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TZID:Europe/Paris
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BEGIN:VEVENT
UID:1-307@lptms.universite-paris-saclay.fr
DTSTART:20141117T110000Z
DTEND:20141117T120000Z
DTSTAMP:20141112T202023Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-julien-heuvingh/
SUMMARY:Physics-Biology interface seminar: Julien Heuvingh - Moyen Amphi\, 
 Building 510\, Université Paris-Saclay Orsay - 17 Nov 14 11:00
DESCRIPTION:Mechanics and growth of the actin cytoskeleton probed by magnet
 ic micro-objects\nJulien Heuvingh (PMMH\, ESPCI)\nThe ability of cells to 
 perform essential processes such as migration or deformation relies on the
 ir cytoskeleton\, and especially on the structures and networks formed by 
 the actin polymer and its associated proteins. Understanding the dynamics 
 and the mechanics of the actin filaments and its multiple partner is a maj
 or goal at the frontier of biology and physics. Our team developed a new e
 xperimental setup to study the mechanics of in vitro reconstituted actin n
 etworks\, with an unprecedented throughput. This technique is based on sel
 f-organized chains of micron-size magnetic beads or cylinders where the co
 ntrolled attractive dipolar force between the colloids deforms the actin n
 etworks. We characterized for the first time the mechanics of actin networ
 ks reconstituted with different concentrations of purified proteins\, lead
 ing to networks of different architectures\, and drew conclusions on the o
 rigin of the elasticity on these networks (Pujol et al PNAS 2012). We are 
 now measuring mechanical properties of networks reconstituted from yeast e
 xtract which allows comparison between a wild type containing hundred diff
 erent actin binding proteins to mutants lacking some of them. Our experime
 ntal setup was decisively improved by the fabrication of magnetic micro-ob
 jects of cylindrical or cubic shape (Tavacoli et al. Soft Matter 2013) all
 owing the deformation of actin networks between two flat surfaces. In this
  way\, we can access properties of dense branched networks such as non-lin
 ear elasticity and Poisson modulus\, which are required to test theoretica
 l models of fiber networks (Mikado). We are currently studying the growth 
 velocity of the actin gel as a function of an applied mechanical stress an
 d the architecture of the networks. I will also present other applications
  of our magnetic methods to probe the mechanics of whole cells.\n\n[captio
 n id="attachment_26491" align="aligncenter" width="502"] Actin networks (g
 reen) growing from the side of magnetic cylinders. Superimposition of brig
 ht field image (gray) and fluorescent image (green). Cylinder length is ~1
 2µm.[/caption]
LOCATION:Moyen Amphi\, Building 510\, Université Paris-Saclay Orsay\, 15 R
 ue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
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  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Moyen Amphi\, Building 510\, Un
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