Dr. Murai Éva szerk.: Parasitologia Hungarica 16. (Budapest, 1983)
RESULTS Lipase activity of the liver fluke Flukes were incubated in a fivefold volume of Tyrode solution containing antibiotics in concentrations described earlier, at 38°C for 24 h. In samples taken from the medium after 24-h incubation, 0. 80 jumol/min/ml (Srj=0.34; n=5) lipase activity was demonstrable on tributyrin substrate. On triolein substrate, samples taken from the medium showed an activity of 0.212 OD/ml (S D =0.041; n=10) as determined by the method of RUFF and READ (1973). The somatic extract of F. hepatica splits both the tributyrin and triolein substrates used for determinations. The mean lipase activity of extracts prepared from homogenates was 4.32 umol/min/ml (Sd=1.10; n=5). To examine the effect on mammalian pancreatic lipase, liver fluke specimens were incubated individually in five times their body mass Tyrode solution containing 1 mg/ml lipase (Koch Light Lab. , E.C. 3. 1. 1. 3) at 38°C for 1 h. Subsequently enzyme activity was determined using tributyrin substrate. After incubation for 1 h, the mean activity of samples taken from lipase-containing medium of flukes was found to be 0.86^imol/ min/ml (Srj = 0. 24; 4=8), while the mean activity of medium containing lipase incubated without flukes was 0. 70 pmol/min/ml. The difference between the two mean values agrees with the value of enzyme activity released by flukes into their environment (0.09 jumol/min/ml) . We obtained similar results when incubating the worms in a lipase-containing medium of higher activity for a longer time (4 h) . The mean activity of samples taken from the incubation medium of worms was 38.27 jumol/min/nil, while the mean of samples from maintenance media containing only lipase and incubated without worms was 36.16 jumol/min/ml. Also taking into consideration the enzyme activity released by the flukes, the difference between the mean values of the two groups is not significant. It can be concluded from these results that "in vitro" the liver fluke does not have an effect on the lipase of pig origin present in its environment. Lipase activity of Ligula intestinalis The experimental design corresponded to that described for F. hepatica , with the exception that examinations were made also under the following conditions: larvae were incubated for 10 min in five times their body mass KRT containing 1 mg/ml lipase (from pig pancreas. Koch Light Lab., EC. 3. 1. 1.3) and 1 mg/ml bovine serum albumin. Subsequently 10 v% Nmethyl-indoxyl-myristate (RUFF and READ, 1973) substrate was added to the incubation medium and incubated at 38°C for a further 10 min, then the worms were removed and the reaction was stopped by the addition of 0. 5% trichloroacetic acid. Based upon its tributyrin and triolein substrate splitting property, the somatic extract of L. intestinalis possesses lipase activity. The value of this activity is 0. 962 (Srj=0. 512; n=10) jimol/min/ml extract. The pH optimum of lipase activity of the tapeworm extract is 8.5. The lipase activity of extracts of plerocercoid larvae was examined by the spectrofluorometric method based upon the decomposition of N-methyl-indoxyl-myristate substrate. The obtained mean activity, expressed in rF%, was 16.64 (Srj=3.21; n=5). By the methods described above, no lipase activity could be demonstrated in the environment of plerocercoid larvae incubated in media of different composition on tributyrin or triolein substrates. On the other hand, larvae decomposed N-methyl-indoxyl-myristate. The mean activity expressed in rF% was 52.66. To examine the effect on mammalian lipase present in the environment, the larvae were incubated in fivefold volume of medium related to their weight, containing lipase of pancreatic origin, for 24 h. In the medium of larvae the lipase activity showed a significant decrease (0. 750 j umol/min/ml; Sp=0.10; n=5) as compared to the control (4. 5 jamol/min/ml). To determine the effect of somatic extract of larvae on pancreatic lipase, the extract was incubated with porcine lipase. To 10 ml Tyrode solution containing 1 mg/ml lipase, 0. 5 ml extract was added, then after incubation for 1 h enzyme activity was determined. No significant changes were observed as compared to the control (control: 4. 5 jamol/min/ml; S D =0.284; n=5).
