The inhibitory effect of glucose on the differentiation of trophic Hartmannella culbertsoni into viable cysts.

During encystation of Hartmannella culbertsoni induced by taurine or epinephrine, 60-70% of the reserve glycogen is degraded. Glycogen phosphorylase is activated and glycogen synthetase is inhibited after 6-8 hr of exposure to the encystation medium. The carbon skeleton of glycogen but not that of protein is utilised in the synthesis of cyst wall cellulose. Exogenously added glucose (225 and 550 mM) blocks encystation, degradation of glycogen and synthesis of cellulose. Cyclic AMP synthesis is also very much reduced in cells exposed to glucose.