TY  - JOUR
A1  - Trinks, Nora
A1  - Reinhard, Sebastian
A1  - Drobny, Matthias
A1  - Heilig, Linda
A1  - Löffler, Jürgen
A1  - Sauer, Markus
A1  - Terpitz, Ulrich
T1  - Subdiffraction-resolution fluorescence imaging of immunological synapse formation between NK cells and A. fumigatus by expansion microscopy
JF  - Communications Biology
N2  - Expansion microscopy (ExM) enables super-resolution fluorescence imaging on standard microscopes by physical expansion of the sample. However, the investigation of interactions between different organisms such as mammalian and fungal cells by ExM remains challenging because different cell types require different expansion protocols to ensure identical, ideally isotropic expansion of both partners. Here, we introduce an ExM method that enables super-resolved visualization of the interaction between NK cells and Aspergillus fumigatus hyphae. 4-fold expansion in combination with confocal fluorescence imaging allows us to resolve details of cytoskeleton rearrangement as well as NK cells' lytic granules triggered by contact with an RFP-expressing A. fumigatus strain. In particular, subdiffraction-resolution images show polarized degranulation upon contact formation and the presence of LAMP1 surrounding perforin at the NK cell-surface post degranulation. Our data demonstrate that optimized ExM protocols enable the investigation of immunological synapse formation between two different species with so far unmatched spatial resolution.
KW  - biological fluorescence
KW  - fluorescence imaging
KW  - imaging the immune system
KW  - infectious diseases
KW  - super-resolution microscopy
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-264996
VL  - 4
IS  - 1
ER  - 
TY  - JOUR
A1  - Mrestani, Achmed
A1  - Pauli, Martin
A1  - Kollmannsberger, Philip
A1  - Repp, Felix
A1  - Kittel, Robert J.
A1  - Eilers, Jens
A1  - Doose, Sören
A1  - Sauer, Markus
A1  - Sirén, Anna-Leena
A1  - Heckmann, Manfred
A1  - Paul, Mila M.
T1  - Active zone compaction correlates with presynaptic homeostatic potentiation
JF  - Cell Reports
N2  - Neurotransmitter release is stabilized by homeostatic plasticity. Presynaptic homeostatic potentiation (PHP) operates on timescales ranging from minute- to life-long adaptations and likely involves reorganization of presynaptic active zones (AZs). At Drosophila melanogaster neuromuscular junctions, earlier work ascribed AZ enlargement by incorporating more Bruchpilot (Brp) scaffold protein a role in PHP. We use localization microscopy (direct stochastic optical reconstruction microscopy [dSTORM]) and hierarchical density-based spatial clustering of applications with noise (HDBSCAN) to study AZ plasticity during PHP at the synaptic mesoscale. We find compaction of individual AZs in acute philanthotoxin-induced and chronic genetically induced PHP but unchanged copy numbers of AZ proteins. Compaction even occurs at the level of Brp subclusters, which move toward AZ centers, and in Rab3 interacting molecule (RIM)-binding protein (RBP) subclusters. Furthermore, correlative confocal and dSTORM imaging reveals how AZ compaction in PHP translates into apparent increases in AZ area and Brp protein content, as implied earlier.
KW  - active zone
KW  - Bruchpilot
KW  - RIM-binding protein
KW  - compaction
KW  - homeostasis
KW  - presynaptic plasticity
KW  - super-resolution microscopy
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265497
VL  - 37
IS  - 1
ER  - 
TY  - JOUR
A1  - Eiring, Patrick
A1  - McLaughlin, Ryan
A1  - Matikonda, Siddharth S.
A1  - Han, Zhongying
A1  - Grabenhorst, Lennart
A1  - Helmerich, Dominic A.
A1  - Meub, Mara
A1  - Beliu, Gerti
A1  - Luciano, Michael
A1  - Bandi, Venu
A1  - Zijlstra, Niels
A1  - Shi, Zhen-Dan
A1  - Tarasov, Sergey G.
A1  - Swenson, Rolf
A1  - Tinnefeld, Philip
A1  - Glembockyte, Viktorija
A1  - Cordes, Thorben
A1  - Sauer, Markus
A1  - Schnermann, Martin J.
T1  - Targetable conformationally restricted cyanines enable photon-count-limited applications
JF  - Angewandte Chemie Internationale Edition
N2  - Cyanine dyes are exceptionally useful probes for a range of fluorescence-based applications, but their photon output can be limited by trans-to-cis photoisomerization. We recently demonstrated that appending a ring system to the pentamethine cyanine ring system improves the quantum yield and extends the fluorescence lifetime. Here, we report an optimized synthesis of persulfonated variants that enable efficient labeling of nucleic acids and proteins. We demonstrate that a bifunctional sulfonated tertiary amide significantly improves the optical properties of the resulting bioconjugates. These new conformationally restricted cyanines are compared to the parent cyanine derivatives in a range of contexts. These include their use in the plasmonic hotspot of a DNA-nanoantenna, in single-molecule Förster-resonance energy transfer (FRET) applications, far-red fluorescence-lifetime imaging microscopy (FLIM), and single-molecule localization microscopy (SMLM). These efforts define contexts in which eliminating cyanine isomerization provides meaningful benefits to imaging performance.
KW  - biology
KW  - super-resolution microscopy
KW  - conformational restriction
KW  - cyanine dyes
KW  - DNA nanotechnology
KW  - fluorescent dyes
KW  - single-molecule fluorescence spectroscopy
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256559
VL  - 60
IS  - 51
ER  -