Dr. Murai Éva szerk.: Parasitologia Hungarica 16. (Budapest, 1983)
Parasit, hung. 16. 1983. Studies on the lipase activity of parasitic Platyhelminths Dr. István MATSKÁSI — Éva HAJDÚ Veterinary Medical Research Institute, Hungarian Academy of Sciences, Budapest, Hungary "Studies on the lipase activitiy of parasitic Platyhelminths" - Matskási, I. - Hajdú, É. - Parasit, hung., 16: 53-57. 1983. ABSTRACT. Both the somatic extract and the maintenance medium of the liver fluke ( Fasciola hepatica ) possess lipase activity. The liver fluke does not enter into interrelation with pancreatic lipase of the host. Enzyme-histochemical reactions proved that lipase activity was localized primarily in the epithelial cells of the intestine, although a weaker positivity was demonstrated also in the tegument. Tapeworms are able to decompose the lipids present in their environment, which property can be attributed to their lipase activity. The species studied failed to inhibit the activity of mammalian pancreatic lipase present in their environment. Enzyme-histochemical studies revealed the presence of lipase activity both in the tegument and the subtegument. KEY WORDS: Lipase activity; enzyme-histochemical reactions; Fasciola hepatica; Ligula intestinalis, plerocercoids; Mesocestoides corti, tetrathyridium larvae. The knowledge available on the lipase activity of parasitic tapeworms is very scanty. Genuine lipase activity has been found by biochemical methods in the extract of Schistosoma man- soni cercaria (MANDLOWITZ et al. , 1960). Twenty-four hours after placing the extract of cercaria on a glycerol-tripalmitate film, the needle-shaped crystals of palmitic acid apperaed, indicating the decomposition of glycerol-tripalmitate. By enzyme-histochemical methods, lipase was demonstrated in the intestinal epithelial cells of the liver fluke (SMYTH, 1966). This agreed with the observation of HALTON (1963) that the extract had lipase activity. Tapeworms do not secrete lipase into their environment. This fact suggests that they adsorb the decomposition products (monoglycerids, fatty acids) derived from lipids digested by the host's lipase (von BRAND, 1973). Nevertheless, tapeworms do have lipase, as it was demonstrated during the analysis of somatic extracts (PENNOIT-DE COOMAN and van GREMBERGEN, 1942; BAILEY and FAIRBAIRN , 1968). The lipase of Hymenolepis diminuta hydrolyses the adsorbed monoolein on the body surface or in its neighbourhood, and uses the resulting fatty acids for its own lipid synthesis (BAILEY and FAIRBAIRN, 1968). In an environment containing bile or sodium-taurocholate the adsorption is much more intensive, i.e. the labelled fatty acids appear in the worm within a shorter time (BAILEY and FAIRBAIRN , 1968). The pancreatic lipase of the host is inhibited by Hymenolepis diminuta (RUFF and READ, 1973). This inhibition is reversible: after removing the worms, the enzyme resumes its original activity. The degree of inhibition depends on the magnitude of the worm's surface and on pH. Studies have proved that Hymenolepis diminuta does not produce a lipase inhibitor,
