A comparative study of transacylation in three insect species

Abstract

The acyl specificity of microsomal glycerophosphate transacylase from the wax moth, Galleria mellonella, and the blowfly, Lucilia sericata, could not explain the fatty acid composition of these two insects. Differences in acyl specificity between the two species did, however, reflect the differences in fatty acid composition of the species.Variable acyl specificity between replicate preparations of L. sericata microsomal glycerophosphate transacylase suggests there are specific sites on the enzyme for each fatty acid and that the number of sites is variable.In the hymenopterous parasitoid Exeristes roborator, glycerophosphate transacylase activity was not detected in the cytosolic, mitochondrial, or microsomal fractions. Microsomal preparations incorporated palmitate from labelled palmitoyl-S-CoA into the diglyceride and triglyceride fractions indicating an active monoglyceride pathway. These results suggest the parasitoid incorporates glycerides directly from the host. The absence of the glycerophosphate pathway partially explains the fatty acid mimicry which is a feature of E. roborator lipid metabolism.