APPLICATIONS OF RATIO FLUORESCENCE MICROSCOPY IN THE STUDY OF CELL PHYSIOLOGY

Quantitative fluorescence microscopy is becoming an increasingly impor tant tool in the study of cell biology. Fluorescence microscopy has lo ng been used for qualitative characterizations of subcellular distribu tions of proteins, lipids, nucleic acids, and ions, but quantifying th ese distributions is complicated by a variety of optical, biological, and physical factors. Many factors that complicate quantification of f luorescence in cells can be circumvented by analyzing fluorescence rat ios derived from pairs of fluorescence images. In this review we will discuss the factors that affect fluorescence quantification, the advan tages of quantifying fluorescence as a ratio, and give examples of how fluorescence ratio microscopy is being applied in studies of cell bio logy.