Effects of salinity changes on variation of cell shape and single cell glycerol content of Dunaliella salina were investigated and effects of salinity changes on the gene expressions of a (NAD+)-dependent G3pdh (EC1.1.1.8) among G3pdh isozymes in D.salina were detected by real-time quantitative PCR.Results showed that the changes of shape and volume of D.salina cell cultured chronically at various salinities were minor.When the salinity changed rapidly,the variations of cell shape and cell volume of D.salina were significant,which were recovered basically after 2 h except treated by high salinity.It was found that some lipid globules in the surface of D.salina cells when the salinity increased from 2.0 to 4.0-5.0 mol/L NaCl rapidly.When D.salina was cultured chronically at various salinities,the accumulation of single cell glycerol increased with increased salinity, and D.salina also could rapidly decrease or increase single cell glycerol contents to adapt to hypoosmotic or hyperosmotic shock.The expression level of G3pdh in D.salina grown at various salinities was significantly inversely correlated with the salinity.There was no significant correlation between the expression level of G3pdh and salinity after two hours of treatment by hyperosmotic or hypoosmotic shock.