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Cell-density dependent effects of low-dose ionizing radiation on E. coli cells
E D Alipov1, V S Shcheglov, R M Sarimov
1Department of Biophysics, Radiation Physics, and Ecology, Moscow Engineering Physics Institute, Moscow, 115409 Russia.
Radiatsionnaia Biologiia, Radioecologiia
|May 21, 2003
Summary
Low-dose ionizing radiation alters bacterial genome conformation, with effects varying by dose and time. Cell density influences radiation response, suggesting cell-to-cell communication via secondary photon emission.
Area of Science:
- Cellular Biology
- Radiation Biology
- Biophysics
Background:
- Low-dose ionizing radiation effects on cellular processes are not fully understood.
- Genome conformational state (GCS) is a critical factor in cellular response to environmental stimuli.
- Anomalous viscosity time dependence (AVTD) offers a method to probe GCS changes.
Purpose of the Study:
- To investigate the impact of low-dose ionizing radiation on the GCS of E. coli cells.
- To characterize the dose-dependent and time-dependent effects of radiation on GCS.
- To explore the role of cell density and radiation type (X-rays vs. gamma-rays) in modulating GCS changes.
Main Methods:
- Measurement of AVTD in cellular lysates of E. coli.
- Irradiation of cells with varying doses of X-rays and gamma-rays.
- Assessment of GCS changes at different post-irradiation times and cell densities.
Main Results:
- Low-dose ionizing radiation induced DNA loop relaxation, decreasing AVTD, with effects dependent on post-irradiation time (5-80 min).
- A U-shaped dose response was observed for AVTD, with increases up to 4 Gy and decreases at higher doses.
- Higher cell density during irradiation prolonged radiation-induced GCS changes, suggesting cell-to-cell communication, potentially through secondary photon emission.
Conclusions:
- Low-dose ionizing radiation significantly alters E. coli GCS, with complex dose and time dependencies.
- Radiation effects are dependent on Linear Energy Transfer (LET), as indicated by differences between X-rays and gamma-rays.
- Cell-to-cell communication plays a role in the response to low-dose radiation and electromagnetic fields, possibly mediated by infrared-submillimeter photon reemission.
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