Molecular biologists and geneticists use autoradiography to read images of radioactivity from electrophoresis gels, blotting membranes, and other media. In autoradiography, the radiation emitted by samples labeled with isotopes exposes photographic film. The silver grains on the film’s emulsion layer precipitate only after repeated exposure to beta or gamma rays. As a result, researchers must use long exposure times or high doses of radiation to get an image. In addition, the linear response range of X-ray film is limited. Researchers therefore, need a series of exposures to measure peaks and bands with a wider dynamic range.
Molecular Dynamics, based in Sunnyvale, Calif., has developed an instrument that represents an alternative to autoradiography. The 400A Phosphorlmager has a storage phosphor screen that absorbs and stores the beta and gamma radiation emitted by isotopes used in labeling experiments. The 400A Phosphorlmager reads the stored energy by scanning the screen with a helium-neon ...
