Influence of ofloxacin on chloroplasts and mitochondria in Euglena gracilis.

Ofloxacin (CAS 83380-47-6), a representative of new quinolones, which exerts inhibitory activity against DNA gyrase in bacteria, damages both semiautonomous organelles in Euglena gracilis: chloroplasts and partly mitochondria. The action of ofloxacin on these organelles was analysed by transmission electron microscopy. The first symptoms of ofloxacin treatment were mass aberrations of chloroplasts with subsequent diluting out of these pathological organelles from the cells, so giving rise to the heterotrophic mutants. The loss of chloroplasts is hereditary. Changes in ultrastructure of mitochondria were observed too. Cup-like (in sections ring-like) mitochondria represented the most frequent abnormalities of these organelles induced by the drug. After repeated subcultivations on ofloxacin-free media the number of damaged mitochondria gradually decreased to the normal.