Schistosoma haematobium: oxidoreductase histochemistry and ultrastructure of niridazole-treated females

Administration of niridazole to Saccostomus campestris produced changes in enzyme activity in Schislosoma haematobium females as indicated histochemically by a decrease in the activity of cytochrome oxidase (EC 1.9.3.1), malate (NAD) dehydrogenase (EC 1.1.1.37), malate (NADP) dehydrogenase (EC 1.1.1.40), succinate dehydrogenase (EC 1.3.99.11), isocitrate (NAD) dehydrogenase (EC 1.1.1.41), isocitrate (NADP) dehydrogenase (EC 1.1.1.42), lactate dehydrogenase (EC 1.1.1.27), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), NADH: tetrazolium oxidoreductase, NADPH: tetrazolium oxidoreductase, and a disappearance of both the activity of phenolase (EC 1.10.3.1) and the reactivity of vitelline phenols. These changes were associated with the following alterations in the ultrastructure of the parasites: a decrease in number of immature vitelline cells of gonial type, a disruption of the tegument surface, a swelling of mitochondria in vitelline cells, a disappearance of the regular structure of the endoplasmic reticulum and a vaeuolization of the cytoplasm in vitelline cells, an appearance of areas of focal cytoplasmic degradation in vitelline cells, and a disruption of shell globules. The degree of changes in enzyme activity and ultrastructure increased both with increase in the dose of niridazole administered to the hosts, and with length of time after treatment.Preincubation of control sectioned material in a buffered niridazole-sucrose solution produced total inhibition of succinate dehydrogenase activity, whereas the activity of other enzymes examined remained unchanged.