Comet-assay and Comet-fish for the detection of individual radiation and toxinesensitivities of genome regions

While in different areas of research, the COMET-Assay has become a standard technique, especially in basic research, the combination of COMET-Assay and fluorescence in situ hybridisation (FISH) is a novel technique used only in a few laboratories. This technique, called COMET-FISH, does not only allow to detect fragmented DNA and to measure the degree of DNA damage, but enables to allocate specific genomic loci in individual cells by specific fluorescence labelling. For the quantitative evaluation of the COMET-Assay commercially available systems with integrated image analysis exist. Such systems are completely missing for COMET-FISH up to now. The biochemical parameters of these technique have been optimised so far, that COMET-FISH has been successfully applied in different fields of research under different questions. Thus it has been achieved to use the COMET-FISH technique for the examination of different risk factors on effects of ionising and non-ionising radiation. In this context first studies are presented to access tumour risk factors of nutrition. Also some basic experiments are presented showing the correlation between sensitivity of selected genomic regions towards UV-A irradiation, repair activity and the density of active genes. The results applying the techniques presented here may be correlated for instance to measure nutrition induced changes on radiation sensitivity. The techniques will allow to use them in future also to examine other risk factors. Finally the COMET techniques could contribute to register risk factors on the individual level in order to obtain a better estimate for individual radiation sensitivity. (orig.)