Dr. Murai Éva szerk.: Parasitologia Hungarica 13. (Budapest, 1980)

Parasit. Hung. 13. 1980. Ligula intestinalis (Cestoda: Pseudophyllidea): Studies on the OC-amylase Activity of Plerocercoid Larvae Dr. István MATSKÁSI Veterinary Medical Research Institute of the Hungarian Academy of Sciences, Budapest "Ligula intestinalis (Cestoda: Pseudophyllidea): Studies on the ct-amylase activity of plerocercoid larvae" - Matskási, I. - Parasit. Hung. _13. 27-34. 1980. ABSTRACT. Pancreatic oC-amylase activity was found to increase in the presence of live plerocercoid larval stages of the cestode Ligula intestinalis. The larvae presumably possess an intrinsic amylase activity, and are capable of adsorbing environmental amylase. The somatic extract of L. intestinalis larvae failed to stimulate the activity of mammalian amylase. The experimental observations suggest that the quantitative relations of enzyme adsorption depend on the actual metabolic rate of the larvae. The tegument of cestodes has multiple functions. It protects the body of the parasite, absorbs the nutriments and eliminates (excretes) or secretes certain metabolic products. Investigations into the structural details of the tegument have led to closer studies of its functions (SMVTH, 1967, 1972; KWA, 1972b; LUMSDEN, 1975; PAPPAS and READ, 1975). In the light of newer experimental observations the tegument of cestodes has been regarded as a special "absorptive-digestive" surface (SMYTH, 1972) which resembles the mammalian gut in many aspects of structure and function. The application of UGOLEV s (1965) "membrane (^contact) digestion" theory to the tegument of cestodes has greatly promoted the development of this conception. The operation of a membrane digestion mechanism in cestodes was implied first from electron microscopic observations (SMYTH et al. , 1967), later from physiological and biochemical studies on several cestode species (TAYLOR and THOMAS, 19 68; KWA, 19 72a; READ, 1973). It was shown that the in vitro amylolytic activity of bacterial oC-amylase tended to increase in the presence of cestodes. The amylolytic activity of Hymenolepis diminuta could be removed by three washes (READ, 1973). The hydrolytic activity of mammalian OC - amylase failed to increase in the presence of dead cestodes. The presence of intrinsic amylase in Hymenolepis diminuta could be neither proved nor disproved. Authors generally agree that, like the mammalian gut, the surface of the cestodean tegument adsorbs mammalian pancreatic or bacterial amylase, which play an important role in the processes of membrane (contact) digestion. The purpose of the present study was to examine the plerocercoid larval stages of Ligula intestinalis for oC-amylase activity, and to obtain more information on the adsorption of mammalian ot-amylase by these stages. MATERIAL AND METHODS Plerocercoid larvae of L. intestinalis were collected from the body cavity of different fish hosts (Rutilus rutilus, Abramis brama, Cobitis taenia) naturally infected by Ligula intestinalis (Cobitis taenia may also harbour larvae of the species L. colymbi Zeder, 1803; /DUBININA, 1966/, but we believe that the stages collected by us were all larvae of L. in testinalis /L. , 1758/.) The larvae were washed, if not stated otherwise, three times in sterile saline, using a fivefold volume relative to larval body weight, or in sterile Krebs-Ringer-Tris solution (KRT; READ, ROTHMAN and SIMMONS, 1963).