BIOTIN AND DIGOXIGENIN AS LABELS FOR LIGHT AND ELECTRON-MICROSCOPY IN-SITU HYBRIDIZATION PROBES - WHERE DO WE STAND

Biotin was recently applied to detect cellular DNA or RNA. In combinat ion with avidin, streptavidin or antibody, it can be conjugated with f luorescent dye, enzyme, ferritin, or gold. However, emphasis has recen tly been placed on the false-positive results that are obtained when t his probe is used, because endogenous biotin may sometimes interfere w ith specific signals. Digoxigenin appears to be an interesting alterna tive because it is present exclusively in Digitalis plants as a second ary metabolite. We discuss in this review the efficiency and the respe ctive advantages and disavantages of these two probes for in situ hybr idization, mainly at the electron microscopic level.