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SUMMARY:Model systems to study embryonic patterning. - Dr Benoit Sorre\, N
 ational Center for Scientific Research\, Paris
DTSTART:20150521T133000Z
DTEND:20150521T143000Z
UID:TALK58079@talks.cam.ac.uk
CONTACT:Caroline Newnham
DESCRIPTION:Genetics and biochemistry have defined the components and wiri
 ng of the signaling pathways that pattern the embryo. Many of these pathwa
 ys have the potential to behave as morphogens: in vitro experiments have c
 learly established that these molecules can dictate cell fate in a concent
 ration dependent manner. How morphogens convey positional information in a
  developing embryo\, where signal levels are changing with time\, is less 
 understood. Recently we showed that the evolutionarily conserved TGFβ pat
 hway responds transiently and adaptively to a step in ligand stimulation. 
 In the first part of my talk I will present how using integrated microflui
 dic cell culture to stimulate the cells with well-defined temporal profile
  of morphogen (TGFβ) and timelapse microscopy to record their response in
  realtime\, we demonstrated that the speed of ligand presentation has a ke
 y and previously unexpected influence on signaling outcomes. Slowly increa
 sing the ligand concentration diminishes the response while well-spaced pu
 lses of ligand combine additively resulting in greater pathway output than
  is possible with constant stimulation.\nOur results suggest that in an em
 bryonic context\, an adaptive pathway can naturally extract positional inf
 ormation as ligand spreads from a fixed source\, thereby providing an alte
 rnative to the static morphogen model where the rate of change of ligand c
 oncentration\, rather than its level\, is the meaningful signal for patter
 ning.\nIn a second part of my talk\, I will present how using adhesive mic
 ro-patterns as a tool to control Embryonic Stem Cells colony size and shap
 e provides a very promising in vitro model system to study the spatial sel
 forganization occurring during one of the first the pattering event in the
  embryo: the transition from pluripotency to the 3 germ layers.
LOCATION:Part II Room\, Department of Genetics
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