Sterol and fatty acid composition of neutral lipids of Paratenuisentis ambiguus and its host eel.

The sterol composition of free sterol and steryl ester fractions of the fish parasite Paratenuisentis ambiguus was determined. In addition, the fatty acid composition of various neutral lipid classes, i.e., wax esters, steryl esters, triacylglycerols and free fatty acids, as well as the composition of the 1-O-alkyl moieties of total ether glycerolipids of the parasite, were investigated. The results of these studies were compared with those obtained on the intestinal tract tissue of its host, the eel (Anguilla anguilla). Cholesterol is the major sterol in both P. ambiguus and A. anguilla. However, the sterols of P. ambiguus contain high proportions (> 20%) of other sterols, such as campesterol and various dehydrosterols. [e.g., 7-dehydrocholesterol and cholesta-5,22(E)-dienol]. The presence of these minor sterols agrees with the known biotransformations of exogenous sterols in various helminths. Considerable differences are found in the fatty acid composition of neutral lipid fractions, as well as the total lipid extract from the endoparasite as compared to the host tissue. In particular, eicosapentaenoic acid (20:5n-3), other polyunsaturated fatty acids, such as 20:4n-6, 22:5n-3 and 22:6n-3, as well as long-chain saturated fatty acids, such as 20:0, are generally enriched in the neutral lipid fractions of the parasite as compared to those of infected eel intestine.(ABSTRACT TRUNCATED AT 250 WORDS)