The fidelity of adaptative phototaxis
CIC nanoGUNE Seminars
- Speaker
-
Idan Tuval, DAMPT, University of Cambridge, Cambridge, UK
- When
-
2010/09/21
13:00 - Place
- nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
- Add to calendar
-
iCal
Along the evolutionary path from single cells to multicellular organisms with
a central nervous system are species of intermediate complexity that move in
ways suggesting high-level coordination, yet have none. Instead, organisms
of this type possess many autonomous cells endowed with programs that have
evolved to achieve concerted responses to environmental stimuli. Here,
experiment and theory are used to develop a quantitative understanding of how
cells of such organisms coordinate to achieve phototaxis, using the colonial
alga Volvox carteri as a model. It is shown that the surface somatic cells act
as individuals, but are orchestrated by their relative position in the
spherical extracellular matrix and their common photoresponse function to
achieve colony-level coordination. Analysis of models that range from the
minimal to the biologically faithful shows that because the flagellar beating
displays an adaptive down-regulation in response to light, the colony needs to
spin around its swimming direction, and that the response kinetics and natural
spinning frequency of the colony appear to be mutually tuned to give the
maximum photoresponse. These models further predict that the phototactic
ability decreases dramatically when the colony does not spin at its natural
frequency, a result confirmed by phototaxis assays in which colony rotation
was slowed by increasing the fluid viscosity