Fig. 7. Assays of cell streaming and chemotaxis. (A) In the cell streaming assay, micrographs were taken 7-8 hours after plating the amoebae on non-nutrient medium. (B) In the chemotaxis assay, cells were pulsed with 75 nM cAMP (final concentration after each pulse) for the time required for maximum expression of cAMP receptors (see text), washed and allowed to adhere to a coverslip, and photographed at 15-second intervals. The micropipette contained 10 µM cAMP.