Background: Enzymes contained in excretion-secretion (ES) products of parasites released to the environment play multiple roles: they facilitate hatching and moulting of larvae, enable a parasite to migrate within tissues, inhibit blood coagulation, defend the parasite from host's immunological response, and enhance feeding and nutrition. The aim of the study was to determine hydrolase activity in ES products and extracts from adult Contracaecum rudolphii.
Materials and methods: Adult nematodes were isolated from intestines of black cormorants nesting at Katy Rybackie (the Vistula Lagoon). Nematode batches of 30 individuals each were placed in 5 ml portions of antibiotic-enriched physiological salt solution and incubated for 24 hours at 37 degrees C. After incubation, the solutions containing ES products were collected and dialysed for 24 h at 4 degrees C against distilled water. Extracts were obtained by homogenising the nematodes with the physiological salt solution (0.9% NaCl). The homogenate was centrifuged for 10 minutes at 3000xg. Enzyme activities were assayed in the supernatant. The enzymatic activity in ES products and homogenates was determined with the API ZYM kit (Bio Merieux S.A., Lyon, France). Hydrolase activities were expressed in volumetric units (nmol) of the hydrolysed substrate.
Results: The nematode ES products showed 10 hydrolases to be active. The highest activity was that of esterases, except for lipase the activity of which was not detected. Among glucosidases, the highest activity was shown by alpha-glucosidase, much lower activities being typical of beta-galactosidase and N-acetyl-beta-glucosaminidase. The remaining glucosidases proved inactive. Among proteases, leucine arylamidase and valine arylamidase were found to be active only. The nematode extracts revealed activities of 15 hydrolases. The highest activity was typical of esterases. Among glucosidases, the highest activity was typical of alpha-glucosidase, beta-glucuronidase and N-acetyl-beta-glucosaminidase. Activities of the remaining glucosidases were much lower. No activity of alpha-galactosidase was detected. Among proteolytic enzymes, leucine arylamidase proved the most active, while activities of valine arylamidase and chymotrypsin were much lower. The remaining proteases revealed no detectable activity.
Conclusions: The ES products of adult C. rudolphii were found to contain active hydrolases which may damage the epithelium lining the host's alimentary tract. Activities of almost all glucosidases in the parasite's extracts suggests that, like in most nematodes, the parasite's main energy source is derived from carbohydrate metabolism.