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

All experimental systems were incubated for 30 minutes at 38 C. Amylase activity assayed by the dinitrosalycilic acid test. Previous experiments suggested that the amylase activity of live plerocercoid larvae recovered from fish hosts can be reduced, but not fully eliminated. The results of examinations performed to learn whether or not L. intestinalis is able to adsorb pancreatic amylase, and whether the adsorbed enzyme can be removed by washing, are shown in Table 4. Table 4 Removal of amylase activity from L. intestinalis larvae by three successive 30 min. washings in KRT Starch h ydrolysing activity Control KRT + 10 jug/ml OC - amylase KRT +parasite (initial activity) KRT +parasite + 10 .ug/ml OC-amylase Activity in washing fluids Control KRT + 10 jug/ml OC - amylase KRT +parasite (initial activity) KRT +parasite + 10 .ug/ml OC-amylase 1. 2. 3. Control KRT + 10 jug/ml OC - amylase X 0. 278 0. 540 0. 134 0. 127 0. 084 0. 220 S

2 0.016 0.0 18 0. 010 0. 001 0 n 5 5 5 5 5 Incubation medium and washing fluids were used throughout in fivefold volume relative to larval body weight. Amylase activity was determined with the dinitrosalycilic acid reagent, in 0. 5 ml samples of incubation medium and washing fluids. The larvae were preincubated in plain KRT before transfer to amylase containing KRT. Amylase activity was measured after preincubation for 30 minutes, and after each of three washes in KRT for 30 min. Adsorption of mammalian pancreatic oC-amylase by the parasites has been implied from the results shown in Table 5. Table 5 Starch hydrolysing effect of L. intestinalis larvae after preincubation in oC-amylase containing medium Per cent starch hydrolysis Larvae preincubated in KRT Larvae preincubated with oC-amylase in KRT Control cC-amylase 17. 5 43. 1 78. 1 Starch hydrolysis was assayed by the iodine method described by TAYLOR and THOMAS (1968). Larvae were washed twice in saline for 60 min. at 5°C. First group of worms was incubated in 10 mg/ml starch containing KRT for 30 min. at 38°C. Second groups of worms was incubated in 10 ug/ml a-amylase containing KRT for 30 min. at 38°C. After incubation the worms were washed in KRT for 20 min., and incubated in starch containing KRT in a similar manner. The per cent hydrolysis of starch by larvae or amylase was calculated from the means of 8-8 trials. To obtain information on the active (life function dependent) or passive nature of the mechanism of larval amylase adsorption, we preincubated larvae in enzyme containing medium at parallel two different temperatures, +5 and 38°C, for we postulated that decrease of the metabolic rate at the low environmental temperature follows a considerable deceleration