The responses of photosystem II and intracellular ATP production of Arabidopsis leaves to salt stress are affected by extracellular ATP.

Hypertonic salt stress with different concentrations of NaCl increased the levels of extracellular ATP of Arabidopsis leaves. And, hypertonic salt stress decreased the levels of F v /F m (the maximal efficiency of photosystem II), Φ PSII (the photosystem II operating efficiency), qP (photochemical quenching), and intracellular ATP (iATP) production. The treatment with ß,γ-methyleneadenosine 5'-triphosphate (AMP-PCP), which can exclude extracellular ATP from its binding sites of extracellular ATP receptors, caused a further decrease in the levels of F v /F m , Φ PSII, qP, and iATP production of the salt-stressed Arabidopsis leaves, while the addition of exogenous ATP rescued the inhibitory effects of AMP-PCP on Φ PSII , qP, and iATP production under hypertonic salt stress. Under hypertonic salt stress, the values of F v /F m , Φ PSII , qP, and iATP production were lower in the dorn 1-3 mutant than in the wild-type plants. These results indicate that the responses of photosystem II and intracellular ATP production to salt stress could be affected by extracellular ATP.

Synthesis of mesoporous silica by a surface charge reversal route.

Pore size adjustable mesoporous silica was synthesized by adsorption of varying amounts of sodium dodecyl benzenesulfonate at the surface of silica activated by zinc ion via a novel surface charge reversal route. The pore size and volume can be adjusted from 5.9 to 13.76 nm and 0.88 to 1.08 cm(3) g(-1), respectively, with increasing the SDBS concentration from 0.77 to 3.08 mmol L(-1). Adsorption of Zn(2+) as a function of pH and N(2) adsorption/desorption isotherms demonstrated that the metal ions such as Zn(2+) could be readily removed with dilute nitric acid without apparent collapse of the pore structure at the proper range of SDBS concentration.