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Show 275 THE UNIVERSITY OF UTAH Calcium channels play a crucial role in neurotransmission by initiating synaptic vesicle exocy-tosis. A better understanding of the coordination of this process will lead to progress in the field of neuroscience. We study the interplay of different types of calcium channels in the nematode Caenorhabditis elegans using two methods of investigation. First, we heterologously express the optoge-netic protein channelrhodopsin (ChR) in mutants with defects in a particular type of calcium channel. By exposing ChR to a particular wavelength of light, we induce a sodium influx that corresponds to an action potential reaching the synapse. This activates calcium channels and triggers neurotransmission. We then analyze the effects of the calcium channel mutations in regard to synaptic vesicle release. Our initial results show that N-type channels, L-type chan-nels and ryanodine receptors all contribute to neurotransmitter release. N- and L-type chan-nels appear to initiate the release of vesicles in close proximity to the dense projection, an organizing center of the synapse, while ryanodine receptors do so at further distances. Our second approach is to ascertain the precise locations of these proteins using correlative fluorescent electron microscopy, a technique developed in the Jorgensen Laboratory. We genetically tag channels and use photo-activated fluorescent electron microscopy (PALM) to localize the proteins of interest. Subsequently, we study the same sections using scanning electron microscopy and combine the two images to create a molecular map of the neurons. Our findings corroborate the channelrhodopsin results; N- and L-type channels appear to localize near the dense projection. We are preparing ryanodine receptors for the same analy-sis and believe they will localize further away, possibly at the tight junctions or even at the surface of the endoplasmic reticulum. We believe the final results will be conclusive and very beneficial to the neuroscience community in furthering our understanding of this vital physi-ological process. VARIOUS TYPES OF CALCIUM CHANNELS ACT IN COORDINATION TO EFFECTIVELY CONTROL SYNAPTIC VESICLE RELEASE IN CAENORHABDITIS ELEGANS Jackson Richards (Erik Jorgensen, Shigeki Watanabe) Department of Biology University of Utah honors college Jackson Richards Erik Jorgensen Shigeki Watanabe |