Super-resolution microscopy for neuroscience

Summary

Date: 
October 22, 2019 - 12:00pm
Location: 
Bio. Labs 1080
About the Speaker
Name: 
Valentin Nägerl
Speaker Title: 
Professor
Speaker Affiliation: 
Université de Bordeaux

Super-resolution microscopy offers tremendous opportunities to unravel the complex and dynamic architecture of living cells. I will present our recent methodological efforts 1) to construct a super-resolution platform for correlative live single-molecule imaging and STED microscopy and 2) to visualize the structural basis of astrocytic Ca2+ signals at tripartite synapses.
Current super-resolution microscopes are well suited for revealing protein distributions or cell morphology, but not both. Here, I will present a new method that combines 3D-STED, and its related SUSHI variant, with two popular SMLM techniques, sptPALM and uPAINT, on a single microscope platform. It is designed for rapid switching and precise alignment of the imaging modalities, enabling live nanoscale correlative analyses of protein dynamics within their changeable morphological cellular environment.
Using 3D-STED microscopy, we resolved the spongiform domain of astrocytes and revealed new aspects of its morphology in brain slices and in vivo. We observed a reticular meshwork of nodes and shafts that featured rings of re-connecting astrocytic processes. The majority of dendritic spines were in contact with nodes, correlating in size with them. FRAP experiments and Ca2+ imaging showed that individual nodes were capable of biochemical compartmentalization and hosted highly localized Ca2+ transients. Our study reveals the nanoscale anatomical organization of astrocytes, identifying nodes as the functional astrocytic component of excitatory tripartite synapses, which may provide the anatomical basis for synapse-specific communication between neurons and astrocytes.

Recent papers:
• Inavalli et al. A super-resolution platform for correlative live single-molecule imaging and STED microscopy. Nature Methods (in press)
• Arizono et al. Structural basis of astrocytic Ca2+ signals at tripartite synapses. Neuron (in revision)
• Pfeiffer et al. Chronic STED imaging reveals high turnover of dendritic spines in the hippocampus in vivo. eLife (2018)
• Tønnesen et al. Super-resolution imaging of the extracellular space in living brain tissue. Cell (2018)
• Chéreau et al. Super-resolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity. PNAS (2017)