Figure 3: Intramolecular topological interlink in plasmid DNA. (A) AFM image of intramolecular topological interlink in pBR322 DNA with 0.5μg/ ml EB intercalation. Arrows point pBR322 DNA molecules in Archimedean spiral-like structure. (B) Model of Archimedean spiral-like DNA structure. The line represents double-strand DNA. (C) Model for intramolecular topological interlink. (D) AFM image of pBR322 DNA. Typical pBR322 DNA (arrows) and the points of ITL (arrowheads). (E) AFM image of pBR322 DNA with 20μg/ ml EB intercalation. (F) Model of pBR322 DNA conformation change with EB intercalation.