ETHER LIPIDS AND THEIR POSSIBLE PHYSIOLOGICAL-FUNCTION IN ADULT SCHISTOSOMA-MANSONI

Schistosomes have lost the capability to synthesize fatty acids de nov o, but they can modify fatty acids by chain elongation. This has a pro found effect on the molecular species composition of the two main phos pholipid fractions of schistosomes, phosphatidylcholine (PC) and phosp hatidylethanolamine (PE). Molecular species of phospholipids are incre asingly recognized as important mediators, or precursors thereof, in s ignal transduction, immune response modulation, and events like membra ne fusion. As these are all important aspects of schistosome membranes and of the tegumental membranes in particular, we analysed the PE and PC molecular species of the tegumental membranes, the worm body and t he blood of the host. With the aid of on-line mass spectrometry, we un equivocally identified a large number of PC and PE species in schistos omes, among which considerable amounts of plasmalogen species. This wa s unexpected, as this lipid subclass has been assumed to be absent in the parasite. Species, like (20:1-16:0) diacyl PC and (16:0-20:1) plas malogen PE, found to be main constituents in schistosomes, were absent from the blood of the host. Large differences were also found between the molecular species composition of the tegumental-membranes and the membranes of the worm body. In the tegumental membranes, 1-hexadecyl 2-palmitoyl PC was detected, which could possibly function as a precur sor for platelet activating factor (PAF). (C) 1998 Elsevier Science B. V. All rights reserved.