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Distribution by Scientific Domains

Selected Abstracts

Co-operative actions and degradation analysis of purified xylan-degrading enzymes from Thermomonospora fusca BD25 on oat-spelt xylan

M. Tuncer
Abstract Aims: To determine and quantify the products from the degradation of xylan by a range of purified xylan-degrading enzymes, endoxylanase, , -xylosidase and , - l -arabinofuranosidase produced extracellularly by Thermomonospora fusca BD25. Methods and Results: The amounts of reducing sugars released from oat-spelt xylan by the actions of endoxylanase, , -xylosidase and , - l -arabinofuranosidase were equal to 28·1, 4·6 and 7% hydrolysis (as xylose equivalents) of the substrate used, respectively. However, addition of , -xylosidase and , - l -arabinofuranosidase preparation to endoxylanase significantly enhanced (70 and 20% respectively) the action of endoxylanase on the substrate. The combination of purified endoxylanase, , -xylosidase and , - l -arabinofuranosidase preparations produced a greater sugar yield (58·6% hydrolysis) and enhanced the total reducing sugar yield by around 50%. The main xylooligosaccharide products released using the action of endoxylanase alone on oat-spelt xylan were identified as xylobiose and xylopentose. , - l -Arabinofuranosidase was able to release arabinose and xylobiose from oat-spelt xylan. In the presence of all three purified enzymes the hydrolysis products of oat-spelt xylan were mainly xylose, arabinose and substituted xylotetrose with lesser amount of substituted xylotriose. Conclusions: The addition of the , -xylosidase and , - l -arabinofuranosidase enzymes to purified xylanases more than doubled the degradation of xylan from 28 to 58% of the total substrate with xylose and arabinose being the major sugars produced. Significance and Impact of the Study: The results highlight the role of xylan de-branching enzymes in the degradation of xylan and suggest that the use of enzyme cocktails may significantly improve the hydrolysis of xylan in industrial processes. [source]

Low-density caveolae-like membrane from Xenopus laevis oocytes is enriched in Ras

Susan E. SadlerArticle first published online: 10 JUL 200
Abstract Detergent-free discontinuous sucrose density gradient centrifugation was used to resolve low- and high-density membrane fractions from Xenopus laevis oocytes. Compared to high-density membrane, low-density oocyte membrane is enriched two-fold in cholesterol and highly enriched in ganglioside GM1. Protein immunoblotting of membrane fractions from whole cells with polyclonal anti-human caveolin antibody detected multiple bands, including a distinctive triad with apparent molecular weights of 21, 33, and 48 kDa. To more clearly determine which of these caveolin-like protein(s) is associated with the oocyte plasma membrane, microdissection was used to separate external membrane (cortical preparations containing plasma membrane) from intracellular membrane. Cortical membrane preparations displayed a single 21-kDa caveolin-like protein in low-density membrane. Internal oocyte membrane displayed the higher molecular weight bands of 33 and 48 kDa and a lesser amount of the 21-kDa protein in low-density membrane fractions. Monoclonal anti-human Ras antibody detected a single 23-kDa immunoblot band that is enriched an average of eight-fold in low-density membrane fractions prepared from whole cells. This is the first report of caveolin-associated, low-density membrane in amphibian oocytes, and is consistent with a role for caveolin and caveolae-like microdomains in oocyte signal transduction. © 2001 Wiley-Liss, Inc. [source]

Solubilization of methanol and ethanol in palm oil stabilized by medium- and long-chain alkanols

K Dzulkefly
Abstract Solubilization of methanol and ethanol in crude palm oil, refined, bleached and deodorized palm oil (RBD PO) and RBD palm olein (POL) was studied using medium- and long-chain alkanols (C4,C12). Ternary phase diagrams were constructed to determine the solubilization (isotropic) region. The results showed that methanol and ethanol are solubilized to a greater extent in an unsaturated palm olein than the saturated CPO and RBD PO in the presence of long-chain alkanols. The minima of the solubilization curves for dodecanol, decanol and octanol were 27%, 30% and 33% of alkanol respectively in the methanol system, whereas in the ethanol system, the minima for the same alkanols were found at 22%, 24% and 27%. The longer chain-length alkanol (dodecanol) requires a lesser amount (21% and 32%) to achieve miscibility compared with 53% and 57% for butanol in mixtures containing 70:30 and 50:50 wt ratios respectively. The kinematic viscosity of the isotropic solutions increases with the chain-length and percentage of alkanols. Solubilization using a POL/methanol/butanol system significantly reduced the kinematic viscosity of POL from 72.7,mm2,s,1 to the value allowable for No 2 diesel fuel (1.9,4.1,mm2,s,1) or about a 96% reduction from the initial kinematic viscosity of POL. © 2002 Society of Chemical Industry [source]

A Human Oral-throat Cast Integrated with a Twin-stage Impinger for Evaluation of Dry Powder Inhalers

The aim of this study was to investigate the applicability of replacing the glass throat from a twin-stage impinger (TSI) with a human oral-throat cast. Monodisperse aerosols were used to calibrate the human oral cast-TSI at 60 L min,1 and cut-off in particle size was compared with that of the TSI described in the British Pharmacopoeia which employs a glass throat. The amount of salbutamol sulphate (and lactose) delivered by the Cyclohaler depositing on various elements of the in-vitro model were determined. The calibration of the model containing a human oral-throat cast at 60 L min,1 gave a particle size cut-off of 5.2 ,m which was less than that of the TSI (6.3 ,m). The oral-throat cast trapped more drug than the glass throat model with a formulation that employed the larger carrier (63,90 ,m; P<0.05) while it trapped a lesser amount of drug with those filled with the lower size carrier (Lactochem, micronised lactose). The greater amount of lactose in the formulation that employed the larger-sized carrier (63,90 ,m) was deposited closer to the inlet of the oral-throat cast than to the inlet of the glass throat model. Replacement of the glass throat in the TSI by the human oral-throat cast, leads to a change in deposition efficiency, with the cast having a higher filter efficiency and hence more aerosol particles being captured before their entry into the TSI. This should be investigated further to determine whether such a model might provide a more realistic assessment of the in-vivo characteristics of an aerosol in comparison with the TSI currently being employed, which utilises the glass throat as the portal of entry. [source]

The porcine trophoblastic interferon-,, secreted by a polarized epithelium, has specific structural and biochemical properties

FEBS JOURNAL, Issue 11 2002
Avrelija Cenci
At the time of implantation in the maternal uterus, the trophectoderm of the pig blastocyst is the source of a massive secretion of interferon-gamma (IFN-,), together with lesser amounts of IFN-,, a unique species of type I IFN. This trophoblastic IFN-, (TrIFN-,) is an unprecedented example of IFN-, being produced spontaneously by an epithelium. We therefore studied some of its structural and biochemical properties, by comparison with pig IFN-, from other sources, either natural LeIFN-, (from adult leucocytes), or recombinant. Biologically active TrIFN-, is a dimeric molecule, of which monomers are mainly composed of a truncated polypeptide chain with two glycotypes, unlike LeIFN-, which is formed of at least two polypeptide chains and four glycotypes. TrIFN-, collected in the uterus lumen was enzymatically deglycosylated and analysed by mass spectrometry (MALDI-TOF). The data revealed that the more abundant polypeptide has a mass of 14.74 kDa, corresponding to a C-terminal cleavage of 17 residues from the expected 143-residue long mature sequence. A minor polypeptide, with a mass of 12.63 kDa, corresponds to a C-terminal truncation of 36 amino acids. MALDI-TOF analysis of tryptic peptides from the glycosylated molecule(s) identifies a single branched carbohydrate motif, with six N -acetylgalactosamines, and no sialic acid. The only glycan microheterogeneity seems to reside in the number of l -fucose residues (one to three). The lack of the C-terminal cluster of basic residues, and the presence of nonsialylated glycans, result in a very low net charge of TrIFN-, molecule. However, the 17-residue truncation does not affect the antiproliferative activity of TrIFN-, on different cells, among which is a porcine uterine epithelial cell line. It is suggested that these specific properties might confer on TrIFN-, a particular ability to invade the uterine mucosa and exert biological functions beyond the endometrial epithelium. [source]

Seawater Mg/Ca controls polymorph mineralogy of microbial CaCO3: A potential proxy for calcite-aragonite seas in Precambrian time

GEOBIOLOGY, Issue 2 2008
ABSTRACT A previously published hydrothermal brine-river water mixing model driven by ocean crust production suggests that the molar Mg/Ca ratio of seawater (mMg/Casw) has varied significantly (~1.0,5.2) over Precambrian time, resulting in six intervals of aragonite-favouring seas (mMg/Casw > 2) and five intervals of calcite-favouring seas (mMg/Casw < 2) since the Late Archaean. To evaluate the viability of microbial carbonates as mineralogical proxy for Precambrian calcite-aragonite seas, calcifying microbial marine biofilms were cultured in experimental seawaters formulated over the range of Mg/Ca ratios believed to have characterized Precambrian seawater. Biofilms cultured in experimental aragonite seawater (mMg/Casw = 5.2) precipitated primarily aragonite with lesser amounts of high-Mg calcite (mMg/Cacalcite = 0.16), while biofilms cultured in experimental calcite seawater (mMg/Casw = 1.5) precipitated exclusively lower magnesian calcite (mMg/Cacalcite = 0.06). Furthermore, Mg/Cacalcite varied proportionally with Mg/Casw. This nearly abiotic mineralogical response of the biofilm CaCO3 to altered Mg/Casw is consistent with the assertion that biofilm calcification proceeds more through the elevation of , via metabolic removal of CO2 and/or H+, than through the elevation of Ca2+, which would alter the Mg/Ca ratio of the biofilm's calcifying fluid causing its pattern of CaCO3 polymorph precipitation (aragonite vs. calcite; Mg-incorporation in calcite) to deviate from that of abiotic calcification. If previous assertions are correct that the physicochemical properties of Precambrian seawater were such that Mg/Casw was the primary variable influencing CaCO3 polymorph mineralogy, then the observed response of the biofilms' CaCO3 polymorph mineralogy to variations in Mg/Casw, combined with the ubiquity of such microbial carbonates in Precambrian strata, suggests that the original polymorph mineralogy and Mg/Cacalcite of well-preserved microbial carbonates may be an archive of calcite-aragonite seas throughout Precambrian time. These results invite a systematic evaluation of microbial carbonate primary mineralogy to empirically constrain Precambrian seawater Mg/Ca. [source]

Differential availability/processing of decorin precursor in arterial and venous smooth muscle cells

Rafaella Franch
Abstract The existence of specific differentiation markers for arterial smooth muscle (SM) cells is still a matter of debate. A clone named MM1 was isolated from a library of monoclonal antibodies to adult porcine aorta, which in vivo binds to arterial but not venous SM cells, except for the pulmonary vein. MM1 immunoreactivity in Western blotting involved bands in the range of Mr 33,226 kDa, in both arterial and venous SM tissues. However, immunoprecipitation experiments revealed that MM1 bound to a 100-kDa polypeptide that was present only in the arterial SM extract. By mass spectrometry analysis of tryptic digests from MM1-positive 130- and 120-kDa polypeptides of aorta SM extract, the antigen recognized by the antibody was identified as a decorin precursor. Using a crude decorin preparation from this tissue MM1 reacted strongly with the 33-kDa polypeptide and this pattern did not change after chondroitinase ABC treatment. In vitro, decorin immunoreactivity was found in secreted grainy material produced by confluent arterial SM cells, although lesser amounts were also seen in venous SM cells. Western blotting of extracts from these cultures showed the presence of the 33-kDa band but not of the high-molecular-weight components, except for the 100-kDa monomer. The 100/33-kDa combination was more abundant in arterial SM cells than in the venous counterpart. In the early phase of neointima formation, induced by endothelial injury of the carotid artery or vein-to-artery transposition, the decorin precursor was not expressed, but it was up-regulated in the SM cells of the media underlying the neointima in both models. Collectively, these data suggest a different processing/utilization of the 100-kDa monomer of proteoglycan decorin in arterial and venous SM cells, which is abolished after vein injury. [source]

Extraction of Anthocyanins and Polyphenolics from Blueberry Processing Waste

J. Lee
ABSTRACT: The effectiveness of temperature, SO2, citric acid, and industrial juice-processing enzymes (n= 9) for producing extracts of blueberries (Vaccinium corymbosum, cv. Rubel) and blueberry skins that are rich in anthocyanins and polyphenolics were evaluated individually and/or in combination. Enzyme treatment had little effect on total monomeric anthocyanins and on total phenolics recovery. Various combinations of heat, SO2, and citric acid yielded extracts with higher concentrations of ACY and TP than the control. The distribution of anthocyanins and polyphenolics in ,Rubel' was also investigated. Anthocyanins existed almost exclusively in the skins, and polyphenolics were mostly in the skins with lesser amounts in flesh and seeds. Skins were also highest in antioxidant activity. All portions contained the same individual anthocyanins but in varying amounts. Cinnamic acid derivatives and flavonol-glycosides were found in the skins and seeds, whereas the flesh contained only cinnamic acids. [source]

Walnut (Juglans regia L.): genetic resources, chemistry, by-products

Marcela L Martínez
Abstract Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry, productivity, physical and chemical nut traits. Some of them have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food mainly owing to its oil content (up to 740 g kg,1 in some commercial varieties), which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols, phospholipids, sphingolipids, sterols, hydrocarbons and volatile compounds. Phenolic compounds, present at high levels in the seed coat but poorly extracted with the oil, have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine, glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by-product obtainment and characteristics. Copyright © 2010 Society of Chemical Industry [source]

Soil chemical quality changes and implications for fertilizer management after 11 years of no-tillage wheat production systems in semiarid Morocco

R. Mrabet
Abstract A long-term experiment comparing no-till with conventional tillage systems across five rotations was evaluated 11 years after initiation. The objectives of the present paper are (1) to report differences in soil chemical properties (namely soil organic matter, total nitrogen, phosphorus, potassium and pH) that have resulted by converting from conventional to no-till under contrasting cropping systems and (2) to draw tentative conclusions and recommendations on fertility status and fertilizer use and management. Soil in the no-till system had increased surface soil organic C levels relative to conventional tillage regardless of rotation. In addition, depending on the rotation, the N and P content of the soil improved with no-till compared with conventional tillage. In other words, no-till has helped to retain soil organic matter (SOM), conserved more N, and resulted in increased extractable P and exchangeable K concentrations in the upper root-zone. Hence, wheat produced in a no-till system may receive more nutrients from decomposition of SOM and acidification of the seed zone. It is possible that lesser amounts of fertilizer nutrients will be needed because of the greater efficiency of nutrient cycling in no-till systems relative to conventional systems. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Soot,additive interactions in engine oils

Dairene Uy
Abstract Soot is known to cause engine wear. In this work, we focus on how engine oil formulation affects soot-related wear, and how the lubricant-derived anti-wear film changes when soot is present. Friction and wear experiments of fully and partially formulated diesel engine oils (containing basestock, dispersants and viscosity modifiers) are conducted with a ball-on-disk rig in the presence of carbon black (CB) as a soot surrogate. The friction coefficient was largely unaffected by CB dispersed in the oils, but electrically insulating film formation, an indication of the formation of anti-wear films, was decreased. Wear on the disk was found to either remain the same or decrease when CB was present, depending on the oil formulation. An examination of the lubricant-derived films using Raman and Auger electron spectroscopies found that the presence of more abundant amorphous carbon and lesser amounts of anti-wear film components on the surface was associated with higher wear. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Petrology and mineralogy of the angrite Northwest Africa 1670

With subordinate clinopyroxene and chrome-spinel microphenocrysts (0.2-0.5 mm), they represent a xenocrystic association. Phenocrysts are surrounded by a groundmass, predominantly comprising bundles of plagioclase and clinopyroxene (typically 20 × 200 ,m crystals). Olivine and kirschsteinite are present in the groundmass in lesser amounts. The olivine xenocrysts (Fo90) are significantly fractured and show mosaicism for their major part, the remaining showing faint undulatory extinction. They are surrounded with a rim of 100,200 ,m zoned down to Fo80 and overgrown with serrated olivine, Fo80 to Fo60 (about 100 ,m). Olivine in the groundmass is zoned from Mg# 0.55 to 0.15; its CaO content ranges 2.0 to 8.4%. Subcalcic kirschsteinite is zoned from Mg# 0.13 to 0.03, CaO increasing from 15.8 to 21.3%. Pyroxenes xenocrysts (Mg# = 0.77) are superseded in the groundmass by less magnesian pyroxenes, Mg# 0.61 to 0.17, with an average FeO/ MnO of 98. Their compositions range from En30 Fs22 Wo27 Al-Ts28 Ti-Ts2 to En2 Fs37 Wo22 Al-Ts40 Ti-Ts1. Anorthite microcrysts (An99-100) are restricted to the groundmass. Accessories are pyrrhotite, kamacite, Ca-phosphate, titanomagnetite, hercynite and Ca-carbonate. The bulk chemical composition confirms that NWA 1670 corresponds to a normal angrite melt that incorporated olivine. High Mg olivine xenocrysts and the associated mineralogy are typical of angrites. We suggest that it is an impact melt with relict phenocrysts. The strong silica undersaturation, the presence of Fo90 olivine xenocrysts and carbonate support their derivation as melilite-like melts in the presence of carbonate. [source]

Photochemistry and Photocytotoxicity of Alkaloids from Goldenseal (Hydrastis canadensis L.) 3: Effect on Human Lens and Retinal Pigment Epithelial Cells

Colin F. Chignell
ABSTRACT The dried root or rhizome of Goldenseal (Hydrastis canadensis L.) contains several alkaloids including berberine, hydrastine, palmatine and lesser amounts of canadine and hydrastinine. Preparations derived from Goldenseal have been used to treat skin and eye ailments. Berberine, the major alkaloid in Goldenseal root powder, has been used in eye drops to treat trachoma, a disease characterized by keratoconjunctivitis. Berberine and palmatine are also present in extracts from Berberis amurensis Ruprecht (Berberidaceae) which are used to treat ocular disorders. We have previously shown that Goldenseal alkaloids are phototoxic to keratinocytes (Chem Res Toxicol. 14, 1529, 2001; ibid 19, 739, 2006) and now report their effect on human lens and retinal pigment epithelial cells. Human lens epithelial cells (HLE-B3) were severely damaged when incubated with berberine (25 ,M) and exposed to UVA (5 J cm,2). Under the same conditions, palmatine was less phototoxic and hydrastine, canadine and hydrastinine were inactive. Moderate protection against berberine phototoxicity was afforded by the antioxidants ascorbate (2 mM) and N -acetylcysteine (5 mM). When exposed to UVA (5 J cm,2) both berberine (10 ,M) and palmatine (10 ,M) caused mild DNA damage as determined by the alkaline comet assay which measures single strand breaks. Berberine and palmatine are the only Goldenseal alkaloids with appreciable absorption above 400 nm. Because light at wavelengths below 400 nm is cut off by the anterior portion of the adult human eye only berberine and palmatine were tested for phototoxicity to human retinal pigment epithelial (hRPE) cells. Although berberine did damage hRPE cells when irradiated with visible light (, > 400 nm) approximately 10 times higher concentrations were required to produce the same amount of damage as seen in lens cells. Palmatine was not phototoxic to hRPE cells. Neither berberine nor palmatine photodamaged DNA in hRPE. Infusions of Goldenseal are estimated to contain ,1 mM berberine, while in tinctures the alkaloid concentration may be more than 10 times higher. Our findings show that eyewashes and lotions derived from Goldenseal or containing berberine must be used with caution when the eyes are exposed to bright sunlight but that oral preparations are not likely to cause ocular phototoxicity. [source]

Sourcing Iron Age softstone artefacts in southeastern Arabia: results from a programme of analysis using Inductively Coupled Plasma-Mass Spectrometry/Optical Emission Spectrometry (ICP-MS/OES)

Peter Magee
Iron Age softstone vessels manufactured in southeastern Arabia are widely distributed across that region and in lesser amounts throughout Western Asia. Results from a pilot programme of analysis using Inductively Coupled Plasma Mass Spectrometry/Optical Emission Spectrometry on vessel fragments from two southeast Arabian sites are presented. These results indicate the existence of geochemically distinct groups that are separated by both transition metals and rare earth elements. While this indicates the potential for the application of the provenance postulate in softstone analysis, these promising results need to be further tested by an expanded programme of analysis which includes quarry fragments. [source]

Lipid analysis of the sex pheromone gland of the moth Heliothis virescens

S.P. Foster
Abstract The sex pheromone gland of female Heliothis virescens was analyzed for fatty acid and lipid content. Base methanolysis of the gland showed a large amount of methyl (Z)-11-hexadecenoate (Z11-16:Acyl), the fatty acyl analog of the major pheromone component, (Z)-11-hexadecenal, as well as a small amount of methyl (Z)-11-octadecenoate. Methyl esters of various common fatty acids were also observed. HPTLC analysis of the glandular lipids revealed large quantities of triacylglycerols (TGs), and lesser amounts of 1,2-diacylglycerols (1,2-DGs), 2- monoacylglycerols (2-MGs), phosphatidyl ethanolamines, and phosphatidyl cholines. The greatest amount of Z11-16:Acyl in these lipids was in the TGs, with lesser amounts in the two phospholipid classes and only trace amounts in the other neutral lipids. The glands of females at various ages and photoperiodic times were extracted, fractionated into neutral and polar fractions by silica SPE, and fatty acid titers in these fractions determined. All fatty acids, but notably Z11-16:Acyl, showed significant total and neutral lipid fraction peaks at mid scotophase for 2-day-old females; a less dramatic, but significant, Z11-16:Acyl peak in the polar fraction was also observed. However, only a relatively small proportion (<50%) of this acid was recovered from the silica at all times. This "non-recoverable" Z11-16:Acyl showed a dramatic and significant peak at mid scotophase for 2-day females, corresponding roughly with maximal pheromone titer. All other acids in the gland were recovered in high proportions, and their respective "non-recoverable" titers were not different at any of the times analyzed. Based on previous work, this non-recoverable Z11-16:Acyl is likely the CoA ester. Therefore, it appears that the pheromone gland of H. virescens maintains pools of Z11-16:Acyl in both CoA ester and TG forms, which are available for biosynthesis of pheromone. These pools are greatest during maximal pheromone production when the biosynthetic enzymes, possibly the fatty acid reductase, are unable to utilize rapidly enough the quantities of Z11-16:Acyl biosynthesized. Arch. Insect Biochem. Physiol. 59:80,90, 2005. © 2005 Wiley-Liss, Inc. [source]