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Postirradiation alterations of neuronal chromatin structure
A Jaberaboansari1, G B Nelson, J L Roti Roti
1Department of Radiation Biophysics, University of Kansas, Lawrence 66045.
Radiation Research
|April 1, 1988
Summary
Ionizing radiation alters neuronal chromatin structure. This study investigated the restoration kinetics of chromatin structure in rat cerebellar neurons, finding a biphasic recovery over minutes and hours.
Area of Science:
- Neuroscience
- Molecular Biology
- Radiation Biology
Background:
- Neuronal chromatin structure may be altered following ionizing radiation exposure.
- Previous studies from our laboratory indicated immediate post-irradiation changes.
Purpose of the Study:
- To investigate the kinetics of chromatin structure restoration in rat cerebellar neurons after 25 Gy irradiation.
- To assess the recovery of DNA superhelical structure, chromatin accessibility, and nuclear-matrix-associated DNA accessibility.
Main Methods:
- Whole brains of male Fisher 344 rats were irradiated (25 Gy).
- Three assays were used: fluorescent halo assay (DNA supercoiling), micrococcal nuclease digestion (chromatin accessibility), and DNase I digestion (nuclear-matrix-associated DNA accessibility).
Main Results:
- Immediately post-irradiation, topological constraints on DNA loops were altered.
- Chromatin showed increased accessibility to micrococcal nuclease.
- Nuclear-matrix-associated DNA exhibited increased resistance to DNase I digestion.
- Restoration followed biphasic kinetics with fast (minutes) and slow (hours) phases.
Conclusions:
- Neuronal chromatin structure undergoes rapid, biphasic recovery post-irradiation.
- The observed kinetics are comparable to DNA damage repair rates in mammalian cells.
- The molecular relationship between the different structural recovery assays requires further investigation.