Carolina Gomis Perez

My project is trying to elucidate how membrane flows affect recycling of synaptic vesicles. Recently, it has been suggested that despite being fluid, the plasma membrane behaves like a two-dimensional gel due to transmembrane domain proteins interacting with the underlying actin cortex acting as immobile obstacles to flow. However, such studies have never been performed at neuronal terminals where synaptic vesicles are recycled rapidly. If the plasma membrane flows as slowly in neuronal terminals as in other cell types tested, this would severely limit the spatiotemporal coupling of exo- and endocytosis. The main reason membrane tension of neuronal terminals has not been studied is due to their small sizes. We have developed a new approach that addresses this challenge. We use goldfish retinal bipolar cells, a neuron of the retina, that possess a single, giant (~10 ┬Ám) terminal. We have built a set-up that combines optical tweezers (for tether pulling and membrane tension measurements), confocal imaging (for visualizing calcium dynamics) and electrophysiology (for controlling membrane potential and measuring capacitance). With this approach we are now able to directly measure how the plasma membrane flows and how membrane tension changes in response to endo-and exocytosis at the synaptic terminal.

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