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SUMMARY:Motility\, Mixing\, and Multicellularity - Professor Raymond E. Go
 ldstein\, Department of Applied Mathematics and Theoretical Physics
DTSTART:20070516T153000Z
DTEND:20070516T163000Z
UID:TALK7425@talks.cam.ac.uk
CONTACT:5684
DESCRIPTION:An important issue in evolutionary biology is the emergence of
  multicellular organisms from unicellular individuals. The accompanying di
 fferentiation from motile totipotent unicellular organisms to multicellula
 r ones having cells specialized into reproductive (germ) and vegetative (s
 oma) functions\, such as motility\, implies both costs and benefits\, the 
 analysis of which involves the physics of buoyancy\, diffusion\, and mixin
 g. In this talk\, I discuss recent results on this transition in a model l
 ineage: the volvocine green algae. Particle Imaging Velocimetry of fluid f
 lows generated by these organisms show that they exist in the regime of ve
 ry large Peclet numbers\, where the scaling of nutrient uptake rates with 
 organism size is highly nontrivial. In concert with metabolic studies of d
 eflagellated colonies\, investigations of phenotypic plasticity under nutr
 ient-deprived conditions\, and theoretical studies of transport in the hig
 h-Peclet number regime\, we argue that flagella-generated fluid flows enha
 nce the nutrient uptake rate per cell\, and thereby provide a driving forc
 e for evolutionary transitions to multicellularity. Thus\, there is a link
  between motility\, mixing\, and multicellularity.\n
LOCATION:Lecture Theatre 1\, Department of Veterinary Medicine
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