Differential autoradiography of tritium and another beta-emitter by a double stripping film technique.

Abstract

An autoradiographic technique for studying the incorporation of two metabolites or the same metabolite at different times by a group of cells, was demonstrated with HeLa cells exposed flrst to tritiated thymidine and then to C14-labeled thymidine. The specific activities were adjusted so that the exposure required for autoradiography of the tritiated compound was ~1/10 of that required for C14. After fixing and staining, the cells were coated with autoradiographic emulsions by the stripping-film technique, the emulsion being without a gelatin supporting layer and thick enough to prevent penetration of tritium BETA particles. After a 1-day exposure to record the tritium, the emulsion was processed to give blue dye-coupled grains. The first autoradiograph was next coated with a second stripping emulsion and processed after 10 days' exposure to give black grains for Cl4. The two images could be separated in the microscope by differential focusing.