Abstract
The kinetoplast DNA (kDNA) of cultured Trypanosoma cruzi consists mostly in a large network of numerous minicircular molecules (.apprx. 25,000), with a very low degree of superhelicity. When the intercalating drugs ethidium bromide and 9-hydroxyellipticine were added to the growth medium in concentrations producing trypanocidal effects, the superhelicity of the kDNA was significantly increased. The nonintercalating drug berenil had no effect on the superhelicity of kDNA. In the kDNA extracted from trypanosomes resistant to ethidium bromide or 9-hydroxyellipticine, those drugs induce similar effects, although to a lesser extent than in the wild strain.