Physiology and lipid metabolism of Littorina saxatilis infected with trematodes

[摘要] ABSTRACT: Physiological and biochemical alterations in Littorina saxatilis infected with larval trematodes were investigated and compared with the metabolism of non-parasitized snails. Oxygen consumption rates of infected snails differed from thoseof non-infected controls in medium sized individuals (30 to 130 mg) but not in very large infected individuals (>200 mg). Small snails (0.5 to 8.5 mg) were seldom infected by parasites, and this size-class consisted only of non-infected specimens. Thespecific oxygen consumption rate of infected snails was not dependent on their mass and remained constant over the size ranges investigated. Alterations in the snail metabolism appeared to be connected to injuries to digestive gland tissues caused by theparasites. The glycogen concentration and fatty acids of neutral lipids and phospholipids in the digestive gland were determined. Infected snails differed from uninfected snails in the complete absence of glycogen in digestive gland and had proportionallyhigher quantities of eicosenoic (20:1) acid in the total phospholipids. It remains unclear whether infection by trematodes activates enzymes in the snail’s digestive gland to synthesize eicosenoic (20:1) acid, or whether the sporocysts themselvespossess these enzymes. The role of phospholipid fatty acids in the regulation and maintenance of the parasite’s metabolism is briefly considered. Biochemical alterations observed in the fatty acid composition may have an adaptive significance, byhelping to stabilize the host-parasite system.

[学科分类] 生物科学（综合）

[关键词] Littorina saxatilis;Metabolism;Trematodes;Digestive gland;Phospholipids;Fatty acids