[About effect of habitat and motor activity of molluscs on fatty acid composition of triglycerides and phospholipids].

A comparative analysis of fatty acids (FA) in neutral and phospholipids of digestive gland and pedal muscle has been performed in molluscs from various ecological groups differing by belonging to sea or fresh water, trophic types or the associated motor activity. In freshwater pulmonary gastropods Lymnaea stagnalis and Limnaea ovalis and marine prosobranchial molluscs Buccinum undatum and Littorina littorea the total content of omega3-acids in phospholipids of the studied tissues differed more than twice, predominantly due to the combined effect of temperature and salinity of the habitat. The lower viscosity of cell membranes in marine species (omega3/omega6 < 1) is determined to the greatest degree by the presence of eicosapentaenoic acid that accounts for 22-25 % of the FA sum in marine species. Comparison of the molluscs by their trophic belonging has revealed the presence of linoleic acid in triglycerides in digestive glands of phytophages (8-12 %), but the practically complete absence of this acid in the predator B. undulatum (<0.8 %. By mobility, L. littorea inhabiting the high-low tide littoral was inferior to freshwater pulmonary gastropods and to marine predator, as it stops moving twice a day during the low tide. In phospholipids of pedal muscle of this mollusc the amount of long-chain polyunsaturated C:22 FA was 3-6 times lower than that in other studied species, which might possibly indicate the role of these acids in functioning of the pedal muscle contractile tissue. On the whole, use of the FA characteristics as parameters determining belonging to certain ecological group requires a certain caution due to a complex action of biotic and abiotic factors on the animal metabolism. The exception is the omega3/omega6 ratio in total phospholipids of freshwater and marine gastropods.