Factors affecting protein synthesis in Hymenolepis diminuta (Cestoda)

Abstract

1. 1. The cestode, Hymenolepis diminuta, incorporated C 14-labeled amino acids from the ambient medium into protein. The amino acids tested were incorporated at rates which did not correspond directly to the apparent internal concentration of the amino acid. The incorporation rate of lysine-C 14 was linear during a 2-hr incubation period. 2. 2. Starvation produced a depression in the corporation of lysine-C 14. Preincubation of starved worms in glucose slightly stimulated the incorporation whereas 3-0-methylglucose produced no stimulation. 3. 3. The presence of CO 2 caused a marked stimulation of lysine-C 14 incorporation in both starved and unstarved worms. The presence of glucose in the preincubation medium further enhanced this stimulation in starved worms. 4. 4. Incubation with 2,4-dinitrophenol inhibited the incorporation of lysine-C 14 by per cent. DNP abolished the stimulatory effects of CO 2 and glucose on lysine-C 14 incorporation in starved worms, substantiating the central role of CO 2 in energy metabolism of the worm. 5. 5. Galactose stimulated lysine-C 14 incorporation, but was not as effective as glucose. 6. 6. The significance of CO 2 and glucose in the metabolism of the parasite is discussed.