ampA null cells are defective migrating on top ofagar; overexpressing cells move very rapidly. A) Chemotaxisplots of individual cells in a representative field. Arrows indicate thelocation of the folic acid source. Note scale difference on the plot ofampA knockout. B) Morphology of cells migrating ontop of agar. Black arrows indicate pseudopods; white arrows, uropods.Time is in seconds. Scale bars are 20 um. C) Difference plotscreated by overlaying the cell outline in frame 1 with the cell outlinein frame 2. Green represents areas of protrusion and red representsareas of retractions. D) Quantification of cell migration. Dataare the averages +/− the standard error of the mean. Differenceswere checked using a 2 tailed paired Student’s t-test with p <0.05 indicating a significant difference (*). Data are compilations of40–100 cells tracked in 6 different experiments. C.I. ChemotacticIndex (see Methods). The distance migrated (total) is in 5 minutes.Productive distance is the Euclidian distance from the start of imagingto the final time point. Directionality is the ratio of productive tototal distance and is a measure of how progressive the movement is.E) Differences in actin organization in ampA mutantcells migrating to folic acid on top of agar. Live cells carry a plasmidcontaining the ABD120-GFP fusion protein (a marker for F-actin). Wt andAmpA overexpressing cells contain the blasticidin resistant version ofthe plasmid and ampA null cells carry the G418 version of theplasmid. The direction of migration is toward the top of the image.Scale bar is 20 um.Time is in seconds.