Title: Gradient Sensing via Cell Communication,
Abstract: The chemotactic dynamics of cells and organisms that have no specialized
gradient sensing organelles is not well understood. In fact, chemotaxis of this
sort of organism is especially challenging to explain when the external
chemical gradient is so small as to make variations of concentrations minute
over the length of each of the organisms. Experimental evidence lends support
to the conjecture that chemotactic behavior of chains of cells can be achieved
via cell-to-cell communication. This is the chemotactic basis for the Local
Excitation, Global Inhibition (LEGI) model.
A generalization of the model for the communication component of the LEGI
model is proposed. Doing so permits us to study in detail how gradient sensing
changes as a function of the structure of the communication term. The key
findings of this study are, an accounting of how gradient sensing is affected
by the competition of communication and diffusive processes; the determination
of the scale dependence of the model outcomes; the sensitivity of communication
to parameters in the model. Together with an essential analysis of the dynamics
of the model, these findings can prove useful in suggesting experiments aimed
at determining the viability of a communication mechanism in chemotactic
dynamics of chains and networks of cells exposed to a chemical concentration
gradient.