Metabolism of [3-¹³C]-pyruvate by cysticerci of Taenia crassiceps

Abstract

Carbon-13 decoupled ¹H spin-echo nuclear magnetic resonance (NMR) spectra, with and without ¹³C population inversion, of extracts of Taenia crassiceps cysticerci incubated in media containing [3-¹³C]-pyruvate showed ¹³C enrichment in alanine, lactate, acetate, succinate, and citrate. Labeling in the latter three metabolites provides substantial evidence that the malic enzyme reaction in this cestode also functions in the direction opposite to that in which it is normally portrayed. The direct passage of pyruvate from the cytosol to the mitochondrion is suggested by the greater percentage of ¹³C detected in acetate relative to succinate.