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ST: Fachverband Strahlen- und Medizinphysik

ST 9: Strahlenbiophysik

ST 9.3: Vortrag

Dienstag, 27. März 2007, 16:30–16:45, Ch 12.0.16

Comparison of laser and charged particle induced DSB formation — •Jörn Splinter, Burkhard Jakob, and Gisela Taucher-Scholz — GSI - Biophysics Darmstadt, Germany

The spatiotemporal dynamics of DNA damage response processes like the fast accumulation of early repair-related proteins can be observed in real time by our newly developed beamline microscope. For this purpose ion beams offer the advantage to generate strictly localized DNA lesions in cell nuclei, thus inducing distinguishable spots of protein formation.

In addition to our beamline microscope, we established a laser system for localized generation of DSBs to look for differences in the recruitment and spatiotemporal behaviour of repair related proteins due to differences in the radiation quality. Therefore we tested the Laser Microdissection System Leica AS LMD and its VSL-337ND-S nitrogen laser (λ = 337.1 nm) for its ability to produce DSBs.

The emerging problems indicate that a laser system is not the simple and predictable DSB-inducing system people want it to be. Accompanied by temperature dependent variation of the laserpower and the intermittent understandings of the mechanisms of UV-laser-induced DSB formation, the main problem are the complications in dosimetry. A discussion of these complications will be done on the vivid example of the only known approach of a visual based comparing dosimetry of γH2AX signals first introduced by Bekker-Jensen et al.

Bekker-Jensen et al. (2006), J. Cell Biol. 173: 195-206