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501.
In a previous study, peptides aggregating at pH 7.0 derived from a whey protein hydrolysate made with Bacillus licheniformis protease were fractionated and identified. The objective of the present work was to investigate the solubility of the fractionated aggregating peptides, as a function of concentration, and their aggregating capacities toward added intact proteins. The amount of aggregated material and the composition of the aggregates obtained were measured by nitrogen concentration and size exclusion chromatography, respectively. The results showed that of the four fractions obtained from the aggregating peptides, two were insoluble, while the other two consisted of 1:1 mixture of low and high solubility peptides. Therefore, insoluble peptides coaggregated, assumedly via hydrophobic interactions, other relatively more soluble peptides. It was also shown that aggregating peptides could aggregate intact protein nonspecifically since the same peptides were involved in the aggregation of whey proteins, beta-casein, and bovine serum albumin. Both insoluble and partly insoluble peptides were required for the aggregation of intact protein. These results are of interest for the applications of protein hydrolysates, as mixtures of intact protein and peptides are often present in these applications. 相似文献
502.
Hannah Toberman Chris D. Evans Christopher Freeman Nathalie Fenner Marie White Bridget A. Emmett Rebekka R.E. Artz 《Soil biology & biochemistry》2008,40(6):1519-1532
Extracellular phenol oxidases play an important role in the soil carbon cycle. The effects of a field-scale summer drought manipulation on extracellular litter and soil phenol oxidase activity, soluble phenolic compounds and dissolved organic carbon concentrations were examined for an upland Calluna heathland on a peaty podsol in North Wales. Litter and organic soil phenol oxidase activity was found to be positively correlated with moisture content. Thus in shallow organic soils, which are sensitive to drying during periods of low rainfall, drought may inhibit soil phenol oxidase activity as a result of water limitations. The release of soluble phenolic compounds and DOC from the droughted plots was found to be lowered during the drought period and elevated outside of the drought period. It is hypothesized that these changes may be a result of the reduced ability of extracellular phenol oxidases to process recalcitrant polyphenolic material under drought conditions. A drying incubation carried out with litter and soil cores from the same site suggests that extracellular phenol oxidase activity displays an optimal moisture level. This reconciled the observed water limitation of phenol oxidase activity at the heathland experimental site with previously observed stimulation of phenol oxidase activity by water table drawdown in deeper peats. 相似文献
503.
Oomah BD Tiger N Olson M Balasubramanian P 《Plant foods for human nutrition (Dordrecht, Netherlands)》2006,61(2):91-97
Eight lupin (Lupinus angustifolius L.) genotypes grown at four locations in south central Alberta in 2004 were evaluated for variability in phenolic constituents and antioxidant activity measured by a photochemiluminescence assay. Genotype was the main source of variation for content of phenolic compounds and antioxidant activities. Phenolic compounds in genotypes varied minimally from 11.9 to 14.7 mg catechin equivalent and 4.15 to 4.95 mg rutin equivalent g(-1) lupin for total phenolic and flavonoid contents, respectively. Lupin genotypes exhibited weak antioxidant activity based on water-soluble substances (ACW) of 0.54 to 1.07 micromole Trolox equivalent antioxidant capacities (TEAC)/g with lag time ranging from 70 to 153 s and an antioxidant index of 6.7 to 14.5 and 1.9 to 3.3 micromole TEAC/g based on measurements of lipid-soluble substances (ACL). Antioxidant activity of lupin genotypes was not related to phenolic contents of seeds. 相似文献
504.
Peyron S Mouécoucou J Frémont S Sanchez C Gontard N 《Journal of agricultural and food chemistry》2006,54(15):5643-5650
The specific effects of heat treatment and/or addition of low/high-methylated pectin (LMP/HMP) on the allergenicity of beta-lactoglobulin (beta-Lg) and its hydrolysis products were investigated through a two-step in vitro digestion approach. beta-Lg was first hydrolyzed by pepsin and then by a trypsin/chymotrypsin (T/C) mixture done in a dialysis bag with a molecular weight cutoff of 1000. The protein digestion was followed by SDS-PAGE electrophoresis performed on each digestion product, and their in vitro allergenicity was analyzed by immunoblotting. Such procedure was applied on beta-Lg samples mixed with the two kinds of pectin before or after heating (80 degrees C, 25 min) to determine the respective impact of heat treatment and pectin addition. Heat denaturation improved significantly the susceptibility of beta-Lg against the pepsin and the T/C. This effect, which was coupled to a reduction in immunoreactivity of the digested beta-Lg, appeared to be distinctively modulated by LMP and HMP. Through nonspecific interaction with the beta-Lg, pectin could reduce the accessibility of cleavage sites and/or epitope sequences. This mechanism of action is discussed in relation to the intra- and intermolecular interactions between beta-Lg and pectin initiated under the experimental conditions. 相似文献
505.
Warren EH Vigneron NJ Gavin MA Coulie PG Stroobant V Dalet A Tykodi SS Xuereb SM Mito JK Riddell SR Van den Eynde BJ 《Science (New York, N.Y.)》2006,313(5792):1444-1447
CD8-positive T lymphocytes recognize peptides that are usually derived from the degradation of cellular proteins and are presented by class I molecules of the major histocompatibility complex. Here we describe a human minor histocompatibility antigen created by a polymorphism in the SP110 nuclear phosphoprotein gene. The antigenic peptide comprises two noncontiguous SP110 peptide segments spliced together in reverse order to that in which they occur in the predicted SP110 protein. The antigenic peptide could be produced in vitro by incubation of precursor peptides with highly purified 20S proteasomes. Cutting and splicing probably occur within the proteasome by transpeptidation. 相似文献
506.
Inhaled fluticasone reduces bronchial responsiveness and airway inflammation in cats with mild chronic bronchitis 总被引:4,自引:0,他引:4
Kirschvink N Leemans J Delvaux F Snaps F Jaspart S Evrard B Delattre L Cambier C Clercx C Gustin P 《Journal of Feline Medicine and Surgery》2006,8(1):45-54
This study investigated the effect of inhaled fluticasone on lower airway inflammation and bronchial responsiveness (BR) to inhaled carbachol in cats with very mild, chronic bronchitis (n = 5) that were compared with healthy cats serving as controls (n = 6). Chest radiographs, BR tests performed non-invasively by barometric whole body plethysmography (BWBP) and bronchoalveolar lavage (BAL) were performed before and after treatment. BR was quantified by calculating the concentration of carbachol inducing bronchoconstriction (C-Penh300%), defined as a 300% increase of baseline Penh, an index of bronchoconstriction obtained by BWBP. BAL fluid was analyzed cytologically and the oxidant marker 8-iso-PGF2alpha was determined. At test 1, healthy cats and cats with bronchitis were untreated, whereas for test 2 inhalant fluticasone (250 microg once daily) was administrated for 2 consecutive weeks to cats with bronchitis. Control cats remained untreated. Inhaled fluticasone induced a significant increase in C-Penh300% and a significant decrease of BAL fluid total cells, macrophages, neutrophils and 8-iso-PGF2alpha in cats with bronchitis, whilst untreated control cats did not show significant changes over time. This study shows that a 2-week fluticasone treatment significantly reduced lower airway inflammation in very mild bronchitis. BR could be successfully monitored in cats using BWPB and decreased significantly in response to inhaled fluticasone. 8-Iso-PGF2alpha in BAL fluid was responsive to treatment and appeared as a sensitive biomarker of lower airway inflammation in cats. 相似文献
507.
Spatial distribution,total length frequencies and otolith morphometry as tools to analyse the effects of a flash flood on populations of roach (Rutilus rutilus) 下载免费PDF全文
Fabien Morat Pierre Gibert Nathalie Reynaud Baptiste Testi Pierre Favriou Virginie Raymond Georges Carrel Anthony Maire 《Ecology of Freshwater Fish》2018,27(1):421-432
Floods are known to be the major source of natural variability and disturbance in stream ecosystems. However, the management and channelisation of large rivers have impacted the fluvial geomorphology and disconnected the main channel and floodplains used as nurseries by many species of fish. This study examines the influence of a first autumnal flood event of the Ardèche River on the roach population, Rutilus rutilus (Linnaeus, 1758), in the Caderousse reach on the Rhône River. This influence was evaluated through an analysis of the spatial distribution for the abundance and size of juvenile roach and an analysis of otolith shape. Juvenile roach from the three sections of the reach formed well‐defined local populations before and after the flood event. Juvenile roach were always more abundant in the less modified section (BPS) of the river than in the other sections (RES and TAIL). While the original primary river channel was directly impacted by the flash flood, no significant difference in otolith shape was observed before or after the flash flood. Our results suggest that this part of the reach provides refuge habitats used by fish during high flow events. 相似文献
508.
Accuracy of computed tomographic arthrography for assessment of articular cartilage defects in the ovine stifle 下载免费PDF全文
Fanny Hontoir Peter Clegg Vincent Simon Nathalie Kirschvink Jean‐Francois Nisolle Jean‐Michel Vandeweerd 《Veterinary radiology & ultrasound》2017,58(5):512-523
Articular cartilage defects are one of the features of osteoarthritis in animals and humans. Early detection of cartilage defects is a challenge in clinical veterinary practice and also in translational research studies. An accurate, diagnostic imaging method would be desirable for detecting and following up lesions in specific anatomical regions of the articular surface. The current prospective experimental study aimed to describe the accuracy of computed tomographic arthrography (CTA) for detecting cartilage defects in a common animal model used for osteoarthritis research, the ovine stifle (knee, femoropatellar/femorotibial) joint. Joints in cadaver limbs (n = 42) and in living animals under anesthesia (n = 13) were injected with a contrast medium and imaged using a standardized CT protocol. Gross anatomy and histological assessment of specific anatomic regions were used as a gold standard for the evaluation of sensitivity, specificity, negative predictive value, and positive predictive value for CTA identification of articular cartilage defects in those regions. Pooled estimated sensitivity and specificity were 90.32% and 97.30%, respectively, in cadaver limbs, and 81.82% and 95.24%, respectively, in living animals. Pooled estimated positive predictive value and negative predictive values were 98.25% and 85.71%, respectively, in cadaver limbs, and 81.82% and 95.24%, respectively, in living animals. The delineation of cartilage surface was good for anatomical regions most frequently affected by cartilage defects in the ovine stifle: medial femoral condyle, medial tibial condyle, and patella. This study supported the use of CTA as an imaging technique for detecting and monitoring articular cartilage defects in the ovine stifle joint. 相似文献
509.
Ammar?ShihanEmail author Stephan?H?ttenschwiler Alexandru?Milcu Fran?ois-Xavier?Joly Mathieu?Santonja Nathalie?Fromin 《Biology and Fertility of Soils》2017,53(2):171-185
This study aimed at quantifying the consequences of reduced precipitation and plant diversity on soil microbial community functioning in a Mediterranean shrubland of southern France. Across a natural gradient of shrub species diversity, we established a total of 92 plots (4 × 4 m) with and without a moderate rain exclusion treatment of about 12 % of total precipitation. Shrub diversity included all possible combinations of the four dominant species (Cistus albidus, Quercus coccifera, Rosmarinus officinalis, and Ulex parviflorus). Respective leaf litter mixtures of these species combinations were exposed in all plots over 2 years. We quantified how litter species richness and the reduction in precipitation affected the soil microbial substrate utilization (measured by CO2 evolution using the MicroResp method) on soil samples collected underneath each individual litter mixture after 1 and 2 years of decomposition. Moderate precipitation reduction had a minor impact, but litter species richness and the dissimilarity in phenolic concentrations (estimated using Rao’s quadratic entropy) showed a positive effect on the diversity of substrates metabolized by the microbial communities. Moreover, litter species richness increased soil microbial activity by increasing the catabolic diversity of the soil microbial community. These effects were mostly driven by the presence of Quercus and Ulex leaf litter, which at the same time reduced microbial metabolic dominance, while the presence of Rosmarinus had opposite effects. Our data suggest that plant species loss can have stronger effects on the functioning of soil microbial communities than moderate drought, with potentially important feedbacks on biogeochemical cycling in Mediterranean shrubland ecosystems. 相似文献