Enrichment and partial enzyme characterization of ATPase activity associated with the outward-facing membrane complex and inward-facing membrane of the surface epithelial syncytium of Schistosoma mansoni

An association between activity of the Na/K‐pump and resistance of Schistosoma mansoni towards complement‐mediated killing

“…It is important to note that the addition of ouabain alone, at the concentration used (40 mM) affects neither the viability of the schistosomula nor the efflux of [ 3 H]Ph 4 P þ . The ouabain concentration used for the experiments reported here, is significantly lower than that required to inhibit 70% of the Na þ /K þ ATPase (1 × 10 ¹3 M) in the schistosoma adult worms (Podesta & McDiarmid 1982).…”

“…This membrane potential is maintained in part by the Na/K-pump (Fetterer, Pax & Bennett 1981, Tarrab-Hazdai et al 1986). Previously, the activity of Na þ /K þ -ATPase in the tegument of Schistosma mansoni has been demonstrated to contribute to the maintenance of the ionic balance and the uptake and extrusion of nutrients (Fetterer et al 1981, Podesta & McDiarmid 1982. However, its role as a possible repair mechanism of C-induced damage has not yet been explored.…”

Isolation and antigen analysis of surface tegument membranes from schistosomula ofSchistosoma mansoni

“…A similar activity was also reported by Simpson et al (1981); however, they recorded a pH optimum of between 9 and 10 for this activity, which contrasts with the pH 7-4-7-8 measured in our experiments. More recently, Podesta & McDiarmid (1982) have described two distinct ATPase activities in membrane fractions purported to comprise either outer tegument membranes or basal tegumental membranes. According to their results that ATPase activity associated with the outer tegumental membrane is inhibited by calcium (assayed at the same concentration used here), whereas a calcium-stimulated ATPase was associated only with the basal membranes.…”

“…According to their results that ATPase activity associated with the outer tegumental membrane is inhibited by calcium (assayed at the same concentration used here), whereas a calcium-stimulated ATPase was associated only with the basal membranes. The membrane fractions assayed by Podesta & McDiarmid (1982) were obtained by incubating adult worms with saponin. As noted earlier, the use of detergents to bring about release of the tegument raises questions as to the validity of these results; nevertheless, the discrepancies discussed clearly need further investigation.…”