No abstract

A method has been developed for the separation and determination of phospholipids by nonaqueous capillary electrophoresis in a separation medium of acetonitrile-2-proponol (3:2, v/v), 0.3% acetic acid and 60 mM ammonium acetate. To optimize the separation conditions, the composition of separation medium including alcohols, acetic acid, n-hexane and ammonium acetate was studied. The solvation interaction and ion-dipole interaction were also investigated. The contents of phospholipids in soybean, sunflower, peanut, apricot kernel, filbert and walnut were determined by the recommended method. The results obtained by the nonaqueous capillary electrophoreses were in good agreement with those determined by micellar electrokinetic chromatography.

In present study, we report our extensive survey on the diversity and biogeography of rhizobia associated with Sophora flavescens, a sophocarpidine (matrine)-containing medicinal legume. We additionally investigated the cross nodulation, infection pattern, light and electron microscopies of root nodule sections of S. flavescens infected by various rhizobia. Seventeen genospecies of rhizobia belonging to five genera with seven types of symbiotic nodC genes were found to nodulate S. flavescens in natural soils. In the cross-nodulation tests, most representative rhizobia in class α-Proteobacteria, whose host plants belong to different cross-nodulation groups, form effective indeterminate nodules, while representative rhizobia in class β-Proteobacteria form ineffective nodules on S. flavescens. Highly host-specific biovars of Rhizobium leguminosarum (bv. trifolii and bv. viciae) and Rhizobium etli bv. phaseoli could establish symbioses with S. flavescens, providing further evidence that S. flavescens is an extremely promiscuous legume and it does not have strict selectivity on either the symbiotic genes or the species-determining housekeeping genes of rhizobia. Root-hair infection is found as the pattern that rhizobia have gained entry into the curled root hairs. Electron microscopies of ultra-thin sections of S. flavescens root nodules formed by different rhizobia show that the bacteroids are regular or irregular rod shape and nonswollen types. Some bacteroids contain poly-β-hydroxybutyrate (PHB), while others do not, indicating the synthesis of PHB in bacteroids is rhizobia-dependent. The extremely promiscuous symbiosis between S. flavescens and different rhizobia provide us a basis for future studies aimed at understanding the molecular interactions of rhizobia and legumes.

A fast, simple, and sensitive CE method was developed to study the separation and degradation of imazaquin enantiomers in field soils. The parameters pH and concentration of the buffer electrolyte, type and concentration of the chiral selectors, applied voltage, and temperature of the CE system were investigated. Sodium hydrogen phosphate (50 mM) at pH 10.1 containing 30 mM hydroxypropyl-beta-CD (HP-beta-CD) was found to be the suitable BGE. The reliable determination for imazaquin enantiomers was obtained at 20 kV applied voltage, 15 degrees C separation system, and detection at 214 nm. Under the optimal conditions, the LODs (S/N = 3) were 0.0097 and 0.0098 mg/kg; linearity ranged from 0.019 to 1.24 and 0.020 to 1.26 mg/kg for the first-eluting peak of imazaquin (imazaquin-I) and the second-eluting peak of imazaquin (imazaquin-II) in soil, respectively. The precision in terms of the percentage of RSD (%RSD) calculated from peak area was not greater than 5%. With the suitable characteristics of the present method, it was applied to the study of enantioselective degradation in field soil. According to the calculated values of the enantiomer ratio (ER) and the rate constant of degradation (k), the results suggested that the degradation rate of the two enantiomers were slightly different, and that the pH of the soil had a strong influence on the rate of degradation.