Dr. Murai Éva szerk.: Parasitologia Hungarica 11. (Budapest, 1978)

Parasit Hung. 11. 1978 The Effect of Bothriocephalus acheilognathi Yamaguti, 1934 Infection on the Protease Activity in the Gut of Carp Fry Dr. István MATSKÁSI Veterinary Research Institute, Hungarian Academy of Sciences, Budapest "The effect of Bothriocephalus acheilognathi Yamaguti, 1934 infection on the protease activity in the gut of carp fry" - Matskási, I, - Parasit. Hung., 11. 51-56. 1978. ABSTRACT. Common carp fry infected by the tapeworm Bothriocephalus acheilo gnathi Yamaguti, 1934, showed significantly lower intestinal trypsin and chymotrypsin activities than non-infected fry reared in the same pond farm. Extracts prepared from larval and adult stages of the tapeworm depressed the trypsin and chymotrypsin activities of fish gut washing fluids "in vitro". Infection by Bothriocephalus acheilognathi* has been found to depress considerably the growth and development of fry. The worms adhering to the host's gut wall injure the lining epithelium, produce and secrete toxic materials, and obstruct the passage of intestinal contents mechanically, by their bulk. Further to these damages, certain not nearer understood influences of the parasite have been supposed to play a role in the pathogenesis of bothriocephalosis (BAUER, MUSSELIUS, NIKOLAEVA and STRELKOV, 1977). Physiological investigations in to the function of digestive enzymes associated with the gut of fishes diclosed that parasite infection depressed the host's intestinal protease activity (BRAUN, HELD and RIEDMÜLLER, 1968). Intestinal trypsin activity was lower in Coregonus lavaretus host's infected by the tapeworm Proteocephalus longicollis than in non-infected ones. In vitro experiments have shown that living parasites depressed the intestinal trypsin activity to a greater degree than parasite extracts added to gut extract (REICHENBACH-KLINKE and REICHENBACH-KLINKE, 1970). Mammalian trypsin and OC- and (3chymotrypsin, added to the maintenance medium of Hymenolepis diminuta, were irreversibly inactivated by the parasite (PAPPAS and READ, 1972a, b). Inhibitors inactivating mammalian parasitic trypsin and chymotrypsin were demonstrated in the maintenance medium of Ligula intestinalis plerocercoid larvae collected from breams (Abramis brama), and in extracts of homogenated larval and adult specimens as well (MATSKÁSI and JUHÁSZ, 1977). The inhibitors could be separated from plerocercoidal somatic extracts by gel chromatography and their molecular weights were estimated (MATSKÁSI and NÉMETH, 1977). Investigations into the influence of Bothriocephalus acheilognathi infection on trypsin and chymotrypsin activities in the gut of the carp fry are reported in this paper. Material and Method Carp fry collected in pond farms in Hungary were used in the experiment. The enzyme activities measured in the gut of the infected fishes were always compared to the similar activities determined in non-infected (control) exemplars taken from the same habitat. With regard to seasonal fluctuations in the intensity of infection, protease activity determinations were carried out in one experimental and one control group each in spring and sumI use the revised specific name Bothriocephalus acheilognathi Yamaguti, 1934 (syn. ; B. gowkongensis Yeh, 1955) as proposed by MOLNÁR (1977).