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. Author manuscript; available in PMC: 2013 Sep 1.
Published in final edited form as: Mol Microbiol. 2012 Jul 26;85(6):1119–1132. doi: 10.1111/j.1365-2958.2012.08163.x

Figure 3. Sub-lethal challenge with polymyxin B alters the distribution of anionic membrane lipids.

Figure 3

Cultures of S. pyogenes SF370 were stained with NAO following challenge with 0 μM (A), 30 μM (B) or 60 μM (C) polymyxin B or heat shock at 42°C (D) and examined by fluorescent microscopy (scale bar = 1μm). The distribution of polymyxin B following higher, but still sub-lethal challenge, was revealed by treatment with biotinylated polymyxin B (1:500) and immunogold electron microscopy using staining with a streptavidin-gold conjugate (scale bar = 200nm) (E) and by fluorescent microscopy following challenge with dansyl-polymyxin B alone at the concentration indicated in the Figure (scale bar = 1μm) (F) or costained with fluorescent vancomycin (G). Staining patterns following challenge were quantitated as described previously (H). Data represents the mean and SEM derived from at least 3 independent experiments and examination of a minimum of 1000 stained cells. The number of cells with multiple foci was significantly higher than any other staining pattern (P < 0.0001) at this polymyxin B concentration.