Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.31.230995v1?rss=1 Authors: Steinkellner, T., Madany, M., Haberl, M. G., Zell, V., Li, C., Hu, J., Mackey, M., Ramachandra, R., Adams, S., Ellisman, M. H., Hnasko, T., BOASSA, D. Abstract: Communication between neurons relies on the release of diverse neurotransmitters, which represent a key-defining feature of a neuron's chemical and functional identity. Neurotransmitters are packaged into vesicles by specific vesicular transporters. However, tools for labeling and imaging synaptic vesicles based on their neurochemical identity remain limited. We developed a genetically encoded probe to identify glutamatergic synaptic vesicles at the levels of both light and electron microscopy (EM) by fusing the mini singlet oxygen generator (miniSOG) probe to an intra-lumenal loop of the vesicular glutamate transporter-2. We then used a 3D imaging method, serial block face scanning EM, combined with a deep learning approach for automatic segmentation of labeled synaptic vesicles to assess the subcellular distribution of transporter-defined vesicles at nanometer scale. These tools represent a new resource for accessing the subcellular structure and molecular machinery of neurotransmission and for transmitter-defined tracing of neuronal connectivity. Copy rights belong to original authors. Visit the link for more info