( Institute of Biophysics and Biochemistry, Huazhong University of Science and Technology, Wuhan 430074, China )

Abstract Fluorescent labeling and dynamic imaging of secretory vesicles are new powerful means to study the mechanisms of protein and membrane trafficking. The large dense-core granules in PC12 cells were labeled by transfecting EGFP-hpNPY chimera and imaged with epi-fluorescence and evanescent field (EF) fluorescence simultaneously. Under epi-fluorescence illumination, the cells exhibited nearly uniform fluorescence, however, EF-fluorescence excitation revealed distinct fluorescent spots corresponding to GFP-labeled granules. The trafficking, docking and fusing with plasma membrane of individual granule in cultured PC12 cells were observed directly by EF fluorescence imaging.