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 incorp orate [C-14]-acetate into phospholipid (PL), triacylglycerol (TG), and free fatty acid (FFA) fractions. In the presence of sodium octanoate (SO) or so dium phenylethylpropionate (PHEP), lipid synthesis is inhibited in a dose-d ependant manner. When eggs are incubated in vivo with [C-14]-acetate, the u sual fatty acid products are largely palmitic and oleic acids. However, in the presence of SO (5-10 mM), the elongation of [C-14]-acetate units is int errupted at [C-14] eight total carbons. Eggs incubated in vivo with [C-14]- 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 fa tty acid synthetases (FAS's), measured as [C-14]-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. (C) 20 00 Elsevier Science Inc. All rights reserved.