequencies.