Effects of heat and piperidine incubations on pBR322 plasmid DNA gel shifts after exposure to chromic chloride for 24 h. Representative gel illustrating reaction of CrCl3•6H2O (0 – 300 μM) with pBR322 DNA (0.2 mM DNA-P, 25.0 mM ACES, pH 6.5, 37 °C, 24 hr) followed by post-treatment exposure to water (30 min, RT) (lanes 1–4), water and heat (30 min, 60 °C) (lanes 5–8) or 30 μM piperidine and heat (30 min, 60 °C) (lanes 9–12).