Chemotaxis in Dictyostelium: how to walk straight using parallel pathways.

Dictyostelium is one of the most successful and best-studied organisms for research into the mechanisms that drive chemotaxis. In this review, we discuss recent progress in the field. Phosphatidylinositol 3-kinase (PI 3-kinase), previously thought by some to be essential for chemotaxis, has now been proven to be dispensable. However, other pathways are emerging which might connect signalling to migration. In particular, phospholipase A2 homologues appear to play an important role. Other areas of current interest include the fundamental processes by which cells move - pseudopods have been found to be generated in many different ways. Similarly, chemotaxis may be mediated by multiple checks on the number of pseudopods, rather than by simple generation of new pseudopods on demand. Finally, we review several advances in the theory of how cells convert shallow, noisy chemical gradients into overt movement.