A study of the neutral lipids and phospholipids of the acanthocephala Macracanthorhynchus hirudinaceus and Moniliformis dubius

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)

Observations on the lipids of Oochoristica agamae (Cestoda)

An investigation of the lipids of Oochoristica agamae, an anoplocephalid cestode of the Agama lizard, was undertaken. Total lipids of the parasite accounted for 8.4% of the fresh weight; neutral lipids comprised 82.98% of the total, glycolipids, 5.01%, and phospholipids, 12.03%. The major lipid classes in O. agamae include triglycerides, cholesterol, phosphatidyl choline, and phosphatidyl ethanolamine. The 16- and 18-carbon fatty acids were predominant in the parasite. Hexadecenoic acid, usually found at low concentrations in the lipids of helminth parasites, was the most abundant of the 16-carbon fatty acids of O. agamae (notably in the neutral lipid fraction). Although octadecatrienoic acid occurred only in trace amounts in the intestinal contents of the host, significant amounts of this fatty acid were detected in the parasite. A lack of 20-carbon fatty acids was determined in the lipids of the host's intestinal contents and the neutral lipid fraction of the parasite. O. agamae is suspected to be capable of modifying fatty acids obtained from dietary sources by chain elongation.

Fatty acids in female Macracanthorhynchus hirudinaceus (Acanthocephala)

Neutral lipids and phospholipids in the body wall, lemnisci and pseudocoel and neutral lipids of fluid found in the "tube" system of the lemnisci and the lacunar system of the body wall of Macracanthorhynchus hirudinaceus (Acanthocephala) were determined by the technique of thin layer chromatography and gas chromatography (GC). Sixteen different fatty acids from nonpolar lipids were identified as follows: 8:0, 10:0, 11:0, 12:0, 13:0, 14:0, 14:1, 16:0, 18:0, 18:1, 18:2 and/or 20:0, 18:3 and/or 20:1, 20:3, 22:1, 24:1 and 22:6. In addition, there were three unidentified GC peaks corresponding to chain lengths greater than 20 carbons. Sixteen different fatty acids from phospholipids were identified in each of the three fractions analyzed. They were as follows: 10:0, 11:0, 12:0, 13:0, 14:0, 14:1, 16:0, 16:1, 18:0, 18:1, 18:2 and/or 20:0, 20:2, 20:3, 22:1, 24:1 and 22:6. Four unidentified peaks were also observed. There was a significant difference in the percentage of lipid as well as the concentration of particular fatty acids when each fraction was compared. There was also an abundant supply of sterols and glycerides in each fraction.

[A study on the lipids of Chinese liverfluke, Clonorchis sinensis]

The present study was undertaken to observe the quality and quantity of lipids in the adult worms of Chinese liverfluke, Clonorchis sinensis. Lipid extraction was done by the methods of Folch et a1. (l957) and Kenny (1952), and then the extracted lipid fractions of the worm were separated by thin layer chromatography. Those fractions were also subjected to perform the quantitative analyses of glycerides, cholesterols and phospholipids. The results obtained were summarized as follows: 1. Total amount of glyceride was 37.56 mg per gram of worm tissue and the amount of monoglyceride was 8.34 mg per gm; diglyceride, 15.46 mg per gm; and triglyceride, 12.86 mg per gm. 2. Total amount of cholesterol was 3.30 mg per gm of worm tissue, and the esterified cholesterol (1.72 mg/gm) was a little more than that of free cholesterol (1.26 mg/gm). 3. The following 8 phospholipids were detected in the worm tissue of C. sinensis, i.e., lysophosphatidylcholine, phosphatidylcholine, phophatidylinositol, sphingomyelin, phosphatidylglycerol, phosphatidylserine, phosphatidylethanolamine and an unknown phospholipid.

The effect of ageing on the metabolism of the infective larvae of Strongyloides ratti Sandground, 1925

The infective larvae ofS. rattihad a high Qo2(9·8 μl/mg dry weight/h at 20 °C). Their R.Q. was 0·74 indicating that lipid was the main metabolite.

As the infective larvae aged there was an exponential decrease in their infectivity and a corresponding decrease with age in the Qo2rate of activity and rate of substrate utilization. The R.Q. of fresh and aged larvae was the same showing that there was no change in the substrate being utilized.

The infective larvae ofS. ratticontained 25% lipid 3% glycogen and 0·25% free sugars (dry weight). The free sugars consisted of glucose and trehalose in approximately equal amounts. Both lipid and glycogen decreased as the larvae aged.

Analyses showed all the normal lipid components to be present, the major lipid fraction detected was free fatty acid. As the larvae aged there was a big decrease in the amounts of triglyceride and free fatty acid. There was, however, no difference in the amounts of cholesterol or in the phospholipid composition of fresh and aged larvae.

The fatty-acid composition of the larvae was analysed; 68% of the total fatty acids were unsaturated and the major fatty acid was C18:1. As the larvae aged, the fatty acids were not all catabolized at the same rate; the acid C18:1was the most heavily catabolized decreasing by 75% in 8 days, whilst C20:1decreased by only half this amount in the same time.

The distribution of lipid and glycogen was investigated histochemically. Lipid droplets were confined to the posterior two-thirds of the infective larvae and occurred in the lateral lines, non-contractile parts of the muscles and in the cells of the intestine. As the larvae aged the lipid in the body wall and lateral lines disappeared first. Dark granules, possibly excretory products, accumulated in old larvae. Glycogen was found in the lateral lines throughout the length of the larva.

I should like to thank Dr P. Tate for his constant advice and encouragement. This work was carried out during the tenure of a Medical Research Council scholarship.