Plots demonstrating the ability of simulated E. coli cells to accumulate in response to both MeAsp and serine concentration gradients. Shown here are typical cases in which both MeAsp and serine are present within the same domain. In (A) we consider a constant concentration of serine across the whole domain, thus demonstrating the ability of simulated cells to respond to a MeAsp concentration gradient. In (B) we consider a constant concentration of MeAsp across the entire domain, thus showing that cells are able to respond to a serine concentration gradient. Within each plot green and red crosses indicate the starting and final locations of each simulated cell, respectively whilst contour lines and colour bars show the concentration of the non-constant ligand across the domain. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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