Dr. Murai Éva szerk.: Parasitologia Hungarica 11. (Budapest, 1978)
No linear relationship was demonstrable between the intensity of infection (i.e. total parasite weight) and drop of the gut protease activity (Table 4) Table 3 Protease activities of gut wall extracts (U/ml.) Infected Non-infected Significance P x SD n x SD n BAEE-splitting activity 3.14 0.65 10 3.18 0.88 10 ^>0.05 BTEE-splitting activity 2.72 0.57 10 3.13 0.79 10 ">0.05 Protease activity determinations in intestinal rinsing fluids were followed by similar assays in the gutwall extracts. Unlike rinsing fluids, neither trypsin nor chymotrypsin activity differed between extracts prepared from the guts of infected and non-infected fry (Table 3). Table 4 Relationship between gut enzyme activities and the intensity of infection April August October BAEE-splitting y= 8.667-83. 333x y = 1. 424-2. 448x y = 1.807+2. 136x activity n 10 16 10 2 r 0. 5 0. 155 0. 12 BTEE-splitting y= 2.888+0.007X y = 4.024-3. 131x y = 0.034+2. 596x activity n 10 16 10 2 r 0.04 0.02 0. 132 I KseuBsion Formerly only a trypsin-like protease had been detected in the fish gut (PHILLIPS, 1969; BARRINGTON, 1957), but later testing in a strong alkaline medium (optimal pH range: 10.0 - 11.0) revealed the presence of certain not nearer identified protease in the gut of the common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix) (ONISHI, MURAYAMA and TAKEUCHI, 1973a; RÁGYANSZKI and JÓNÁS, 1977). The activity of the digestive enzymes, including protease, depends on many factors in fishes. Secretion and function of such enzymes are considerably influenced by the temperature and pH of the water habitat, seasonal fluctuations in the external environment, length of time between feed intakes and quality of the feed (PHILLIPS, 1969; REICHENBACH-KLINKE and REICHENBACHKLINKE, 1969; ONISHI, MURAYAMA and TAKEUCHI, 1973a, b). Activity was also found to differ between given intestinal segments (BRAUN, HELD and RIEDMÜLLER, 1969; RÁGYANSZKI and JÓNÁS, 1977). Variations due to these factors were eliminated in the present study by comparing the gut enzyme activities measured in infected fishes to those found in contemporary non-infected fry hatched and kept under identical conditions in the same pond of
