Effects of accumulation of 3-O-Methylglucose on levels of intracellular glycerol inDunaliella tertiolecta

Regulation of the concentration of osmotic solute was studied inDunaliella tertiolecta grown at an external salinity ranging between 0.5 and 1.5 mol/L NaCl. The total solute content of the cells was increased by applying 3-O-methylglucose (8 mmol/L), which was not metabolized, but accumulated at concentrations ranging between 7.5 and 12.5 μmol per mg dry mass within 2 h after its addition to the medium. 3-O-Methylglucose uptake resulted in a decreased concentration of glycerol, the solute mainly responsible for adaptation ofD. tertiolecta to high external salinity. 3-O-Methylglucose had no direct effect on the pathway of glycerol synthesis or degradation after external salinity increased or decreased, respectively. Thus, 3-O-methylglucose had no direct effects on glycerol metabolism, and it can bo assumed that it acts solely as an inert osmotic solute with the cells. 3-O-Methylglueose accumulation increased the respiration rate, as expected from an active transport.