Time-lapse imaging of conformational changes in supercoiled DNA by scanning force microscopy

Fuji Nagami, Giampaolo Zuccheri, Bruno Samorì, Reiko Kuroda

    Research output: Contribution to journalArticlepeer-review

    26 Citations (Scopus)


    Most of the scanning force microscopy (SFM) images of supercoiled DNA on untreated mica thus far reported have not shown tight plectonemic structure seen by electron microscopy, but instead less coiled molecules and sometimes a partly "condensed" state with intimate chain-chain interactions. By observing time-lapse images of conformational changes of DNA induced by decreasing ionic strength of imaging buffer in solution SFM, we could show that the process of water rinsing, an indispensable step for preparation of dried samples, may be responsible for some of the conformational anomalies in the images previously reported. We have studied several protocols to observe supercoiled DNA molecules by SFM and discuss the merits and the demerits. Images obtained following uranyl acetate treatment may be ideal for the detection of DNA damage, as the supercoiled and nicked forms are easily distinguishable.

    Original languageEnglish
    Pages (from-to)170-176
    Number of pages7
    JournalAnalytical Biochemistry
    Issue number2
    Publication statusPublished - 2002 Jan 15

    ASJC Scopus subject areas

    • Biophysics
    • Biochemistry
    • Molecular Biology
    • Cell Biology


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