Journal of Cell Science, Vol 107, Issue 2 659-667, Copyright © 1994 by Company of Biologists

JOURNAL ARTICLES

The regulation of chemotaxis and chemokinesis in Dictyostelium amoebae by temporal signals and spatial gradients of cyclic AMP

MG Vicker
Department of Biology, University of Bremen, Federal Republic of Germany.

The tactic and kinetic locomotion of Dictyostelium discoideum amoebae were examined in cyclic AMP (cAMP) spatial gradient and temporal signal fields. The distributions of migrating cells were examined within 150 microns-thick micropore filters after incubation with different cAMP concentrations, [cAMP], applied in three ways across the fields: as positively or negatively developing gradients, generated either by increasing or decreasing the [cAMP] on one side of the filter, respectively, or as static, linear gradients after negative development. Chemotaxis was only induced by oriented, temporally increasing [cAMP]. Pulses propagated by molecular diffusion or mechanical flow were equally effective. Negatively developing cAMP gradients had no initial effect on cell accumulation. However, if the subsequent static spatial gradient was maintained by an infusion system, some gradients also induced cell accumulation, whose degree and direction depended on the gradient [cAMP]. The basis of this new effect was examined by tracking individual cells by computer-assisted videomicroscopy during locomotion in different [cAMP]. Cells produced a triphasic [cAMP]-dependent response, with optimal cell motility induced by 10-30 nM. The results demonstrate that cell accumulation either up-field or down-field in spatial gradients is governed by the field locations of the attractant concentrations that induce the relative locomotory maxima and minima in the gradient field. Cells perceive the ambient [cAMP], but cannot read the spatial gradient orientation in static or yet steeper regions of developing gradients. Accumulation in static spatial gradients is a function of klino- and orthokinesis, but chemotaxis requires an oriented cAMP pulse or impulse.(ABSTRACT TRUNCATED AT 250 WORDS)
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				E. Decave, D. Rieu, J. Dalous, S. Fache, Y. Brechet, B. Fourcade, M. Satre, and F. Bruckert Shear flow-induced motility of Dictyostelium discoideum cells on solid substrate J. Cell Sci., November 1, 2003; 116(21): 4331 - 4343. [Abstract] [Full Text] [PDF]

				T Tani and Y Naitoh Chemotactic responses of Dictyostelium discoideum amoebae to a cyclic AMP concentration gradient: evidence to support a spatial mechanism for sensing cyclic AMP J. Exp. Biol., January 1, 1999; 202(1): 1 - 12. [Abstract] [PDF]

				E. Albrecht and H. R. Petty Cellular memory: Neutrophil orientation reverses during temporally decreasing chemoattractant concentrations PNAS, April 28, 1998; 95(9): 5039 - 5044. [Abstract] [Full Text] [PDF]

				Y. Tintut, F. Parhami, K. Bostrom, S. M. Jackson, and L. L. Demer cAMP Stimulates Osteoblast-like Differentiation of Calcifying Vascular Cells. POTENTIAL SIGNALING PATHWAY FOR VASCULAR CALCIFICATION J. Biol. Chem., March 27, 1998; 273(13): 7547 - 7553. [Abstract] [Full Text] [PDF]