[PhD Thesis Presentation] -Lashmi Piriya Ananda Babu- Functional roles of microtubules in a giant presynaptic terminal

Speaker: Lashmi Piriya Ananda Babu

Title: Functional roles of microtubules in a giant presynaptic terminal

Abstract: Roles of microtubules (MTs) in cell division and organelle transport are well established. In neurons, axonal MTs are extended to terminals and transport mitochondria and various molecules in vesicles. However, it is unknown whether MTs play functional roles in presynaptic terminals. To address this, I first identified MTs at the calyx of Held giant terminal, using immunofluorescence, electron-microscopic and live-staining methods, and found that MTS were co-localized with synaptic vesicles (SVs). I then disrupted MTs using vinblastine and tested its effect on synaptic efficacy and properties, using whole-cell patch-clamp recording methods at the calyx of Held. Acute MT disruption caused (i) a prolongation of recovery time after short-term depression and (ii) a desynchronization of quantal release, but had no effect on the basal synaptic transmission efficacy or the magnitude or time course of SV exo-endocytosis, measured using presynaptic membrane capacitance measurements. These results suggest that presynaptic MTs contribute to SV transport for release site replenishment, and in parallel, promote synchronous transmitter release for high-precision neurotransmission at this fast synapse.