Effects of galactose, mannitol, glucose and α-methyl-D-glucoside on the incorporation of32P-inorganic phosphate into phospholipids inHymenolepis diminuta(Cestoda)

Abstract

ABSTRACTIn the presence of glucose and galactose, the incorporation of radioactive inorganic phosphate (32Pi) into phosphatidylcholine ofHymenolepis diminutawas significantly lowered as compared to the control, whereas other phospholipids remained unaffected. α-methyl-D-glucoside, however, significantly lowered the amount of32Pi incorporated into phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and phosphatidic acid. Mannitol did not have any effect on the incorporation of32Pi into the phospholipids ofH. diminuta. The effect of glucose and α-methylglucoside on phospholipid metabolism was both time and concentration dependent. The inorganic, organic, total and phosphatidylcholine-bound phosphate ofH. diminutain the presence of various substrates were not significantly different from the control values under all incubation conditions. The results indicate that the observations made in the presence of external glucose, galactose and α-methylglucoside were due to their physical interaction with the transport mechanism in the tegumental membrane ofH. diminutaand also their being subsequently metabolized in the cases of the former two hexoses.