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A simple structure, a rhodamine fluorescent derivative, was synthesized easily by a one-step condensation reaction of rhodamine B ethylenediamine and acetylacetone. Its structure was characterized by X-ray crystallography, NMR, MS and IR spectroscopy. As a bi-functional and highly selective “OFF–ON” chemosensor for Fe3+ or Cu2+, the derivative displayed a selective fluorescence enhancement effect only with Fe3+ and an absorption enhancement effect only with Cu2+ by modulating the pH value. In an aqueous ethanol medium, Fe3+ formed a 1:1 complex with the derivative at pH 6, while Cu2+ formed a 1:1 complex at pH 8.5. The limits of detection of the ions were low: 3.9 × 10−9 and 4.8 × 10−8 mol L−1. The derivative also functioned as a fluorescence sensor for CT-DNA, in which the Fe3+ ion that was used as a bridge between the derivative and DNA forming a ternary complex.

Plasma membrane (PM) vesicles were purified from two wheat ( Tritium aestivum yiujian24 (Y-J24) and longchun20 (L-Ch20)) roots by discontinuous sucrose gradient centrifugation to study the regulatory mechanism of the H + -ATPase activities in response to NaCl treatment. Salt-stress reduced the PM H + -ATPase activity in Y-J24 roots, but increased in L-Ch20 roots. Analysis of lipid peroxidation in the wheat root PM vesicles indicated that NaCl treatment induced a higher degree of oxidative damage on Y-J24 root PM, but did not affect lipid peroxidation of L-Ch20 root PM. Further studies showed that the PM protein thiol (P-SH) contents correlated with the changes of H + -ATPase activity in Y-J24 and L-Ch20 root PM. Western blot analysis revealed a decrease in the amount of the PM H + -ATPase in Y-J24 roots exposed for 72 h to 100 mM NaCl, and an increase in L-Ch20 roots, respectively. Therefore, thiol oxidation and a decrease in the enzyme content might be responsible for the inhibition of the PM H + -ATPase activity in Y-J24 roots in response to salt-stress; the increased H + -ATPase activities in L-Ch20 root PM might be due to up-regulation of the expression of the PM H + -ATPase.