Wolfhard Almers
Ph.D., University of Rochester, 1971
Senior Scientist, Vollum Institute
Joint Professor, Cell and Developmental Biology
Eukaryotic cells pack enzymes, hormones and transmitters into secretory vesicles and release them when the vesicles fuse with the plasma membrane during exocytosis. Cells must next retrieve the vesicle membrane by endocytosis to keep the plasma membrane from getting too large or contaminated. In the Almers lab, exo- and endocytosis are studied in neurons and endocrine cells at the level of single cells and single vesicles. Capacitance measurements are used to track the cell surface with millisecond time resolution as it changes during exo- and endocytosis. Recordings during single exocytic events provide a readout of the final events in exocytosis. Fluorescence imaging methods capture exo- and endocytosis of single vesicles in real time and can potentially detect single molecules. Questions of interest to the laboratory include: How do cells determine where on their surface vesicles dock for exocytosis? How is exocytosis regulated? What is the mechanism of membrane fusion? How do cells select membrane for endocytosis, how is endocytosis regulated and what is the mechanism of membrane fission? Although the primary focus is synaptic transmission, these questions relate broadly also to how cells crawl and determine their shape.
Merrifield CJ, Feldman ME, Wan L, Almers W. (2002) Imaging actin and dynamin recruitment during invagination of single clathrin-coated pits. Nat. Cell. Biol. 4:691-698.
Zenisek D, Steyer J, Feldman M, Almers W. (2002) A membrane marker leaves synaptic vesicles in milliseconds after exocytosis in retinal bipolar cells. Neuron 35:1085-1097.
Steyer JA, Almers W. (2001) A real-time view of life within 100 nm of the plasma membrane. Nat. Rev. Mol. Cell. Biol. 2:268-275.
Zenisek D, Steyer JA, Almers W. (2000) Transport, capture and exocytosis of single synaptic vesicles at active zones. Nature 406:849-854.
Henkel, A.W., Meiri, H., Horstmann, H., Lindau M., and Almers, W. (2000) Rhythmic opening and closing of vesicles during constitutive exo- and endocytosis in chromaffin cells. EMBO J. 19:84-93.