Fig. 1. DNA damage after UV-A exposure measured by the alkaline and neutral Comet assay. , DNA single- and double-strand damages as detected by the alkaline Comet assay; , solely DNA double-strand breaks as measured with the neutral Comet assay. (A) Time- and fluence-dependent induction of DNA damage relative to the control level. (B) The removal of damages during repair. (Inset) Semi-logarithmic plot of the first 5 hours of repair. The values can be fitted by an exponential function. Comet specimens from non-exposed control cells (C), directly after 40 minutes of UV-A (D), and 5 hours post UV exposure of 1280 kJ/m² (E). Bars, 20 µm. The data are pooled from four experiments with two slides analysed per experiment (60 cells each). The median from each experiment was calculated and the mean of each median value, together with the standard deviation, is plotted.