The major interest of the laboratory concerns the mechanisms underlying Ca2+-dependent exocytosis. The molecular mechanisms underlying secretion of prepackaged hormones and neurotransmitters are studied using primary adrenal chromaffin cells in tissue culture. Biochemical, electrophysiological, and molecular genetic techniques are employed to study the effects of specific proteins on regulated secretion. A powerful optical technique, total internal reflection fluorescence microscopy (TIRFM) is extensively used in collaboration with Dr. Daniel Axelrod (Department of Physics, LSA Biophysics, University of Michigan), to study granule motion and physiolgical events immediately adjacent to the plasma membrane before, during and after exocytosis. (Image: combined DIC and fluorescence of chromaffin cells with one cell transiently-expressing ANP-GFP in secretory granules)

TIRFM movie of exocytosis of secretory granules labeled with VAMP-eGFP in bovine chromaffin cells. Exocytosis is stimulated by a nicotinic cholinergic agonist. The first exocytotic event occurs at 9 sec. View