Geldoc itts2 310 imager system

pBR322 DNA plasmid (New England Biolabs, UK) in PBS (100 ng, 20 µL) was incubated with 0.5 MBq (8 µL) [²⁰¹Tl]TlCl₃ for upto144 h. [²⁰¹Tl] TlCl₃, originally formed using chloramine-T (method 6), was neutralised with Na₂CO₃ (0.1 M). Controls included untreated plasmid in PBS and equivalent amounts of non-radioactive [^natTl]TlCl₃ (Sigma). After treatment, plasmid (50 ng in PBS) was mixed with 6× loading dye (16 µL total volume), loaded onto a 0.8% agarose gel containing 10 µL GelRed Nucleic Acid stain (Biotium, USA) and run at 100 V (400 mA, 50 W) for 40 min. Gels, imaged using a GelDoc-ItTS2 310 Imager system (BioRad, UK) coupled with a Benchtop UV transilluminator (UVP) and GelCam 310, were analysed by ImageJ, measuring supercoiled (intact DNA), relaxed circular (single strand breaks) and linear band (double strand breaks) percentages within a lane (n = 3–12) [33 (link)].