De novo biosynthesis of linoleic acid in two non-insect invertebrates: The land slug and the garden snail

Abstract

The de novo biosynthesis of linoleic acid [18:2(n-6)], a fatty acid considered to be essential for most animals, was demonstrated in the land snail,Bulimulis alternatus mariae, and the garden slug,Arion circumscriptus. Radiolabeled acetate injected into the animals was incorporated into both 18:2 and 20:2, as demonstrated by radio-high performance liquid chromatography (radio-HPLC) and radio-gas chromatography (radio-GC). GC-mass spectrometry (GC-MS) of the methoxy derivatives of the 18:2 and 20:2 isolated from the snail showed that major isomers had the double bonds in the n-6,9 positions. Radio-gas-liquid chromatography (radio-GLC) of the ozonolysis products from the labeled dienoic fatty acid methyl esters showed that both ends of the molecules were labeled, confirming de novo synthesis. The production of linoleic acid by these animals suggests the capability to produce linoleic acid may be widespread in invertebrates.