Chemotactic Patterns without Chemotaxis

Entry: Chia Wei Hsu, AP 225, Fall 2010

M.P. Brenner, Chemotactic Patterns without Chemotaxis, Proc. Natl. Acad. Sci, 107, 11653–11654 (2010).

Summary

This commentary addresses the study by Cates et al (ref 1) where an effective model is used to describe the pattern formation in chemotaxis. In particular, the effective model ignores the details of the chemotactic mechanisms but focuses on averaged effect, thus greatly reducing the complexity of the modeling. Brenner uses this study as an example to show the promise of using effective models to understand biological systems.

Pattern Formation in Chemotaxis

Chemotaxis is the phenomenon where bacteria and other organisms direct their motion based on the environment. For example, bacteria can swim up the food concentration gradient to get to a region with more food, or swim down the poison concentration gradient to avoid poisoning.

The chemotaxis phenomenon results in pattern formation. Is has been found that (ref 2) when chemotactic bacteria swim through a small tube of rich medium, the bacteria form a dense band that moves at constant velocity.

References

[1] Cates ME, Marenduzzo D, Pagonabarraga I, and Tailleur J, "Arrested phase separation in reproducing bacteria: A generic route to pattern formation," Proc Natl Acad Sci USA 107, 11715–11720 (2010).

[2] Adler J, "Chemotaxis in bacteria," Science 153, 708–716 (1966).