Aggregation of a proline-rich protein induced by epigallocatechin gallate and condensed tannins: effect of protein glycosylation     

Pascal C  Poncet-Legrand C  Cabane B  Vernhet A 《Journal of agricultural and food chemistry》2008,56(15):6724-6732

Astringency is one of the most important organoleptic qualities of numerous beverages, including red wines. It is generally thought to originate from interactions between tannins and salivary proline-rich proteins (PRPs). In this work interactions between a glycosylated PRP, called II-1, and flavan-3-ols were studied in aqueous solutions and at a colloidal level, by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). The flavan-3-ols were a monomer, epigallocatechin gallate (EGCG), and polymerized flavan-3-ol fractions extracted from grape seeds. In aqueous solutions containing EGCG and protein II-1, protein aggregation took place when protein concentration and the EGCG/protein ratio exceeded a threshold. The aggregates had a small size, comparable with the dimensions of protein monomers, and formed stable dispersions (no phase separation). Most proteins remained free in solution. This behavior is in sharp contrast with the phase separation observed for nonglycoslated PRP in the same conditions. Moreover, this slight aggregation of II-I in the presence of EGCG was disrupted by the addition of 12% ethanol. Increasing the flavan-3-ol molecular weight strongly enhanced II-I/tannin aggregation: the threshold was at a lower protein concentration (0.2 mg/mL) and a lower tannin/protein ratio. Still, in most cases, and in contrast with that observed with a nonglycosylated PRP, the aggregates remained of discrete size and stable. Only at low ethanol content (2%) did the addition of tannin polymers finally lead to phase separation, which occurred when the molar ratio of tannins to proteins exceeded 12. This systematic effect of ethanol confirmed the strong effect of cosolvents on protein/tannin interactions.  相似文献   

Influence of DCD and DMPP on soil N dynamics after incorporation of vegetable crop residues   总被引：5，自引：0，他引：5  

Barbara Chaves  Andrews Opoku  Stefaan De Neve  Pascal Boeckx  Oswald Van Cleemput  Georges Hofman 《Biology and Fertility of Soils》2006,43(1):62-68

We have investigated the effect of two nitrification inhibitors, 3,4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD), on the accumulation of and after incorporation of cauliflower residues in incubation experiments. Cauliflower leaves were incubated with soil and DCD or DMPP at two application rates [8.93 and 17.9 mg active component (ac) kg⁻¹ for DCD; 0.89 and 1.79 mg ac kg⁻¹ for DMPP]. Both doses of DCD and DMPP increased on average by 18.9 and 26.0 mg N kg⁻¹ for DCD1 (during 30 days) and DCD2 (during 45 days), respectively, and on average by 14.4 mg N kg⁻¹ for DMPP1 and DMPP2 during a period of at least 95 days. In DCD-treated soils, data followed an S-shaped curve, indicating that nitrification restarted during the experiment: inhibition was on average 24% during 35 days for DCD1 and on average 45% during 49 days for DCD2. Thereafter, amount in DCD-treated soils exceeded that of the cauliflower-only treatment by 31% for DCD1 and 78% for DCD2, probably due to a nitrogen release from DCD itself and a priming effect induced by DCD. In DMPP-treated soils, data followed a linear pattern since nitrification was inhibited during the complete incubation (95 days): inhibition was on average 56 and 64% for DMPP1 and DMPP2, respectively. DMPP did not affect the N mineralization of the crop residues. Under favourable conditions, DCD is able to inhibit the nitrification from crop residues for 50 days and DMPP for at least 95 days. Hence, especially DMPP shows a potential to reduce leaching after incorporation of crop residues.  相似文献   

Probing the solvent-assisted nucleation pathway in chemical self-assembly     

Jonkheijm P  van der Schoot P  Schenning AP  Meijer EW 《Science (New York, N.Y.)》2006,313(5783):80-83

Hierarchical self-assembly offers a powerful strategy for producing molecular nanostructures. Although widely used, the mechanistic details of self-assembly processes are poorly understood. We spectroscopically monitored a nucleation process in the self-assembly of p-conjugated molecules into helical supramolecular fibrillar structures. The data support a nucleation-growth pathway that gives rise to a remarkably high degree of cooperativity. Furthermore, we characterize a helical transition in the nucleating species before growth. The self-assembly process depends strongly on solvent structure, suggesting that an organized shell of solvent molecules plays an explicit role in rigidifying the aggregates and guiding them toward further assembly into bundles and/or gels.  相似文献   

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   

Development of an attract‐and‐kill co‐formulation containing Saccharomyces cerevisiae and neem extract attractive towards wireworms          下载免费PDF全文

Pascal Humbert  Marina Vemmer  Frauke Mävers  Mario Schumann  Stefan Vidal  Anant V Patel 《Pest management science》2018,74(7):1575-1585

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Particularities of early life stages in temperate freshwater fish species: comparisons with marine species and implications for aquaculture practices     

Fabrice Telehea  Pascal Fontaine 《Aquaculture Research》2011,42(5):630-654

Both egg and larvae are different between freshwater and marine fish species. Freshwater fish species have generally larger and fewer eggs than marine species. Most freshwater fish species have demersal eggs that develop stuck to various substrata, such as plants or gravels, while eggs of most marine fish species develop in the water column. These differences have consequences for both the evaluation of the quality and the incubation of eggs of freshwater fish species compared with marine species. The larvae of many freshwater fish species are larger and more developed at hatching than their marine counterparts: thus, larval feeding regimes could be different and cannibalism may emerge sooner in certain freshwater fish species. The main differences of egg and larvae between freshwater and marine species are highlighted and the possible implications for aquaculture practices are discussed.  相似文献   

Determining long‐term changes in a skate assemblage with aggregated landings and limited species data     

Florianne Marandel  Pascal Lorance  Verena M. Trenkel 《Fisheries Management and Ecology》2019,26(4):365-373

Sustainable fisheries management requires assessment of exploited populations and communities. Traditional fisheries stock assessment methods need species‐specific input data, which for skates have only recently become available in Europe. To overcome this limitation, a Bayesian multispecies biomass production model was developed. In addition to aggregated landings, input data are short time series with species‐specific information (landings and biomass indices). Applying the approach to four main skate species and a group of two skate species, all managed together in the Bay of Biscay (Northeast Atlantic), long‐term changes in the skate assemblage composition were identified. Since the 1990s, Leucoraja naevus became increasingly dominant, while the contributions of the other three species (Raja brachyura, Raja clavata and Raja montagui) declined. The abundance of the grouped Leucoraja fullonica and L. circularis has also strongly decreased, suggesting long‐term overexploitation. All species except this species group are expected to increase over the next decade under current harvest rates. Currently, the species considered here are managed under a single fishing quota making it unlikely that the group of the two most depleted species will recover soon. The multispecies modelling approach bears promise for other harvested assemblages for which only grouped harvest information is available for certain periods.  相似文献   

Chemical alarm cues in juvenile African catfish,Clarias gariepinus Burchell: A potential stressor in aquaculture?     

Pascal G. van de Nieuwegiessen  Heling Zhao  Johan A.J. Verreth  Johan W. Schrama 《Aquaculture (Amsterdam, Netherlands)》2009,286(1-2):95-99

Previous studies on the effects of stocking density on the behaviour of African catfish have shown that at low densities, especially directly after restocking of tanks, increased aggression might occur. This aggression may directly affect the welfare of the fish. In addition, the resulting skin damage may also lead to the release of chemical alarm cues from the skin of the fish, possibly acting as a secondary stressor in a farming situation. Moreover, in a recirculation aquaculture system, a build-up of chemical alarm cues might occur. The objective of this study was to examine the effects of a single chemical alarm cue administration on the behaviour and growth performance of group-housed African catfish. Furthermore, the effects of a single passage over a biofilter on the behavioural response of African catfish to chemical alarm cues were tested. Although African catfish responded to chemical alarm cues with a short-term 35% increase in the number of active fish, no long-term effects were observed on both behaviour and growth performance of the fish. Furthermore, the results indicated that a single passage over a biofilter did not strongly alter the response of African catfish to the alarm cue, indicated by a 25% increase in the number of active fish. In conclusion, the results of this study indicate that chemical alarm cues, at the concentration applied in this study, cannot be considered a stressor for African catfish, although the effects of higher cue concentrations need further study. In addition, further study into the effects of chemical alarm cues on other, non-predatory, farmed fish is recommended.  相似文献