Peroxisomal acyl-CoA oxidase and chain-shortening of dietary fatty acids in the midgut of dragonfly larvae, Aeshna cyanea

Abstract

Activity of peroxisomal acyl-CoA oxidase was measured in homogenates of Aeshna cyanea midguts and found to be reversibly influenced by long-term fasting and refeeding. The enzyme was immunocytochemically colocalized with catalase in the peroxisomes of the intestinal absorptive cells. Orally administered nervonic and erucic acids were present in the triacylglycerol fraction of the midgut epithelium together with chain-shortened intermediates. But they were not detected in the diacylglycerol fraction of the haemolymph and triacylglycerol fraction of the fat body, which only contained chain-shortened intermediates. The prevalence of oleic acid in these three fractions suggests that the very long-chain fatty acids tested are assimilated by chain-shortening on their absorptive-pathway across the midgut epithelium.