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Christian Specht"Connect the dots: Photoactivated Localisation Microscopy of Synapses"

Abstract :

The visualisation of the sub-synaptic organisation has been hampered by the limited spatial resolution of optical microscopy.
The recent development of super-resolution imaging strategies makes it now possible to achieve a spatial resolution below the diffraction limit of light. In the case of photoactivated localisation microscopy (PALM) the sequential photo-conversion and imaging of individual fluorophores provides a means to calculate their location with very high precision. Nanoscopic images can then be reconstructed from a large number of such image frames. In contrast to electron microscopy the advantage of PALM imaging is that it can also be performed on living cells to study temporal morphological changes that a structure undergoes.
The actin cytoskeleton of dendritic spines plays a key role in morphological aspects of synaptic plasticity. We have implemented a strategy for the visualization of morphological changes of dendritic spines over tens of minutes at a lateral resolution of 25 to 65 nm. We have generated a low-affinity photoconvertible probe, capable of reversibly binding to actin and thus allowing long-term photoactivated localisation microscopy of the spine cytoskeleton. Using this approach, we can resolve structural parameters of spines and record their long-term dynamics at baseline conditions and in response to pharmacologically induced synaptic activity. 

Selected publications

Super-resolution dynamic imaging of dendritic spines using a low-affinity photoconvertible actin probe.Izeddin I, Specht CG, Lelek M, Darzacq X, Triller A, Zimmer C, Dahan M.PLoS One. 2011 Jan 17;6(1):e15611.
Behavioral deficits and subregion-specific suppression of LTP in mice expressing a population of mutant NMDA receptors throughout the hippocampus.Chen PE, Errington ML, Kneussel M, Chen G, Annala AJ, Rudhard YH, Rast GF, Specht CG, Tigaret CM, Nassar MA, Morris RG, Bliss TV, Schoepfer R.Learn Mem. 2009 Sep 30;16(10):635-44. Print 2009.
SAP97 and CASK mediate sorting of NMDA receptors through a previously unknown secretory pathway.Jeyifous O, Waites CL, Specht CG, Fujisawa S, Schubert M, Lin EI, Marshall J, Aoki C, de Silva T, Montgomery JM, Garner CC, Green WN.Nat Neurosci. 2009 Aug;12(8):1011-9. Epub 2009 Jul 20.

groupe Valentin Nagerl