Effects of organic acids on lipid synthesis and ecdysis in Triatoma infestans eggs.

Medium chain fatty acids are known inhibitors of the activity of lipogenic enzymes at the transcriptional level. Mature Triatoma infestans eggs incorporate [14C]-acetate into phospholipid (PL), triacylglycerol (TG), and free fatty acid (FFA) fractions. In the presence of sodium octanoate (SO) or sodium phenylethylpropionate (PHEP), lipid synthesis is inhibited in a dose-dependent manner. When eggs are incubated in vivo with [14C]-acetate, the usual fatty acid products are largely palmitic and oleic acids. However, in the presence of SO (5-10 mM), the elongation of [14C]-acetate units is interrupted at [14C] eight total carbons. Eggs incubated in vivo with [14C]-SO, accumulate most of the label in the FFA fraction. SO (> 0.1 mM) but not sodium hexanoate (SH), inhibits the activity of microsomal and cytosolic fatty acid synthetases (FAS's), measured as [14C]-malonyl-CoA incorporation. PHEP (1 mM) and SO (10 mM) also produce major alterations in egg hatching and survival of the emerged insects, after a 1 h immersion bioassay.