The alkaline single cell gel electrophoresis: a new test for assessing DNA single strand breaks in Neurospora crassa

The single cell gel electrophoresis (comet assay) is a potent technique in testing double and single strand breaks in DNA. In this paper, we present an application of alkaline comet assay to filamentous fungi for genotoxicological assessment of heavy metals for the first time. A wild strain of Neurospora crassa SLA 4200 was grown in presence of cadmium sulfate (CdSO4) (10 microM and 100 microM) for 12 h. Protoplasts from 12-h old mycelia were prepared by using Novozym 234 and DNA damage was evaluated by alkaline comet assay. Hydrogen peroxide (H2O2) (50 microM and 100 microM) was taken as an internal standard for DNA damage. Both CdSO4 and H2O2 induced significant single strand breaks in DNA. The results indicate that alkaline comet assay is a sensitive and rapid method for DNA damage analysis in filamentous fungal systems.