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SUMMARY:Guided mechanochemical self-organization
DTSTART:20170202T103000
DTEND:20170202T113000
DTSTAMP:20260406T185235Z
UID:cd39d9cfa37a7ffbefab423937a7bc1230236318b5ad796481177ae8
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Peter Gross\, TU Dresden\nAbstract:\nBiological systems ha
 ve the fascinating ability to form very intricate spatial structures. Non-
 linear\, out-of-equilibrium processes have long been recognized for their 
 ability to generate complex patterns\, like e.g. the prominent Turing patt
 erns. These self-organized reaction-diffusion mechanisms are thought to be
  at the heart of many biological patterning process\, however\, the impact
  of forces and flows on pattern formation are largely unexplored.\nHere\, 
 we uncovered a new class of biological pattern-formation mechanism that is
  based on guided mechanochemical self-organization\, in the PAR polarity e
 stablishment in the C. elegans embryo. During this stage\, the C. elegans 
 egg generates two membrane-domains. These are populated with either the an
 terior or the posterior PAR proteins\, which coordinate the first asymmetr
 ic cell division. In this process\, we identified mechanochemical feedback
  as a crucial network motif that couples flows in the actomyosin cytoskele
 ton and membrane-bound PAR proteins. Essential for this was a combination 
 of quantitative fluorescence microscopy\, cell biological perturbations an
 d theoretical modeling. We measured the cellular and subcellular concentra
 tion dynamics of posterior and anterior PAR proteins and non-muscle myosin
  (NMY-2) as the mechanical force generator\, along with the cortical flow 
 field. We uncovered that the PAR domains differentially alter the binding 
 / unbinding kinetics of NMY-2 to establish a contractility gradient and th
 us drive flow of the actomyosin cytoskeleton. Finally\, we developed a nov
 el physical theory for PAR polarity patterning\, incorporating mechanical 
 forces via active gel theory. We find that mechanochemical feedback betwee
 n the PAR domains and the actomyosin cortex is strong enough to overcome a
  system-intrinsic velocity threshold of PAR polarity establishment\, but n
 ot so strong that the mechanochemical system becomes unstable to spontaneo
 us fluctuations. This study aims to provide new insight into the role of a
 ctive mechanics in the biological pattern formation process.\n 
LOCATION:PH H3 31 https://plan.epfl.ch/?room==PH%20H3%2031
STATUS:CONFIRMED
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