During the past several years, advances in light microscopy coupled with advances in fluorescence analog chemistry have permitted the analysis of a variety of processes in living cells. Numerous cellular compartments, including mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, nuclei, and cytoskeleton, can now be fluorescently labeled and monitored in living cells. In addition, other fluorescent probes are allowing researchers to study local changes in divalent cation concentration, such as calcium (The Scientist, April 3, 1989, page 20), and pH during signal transduction processes.
A persistent problem associated with these techniques, however, is that the fluorescent signals are often relatively weak, thus reducing the signal sensitivity and time available for analysis. Photon Technology International (PTI) Inc., based in South Brunswick, N.J., has developed a photon detection system and software package (MS-DOS compatible) that is particularly suitable for low light levels encountered in all types of fluorescence labeling. Unlike conventional analog detection ...
