Effect of Environmental Silicic Concentration on ATPases of Diatom Ditylum Brightwelli Plasma Membrane

Diatom Ditylum brightwelli (West) Grunow was cultivated for 5 days, under the environment of low silicon concentration (6 mg/L), high silicon concentration (150 mg/L) and normal silicon concentration (30 mg/L, control ) respectively. Then the plasma membrane of the diatom was extracted and purified by two-phase method. After the analysis of the Na⁺/K⁺-ATPase, Ca²⁺/Mg²⁺-ATPase and total ATPase activities of the plasma membrane, the results showed that the different environmental silicic concentrations had the different influences on the ATPases of the diatom plasma membrane. In the high silicic environment, the total ATPase activity of the diatom plasma membrane was significantly higher than that of the control (p < 0.05), while the Na⁺/K⁺-ATPase activity was remarkable lower than that of the control in the low silicon environment (p < 0.01); but the Ca²⁺/Mg²⁺-ATPase activity did not change remarkably in either high or low silicon environment. These results showed that the ATPases of the diatom plasma membrane and their activities had a close relationship with the environmental silicic content, and was able to be a potential responding indicator to the environmental silicon signal.