Effects of chemoattractant pteridines upon speed of D. discoideum vegetative amoebae.

Movements of D. discoideum vegetative amoebae responding to pteridine chemoattractants, folate acid and pterin, were recorded. A vector analysis of these images was performed to partition the speed and orientation components of these motility patterns. This study demonstrates that in addition to orientation (chemotaxis), stimulated speed (chemokinesis) is an important component of the directed migration of these amoebae. Furthermore, the primary difference in their response to folate versus pterin is in speed rather than orientation. The data support a model of directed migration of these cells in which there are (1) separate signal translation pathways consequent from folate versus pterin reception and (2) specific pathways leading to increase in orientation versus speed.