DEPARTMENT OF MATHEMATICAL & STATISTICAL SCIENCES
UNIVERSITY OF ALBERTA
  

MATHEMATICAL BIOLOGY SEMINAR
 

MONDAY, NOVEMBER 4, 2002

3:00 PM

CAB 657
 

Dr. R. Tyson

Department of Mathematics and Statistics
 
Okanagan University College

 

A Minimal Mechanism of Bacterial Pattern Formation

 

Colonies of Escherichia coli or Salmonella typhimurium form geometrically complex patterns when exposed to, or feeding on, intermediates of the tricarboxylic acid (TCA) cycle.  In response to the TCA cycle intermediate, the bacteria secrete aspartate, a potent chemoattractant.  As a result, the cells form high-density aggregates arranged in striking regular patterns.  The simplest are temporary spots formed in a liquid medium by both E. coli and S. typhimurium.  In semi-solid medium S. typhimurium forms concentric rings arising from a low-density bacterial lawn, which are either continuous or spotted.  In contrast, E. coli forms complex patterns arising from a dense swarm ring, including interdigitated spots (also called sunflower spirals), radial spots, radial stripes and chevrons.  We present a mathematical model that captures all three of the pattern-forming processes experimentally observed in both E. coli and S. typhimurium, using a minimum of assumptions.

 

 

This seminar is partially funded by the Pacific Institute for the Mathematical Sciences (PIMS)