TY  - JOUR
A1  - Mrestani, Achmed
A1  - Lichter, Katharina
A1  - Sirén, Anna-Leena
A1  - Heckmann, Manfred
A1  - Paul, Mila M.
A1  - Pauli, Martin
T1  - Single-molecule localization microscopy of presynaptic active zones in Drosophila melanogaster after rapid cryofixation
JF  - International Journal of Molecular Sciences
N2  - Single-molecule localization microscopy (SMLM) greatly advances structural studies of diverse biological tissues. For example, presynaptic active zone (AZ) nanotopology is resolved in increasing detail. Immunofluorescence imaging of AZ proteins usually relies on epitope preservation using aldehyde-based immunocompetent fixation. Cryofixation techniques, such as high-pressure freezing (HPF) and freeze substitution (FS), are widely used for ultrastructural studies of presynaptic architecture in electron microscopy (EM). HPF/FS demonstrated nearer-to-native preservation of AZ ultrastructure, e.g., by facilitating single filamentous structures. Here, we present a protocol combining the advantages of HPF/FS and direct stochastic optical reconstruction microscopy (dSTORM) to quantify nanotopology of the AZ scaffold protein Bruchpilot (Brp) at neuromuscular junctions (NMJs) of Drosophila melanogaster. Using this standardized model, we tested for preservation of Brp clusters in different FS protocols compared to classical aldehyde fixation. In HPF/FS samples, presynaptic boutons were structurally well preserved with ~22% smaller Brp clusters that allowed quantification of subcluster topology. In summary, we established a standardized near-to-native preparation and immunohistochemistry protocol for SMLM analyses of AZ protein clusters in a defined model synapse. Our protocol could be adapted to study protein arrangements at single-molecule resolution in other intact tissue preparations.
KW  - active zone
KW  - nanotopology
KW  - neuromuscular junction
KW  - high-pressure freezing/freeze substitution
KW  - PFA in ethanol
KW  - dSTORM
KW  - Drosophila melanogaster
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-304904
SN  - 1422-0067
VL  - 24
IS  - 3
ER  -