Polyunsaturated fatty acids in neutral lipids and phospholipids of some freshwater insects

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 114; no. 2; pp. 161 - 170
• Main Authors: Ghioni, C., Bell, J.G., Sargent, J.R.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1996
• Subjects: Coleoptera; Diptera; Ephemeroptera; Freshwater; Hemiptera; insects; lipids; phospholipids; Plecoptera; polyunsaturated fatty acids; lipids; PC; phosphatidylethanolamine; PS; PE; PUFA; polyunsaturated fatty acids; PI; TLC; phospholipids; insects; Freshwater
• ISSN: 1096-4959; 0305-0491; 1879-1107
• DOI: 10.1016/0305-0491(96)00019-3

The fatty acid compositions of total neutral lipids and total polar lipids from eight species of freshwater insects were determined: stonefly nymphs (Plecoptera), beetle larvae (Coleoptera), Chironomidae (Diptera), water boatmen (Corixidae and Notonecta; Heteroptera) and mayfly nymphs ( Ecdyonurus venosus, Caenis, Ephemerella; Ephemeroptera). In addition, the compositions of individual phosphoglycerides were determined for four of the species (Plecoptera, Corixidae, Ecdyonurus venosus and Emphemerella). Saturated and monounsaturated fatty acids together represented up to 85% of the fatty acids of total neutral lipids with 16:0 (18–31%) being the most abundant saturated fatty acid and 16:1n-7 (10–28%), 18:1n-9 (6–12%) and 18:1n-7 (3–12%) the most abundant monounsaturates. Polyunsaturated fatty acids (PUFA) accounted for between 16% and 33% of the total fatty acids of neutral lipids, with 20:5n-3 (4–12%), 18:3n-3 (3–30%) and 18:2n-6 (1–8%) all being major components. Arachidonic acid, 20:4n-6 (0.4-1.0%) and 22:6n-3 were, respectivety, minor and insignificant components of total neutral lipids. PUFA were major fatty acids (34–56% of the total) in total polar lipids and in phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. The major PUFA present were 20:5n-3 (14–27%) and 18:3n-3 (6–23%). The most abundant n-6 PUFA, especially in phosphoglycerides from Corixidae, was 18:2n-6 (3–11%). Arachidonic acid, 20:4n-6, was present in all phosphoglycerides accounting for 1–4% of the total fatty acids, except in the phosphatidylinositol of Corixidae where it accounted for 12% of the total. 22:6(n-3) was not present in significant amounts in any phosphoglyceride in any species. 18:1n-9 (8–20%) and 18:1n-7 (2–14%) were the most abundant monounsaturated fatty acids, especially in phosphatidylethanolamine. 16:0 was abundant in phosphatidylcholine (11–21%), and 18:0 (17–23%) was abundant in phosphatidylserine. The results are discussed in relation to the functions and origins of PUFA in freshwater insects.