Quantitative Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS) Imaging of Individual Vesicles to Investigate the Relation between Fraction of Chemical Release and Vesicle Size.

Nguyen TDK, Rabasco S, Lork AA, Toit AD, Ewing AG

Angew. Chem. Int. Ed. Engl. 62 (28) e202304098 [2023-07-10; online 2023-06-05]

We used correlative transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to quantify the contents of subvesicular compartments, and to measure the partial release fraction of 13 C-dopamine in cellular nanovesicles as a function of size. Three modes of exocytosis comprise full release, kiss-and-run, and partial release. The latter has been subject to scientific debate, despite a growing amount of supporting literature. We tailored culturing procedures to alter vesicle size and definitively show no size correlation with the fraction of partial release. In NanoSIMS images, vesicle content was indicated by the presence of isotopic dopamine, while vesicles which underwent partial release were identified by the presence of an 127 I-labelled drug, to which they were exposed during exocytosis allowing entry into the open vesicle prior to its closing again. Demonstration of similar partial release fractions indicates that this mode of exocytosis is predominant across a wide range of vesicle sizes.

Integrated Microscopy Technologies Gothenburg [Technology development]

PubMed 37195146

DOI 10.1002/anie.202304098

Crossref 10.1002/anie.202304098