Metabolic pathways for diacylglycerol biosynthesis and release in the midgut of larval Manduca sexta.

CANAVOSO, LE; WELLS, MA

INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2000 vol. 30 p. 1173 - 1173

0965-1748

he pathway for the synthesis of diacylglycerol in larval Manduca sexta midgut was studied. Fifth instar larvae were fed with [9,10?3H]?oleic acid?labeled triolein and the incorporation of the label into lipid intermediates was analyzed as a function of time. The results showed that the triacylglycerol was hydrolyzed to fatty acids and glycerol in the midgut lumen. In midgut tissue, the labeled fatty acids were rapidly incorporated into phosphatidic acid, diacylglycerol and triacylglycerol, but no significant labeling of monoacylglycerol was observed. Dual-labeling experiments were performed in order to characterize the kinetics of diacylglycerol biosynthesis in the midgut, its incorporation into hemolymph lipophorin and its clearance from hemolymph. The results were best described by a model in which the rate-limiting step in diacylglycerol biosynthesis was the uptake of fatty acid from the lumen of the midgut. Once in the cell the fatty acid was rapidly incorporated in phospha