title: Signal input for a chemotactic response in the cellular slime mold Dictyostelium discoideum.
abstract: Drops with different concentrations of 3':5'-cyclic AMP were deposited at various distances from small populations of Dictyostelium discoideum amoebae, and the distances over which 50% of the amoebae drops reacted positively were determined. The linear regression analysis of a bouble logarithmic plot of distance against concentration gives a straight line with a slope of 1/4.25, which value suggests that the amoebae respond to a spatial gradient of cyclic AMP concentration. The threshold value for the signal is 3.6 X 10(-9) M/mm with a sensitivity of measurement of about 1%. These findings are discussed in relation to our present knowledge of cyclic AMP receptors.
mesh_terms: D002633:Chemotaxis; D000242:Cyclic AMP / Q000494:pharmacology; D004023:Dictyostelium / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D008433:Mathematics; D009235:Myxomycetes / Q000502:physiology*
chemical_list: D000242:Cyclic AMP