B R I E F N O T E S Freeze-fracture Autoradiography: Feasibility

Membrane splitting by freeze-fracture (2) could provide chemical information about the transmembrane distribution of constituents if the individual halves of the membrane could be analyzed separately. One means of analysis is the detection of membraneincorpora ted radioisotopic labels by autoradiography after freeze-fracturing (6). We have examined three model systems, two nonbiological and one b iomembrane , that test the feasibility of combining freeze-fracture with electron microscope autoradiography ( F A R G ) and that demonstra te F A R G ' s potential in studies of b iomembrane organization. We describe here a method for the formation and application of a dry, parlodion-stabilized monolayer of autoradiographic emulsion to frozen replicas of fractured surfaces (Fig. 1).