Some MglA point mutations give a dominant-negative phenotype. Addition of a second copy of the mgl locus depressed the motility phenotypes of merodiploids. A: Linear model of MglA. B: Swarming on 1.5% CTPM agar (top graph) and 0.3% CTPM agar (bottom graph). Bars are colored with respect to location within a conserved motif (red for PM1, green for PM3 and purple for G2), matching the colors used in Figure 10A. Yellow bars represent the mgl merodiploids MxH2375 (WT+mglBA) and MxH2391 (WT+mglB) respectively. The dashed lines provide comparison to merodiploid control, while the dotted line in the upper panel provides comparison to MxH2391. Strains which make detectable mutant MglA in complementing strains are circled. C. Colony edge morphology of selected merodiploids relative to WT and merodiploid controls. Pictures were obtained from isolated colonies on 1.5% CTPM agar at 100× magnification. Bar = 25 μm.