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SUMMARY:The magic of membranes - where differential geometry and biology m
 eet - Timon Idema and Stefan Semrau\, Leiden University
DTSTART:20090507T120000Z
DTEND:20090507T130000Z
UID:TALK17925@talks.cam.ac.uk
CONTACT:Jan-Willem van de Meent
DESCRIPTION:Closed vesicles bounded by a single lipid bilayer membrane are
  known to exhibit a rich variety of shapes\, especially when the bilayer i
 s composed of more than one type of lipid. Using multiple-dye fluorescence
  imaging it is now possible to directly visualize these shapes in the lab.
  Some of the shapes observed in this way have surprising characteristics a
 nd appear to be caught in a dynamic\, nonequilibrium\, yet (meta)stable st
 ate. We study the vesicle shapes and use them to extract biologically rele
 vant material parameters. Moreover\, we study the dynamics of these vesicl
 es\, focussing on the most prolific shape: a vesicle containing many domai
 ns. These domains interact by deforming the membrane around them\, creatin
 g a membrane mediated repulsion which results in a patterned vesicle shape
 . We can quantify this interaction experimentally and model it by consider
 ing the effect the domains have on the curvature of the surrounding membra
 ne. From this model we can explain both the measured interaction strengths
  and observed domain size distribution. Finally\, the membrane mediated in
 teractions do not only stop the domains from coalescing and growing\, but 
 also sort them by size\, resulting in regions of largely equal-sized domai
 ns. This new sorting mechanism can be understood theoretically in a model 
 where the domains are allowed to reorganize and search for a configuration
  in which the total curvature of the entire membrane is minimized.
LOCATION:MR12\, Centre for Mathematical Sciences\, Wilberforce Road\, Camb
 ridge
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