Lipogenesis from C14-Acetate by the American Cockroach1

Abstract

Adult American cockroaches (Periplaneta americana L.) were injected with an aqueous solution of 1-C14-sodium acetate, and held for 24 hours. On analysis, the rate of fatty acid synthesis from C14-acetate was found to be 2.5 to 4.7 times greater in male than in female cockroaches. Analysis of the fatty acid methyl esters by gas-liquid chromatography demonstrated the relative distribution of radioactivity to be similar for both sexes. Both the male and female cockroaches incorporated approximately the same percentage of radioactivity into the unsaponifiable fraction. Fractionation by column chromatography demonstrated that 59% to 68% of the radioactivity behaved as hydrocarbons and 5% to 8% as sterols. None of the radioactivity in the hydrocarbon fraction behaved as squalene when analyzed by paper chromatography. Only low levels of radioactivity were found in the digitonin precipitates of the sterol fraction, none of which showed distinct peaks corresponding to either the Δ5 or Δ5,7 sterol acetates following acetylation and chromatography on alumina.