Vorträge & Seminare

  • 24.05.2018: CNMPB Lecture: Real-time Three-dimensional, Nanometer-Accuracy Tracking of Single Synaptic Vesicles in Live Hippocampal Neurons.
    Vorträge & Seminare
    Donnerstag, den 24. Mai 2018, 13 Uhr,
    Max Planck Institute of Experimental Medicine, Library Seminar Room

    CNMPB Lecture: Real-time Three-dimensional, Nanometer-Accuracy Tracking of Single Synaptic Vesicles in Live Hippocampal Neurons.

    Hyonkeun Park, Hong Kong University of Science and Technology, Hong Kong, China

    The position and movement of synaptic vesicles in presynaptic terminals are important for synaptic transmission. However, accurate three-dimensional tracking of single synaptic vesicles in presynaptic terminals has remained a challenge. Using dual-focus imaging optics, we have been able to track quantum dot (Qdot)-labeled single vesicles in three-dimensions, with an accuracy of 20 nm in x-y and 30 nm in z in 10 Hz imaging. We observed three typical patterns of movement of single vesicles up to the moment of exocytosis – minimal (almost stationary), intraboutonic, and intersynaptic movement. Interboutonic movement was the most prevalent whereas intersynaptic movement was the least prevalent and sometimes appeared as largely unidirectional motion, in some cases for distances larger than the average interbouton spacing.

    Using different loading protocols, we tracked the dynamics of synaptic vesicles derived from either the readily releasable pool (RRP) or total recycling pool (TRP). The vesicles from the RRP were located much closer to fusion sites than those from the TRP. This spatial disparity determines the identity of the synaptic vesicles pool but is not mutually exclusive of other possible sources of functional differences. Also two different modes of exocytosis - full-collapse-fusion and kiss-and-run - were distinguished using the degree of quenching of quantum dot photoluminescence by micromolar trypan blue. Vesicles that underwent kiss-and-run traveled shorter distances before fusion than those which underwent full-collapse fusion; vesicles originating from the RRP before Qdot loading showed more kiss-and-run than ones drawn from the whole recycling pool. Both findings support the idea that the choice between fusion modes is not solely determined at the last moment but depends on prior vesicle state, including starting position before stimulation and pool of origin.

    In order to determine the location of releasing position relative the center of the active zone, we localized the centroids of spectrally separable markers, FM 4-64 (presynaptic sites) and PSD 95-GFP (postsynaptic sites) in three dimensions using the same methods as Qdot loaded vesicles. The vector connecting these centroids approximated the central axis of the synapse, and allowed us to estimate the degree to which fusion occurred at positions away from the center of the active zone. We found that synaptic vesicles undergoing kiss-and-run tend to fuse close to the center of the active zone whereas vesicles undergoing full-collapse fusion tend to fuse all around the synapse. This difference of fusion mode may be related to the difference in the spatial distribution of AMPA and NMDA receptors, implying the relation between fusion mode and synaptic transmission.


    Announcement_incl. Abstract



    organizer: Katrin Willig / CNMPB
    publisher: cnmpb

Kurse & Konferenzen

  • 24.05.2018: Barrells and Beyond 2018
    Kurse & Konferenzen
    Donnerstag, den 24. Mai 2018 — Freitag, den 25. Mai 2018,
    Max Planck Institute for Experimental Medicine, Hermann-Rein-Str. 3, 37075 Göttingen

    Barrells and Beyond 2018

    various speakers / cf program

    May 24-25th 2018

    This conference is jointly organized by the Collaborative Research Center SFB 889 "Cellular Mechanisms of Sensory Processing" and the previous Swiss-German Research Unit Barrel Cortex Function.

    For further information please visit http://www.barrels2018.uni-goettingen.de/index.html.


    organizer: SFB889, Swiss-German Research Unit Barrel Cortex Function
    publisher: cnmpb

Microscopy Club

  • 12.07.2018: A chemometric view of super-resolution fluorescence imaging
    Microscopy Club
    Donnerstag, den 12. Juli 2018,
    Laser Laboratory Göttingen - Hans-Adolf-Krebs-Weg 1, 37075 Göttingen, Seminar Room

    A chemometric view of super-resolution fluorescence imaging

    Cyril Ruckebusch, Université des Sciences et Technologies de Lille, Lille, France

    Super-resolution wide-field fluorescence microscopy can provide structural information at the nanoscale and dynamic insight about biological processes in live cell samples. In general, the available information in super-resolution images is related to the density of emitters, with more emitters leading to more information. One of the strategies for obtaining a high spatial resolution is based on the sequential imaging and localization of sparse subsets of blinking fluorophores distributed over thousands of images, resulting in a high-density image of their positions and intensities. However, to obtain a high spatial resolution on short time sampling, and potentially probe dynamic processes in live cells, this principle must be extended to the analysis of high-density of emitters distributed over a few tens of movies frames only. As many emitters are simultaneously active, their emissions strongly overlap and single-emitter fitting methods collapse. Thus, analyzing high-density super-resolution data, the development of new methods remains a challenging issue for dynamic imaging and faster super-resolution. 

    The core of our approach is the SPIDER algorithm for SParse Image DEconvolution and Reconstruction.1 Image deconvolution is tackled in a penalized regression framework with a combination of a sparseness and an inter-frame penalty. Sparseness of the spatial distribution of the fluorophore is obtained with an L0-norm penalty on their estimated intensities, effectively constraining the number of fluorophores per frame. Simultaneously, continuity of the fluorophore localizations is obtained penalizing the total numbers of pixel status changes between successive frames.2 Additionally, a high-density of the fluorophore labelling translates into the presence of significant auto-fluorescence background and strong bleaching of the fluorophores, masking the blinking.3 Preprocessing is thus required at a very first step towards a super-resolution image, and combination of spatial and temporal approaches might be required. Overall, we show on simulations and read data that better contrasted, better resolved and more accurate estimates of the final super-resolution images of cellular structures can be obtained.




    organizer: CNMPB
    publisher: CNMPB

Mikroskopie im Nanometerbereich und Molekularphysiologie des Gehirns
Exzellenzcluster 171 — DFG Forschungszentrum 103

Das menschliche Gehirn ist eine der komplexesten Strukturen, die die Natur jemals hervorgebracht hat. Mindestens einhundert Milliarden Neurone und zehn mal so viele Glia-Zellen bilden ein kompliziertes Netzwerk, das tagtäglich Außergewöhnliches leistet - wie z.B. Wahrnehmen, Lernen und Erinnern. Die moderne Molekularphysiologie untersucht dabei wie die molekularen Prozesse in Zellen und Zellverbänden komplexe physiologische Netzwerkprozesse des Gehirns steuern. Umfassende Kenntnisse dieser Vorgänge sind Voraussetzung für ein besserers Verständnis von Krankheitsprozessen und für die Entwicklung verfeinerter Diagnose- und Therapienverfahren von Erkrankungen wie dem Morbus Parkinson oder der Schizophrenie. Das CNMPB verfolgt diese Ziele mit einem interdisziplinären Forschungsprogramm.

Molekulare Abläufe in Nervenzellen können am besten mit Hilfe hochauflösender Mikroskope untersucht werden. Neueste Entwicklungen, wie beispielsweise die STED-Mikroskopie, erlauben es uns mittlerweile Strukturen in lebenden Zellen im Nanometerbereich zu beobachten. Im Rahmen des Exzellenzclusters werden verschiedene Mikroskopie-Methoden weiterentwickelt, um noch höhere Auflösungen zu erzielen, um sie den Anforderungen moderner molekularbiologischer Experimente anzupassen und die oben skizzierten Fragestellungen zu adressieren.