AmpA null cells migrate better than wild type underagar; overexpressing cells show reduced migration. Cells wereallowed to migrate to folic acid under agar as described in methods.Images were acquired every 10 seconds for 5 min. A) Chemotacticplots are a representative field. Arrows indicate the location of thefolic acid source. B) Morphological differences between the celltypes under agar. Black arrows represent pseudopods; white arrowsindicate uropods. Time is in seconds. Scale bar is 20 um. C)Difference plots were created by overlaying the outline of a cell inframe 1 with its outline in frame 2. Green represents areas ofprotrusion and red represents areas of retractions. D)Quantification of migration under agar on glass. The data are theaverages +/− the standard error of the mean. Differences werechecked for significance (*) using a 2 tailed paired Student’st-test, p < 0.05 was deemed significant. Data are the compilations of90–120 cells tracked in 6 experiments. The distance migrated is in5 minutes. E) Migrating under agar on glass ampAknockout cells form true pseudopods and uropods. Live cells carrying theABD-GFP plasmid were placed in a well cut in 0.8% agar opposite a wellcontaining 0.5 mM folic acid. Cells were allowed to sense the gradientfor 4–5 hours before imaging on a Leica SP5 confocal microscope.Time is in seconds. Scale bar is 10 um. The direction of migrationis to the top of the image. Wt and overexpressing cells contain theblasticidin resistant version of the plasmid and ampA nullcells carry the G418 version of the plasmid.