title: Dictyostelium discoideum chemotaxis: threshold for directed motion.
abstract: The chemotactic response of Dictyostelium discoideum cells to stationary, linear gradients of cyclic adenosine 3',5'-monophosphate (cAMP) was studied using microfluidic devices. In shallow gradients of less than 10(-3) nM/microm, the cells showed no directional response and exhibited a constant basal motility. In steeper gradients, cells moved up the gradient on average. The chemotactic speed and the motility increased with increasing steepness up to a plateau at around 10(-1) nM/microm. In very steep gradients, above 10 nM/microm, the cells lost directionality and the motility returned to the sub-threshold level. In the regime of optimal response the difference in receptor occupancy at the front and back of the cell is estimated to be only about 100 molecules.
authors.affiliation: Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Loling
authors.initials: L
authors.lastname: Song
authors.forename: Sharvari M
authors.initials: SM
authors.lastname: Nadkarni
authors.forename: Hendrik U
authors.initials: HU
authors.lastname: Bödeker
authors.forename: Carsten
authors.initials: C
authors.lastname: Beta
authors.forename: Albert
authors.initials: A
authors.lastname: Bae
authors.forename: Carl
authors.initials: C
authors.lastname: Franck
authors.forename: Wouter-Jan
authors.initials: WJ
authors.lastname: Rappel
authors.forename: William F
authors.initials: WF
authors.lastname: Loomis
authors.forename: Eberhard
authors.initials: E
authors.lastname: Bodenschatz
mesh_terms: D000818:Animals; D002633:Chemotaxis / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D004023:Dictyostelium / Q000166:cytology / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D044085:Microfluidics / Q000295:instrumentation / Q000379:methods
chemical_list: D000242:Cyclic AMP