Increased tolerance to photooxidative stress by overexpression of mitochondrial superoxide dismutase in transgenic tobacco

76-80Under abiotic stress conditions, plants suffer from oxidative damage caused by increased generation of reactive oxygen species (ROS). Although chloroplasts are the main source of ROS generation in plant cells, changes in ROS level in mitochondria affect plant stress response. In this study, we investigated whether overexpression of mitochondrial manganese superoxide dismutase (Mn-SOD) can enhance tolerance to photooxidative stress. We produced transgenic tobacco plants overexpressing rice Mn-SOD under the control of cauliflower mosaic virus 35S promoter, and assessed the stress tolerance of those plants. The transgenic lines showed higher total SOD activity by 2.8 to 5.2 fold than wild type plants. Chlorophyll fluorescence measurement revealed that the stress-induced inhibition of photosystem II was alleviated under high light, chilling and heat stresses in the transgenic lines. This result indicates that the Mn-SOD contributes to the defense against photooxidative damages in chloroplasts under these stress conditions

Studies on metal-ion complex formation of crown ether derivatives incorporating a photoionizable spirobenzopyran moiety by electrospray ionization mass spectrometry

Metal-ion complexation of crown ether derivatives incorporating one and two spirobenzopyran units was investigated by electrospray ionization mass spectrometry.The crowned spirobenzopyran derivatives exhibited very different metal ion-complexing behavior from their corresponding parent crown ether rings,preferring multivalent to monovalent metal ions owing to the additional ionic interaction with the nitrophenolate anion of the merocyanine moiety.The on-line photochemical reaction for mass spectrometry indicated that the metal ion-complexing ability and ion selectivities of the crowned spirobenzopyrans can be switched photochemically,taking advantage of the difference between the spiropyran and merocyanine isomers

Total synthesis of (+)-azimine via diastereoselective aminopalladation

The aminopalladation of amino allylic alcohol using Cl2Pd(MeCN)(2) in CH2Cl2 gave the 2,6-disubstituted piperidine with excellent diastereoselectivity. This compound was successfully converted into (+)-azimine (1) using cross-metathesis and Shiina macrolactonization.ArticleTETRAHEDRON. 69(39):8349-8352 (2013)journal articl