FAIR experimental program: Research team analyses repair processes in radiation-damaged cells
These are future-oriented research results, combining most advanced physics and biology and at the same time demonstrating the great potential of the future accelerator center FAIR: Scientists at the GSI Helmholtzzentrum für Schwerionenforschung have been able to observe the repair processes in human cells after radiation damage more directly and with higher resolution than ever before. A precise understanding of DNA repair mechanisms is of great importance, for example, for risk assessments during long-term space missions.
For the radiation experiments at the accelerator facility on the GSI and FAIR campus in Darmstadt, high-energy ion beams, which are also characteristic of cosmic radiation in space, were used and combined with modern microscopy techniques. The investigations were carried out as part of the first stage of the FAIR experimental program, "FAIR Phase 0". The team of the GSI Biophysics Department has now published its results in the journal "Scientific Reports", which is edited by the Nature Publishing Group and which covers all areas of the natural sciences.
At the specially developed measuring station at the accelerator, the scientists irradiated established human cell cultures with heavy ions that cause double-strand breaks and thus damage the genetic information (DNA). During and immediately after irradiation, the research team was able to closely observe the dynamic processes of the induction of the damage and the subsequent repair processes in the genetically damaged cells using so-called "live cell imaging" on a specially constructed microscope directly at the accelerator beamline. For this purpose, the proteins responsible for repair in the cell were provided with fluorescent dyes so that they were visible under the microscope. The remote controlled arrangement made it possible to observe the protein dynamics in the cell core seamlessly and without interruption from the damage track to the biological response of the cell and to record it visually on film.
Particularly valuable for new fundamental insights into the repair processes in human cells is the possibility of using high energetic heavy ion beams to simultaneously generate simple and clustered DNA damage in the same cell and to investigate this damage in real time, which was previously possible only separately. In such a distribution of damage, many DNA double-strand breaks are concentrated along a densely ionizing damage path and only single, simple damages are off track. The researchers were thus able to observe parallel how the same cell reacts to complex damages and to single damages.
The results of the measurements show differences in this damage response: The DNA repair proteins seem to be recruited faster to the clustered damage than to the individual DNA damage outside the ion track. On the other hand, the delayed repair there seems to be faster and less difficult. Thus, the results clearly demonstrate the impact of the quality of DNA lesion on the dynamics of early radiation response and repair and indicate that simple and clustered DNA damage should be treated separately when assessing radiation effects. (BP)