Speaker
Mr
Christian Siebenwirth
(Department of Radiation Oncology, Technische Universität München, Germany)
Description
With the development of a highly precise targeted irradiation at the ion microbeam SNAKE, installed at the Munich 14 MV tandem accelerator, cellular response after irradiation of subcellular or even sub nuclear structures can be studied. Based on the live cell setup at SNAKE [1,2] it provides a sub micrometer single ion irradiation facility in combination with a high-resolution optical microscopy. To reduce systematic errors, for beam spot verification and the target recognition the same light path is used. The optical microscope and the beam delivering system are controlled by a self-developed software which optional integrates the CellProfiler software [3] for automated target recognition.
Targeting accuracy was determined by 55 MeV carbon ion irradiation of fluorescence labeled cells carrying red chromatin domains as targets and GFP-tagged MDC1 protein for damage response. Analysis of hit positions relative to the target in 140 irradiated red chromatin cells shows a systematic shift of 1.1 µm and a random distribution relative to the mean of about 3 µm fwhm.
First application of the targeted irradiation is the investigation of the accumulation of GFP-tagged Ku70 and XRCC4 protein, which are reported to form foci in the cell nucleus after UV Laser irradiation [4]. This accumulation is not observed after sparsely ionizing radiation or single carbon ion irradiation. In the targeted irradiation mode specific irradiation patterns with an exact number of 1-1000 carbon ions per point are applied less than 5 s. Hereby in U2OS cells expressing XRCC4-GFP after 100 carbon ions per point foci were formed after 13 s, in stably transfected HT1080 cells the Ku70-GFP protein with 300 carbon ions per point after 4 s. These results show that an enormous amount of DNA lesions is responsible for the foci formation of Ku70 and XRCC4 after UV Laser irradiation.
[1] V. Hable et al., Nucl. Instr. and Meth. B 267 (2009) 2090-2097
[2] V. Hable at al., Plos One, 7 (2012) e41943
[3] www.cellprofiler.org
[4] P.O. Mari et al., PNAS 103 (2006) 18597–18602
Primary author
Mr
Christian Siebenwirth
(Department of Radiation Oncology, Technische Universität München, Germany)
Co-authors
Dr
Anna Friedl
(Department of Radiation Oncology, Ludwig-Maximilians-Universität München, Germany)
Dr
Christoph Greubel
(Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Germany)
Dr
Guido A. Drexler
(Department of Radiation Oncology, Ludwig-Maximilians-Universität München, Germany)
Prof.
Günther Dollinger
(Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Germany)
Mrs
Judith Reindl
(Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Germany)
Mrs
Sophie E. Drexler
(Department of Radiation Oncology, Ludwig-Maximilians-Universität München, Germany)
Ms
Stefanie Girst
(Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Germany)
Dr
Thomas Schmid
(Department of Radiation Oncology, Technische Universität München, Germany)
