Biophysical Society Thematic Meeting| Padova 2019

Quantitative Aspects of Membrane Fusion and Fission

Poster Abstracts

20-POS Board 20 CHARACTERIZATION OF SPONTANEOUS CALCIUM EVENTS AND CORRELATION TO QUANTAL RELEASE IN PRIMARY NEURONS Roberta Mancini 1 ; Yong Qian 2 ; Quentin Bourgeois-Jaarsma 1 ; Rizky Lasabuda 1 ; Robert E Campbell 2 ; Alexander J. Groffen 1,3 ; 1 Center for Neurogenomics and Cognitive Research, Functional Genomics, Amsterdam, Noord- Holland, The Netherlands 2 University of Alberta, Chemistry, Alberta, Canada 3 VU Medical Center, Clinical Genetics, Amsterdam, Noord-Holland, The Netherlands Ca 2+ is an important signalling molecule which is critical for evoked neurotransmission and regulates spontaneous release. Resting neurons exhibit spontaneous local Ca 2+ fluctuations, but their relation to quantal release events is uncertain. Here we measured miniature excitatory postsynaptic currents (mEPSCs) and spontaneous Ca 2+ events (SCEs) simultaneously in the same neuron using the Ca 2+ indicator syGCaMP6f. This approach did not show a strict correlation. Second, we developed a new fluorescent probe sypHyJRex which can detect Ca 2+ signals and secretion events for a single synaptic vesicle. The latter approach showed spontaneous Ca 2+ events that were immediately followed by vesicle fusion events in the same synapse, suggesting that spontaneous Ca 2+ events can trigger vesicle release events. However, the lack of a strict correlation with mEPSCs suggests that these events may contribute to only a small fraction of the spontaneous release events, or alternatively, involve non-glutamatergic vesicles.

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