A new technique for retarding fading of fluorescence: DPX-BME.

The antioxidant beta-mercaptoethanol (BME) used in conjunction with the permanent mountant DPX (DPX-BME) retarded fluorescent fading of mithramycin, acridine orange and Hoechst 33258 stained chicken erythrocytes, each to a varying degree. The initial fluorescence of all dyes examined was more intense with DPX-BME than with DPX alone. Specimens mounted in DPX-BME showed strong fluorescence and excellent morphology; if kept in the dark, they could be stored indefinitely without deterioration. Retarding fading of fluorescence with DPX-BME faciliated quantitation of DNA using fluorescence cytophotometry.