Fatty acid composition of Echinostoma trivolvis (Trematoda) rediae and adults and of the digestive gland-gonad complex of Helisoma trivolvis (Gastropoda) infected with the intramolluscan stages of this echinostome.

Gas-liquid chromatographic studies were done to determine the fatty acid composition of the digestive gland-gonad (DGG) complex of Helisoma trivolvis snails infected with the intramolluscan stages of Echinostoma trivolvis, of rediae freed from the DGG, of uninfected DGG, and of 41-day-old adult worms grown in golden hamsters. The DGG of infected snails showed significantly higher levels of stearic acid (18:0), hexatrienoic acid (16:3n-4), and docosahexanoic acid (22:6n-3) than that of uninfected snails. However, the DGG of uninfected snails showed significantly higher levels of 20:2 non-methylene-interrupted diene (NMID) and adrenic acid (22:4n-6) than that of infected snails. The profiles of other fatty acids were remarkably similar in both infected and uninfected snails. Adult worms showed significantly higher amounts of numerous saturated fatty acids and dienes as compared with the rediae. However, the rediae showed significantly higher amounts of certain monoenes and trienes as compared with the adults. Fatty acid differences between rediae and adults probably reflect differences in either the available lipid pools in the immediate host sites or the metabolic activity of each stage of this echinostome.