See below for details of Christian Eggeling’s STED talk at IC next month…

 

 

 

Dear All

 

The next Chemical Physics seminar will be given by, Dr Christian Eggeling, Weatherall Institute of Molecular Medicine, University of Oxford.  To be held at 12 noon, Thursday 27^th March ‘14, Pippard Lecture Theatre, Sherfield Building.

 

“Investigation of nanoscale membrane dynamics using super-resolution STED microscopy”

 

 

 Abstract

 

Lipid-lipid and lipid-protein plasma membrane interactions such as the formation of lipid nanodomains (often denoted “rafts”) or restrictions of molecular plasma-membrane diffusion by cortical cytoskeleton compartments are considered to play a functional part in a whole range of membrane-associated processes. However, the direct and non-invasive observation of such structures in living cells is impeded by the resolution limit of >200nm of a conventional far-field optical microscope. With the superior spatial resolution of STED nanoscopy with effective focal spot sizes down to 20-30 nm in living cells, it is now possible to directly resolve such membrane heterogeneities, e.g., by imaging and investigating protein nanoclusters on the membrane surface [1]. On the other hand, the combination of STED nanoscopy with tools such as fluorescence correlation spectroscopy (FCS) allows the disclosure of complex nanoscopic dynamical processes. By performing FCS measurements in focal spots tuned to a diameter of down to 30 nm, we have obtained new details of molecular membrane dynamics. Unlike fluorescent phosphoglycerolipids, fluorescent sphingolipids or a number of proteins are transiently (~ 10 ms) trapped on the nanoscale in often cholesterol-mediated molecular complexes [2]. These interactions are distinct for different lipids and proteins and may play an important role in cellular functionality [3]. Comparison of these trapping characteristics to the organization and dynamics of the different fluorescent lipid analogues in model membranes reveals details of the role of lipid “rafts” [4]. On the other hand, the comparison of lipid and protein dynamics in different cells reveals different diffusion modes, mainly depending on the organization of the underlying (actin) cytoskeleton. Further, improved insights into membranes heterogeneities are realized by recent technological developments of the STED-FCS approach [5]. The novel observations shed new light on the role of lipid-protein interactions and nanodomains for membrane bioactivity in a whole gamut of cellular processes. Examples will be given for molecular processes of immune cells following infection.

 

[1] G Donnert... PNAS (2006), 103, 11440; J Sieber… Science (2007), 317, 1072

[2] C Eggeling… Nature (2009), 457, 1159; C Ringemann… New J Physics (2009) 11, 103054; G Vicidomini… Nat Meth (2011) 8, 571

[3] V Mueller… Biophys J (2011) 101, 1651

[4] E. Szegin … BBA Membr (2012) 1818, 1777; A. Honigmann… Fraday Disc. (2012) doi:10.1039/C2FD20107K

[5] G Vicidomini ... Nat. Meth. (2011)  8, 571; A Honigmann ... Laser Focus World (2012) 48, 75; V Mueller ... Biophotonics (2012) 19, 30.

 

 

 

 

All Welcome