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Summary: 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.

Fragestellung: Olecranonmehrfragmentfrakturen werden in der Regel mittels Plattenosteosynthese operativ stabilisiert. Postoperative Weichteilirritationen bis hin zur Wundheilungsstörung und Infektion stellen die häufigste Komplikation dar. Neue Flachprofilplatten mit Reduktion der Weichteilprobleme[zum vollständigen Text gelangen Sie über die oben angegebene URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019)

Synaptic plasticity is considered to underly information processing and memory formation in the brain and stabilization of neurotransmission during plasticity likely includes reorganization of active zones (AZs). Here, we used localization microscopy and hierarchical density-based spatial clustering to probe AZ architecture at the Drosophila melanogaster neuromuscular junction. We observed distinct arrangements of the scaffold protein Bruchpilot (Brp) at AZs of high release probability type Is and low release probability type Ib boutons. Most remarkably, Brp proteins at type Is AZs were arranged more compact than at type Ib AZs. To ascertain whether adaptations of the AZ scaffold also occur in response to short-term demands, we used philanthotoxin (PhTx) to induce acute homeostatic plasticity. PhTx decreased AZ size, the distance between Brp subclusters and the AZ center, leading to compaction of the Brp scaffold. These changes only occurred at type Ib but not type Is AZs which, already compact, did not undergo structural rearrangement. In summary, our data describe a molecular compaction of the AZ scaffold reflecting the functional demands at high release probability synapses and during an acute homeostasic challenge.