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Sequential Extraction (sequential + extraction)
Selected AbstractsEXTRACELLULAR MATRIX ASSEMBLY IN DIATOMS (BACILLARIOPHYCEAE).JOURNAL OF PHYCOLOGY, Issue 2 2006The effects of phosphate (P) limitation, varying salinity (5,65 psu), and solid media growth conditions on the polysaccharides produced by the model diatom, Phaeodactylum tricornutum Bohlin were determined. Sequential extraction was used to separate polymers into colloidal (CL), colloidal extracellular polymeric substances (cEPS), hot water soluble (HW), hot bicarbonate soluble (HB), and hot alkali (HA) soluble fractions. Media-soluble polymers (CL and cEPS) were enriched in 4-linked mannosyl, glucosyl, and galactosyl residues as well as terminal and 3-linked xylosyl residues, whereas HW polymers consisted mainly of 3-linked glucosyl as well as terminal and 2,4-linked glucuronosyl residues. The HB fraction was enriched in terminal and 2-linked rhamnosyl residues derived from the mucilage coating solubilized by this treatment. Hot alkali treatment resulted in the complete dissolution of the frustule releasing 2,3- and 3-linked mannosyl residues. The fusiform morphotype predominated in standard and P-limited cultures and cultures subjected to salinity variations, but growth on solid media resulted in an enrichment of the oval morphotype. The proportion and linkages of 15 residues, including neutral, uronic acid, and O -methylated sugars, varied with environmental conditions. P limitation and salinity changes resulted in 1.5- to 2.5,fold increase in carbohydrate production, with enrichment of highly branched/substituted and terminal rhamnose, xylose, and fucose as well as O -methylated sugars, uronic acids, and sulfate. The increased deoxy- and O -methylated sugar content under unfavorable environments enhances the hydrophobicity of the polymers, whereas the anionic components may play important roles in ionic cross-linking, suggesting that these changes could ameliorate the effects of salinity or P-stress and that these altered polysaccharide characteristics may be useful as bioindicators for environmental stress. [source] Towards second-generation proteome analysis of murine enamel-forming cellsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2006Jonathan E. Mangum Proteome analysis of rat enamel-forming cells, initiated over a decade ago, has provided valuable insights to enamel biology. In preparation for a more comprehensive, second-generation proteomic exploration, we evaluated an updated microsample-profiling strategy that comprises sequential extraction of enamel epithelium, parallel one- and two-dimensional gel electrophoresis, and mass spectrometric sequence analysis. The results indicated that several hundred proteins, representing various cellular compartments (including membranes), are amenable to identification with a starting tissue volume of <,10 µl. With its increased proteomic depth and breadth, this straightforward approach constitutes a major advance from the first-generation work (10-fold increased proteome coverage), although care was needed to ensure a comparably high stringency of protein identification. Expression proteomics has an exciting potential to elucidate the inner workings of murine enamel epithelial cells, leading to an improved understanding of enamel in health and disease. [source] Loss of phosphorus from soil in semi-arid northern Tanzania as a result of cropping: evidence from sequential extraction and 31P-NMR spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2000D. Solomon Summary In semi-arid northern Tanzania, the native woodland is being rapidly cleared and replaced by low input agriculture. This has resulted in pronounced environmental degradation, and in particular loss of phosphorus (P) from the soil. We have used sequential extraction and 31P-NMR to investigate the effects of land use changes, i.e. native woodland, degraded woodland, cultivation for 3 and 15 years and homestead fields where manure was applied, on the amount and structural composition of P in this soil. Clearing and continuous cultivation reduced both organic and inorganic P in the soil. The difference in the amount of organic P from the bulk soil of the fields cultivated for 3 and 15 years was not statistically significant (P <,0.05), suggesting that most of the depletion in organic P occurred during the first 3 years of cultivation. By contrast, in the homesteads, there was much organic and inorganic P in the soil. The 31P-NMR revealed that cultivation resulted in a 53% depletion of orthophosphate diester P, whereas only a 30% and 39% reduction of orthophosphate monoester P was found in the bulk soil after 3 and 15 years of cultivation, respectively. These results concur with the suggestion that diester P constitutes more easily mineralizable forms of organic P in soil than does monoester P. Our 31P-NMR also showed that 70% of the inorganic orthophosphate P was depleted from the coarse and fine sand separates as a result of cultivation. The influence of clearing and subsequent cropping on the amount and forms of P was more pronounced in the coarse and fine sand than in the silt and clay, stressing the importance of particle size and chemical properties such as organic matter and oxides in the availability of P in this soil. Our results show that the current low input agricultural practice is not sustainable, and that practices must be developed to combat the ongoing degradation of the soil. A combined use of available organic materials such as animal manure with the judicious use of inorganic fertilizers can replenish the soil's fertility. [source] Essential oil composition and antimicrobial activity of tuberous roots of Pimpinella tirupatiensis Bal.FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2002& Subr., India, an endemic taxon from eastern ghats Abstract The tuberous roots of Pimpinella tirupatiensis (Apiaceae) were subjected to sequential extraction with different polar solvents and the extracts were tested against eight bacterial and three fungal pathogenic strains for antimicrobial activity. The minimum inhibitory concentration of active extracts against six bacterial and two fungal strains were determined. The hexane and ethyl acetate fractions exhibited a broad spectrum of antimicrobial activity and were analysed for different phytochemicals. The active extracts contained significant amounts of alkaloids, flavonols, flavones and volatile oils. The hexane extract yielded an essential oil when subjected to GC with FID. The compounds were identified based on their retention indices and yielded 24 known compounds and one unknown compound. The major compounds are ,-bisabolene (9.2%), ,-3-carene (8.9%), cis -carveol (6.7%), elemol (5.8%), ,-cadinol (4.4%), methyl geranate (4.3%) and ,-nonalactone (3.4%). Copyright © 2002 John Wiley & Sons, Ltd. [source] Evaluation of municipal compost/limestone/iron mixtures as filling material for permeable reactive barriers for in-situ acid mine drainage treatmentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2003Oriol Gibert Abstract The aim of the present study was to assess the potential of municipal compost as a carbon source for sulfate-reducing bacteria for acid mine drainage bioremediation for use in permeable reactive barriers at high flow rates (>0.1 m d,1). Two different mixtures of municipal compost, limestone and zero-valent iron were assessed in two column experiments. The effluent solution was systematically analysed throughout the experiments. At the end of the experiments precipitates from both columns were withdrawn for scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffractometry examination and solid digestion and sequential extraction were carried out. Results showed that the effluent was free of metals and acidity. It seems that metal removal was not due to biogenic sulfide generation but to pH increase, ie metal (oxy)hydroxides precipitation. These precipitates can sorb other metals onto the surface. Sorption to organic matter could also contribute to metal removal. When zero-valent iron was present, cementation of copper also occurred. It can be concluded that municipal compost was a poor carbon source to support continuous bacterial activity under high flow rates. Copyright © 2003 Society of Chemical Industry [source] Peptide profile of human acquired enamel pellicle using MALDI tandem MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3 2008Rui Vitorino Abstract The present study proposes a strategy for human in vivo acquired enamel pellicle (AEP) peptidome characterisation based on sequential extraction with guanidine and TFA followed by MALDI-TOF/TOF identification. Three different nanoscale analytical approaches were used: samples were subjected to tryptic digestion followed by nano-HPLC and mass spectrometry (MS and MS/MS) analysis. Undigested samples were analysed by LC-MS (both linear and reflector modes) and LC-MS/MS analysis, and samples were subjected to nano-HPLC followed by on-plate digestion and mass spectrometry (MS and MS/MS) analysis. The majority of the identifications corresponded to peptide/protein fragments of salivary protein, belonging to the classes: acidic PRPs, basic PRPs, statherin, cystatins S and SN and histatin 1 (all also identified in intact form). Overall, more than 90 peptides/proteins were identified. Results clearly show that peptides with acidic groups are enriched in the TFA fraction while peptides with no acidic or phosphate groups are prevalent on the guanidine extract. Also, phosphorylated peptides were observed mainly on the TFA fraction. Fragments present in the AEP show a predominance of cleavage points located at Arg, Tyr and Lys residues. Obtained data suggest that proteolytic activity could influence AEP formation and composition. [source] Characterisation of Chilean hazelnut (Gevuina avellana) tissues: light microscopy and cell wall polysaccharidesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2003Fernando Dourado Abstract By applying several differential staining techniques and light microscopy, the structure and composition of Chilean hazelnut (Gevuina avellana) seeds were analysed. The structure of the G avellana seed is very simple, with a thin, heavily lignified seed coat and two voluminous cotyledons. The embryo food reserves are uniformly distributed over the cotyledon cells. The cell wall polysaccharides were recovered from the alcohol-insoluble residue by mild treatment with warm chlorite solution and sequential extraction with alkali solutions of increasing concentration. FT-IR spectra in the 1200,850,cm,1 region were used together with chemometric techniques to distinguish the hemicellulosic and pectic polysaccharides in the extracts. The most abundant extracts were fractionated by graded precipitation in ethanol. A xyloglucan was identified by 1H and 13C NMR as the major hemicellulosic polysaccharide, with a sugar composition of 4Glc:3.5Xyl:1Gal:0.5Fuc. The hazelnut cell walls are composed of equivalent amounts of pectic polysaccharides, xyloglucans and cellulose. © 2003 Society of Chemical Industry [source] Development of a method to assess binding of astaxanthin to Atlantic salmon Salmo salar L. muscle proteinsAQUACULTURE RESEARCH, Issue 4 2005Madhury R Saha Abstract Several methods were examined to characterize the binding between astaxanthin and salmon muscle protein(s) in order to provide tools for evaluation of the role of muscle proteins on astaxanthin retention in Atlantic salmon Salmo salar L. flesh. The methods included gel filtration chromatography, displacement of a hydrophobic probe and ultrafiltration. With gel filtration chromatography, aggregation of astaxanthin under the experimental conditions was a major problem for the separation of bound astaxanthin from free astaxanthin because the apparent molecular weight of aggregated astaxanthin or astaxanthin micelles was in the range of protein,astaxanthin complexes. Displacement of the fluorescent probe 8-anilino-1-naphthalenesulphonate (ANS) was not effective as astaxanthin quenched the fluorophore so that displacement could not be observed. An ultrafiltration method was developed using 200-mM sodium cholate for dispersion of astaxanthin aggregates. This allowed unbound astaxanthin to be separated from bound astaxanthin using a 30-kDa filter. After salmon muscle proteins were solubilized in different fractions by sequential extraction using low ionic strength solutions, the astaxanthin binding of different fractions was assessed using the ultrafiltration method. The significant difference (P<0.05) observed in the astaxanthin binding of the various fractions suggests an application of this assay to detect differences in affinity of proteins for astaxanthin. The results also suggest that proteins other than actomyosin or actin can bind astaxanthin in Atlantic salmon flesh. This method can be used for the identification of astaxanthin-binding proteins in salmon flesh and other tissues. [source] Determination of organic acids in urine by solid-phase microextraction and gas chromatography,ion trap tandem mass spectrometry previous ,in sample' derivatization with trimethyloxonium tetrafluoroborateBIOMEDICAL CHROMATOGRAPHY, Issue 10 2008Marco Pacenti Abstract A method for the determination of the organic acids directly in the urine employing derivatization with trimethyloxonium tetrafluoroborate as a methylating agent and sequential extraction by head space and direct immersion/solid phase microextraction is reported. Furoic acid, hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid and trans, trans muconic acid contained in urine and proposed by the American Conference of Governmental Industrial Hygienists as biological exposure indices were determined after a fast and economically convenient preparation step and sensitive gas chromatography,ion trap,mass spectrometry/tandem mass spectrometry analysis. Urine is rather a complex sample and hence the acquisition method required specific GC-MS instrumentation capable of supporting the changeover, fully automated during a single chromatographic separation, from mass to tandem mass spectrometry and both chemical and electron ionization modes. The automation of the analytical method provides a number of advantages, including reduced analysis time for both routine analysis and method development, and greater reproducibility. The equilibrium and kinetics of this substances vs head space/direct immersion-solid phase microextraction were investigated and evaluated theoretically. Copyright © 2008 John Wiley & Sons, Ltd. [source] Long-term corrosion-induced copper runoff from natural and artificial patina and its environmental impact,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Sofia Bertling Abstract The overall objective of this paper is to present an extensive set of data for corrosion-induced copper dispersion and its environmental interaction with solid surfaces in the near vicinity of buildings. Copper dispersion is discussed in terms of total copper flows, copper speciation and bioavailability at the immediate release situation, and its changes during transport from source to recipient. Presented results are based on extensive field exposures (eight years) at an urban site, laboratory investigations of the runoff process, published field data, generated predictive site-specific runoff rate models, and reactivity investigations toward various natural and manmade surfaces, such as those in soil, limestone, and concrete. Emphasis is placed on the interaction of copper-containing runoff water with different soil systems through long-term laboratory column investigations. The fate of copper is discussed in terms of copper retention, copper chemical speciation, breakthrough capacities, and future mobilization based on changes in copper concentrations in the percolate water, computer modeling using the Windermere Humic Aqueous Model, and sequential extractions. The results illustrate that, for scenarios where copper comes in extensive contact with solid surfaces, such as soil and limestone, a large fraction of released copper is retained already in the immediate vicinity of the building. In all, both the total copper concentration in runoff water and its bioavailable part undergo a significant and rapid reduction. [source] Theoretical framework for the distribution of trace metals among the operationally defined speciation phases of a sedimentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2001René A. Nome Abstract The use of a model based on Langmuir's isotherm to evaluate the metal associated with separate geochemical phases of a sediment is proposed and its validity tested with sediments of certified composition. The model takes into account a standard procedure for a certified reference material (CRM601), which defines, experimentally, a set of sequential extractions that divide the sediment into four operational fractions. The derived equations allow the treatment of data from sediment of Flumendosa Lake, Italy, and certified material CRM601 and also allow the computation of corrected concentrations, i.e., the metal affinities for each fraction. Experimental values for Ni show its low sensitivity and an equal distribution among different phases, which suggests a similar adsorption mechanism in all cases. In the case of Cd, the corrected concentration in the Fe/Mn oxide phase is nine times higher than for the residual fraction. For sediment of the Bèsos River, Spain, results show the percentage distribution of Ni over different fractions. Affinity values for Ni on a Flumendosa Lake sediment have also been calculated. The present model is simple to apply and shows satisfactory agreement with experimental data. [source] INTERACTIONS OF THE MIX-LINKED ,-(1,3)/,-(1,4)- d -XYLANS IN THE CELL WALLS OF PALMARIA PALMATA (RHODOPHYTA),JOURNAL OF PHYCOLOGY, Issue 1 2003Estelle Deniaud Algal cell wall mechanical properties, crucial for biological functions and commercial applications, rely on interactions in macromolecular assemblies. In an effort to better understand the interactions of the matrix-phase ,-(1,3)/(1,4)- d -xylan in the edible seaweed Palmaria palmata ((L.) O. Kuntze, Rhodophyta, Palmariales), sequential extractions by saline, alkaline, and chaotropic solutions were done. The chemical composition and structure and the physicochemical properties of the isolated xylan revealed that it was partly acidic, probably due to the presence of sulfate (up to 5%) and phosphate groups (up to 4%). Although such acidity suggested ionic interactions of xylan in the cell walls, the high yields of polysaccharide extracted by alkali and particularly by 8 M urea and 4.5 M guanidium thiocyanate demonstrated that it was mainly hydrogen bonded in the cell wall. H-bonds did not appear to be related to the mean proportions of ,-(1,3) and ,-(1,4)- d -xylose linkages because these did not differ between extracts of increasing alkalinity. However, the decreasing molar weight and intrinsic viscosity of extracts obtained by alkaline solution containing a reducing agent used to prevent polysaccharide degradation suggested the presence of an alkali-labile component in the xylan. These results are discussed with regard to the role of potential wall proteins as a means of control of these interactions. [source] Quantification of monomeric and polymeric wheat proteins and the relationship of protein fractions to wheat quality,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2003Jerry Suchy Abstract Wheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low cross-contamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan-1-ol and 0.3 M sodium iodide (monomeric-rich protein), 50% propan-1-ol (soluble glutenin-rich protein) and 40% propan-1-ol and 0.2% dithiothreitol (insoluble glutenin-rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross-contamination of protein fractions was evaluated by SDS-PAGE, SE-HPLC and RP-HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric-rich protein (<2%) and insoluble glutenin-rich protein (<4%). Three wheats with similar high-molecular-weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P , 0.05) in the proportion of monomeric-rich and insoluble glutenin-rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin-rich protein and inversely related to the proportion of monomeric-rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter-cultivar differences in the proportion of monomeric-rich, insoluble glutenin-rich protein and glutenin-to-gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat-breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri-Food, Government of Canada, Copyright © Minister of Public Works and Government Services Canada 2003. Published for SCI by John Wiley & Sons, Ltd. [source] | ||||||||||||||||