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bioRxiv · 10.1101/336891

Multiplex imaging of quantal glutamate release and presynaptic Ca2+ at multiple synapses in situ

Jensen, T. P.·Zheng, K.·Cole, N.·Marvin, J. S.·Looger, L. L.·Rusakov, D. A.
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Abstract

Information processing by brain circuits depends on Ca2+-dependent, stochastic release of the excitatory neurotransmitter glutamate. Recently developed optical sensors have enabled detection of evoked and spontaneous release at common glutamatergic synapses. However, monitoring synaptic release probability, its use-dependent changes, and its underpinning presynaptic machinery in situ requires concurrent, intensity-independent readout of presynaptic Ca2+ and glutamate release. Here, we find that the red-shifted Ca2+ indicator Cal-590 shows Ca2+-sensitive fluorescence lifetime, and employ it in combination with the novel green glutamate sensor SF-iGluSnFR variant to document quantal release of glutamate together with presynaptic Ca2+ concentration, in multiple synapses in an identified neural circuit. At the level of individual presynaptic boutons, we use multi-exposure and stochastic reconstruction procedures to reveal nanoscopic co-localisation of presynaptic Ca2+ entry and glutamate release, a fundamental unknown in modern neurobiology. This approach opens a new horizon in the quest to understand release machinery of central synapses.

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Jensen, T. P., Zheng, K., Cole, N., Marvin, J. S., Looger, L. L., Rusakov, D. A.. 2018-06-02. Multiplex imaging of quantal glutamate release and presynaptic Ca2+ at multiple synapses in situ. https://doi.org/10.1101/336891

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