Proof of principle: detection of genotoxicity by a fluorescence-based recombination test in mammalian cells.

Genotoxicity tests available today have several shortcomings. The widely applied Ames assay measures mutations in bacteria, thereby disregarding the physiological particularities of the human cell and organism.We provide first evidence for a new concept of genotoxicity detection in living human cell cultures. The data were obtained by use of a newly developed assay, which is based on the quantification of fluorescent signals, i.e. counting of the relative number of fluorescent cells in the sample. It is characterised by a short reaction time and fulfills the requirements for automated performance. The new system monitors chromosomal rearrangements and, therefore, is predicted to detect a broad spectrum of genotoxic substances. Indeed, we demonstrate the genotoxic effect of ionising radiation, of an Ames assay positive compound, and of two compounds which are poorly mutagenic in the Ames assay. The new assay will be optimised further and adapted to the requirements for routine analysis in order to help to further reduce animal experimentation in genotoxicity testing.