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排序方式: 共有63条查询结果,搜索用时 187 毫秒
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Philippe Régnier Jorge Bastias Violeta Rodriguez-Ruiz Noelia Caballero-Casero Carmen Caballo Dolores Sicilia Axelle Fuentes Murielle Maire Michel Crepin Didier Letourneur Virginie Gueguen Soledad Rubio Graciela Pavon-Djavid 《Marine drugs》2015,13(5):2857-2874
Astaxanthin, a powerful antioxidant, is a good candidate for the prevention of intracellular oxidative stress. The aim of the study was to compare the antioxidant activity of astaxanthin present in two natural extracts from Haematococcus pluvialis, a microalgae strain, with that of synthetic astaxanthin. Natural extracts were obtained either by solvent or supercritical extraction methods. UV, HPLC-DAD and (HPLC-(atmospheric pressure chemical ionization (APCI)+)/ion trap-MS) characterizations of both natural extracts showed similar compositions of carotenoids, but different percentages in free astaxanthin and its ester derivatives. The Trolox equivalent antioxidant capacity (TEAC) assay showed that natural extracts containing esters displayed stronger antioxidant activities than free astaxanthin. Their antioxidant capacities to inhibit intracellular oxidative stress were then evaluated on HUVEC cells. The intracellular antioxidant activity in natural extracts was approximately 90-times higher than synthetic astaxanthin (5 µM). No modification, neither in the morphology nor in the viability, of vascular human cells was observed by in vitro biocompatibility study up to 10 µM astaxanthin concentrations. Therefore, these results revealed the therapeutic potential of the natural extracts in vascular human cell protection against oxidative stress without toxicity, which could be exploited in prevention and/or treatment of cardiovascular diseases. 相似文献
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David I Forrester Rubén Guisasola Xiaolu Tang Axel T Albrecht Tran Lam Dong Guerric Ie Maire 《中国林学(英文版)》2014,1(3):158-176
Background: Forest ecosystem functioning is strongly influenced by the absorption of photosynthetically active radiation (APAR), and therefore, accurate predictions of APAR are critical for many process-based forest growth models. The Lambert-Beer law can be applied to estimate APAR for simple homogeneous canopies composed of one layer, one species, and no canopy gaps. However, the vertical and horizontal structure of forest canopies is rarely homogeneous. Detailed tree-level models can account for this heterogeneity but these often have high input and computational demands and work on finer temporal and spatial resolutions than required by stand-level growth models. The aim of this study was to test a stand-level light absorption model that can estimate APAR by individual species in mixed-species and multi-layered stands with any degree of canopy openness including open-grown trees to closed canopies. Methods: The stand-level model was compared with a detailed tree-level model that has already been tested in mixed-species stands using empirical data. Both models were parameterised for five different forests, including a wide range of species compositions, species proportions, stand densities, crown architectures and canopy structures. Results: The stand-level model performed well in all stands except in the stand where extinction coefficients were unusually variable and it appears unlikely that APAR could be predicted in such stands using (tree- or stand-level) models that do not allow individuals of a given species to have different extinction coefficients, leaf-area density or analogous parameters. Conclusion: This model is parameterised with species-specific information about extinction coefficients and mean crown length, diameter, height and leaf area. It could be used to examine light dynamics in complex canopies and in stand-level growth models. 相似文献
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Microbiological processes in soil organic phosphorus transformations in conventional and biological cropping systems 总被引:5,自引:0,他引:5
We studied microbiological processes in organic P transformations in soils cultivated with conventional and biological farming systems during the 13th and 14th year of different cropping systems. The treatments included control, biodynamic, bioorganic, and conventional plots and a mineral fertilization treatment. Different P fractions were investigated using a sequential fractionation method. Labile organic P, extracted by 0.5 M NaHCO3, was not affected by the farming systems. However, residual organic P remaining in the soil at the end of the sequential fractionation procedure showed that the biodynamic treatment, in particular, led to a modification of the composition of organic P. Labile organic P, organic P extractable in 0.1 M NaOH, and total residual P all showed temporal fluctuations. As total residual P consists of more than 70% organic P, it can be assumed that residual organic P contributed to these variations. This result indicates that chemically resistant organic P participates in short-term accumulation and mineralization processes. All biological soil parameters tested in this study showed significant temporal fluctuations, mainly attributed to differences in climatic conditions between years, but possibly also related to the growth cycle of the crop. The higher values of the biological soil parameters in the biodynamic and bioorganic treatments were explained by the greater importance of manure and the different plant protection strategies. The level of phosphatase activity and mineralization of organic C indicated a higher turnover of organic substrates, and thus of organic P, in the biodynamic and bioorganic treatments. Biological parameters were shown to be critical for assessing the significance of organic P in the soil P turnover. 相似文献
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Effect of soil drying on mucilage exudation and its water repellency: a new method to collect mucilage 下载免费PDF全文
Mutez A. Ahmed Maire Holz Susanne K. Woche Jörg Bachmann Andrea Carminati 《植物养料与土壤学杂志》2015,178(6):821-824
Despite the importance of mucilage for soil–plant relations, little is known about the effect of soil drying on mucilage exudation. We introduce a method to collect mucilage from maize growing in wet and dry soils. Mucilage was collected from brace roots. The amount of mucilage exuded did not change with soil water content and transpiration rate. Mucilage exuded in dry soils had a higher degree of hydrophobicity, suggesting that the wetting properties of mucilage change in response to soil drying. 相似文献
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Nicolas Marinval Pierre Saboural Oualid Haddad Murielle Maire Kevin Bassand Frederic Geinguenaud Nadia Djaker Khadija Ben Akrout Marc Lamy de la Chapelle Romain Robert Olivier Oudar Erwan Guyot Christelle Laguillier-Morizot Angela Sutton Cedric Chauvierre Frederic Chaubet Nathalie Charnaux Hanna Hlawaty 《Marine drugs》2016,14(10)
Herein we investigate the structure/function relationships of fucoidans from Ascophyllum nodosum to analyze their pro-angiogenic effect and cellular uptake in native and glycosaminoglycan-free (GAG-free) human endothelial cells (HUVECs). Fucoidans are marine sulfated polysaccharides, which act as glycosaminoglycans mimetics. We hypothesized that the size and sulfation rate of fucoidans influence their ability to induce pro-angiogenic processes independently of GAGs. We collected two fractions of fucoidans, Low and Medium Molecular Weight Fucoidan (LMWF and MMWF, respectively) by size exclusion chromatography and characterized their composition (sulfate, fucose and uronic acid) by colorimetric measurement and Raman and FT-IR spectroscopy. The high affinities of fractionated fucoidans to heparin binding proteins were confirmed by Surface Plasmon Resonance. We evidenced that LMWF has a higher pro-angiogenic (2D-angiogenesis on Matrigel) and pro-migratory (Boyden chamber) potential on HUVECs, compared to MMWF. Interestingly, in a GAG-free HUVECs model, LMWF kept a pro-angiogenic potential. Finally, to evaluate the association of LMWF-induced biological effects and its cellular uptake, we analyzed by confocal microscopy the GAGs involvement in the internalization of a fluorescent LMWF. The fluorescent LMWF was mainly internalized through HUVEC clathrin-dependent endocytosis in which GAGs were partially involved. In conclusion, a better characterization of the relationships between the fucoidan structure and its pro-angiogenic potential in GAG-free endothelial cells was required to identify an adapted fucoidan to enhance vascular repair in ischemia. 相似文献
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Diogenes Dezen Franciscus Antonius Maria Rijsewijk Thais Fumaco Teixeira Carine Lidiane Holz Samuel Paulo Cibulski Ana Cláudia Franco Odir Antonio Dellagostin Paulo M. Roehe 《Research in veterinary science》2010,88(3):436-440
Multiply-primed rolling-circle amplification (MPRCA) was used to amplify porcine circovirus type 2 (PCV2) genomes isolated from tissues of pigs with signs of post-weaning multisystemic wasting syndrome (PMWS). Two of the amplified PCV2 genomes were cloned in prokaryotic plasmids and sequenced. Both were nearly identical (1767 nt) except for one silent substitution in the region coding for the capsid protein (ORF2). In addition, they showed high nucleotide sequence similarity with PCV2 isolates from others countries (93–99%). To investigate whether the MPRCA amplified PCV2 genomes could be used to produce infectious virus, the cloned genomes were isolated from the plasmids, recircularized and used for transfection in PK-15 cells. This procedure led to the production of infectious virus to titres up to 105.55 TCID50/mL. It was concluded that MPRCA is a useful tool to amplify PCV2 genomes aiming at sequencing and virus isolation strategies, where particularly useful is the fact that it allows straightforward construction of PCV2 infectious clones from amplified genomes. However, it was less sensitive than PCR for diagnostic purposes. 相似文献
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