中国珍稀植物明党参嫩茎叶挥发油化学成分研究

采用毛细管气相色谱－质谱－计算机联用技术对明党参嫩茎叶挥发油的化学成分进行研究,从挥发油中鉴定出２７种成分,占总油量的９７．５０２％,其主要成分是Ｍａｎｇ牛儿醇乙酸酯（４６．６３６％）,明党参炔（１１．４８３％）,β－金合欢烯（１０．９８６％为阐明明党参特征性化学及茎叶的一切利用提供了依据。     

Isolation of a purified mitochondrial fraction from viable clonal insulin-producing cells (RINm5F) by percoll density gradient centrifugation

Summary A Percoll density gradient was employed for selecting large numbers of viable insulin-producing RINm5F cells. Homogenates of these cells were then subjected to gradient centrifugation and two clearly visible bands were obtained. The light fraction was essentially composed of mitochondria banded at a density of about 1.06 g/ml. The heavier fraction banded at 1.09 to 1.10 g/ml and contained lysosomes and a small number of secretory granules. The distribution of Percoll particles was restricted to the extracellular space and there was no adsorption to any membrane structures. The distribution pattern of marker enzymes for the mitochondria and lysosomes was similar to that of normal pancreatic β-cells. With the use of a Percoll density gradient it was thus possible to isolate a purified mitochondrial fraction from viable RINm5F cells. This work was supported by the Swedish Medical Research Council (03x-4, 12x-562, 12x-6240), the Swedish Diabetes Association, the Nordic Insulin Foundation, Syskonen Svenssons Foundation, and ?ke Wiberg’s Foundation. Per-Olof Berggren is a recipient of a postdoctoral fellowship from the Swedish Medical Research Council.     

Relationship between intracellular ice formation in oocytes of the mouse and Xenopus and the physical state of the external medium--a revisit

We have previously reported that intracellular ice formation (IIF) in mouse oocytes suspended in glycerol/PBS solutions or ethylene glycol (EG)/PBS solutions and rapidly cooled to −50 °C or below occurs at temperatures where a critical fraction of the external water remains unfrozen [P. Mazur, S. Seki, I.L. Pinn, F.W. Kleinhans, K. Edashige, Extra- and intracellular ice formation in mouse oocytes, Cryobiology 51 (2005) 29-53; P. Mazur, I.L. Pinn, F.W. Kleinhans, The temperature of intracellular ice formation in mouse oocytes vs. the unfrozen fraction at that temperature, Cryobiology 54 (2007) 223-233]. For mouse oocytes in PBS or glycerol/PBS that fraction is 0.06; for oocytes in EG that fraction was calculated to be 0.13, more than double. The fractions unfrozen are computed from ternary phase diagrams. In the previous publication, we used the EG data of Woods et al. [E.J. Woods, M.A.J. Zieger, D.Y. Gao, J.K. Critser, Equations for obtaining melting points for the ternary system ethylene glycol/sodium chloride/Water and their application to cryopreservation., Cryobiology 38 (1999) 403-407]. Since then, we have determined that ternary phase diagrams for EG/NaCl/water synthesized by summing binary phase data for EG/water NaCl/water gives substantially different curves, which seem more realistic [F.W. Kleinhans, P. Mazur, Comparison of actual vs. synthesized ternary phase diagrams for solutes of cryobiological interest, Cryobiology 54 (2007) 212-222]. Unfrozen fractions at the temperatures of IIF computed from these synthesized phase diagrams are about half of those calculated from the Woods et al. data, and are in close agreement with the computations for glycerol; i.e., IIF occurs when about 92-94% of the external water is frozen. A parallel paper was published by Guenther et al. [J.F. Guenther, S. Seki, F.W. Kleinhans, K. Edashige, D.M. Roberts, P. Mazur, Extra-and intra-cellular ice formation in Stage I and II Xenopus laevis oocytes, Cryobiology 52 (2006) 401-416] on IIF in oocytes of the frog Xenopus. It too examined whether the temperatures of IIF were related to the unfrozen fractions at those temperatures. It also used the Woods et al. ternary phase data to calculate the unfrozen fractions for EG solutions. As reported here, once again the values of these unfrozen fractions are substantially different from those calculated using synthesized phase diagrams. With the latter, the unfrozen fractions at IIF become very similar for EG and glycerol.     

Net ecosystem fluxes and composition of biogenic volatile organic compounds over a maize field–interaction of meteorology and phenological stages

Bioenergy crop production is rapidly expanding in Europe, and the potential emissions of biogenic volatile organic compounds (BVOCs) might change the chemical composition of the atmosphere, influencing in turn air quality and regional climate. The environmental impacts of bioenergy crops on air chemistry are difficult to assess due to a lack of accurate field observations. Therefore, we studied BVOC fluxes from a bioenergy maize field in North‐Eastern Germany throughout the entire reproductive growth stage of the plants. Combining automated large chambers and proton transfer reaction mass spectrometry (PTR‐MS), we successfully measured fluxes of the highly reactive hydrocarbons monoterpenes (MTs) and sesquiterpenes (SQTs), together with several other BVOCs, including alcohols, aldehydes, ketones, benzenoids, and fatty acid derivatives. Emissions of MTs and SQTs were relatively high (17.0% and 3.6% of total mean molar BVOC emission, respectively) compared to methanol emissions (17.6%). Seasonal MT and SQT fluxes were clearly associated with the flowering phase, originating mainly from the flowering tissues as shown in additional laboratory experiments. From the observations of CO₂ net ecosystem exchange and evapotranspiration rates, we could exclude heat and drought stress‐induced BVOC emissions. Standard emission factors calculated for all compounds, chemical groups, and growth stages, showed that the temperature dependency of volatile terpenoid fluxes decreased distinctively with proceeding development stage. The results indicate that emissions from large‐scale bioenergy maize fields should be better differentiated and considered in regional estimates of aerosol formation. For the implementation of such relation into biogeochemical modelling, it should be considered that not only seasonal weather development but also phenological growth stages are determining the BVOC patterns and emission potentials.     

Composition and emission dynamics of migratory locust volatiles in response to changes in developmental stages and population density

Chemical communication plays an important role in density‐dependent phase change in locusts. However, the volatile components and emission patterns of the migratory locust, Locusta migratoria, are largely unknown. In this study, we identified the chemical compositions and emission dynamics of locust volatiles from the body and feces and associated them with developmental stages, sexes and phase changes. The migratory locust shares a number of volatile components with the desert locust (Schistocerca gregaria), but the emission dynamics of the two locust species are significantly different. The body odors of the gregarious nymphs in the migratory locust consisted of phenylacetonitrile (PAN), benzaldehyde, guaiacol, phenol, aliphatic acids and 2,3‐butanediol, and PAN was the dominant volatile. Volatiles from the fecal pellets of the nymphs primarily consist of guaiacol and phenol. Principal component analysis (PCA) showed significant differences in the volatile profiles between gregarious and solitary locusts. PAN and 4‐vinylanisole concentrations were significantly higher in gregarious individuals than in solitary locusts. Gregarious mature males released significantly higher amounts of PAN and 4‐vinylanisole during adulthood than mature females and immature adults of both sexes. Furthermore, PAN and 4‐vinylanisole were completely lost in gregarious nymphs during the solitarization process, but were obtained by solitary nymphs during gregarization. The amounts of benzaldehyde, guaiacol and phenol only unidirectionally decreased from solitary to crowded treatment. Aliphatic aldehydes (C7 to C10), which were previously reported as locust volatiles, are now identified as environmental contaminants. Therefore, our results illustrate the precise odor profiles of migratory locusts during developmental stages, sexes and phase change. However, the function and role of PAN and other aromatic compounds during phase transition need further investigation.     

Different headspace profiles in wild crucifer species in response to Plutella xylostella herbivory and exogenous jasmonic acid application

Abstract  Although exogenous treatment of plants with jasmonic acid (JA) may result in induced responses similar to plant defences induced by herbivory, few studies have compared the details of insect herbivory and JA-mimicked responses. We compared volatiles of two crucifer species, Cardamine impatiens and Lepidium virginicum , in response to Plutella xylostella larval feeding and exogenous application of JA, over the entire period of time when induced changes were detectable. Significant differences in the composition and timing of volatiles occurred between herbivory and JA treatments in both plants. The quantity of nitrile and isothiocyanate released in response to herbivory was significantly larger than that upon JA treatment. In each of the two plant species, most volatile components were emitted immediately upon larval feeding and their quantity dropped rapidly once feeding ceased. In contrast, the emission of volatiles in response to JA treatment lasted for a longer period of time, and the maximum emission rate was recorded 2 and 3 days after JA treatment in L. virginicum and C. impatiens respectively. These findings are discussed in the context of signal-transduction pathways and mechanisms involved in induced emissions of plant volatiles, as well as induced defences mediated by plant volatiles.     

Selenium in platelets

Blood and its main components are commonly used to detect states of selenium deficiency. In order to examine whether human platelets are able to provide better or additional information, improvements analytical method resulted in surprisingly narrow normal ranges for selenium and other mineral elements using neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS), and controlling thermal neutron flux, (n,γ)-cross sections, mean platelet wet wt, and water fraction of the platelets. Previously reported selenium concentrations in platelets on wet wt basis in the order of 500 ng/g—half of which had been found to derive from early bone marrow precursors using⁷⁴Se-selenite—were reproduced by NAA and AAS. However, with the new analytical method the selenium concentrations showed a narrower normal range than that of plasma. Moreover, platelet selenium did not in all cases correlate with plasma selenium. Cellular tissues such as platelets should, therefore, help to detect latent states of selenium deficiency.     

Cytotoxic immune cells with specificity for defined soluble antigens. II. Chasing the killing cells

Cells from mice immune against soluble antigens were tested for their in vitro cytotoxicity against chicken red blood cells (CRBC) coated with these antigens. In parallel, cells from mice immune against allogeneic P815 mastocytoma cells were tested for their in -vitro cytotoxicity against P815 cells. Before the cytotoxicity test, the immune cell populations were fractionated, using four different types of techniques, to check the impact of the removal of given subpopulations of cells on cytotoxic activity.Fractionation on anti-immunoglobulin coated columns did not affect the anti P815 cytotoxicity, but markedly decreased the cytotoxicity against antigen-coated CRBC. The same results were obtained by incubation on a plastic surface and/or an “ironplus-magnet” technique. Preincubation of the cytotoxic cell populations with homologous anti-θ or heterologous anti-T antiserum, plus complement, abolished both types of cytotoxicity. However, preincubation with anti-θ or anti-T antiserum alone, without complement, also blocked the cytotoxicity against antigen-coated CRBC, but not the anti P815 cytotoxicity. In vivo injection of heterologous anti-lymphocyte gammaglobulin completely abolished the anti P815 cytotoxicity, but not the cytotoxicity against antigen-coated CRBC.These results confirm that T cells (thymus-processed lymphocytes) can kill autonomously in the anti P815 system. They also suggest that, in the cytotoxicity against antigen-coated CRBC, as effector cells, (1) non-T cells are involved, (2) T cells might not be involved.     

High-pH reversed-phase chromatography with fraction concatenation for 2D proteomic analysis

Orthogonal high-resolution separations are critical for attaining improved analytical dynamic range and protein coverage in proteomic measurements. High-pH reversed-phase liquid chromatography (RPLC), followed by fraction concatenation, affords better peptide analysis than conventional strong cation-exchange chromatography applied for 2D proteomic analysis. For example, concatenated high-pH RPLC increased identification of peptides (by 1.8-fold) and proteins (by 1.6-fold) in shotgun proteomics analyses of a digested human protein sample. Additional advantages of high-pH RPLC with fraction concatenation include improved protein sequence coverage, simplified sample processing and reduced sample losses, making this an attractive alternative to strong cation-exchange chromatography in conjunction with second-dimension low-pH RPLC for 2D proteomics analyses.