Oxidative enzymes in the development of Fasciola hepatica L. V. Activity of oxidases and dehydrogenases in the Cercaria and Metacercaria.

The object of the study was the investigation of the occurrence and localization of oxidative enzymes in the 4th and 5th larval stages of the liver fluke, i. e. in the cercaria and metacercaria. The following enzymes were detected: cytochrome oxidase, peroxidase, NADH and NADPH tetrazolium reductases/diaphorases) as well as succinate, isocitrate, malate, lactate, alpha-glycerophosphate, glyceraldehyde phosphate, glucose-6-phosphate, 6-phosphogluconate, beta-hydroxybutyrate, L-glutamate and alcohol dehydrogenases. The occurrence and localization of the enzymes were investigated histochemically in the cercaria still unreleased from the snail tissues, in the free natatorial cercaria, and in the encysted specimen, i.e. metacercaria. Among the enzymes studied only peroxidase was found to be absent from the cercaria and metacercaria, the latter larva being deprived of alcohol and L-glutamate dehydrogenases as well. The aerobic path, i.e. the Krebs cycle, was ascertained as the principal mode of obtaining energy in the free natatorial cercaria and metacercaria, and glycolysis as the main energy path for the undetached larva. The analysis of the above-mentioned oxidative enzymes was the basis for the description, within the available range, of the function and metabolism of individual organs of cercaria in different periods of its development. In the recapitulation the author discusses the effect of the parasitic way of life of the larval forms of Fasciola hepatica on their energy metabolism.