PHOTOACTIVATION OF CAGED COMPOUNDS IN SINGLE LIVING CELLS - AN APPLICATION TO THE STUDY OF CELL LOCOMOTION

Caged compounds are molecules whose biological function is masked unti l UV light induces a photo-chemical reaction that converts the molecul es into a biologically active state. These probes provide very powerfu l tools in cell biology research, since the activation can be precisel y controlled temporally and spatially by limiting their exposure to li ght. This report describes a simple caged compound illuminator that ca n be attached to an inverted microscope; it can simultaneously provide both sufficient UV illumination for photoactivation and epifluorescen ce excitation to monitor indicator fluorescence. As an example, we sho w that the cytoplasmic calcium level can be raised very rapidly by the photoactivation of a new caged compound, caged calcium ionophore DMNP E-A23187, and that this [Ca2+](i) increase is associated with tail ret raction of motile keratocytes.