Inducing local DNA damage by visible light to study chromatin repair

Dynamics of DNA repair and recruitment of repair factors to damaged DNA can be studied by live cell microscopy. DNA damage is usually inflicted by a laser beam illuminating a DNA-interacting photosensitizer in a small area of the nucleus. We demonstrate that a focused beam of visible low intensity light alone can inflict local DNA damage and permit studies of DNA repair, thus avoiding potential artifacts caused by exogenous photosensitizers.

► Blue light (1.7 mW) focused in a live cell nucleus inflicts sublethal DNA damage. ► Blue light induces DNA breaks; no UV or oxidative damage is detected. ► Damage induced by blue light can be used to study recruitment of DNA repair factors.