DIRECT SOMATIC EMBRYOGENESIS AND PLANT REGENERATION FROM PROTOPLAST-DERIVED CELLS OF WHEAT (Triticum aestivum L.)

Protoplasts were isolated from embryogenic calli derived from immature embryos ofwheat (Triticum aestivum L. cv. Jinan 177). The protoplasts were cultured in NMB mediumsupplemented with 1mg/L 2,4- D and 500mg/l casein hydrolysate (CH). The regenerated cellsfrom protoplasts divided to form somatic embryos directly. The somatic embryos grown to1.5- 2 mm in size directly developed into complete plants on solid MB medium without hor-mones.     

Numerical solution of delay differential equations by uniform corrections to an implicit Runge-Kutta method

Summary In this paper we develop a class of numerical methods to approximate the solutions of delay differential equations. They are essentially based on a modified version, in a predictor-corrector mode, of the one-step collocation method atn Gaussian points. These methods, applied to ODE's, provide a continuous approximate solution which is accurate of order 2n at the nodes and of ordern+1 uniformly in the whole interval. In order to extend the methods to delay differential equations, the uniform accuracy is raised to the order 2n by some a posteriori corrections. Numerical tests and comparisons with other methods are made on real-life problems.This work was supported by CNR within the Progetto Finalizzato Informatica-Sottopr. P1-SOFMAT     

三元配合物钯（Ⅱ）-2,2''-联吡啶-L-天冬氨酸与DNA作用研究

The ternary complex Pd(Ⅱ)-2,2‘-bipyridine-L-asparagic acid was synthesized and characterized by elemental analysis, IR-spectra and molar conductance. The formula of the complex is Pd(bipy)(L-asp). The interaction of the complex with DNA has been studied by UV-spectra, fluorescence spectra, CD-spectra and gel electrophoresis. The results showed that the interaction of the complex with DNA performed mainly in intercalative mode and the extent of interaction was dependent on the concentration of the complex.     

Study of cork (from Quercus suber L.)-wine model interactions based on voltammetric multivariate analysis

The cork from Quercus suber L. is the premium raw material used to produce wine-bottling stoppers; however, being a natural product, cork can be contaminated and attacked in different ways that could promote differences in its proprieties. A specific contamination is the defect known in the industry as “Mancha Amarela—Yellow spot” (MA). This cork shows modifications in its mechanical, structural and optical properties and is potentially able to cause off-flavours in wine. In this study, a new analytical approach is proposed for the rapid screening of cork-wine model interactions in order to determine if the cork were able to contaminate a wine. Cork samples classified as standard (S) and cork MA were put in contact with a wine model matrix. The model matrix was analysed by cyclic voltammetry and square wave voltammetry in function of different contact times. Considering that matrices in contact with cork S and MA exhibited different pH, the influence of this parameter on the distinction power was also evaluated. The data sets obtained from the different techniques were treated by principal component analysis (PCA) and PLS_Cluster. The major difference between samples S and MA is the occurrence of an important peak at ca. 580 mV in the MA voltammograms. This more positive peak may be assigned to lignin related phenolics; therefore, it can be proposed as a possible marker to follow lignin degradation.     

The use of chiral interaction reagents in the separation of D(−)-and L(+)-ascorbic acid by ion interaction reversed-phase HPLC

Summary An HPLC reversed-phase ion interaction reagent method is presented, which makes use of chiral compounds as the interaction reagents. By employing the optical isomeric forms of malic, tartaric and mandelic acids as the interaction reagents, a good separation of D(−) and L(+) ascorbic acid has been achieved. The method has also been applied to the identification of vitamin C in some medical formulations. The separation of te enantiomeric forms of DL malic acid has been attempted and a shor discussion is presented about the elution sequence in chromatographic separation of D- and L-enantiomers.     

L-histidine decarboxylase as a probe in studies on histamine

Because the Falck-Hillarp formaldehyde fluorescence method, which was superbly applied to identify catecholaminergic and serotonergic neurons, is not applicable to histamine, the first author (T.W.) developed an antibody to L-histidine decarboxylase (HDC) for identification of the histaminergic neuron system in the brain. The anti-HDC antibody was of great use for mapping the location and distribution of this histaminergic neuron system. (S)-alpha-fluoromethylhistidine, a specific and potent irreversible inhibitor of HDC, was also very useful in studies on functions of the neuron system. The activity of HDC is increased by various agents, treatments, and physiological conditions. We found new compounds that increased HDC activity (i.e., tetradecanoylphobol acetate (TPA), other tumor promoters, and staphylococcal enterotoxin A); and using mast cell-deficient mutant (W/W(v)) mice, we obtained evidence that this increase occurred in macrophages. To further characterize the mechanism of increases in HDC activity, the second author (H.O.) cloned human HDC cDNA and a human HDC gene. In studies on the regulation mechanism of the HDC gene, which is expressed only in limited types of cells such as mast cells, enterochromaffin-like cells in the stomach, cells in the tuberomammillary nucleus of the brain, and macrophages, CpG islands in the promoter region of the HDC gene were found to be demethylated in cells expressing the gene, whereas they are methylated in other cells that do not express the HDC gene. In collaboration with many other researchers, we developed HDC knockout mice. The resulting research is producing a lot of interesting findings in our laboratory as well as in others. In summary, HDC has been and will be useful in studies on functions of histamine.     

Xyloccensin L, a novel limonoid from Xylocarpus granatum

The isolation and structure elucidation of xyloccensin L from the stem bark of Xylocarpus granatum is described. Xyloccensin L is a highly oxidized heptacyclic A, B, D-seco limonoid with an α-8, 30-epoxy ring and a rare 1, 29 oxygen bridge.     

Simultaneous determination of noradrenaline and dopamine in Portulaca oleracea L. by capillary zone electrophoresis

A simple and rapid capillary electrophoretic method was developed for the simultaneous determination of noradrenaline (NA) and dopamine (DA) in Portulaca oleracea L. The buffer solution used in this method was 40 mM tris (hydroxymethyl) aminomethane (Tris)-H3PO4 at pH 2.00 containing 15% methanol. The effects of pH value, organic modifier, and applied voltage were investigated. The linear ranges of NA and DA were 0.5-100 microg/mL (r=0.9952) and 6.25-200 microg/mL (r=0.9992), respectively. The relative standard deviations of the corrected peak area were 6.73% and 4.26%, respectively. NA and DA in Portulaca oleracea L. were simultaneous determined successfully within 5.6 min. In this way, the contents of NA and DA in different parts (stem, leaves, and seeds) of P. oleracea L. and in different extracts of leaves with different solvents (distilled water, 50% methanol, and methanol) were studied.