Differential absorption and esterification of dietary long‐chain fatty acids by larvae of the dragonfly,Aeshna cyanea

In order to evaluate whether dietary long‐chain fatty acids were differentially absorbed, Aeshna cyanea larvae received 5 μl oral doses containing combinations of two radiolabeled fatty acids at nearly equal radioactive and nmolar concentrations: (1) ³H‐oleic and ¹⁴C‐palmitic acids; (2) ³H‐oleic and ¹⁴C‐stearic acids; and (3) ³H‐palmitic and ¹⁴C‐stearic acids. After 3 h or 1 day, hemolymph samples, midgut tissue, midgut contents and fat body tissue were collected and assayed for labeled fatty acids. The ³H/¹⁴C ratios indicated that there was a preference for absorption of the monounsaturated oleic acid over both saturated palmitic and stearic acids and that the shorter palmitic acid was absorbed at a higher rate than the longer stearic acid. There were also differences in the ³H/¹⁴C ratios of the various lipid classes of the midgut wall, hemolymph, and fat body that reflected differential esterifications and transport of these fatty acids. Arch. Insect Biochem. Physiol. 40:183–193, 1999. © 1999 Wiley‐Liss, Inc.