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. Author manuscript; available in PMC: 2012 Feb 1.
Published in final edited form as: Mol Microbiol. 2010 Dec 13;79(3):729–742. doi: 10.1111/j.1365-2958.2010.07481.x

Figure 6. Analysis of DNA supercoiling by chloroquine-agarose gel electrophoresis of the gonococcal cryptic plasmid.

Figure 6

Extracted plasmid DNA from the parental, phrB mutant (PhrB−), and complement strains were analyzed by agarose-gel electrophoresis in the presence of 2.5 μg/ml chloroquine. The direction of migration of less negatively supercoiled DNA (+) and more negatively supercoiled DNA (−) is indicated next to each chloroquine gel image. Plots show the relative density of the parental (black), phrB mutant (red), and complement (blue) strains at the relative distance from the nicked circular plasmid DNA (arrowed). A. Shows untreated gonococci. B. Shows gonococci treated with the DNA gyrase inhibitor, nalidixic acid. C. Shows gonococci treated with the oxidative damaging agent, H2O2.