The Effect of Trematode Infection on the Content of Certain Lipid Groups in the Organism of Planorbarius purpura

Investigating the effect of trematode infection on the physiological and biochemical status of freshwater molluscs is an important area of hydrobiological research, as trematodes are widespread parasitic organisms capable of significantly affecting the metabolic homeostasis and adaptive capabilities of their host organisms. The aim of this study was to determine the nature of changes in the content and tissue-organ distribution of total lipids and their individual groups (triacylglycerols, phospholipids and cholesterol) in the haemolymph, hepatopancreas, mantle and foot of Planorbarius purpura under the influence of trematode infection. The content of total lipids was determined by the gravimetric method following extraction using the Folch method, whilst that of individual lipid groups was determined by one-dimensional thin-layer chromatography. Statistical analysis of the results was carried out using one-way analysis of variance. It was established that trematode infection causes pronounced tissue-specific changes in the content and ratio of individual lipid groups in the bodies of the studied molluscs. In the hepatopancreas of infected animals, a statistically significant increase in total lipid content of 87.6% was recorded (p < 0.001), whilst in the foot and haemolymph this figure decreased by 21.1% and 41.18%, respectively (p < 0.05). This increase in total lipid content in the hepatopancreas may be associated with the accumulation of triacylglycerols and the development of compensatory and adaptive responses in the molluscs’ bodies. The content of phospholipids and cholesterol decreased in most of the tissues and organs studied under trematode infection, which may indicate a disruption in the structural organisation of biological membranes. The exception was the mantle of P. purpura, in which the cholesterol content increased by 44.4% (p < 0.01). Analysis of the tissue- and organ-specific distribution of individual lipid groups showed that phospholipids were quantitatively predominant in the hepatopancreas, mantle, foot and haemolymph of intact molluscs. Under conditions of trematode infection, the most pronounced changes were observed in the hepatopancreas, mantle and foot of P. purpura, where the proportion of triacylglycerols increased, whilst in the haemolymph, phospholipids remained the dominant lipid group. Thus, trematode infection is accompanied by marked tissue-specific changes in the content and distribution of individual lipid groups within the body of P. purpura. The parameters determined can be used as biochemical markers of the physiological and biochemical status of freshwater molluscs during the biomonitoring of aquatic ecosystems.