The goal of this project is to detect calcium induced changes in contact regions of biological membranes just prior to fusion. This aim, as well as the methodology employed, is based on physical-chemical studies of calcium binding between phospholipid lamellae that contain phosphatidylserine. Low-light level microscopy will be used to detect a fluorescence signal from the calcium induced rigid phase, simultaneous by with a phase contrast image, in order to identify the cell biological event that accompanies fluorescence. An increase in cytoplasmic calcium concentration can affect exocytosis, cell movement, cell division, metabolism and other processes. This proposal examines one aspect of exocytosis model and real biological membranes in the binding of calcium between bilayer membranes and the resulting lipid and protein rearrangements. The synthesis of fluorescent phospholipids and the development of low-light level microscope systems make possible a search for the small signal from calcium induced membrane contact regions in fusing biological membranes.
