Development and application of a nonradioactive phosphorescent autoradiograph marker

A simple and rapid method for permanently marking autoradiographs is described. This procedure is based on the phosphorescence of light-activated zinc sulfide and the subsequent exposure of x-ray films by this light emission. A lacquer-based carrier allows the zinc sulfide to remain in suspension and permits permanent marking onto diverse laboratory substrates such as x-ray films, paper, plastic wraps and nitrocellulose- and nylon-based membranes. An analogous wax-based carrier allows marking onto paper and dried acrylamide gels, which is useful for processing large numbers of radioactive DNA sequencing gels on a high-throughput scale. These inexpensive and nonhazardous markers will be useful in protocols that use x-ray films, regardless of whether radioactive or nonradioactive detection systems are used.