Kinetics of acid hydrolysis of water-soluble spruce O-acetyl galactoglucomannans     

Xu C  Pranovich A  Vähäsalo L  Hemming J  Holmbom B  Schols HA  Willför S 《Journal of agricultural and food chemistry》2008,56(7):2429-2435

Water-soluble O-acetyl galactoglucomannan (GGM) is a softwood-derived polysaccharide, which can be extracted on an industrial scale from wood or mechanical pulping waters and now is available in kilogram scale for research and development of value-added products. To develop applications of GGM, information is needed on its stability in acidic conditions. The kinetics of acid hydrolysis of GGM was studied at temperatures up to 90 degrees C in the pH range of 1-3. Molar mass and molar mass distribution were determined using size exclusion chromatography with multiangle laser light scattering and refractive index detection. The molar mass of GGM decreased considerably with treatment time at temperatures above 70 degrees C and pH below 2. The molar mass distribution broadened with hydrolysis time. A first-order kinetic model was found to match the acid hydrolysis. The reaction rate constants at various pH values and temperatures were calculated on the basis of the first-order kinetic model. Furthermore, the activation energy, E, was obtained from the Arrhenius plot. The activation energy E was 150 kJ mol (-1) for acid hydrolysis of spruce GGM. The apparent rate constant during acid hydrolysis increased by a factor of 10 with a decrease in pH by 1 unit, regardless of temperature. In addition, gas chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were applied to study the released GGM monomers and oligomers.  相似文献   

'Preparation leeds to maximum measures'. Veterinarian head inspector Henk Verburg says goodbye. Interview by B. Hendricks     

Verburg H 《Tijdschrift voor diergeneeskunde》2003,128(12):380-381

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Electromyographic changes of motor unit activity in horses with induced hypocalcemia and hypomagnesemia     

Wijnberg ID  van der Kolk JH  Franssen H  Breukink HJ 《American journal of veterinary research》2002,63(6):849-856

OBJECTIVE: To determine whether electromyographic abnormalities are evident in skeletal muscles in horses with induced hypocalcemia and hypomagnesemia. ANIMALS: 7 healthy adult Dutch Warmblood horses. PROCEDURES: Electromyographic examination was performed in the lateral vastus, triceps, and subclavian muscles before and after IV infusion of EDTA. An initial dose (mean +/- SD, 564+/-48 ml) of a 10% solution of sodium EDTA was administered IV during a period of 21+/-73 minutes to establish a blood concentration of ionized calcium of approximately 0.5 mmol/L. Average rate of EDTA infusion to maintain ionized calcium at this concentration was 6.6 ml/min. RESULTS: Mean blood concentrations of ionized calcium and magnesium were 1.39+/-0.06 and 0.84+/-0.09 mM, respectively before EDTA infusion; after EDTA infusion, concentrations were 0.48+/-0.05 and 0.44+/-0.20 mM, respectively. This state induced positive waves; fibrillation potentials; doublets, triplets, and multiplets; complex repetitive discharges; and neuromyotonia. Analysis of motor unit action potentials (MUAP) after EDTA infusion revealed an increase in prevalence of polyphasic and complex MUAP in all muscles. CONCLUSIONS AND CLINICAL RELEVANCE: None of the horses had classical signs of hypocalcemia and hypomagnesemia. In contrast, all horses had spontaneous activity in the measured muscles indicative of nerve hyperirritability. Calcium and magnesium deficits appear to have consequences, which may be subclinical, affecting functions of the neuromuscular system. This is of interest for equestrian sports in which hypocalcemia and hypomagnesemia are expected, such as during endurance rides.  相似文献   

Quantitative analysis of motor unit action potentials in the subclavian muscle of healthy horses     

Wijnberg ID  Franssen H  van der Kolk JH  Breukink HJ 《American journal of veterinary research》2002,63(2):198-203

OBJECTIVE: To evaluate the application of analysis of motor unit action potentials (MUAP) in horses and to obtain values of MUAP for the subclavian muscle of horses. ANIMALS: 10 healthy adult Dutch Warmblood horses. PROCEDURE: Electromyographic examination of the subclavian muscle in conscious nonsedated horses was performed to evaluate insertional activity, spontaneous activity, MUAP variables, and recruitment patterns. Muscle and body temperatures were measured at the beginning and end of the procedure. Amplitude, duration, number of phases, and number of changes in direction (ie, turns) for all representative MUAP were analyzed to determine values for this muscle in this group of horses. RESULTS: Mean +/- SD duration of insertional activity was 471.7 +/- 33.45 milliseconds. Mean MUAP amplitude in the examined horses was 379 RV (95% confidence interval [CI], 349 to 410 microV). Mean MUAP duration of the subclavian muscle was 727 milliseconds (95% CI, 6.84 to 7.71 milliseconds). Mean number of phases was 2.9, and mean number of turns was 3.0. Prevalence of polyphasic MUAP defined as MUAP with > 4 phases, was 77%. Number of MUAP that had > 5 turns was 2.4%. Satellite potentials were found in 1.0% of the MUAP CONCLUSIONS AND CLINICAL RELEVANCE: This study revealed that electromyography including MUAP analysis can be performed in horses, and values for the subclavian muscle in healthy adult horses can be obtained. Analysis of MUAP could be a valuable diagnostic tool for use in discriminating between myogenic and neurogenic problems in horses.  相似文献   

Dominant rhizosphere bacteria as a source for antifungal agents     

Katelijn H. Lievens  Ronan van Rijsbergen  Frederik R. Leyns  Bart J. Lambert  Paul Terming  Jean Swings  Henk J.-P. Joos 《Pest management science》1989,27(2):141-154

A search for micro-organisms associated in high numbers with roots or leaves of corn, grapevine, chicory, soybean, sunflower, barley and sugarbeet yielded a collection of over 10 000 bacterial strains. Within this collection, antifungal strains have been selected, using direct or indirect in-vitro assays against one target fungus per crop. The target fungi were selected based on their agronomic relevance as pests. Isolates with antifungal activity were tested for their spectrum of activity against a set of phytopathogenic fungi. In 15 bacterial strains with broad-spectrum activity, belonging to the species Erwinia herbicola. Serratia plymuthica, Pseudomonas fluorescens, P. aureofaciens, P. cepacia and Bacillus subtilis, the active compounds have been identified. Bacterial strains belonging to the same taxon, but isolated from different ecological niches and/or different places in Europe, produce identical compounds. In two bacterial taxa (Erwinia and Serratia) this was reflected in a genetic conservation of the regions coding for antifungal activity. In both cases, the biosynthetic pathways proved to be genetically complex. All of the compounds identified in this study have been described previously in bacterial strains isolated from analogous or completely different ecosystems.  相似文献   

DNA fingerprinting of plasmid-containing serotype A: 3,4 Pasteurella multocida isolated from cases of fowl cholera in chickens and turkeys     

Lee MD  Burch FT  Maurer JJ  Henk A  Thayer S 《Avian diseases》2000,44(1):201-204

The live, attenuated vaccine strains of Pasteurella multocida have been hypothesized to be responsible for homologous serotype outbreaks of fowl cholera on farms that use the commercial vaccines. We have further hypothesized that the naturally occurring Clemson University (CU) vaccine strain may be transformed to virulence by the acquisition of plasmid DNA. To test this hypothesis, we obtained seven homologous serotype (A:3,4) P. multocida isolates, all plasmid bearing, that were cultured from fowl cholera cases in vaccinated flocks and compared the isolates with the CU reference vaccine by molecular methods. Restriction fragment length polymorphisms (RFLPs) were detected by DNA/DNA hybridization with labeled probes specific for the cya, aroA, and rrn genes of P. multocida. The RFLPs obtained from BglII-digested genomic DNA probed with cya demonstrated no differences among the isolates. Although three isolates probed with aroA showed a RFLP identical to the vaccine strain, five isolates were distinctly different. Isolates probed with rrn grouped into three different restriction patterns that were dissimilar from that of the vaccine strain. Therefore, we have shown that these fowl cholera isolates are different from the CU vaccine strain and that these outbreaks were not vaccine related.  相似文献   

Protease-induced solubilisation of carbohydrates from brewers' spent grain     

Craig B. Faulds  Samuel Collins  James A. Robertson  Janneke Treimo  Vincent G.H. Eijsink  Sandra W.A. Hinz  Henk A. Schols  Johanna Buchert  Keith W. Waldron 《Journal of Cereal Science》2009

The impact of microbial proteases on the release of carbohydrates from BSG was studied. The proteases were able to release the non-cellulosic glucose, a portion of feruloylated arabinoxylan and over 50% of the protein from brewers' spent grain (BSG) after 24 h hydrolysis. The non-cellulosic glucose was derived from residual starch-derived products persisting in BSG after mashing. The proteases did not cleave the hydroxycinnamate ester linkages present on the arabinoxylan backbone, and thus do not behave as feruloyl esterases. However, the material solubilised from spent grain by the proteases contained up to 198 μg bound ferulic acid/g extract, which represented 8.6% of the total ferulic acid present in BSG. These results suggest that a portion of water-extractable feruloylated arabinoxylan and starch is trapped within the BSG matrix by a proteinaceous barrier.  相似文献   

Hemicellulase production in Chrysosporium lucknowense C1     

Sandra W.A. Hinz  Laurice Pouvreau  Rob Joosten  Jeffrey Bartels  Meliana C. Jonathan  Jan Wery  Henk A. Schols 《Journal of Cereal Science》2009

Filamentous fungi are widely used for enzyme production for the biofuel industry. The ascomycetous fungus Chrysosporium lucknowense C1 was isolated as a natural producer of neutral cellulases. It is at present an attractive alternative to well known fungi like Aspergillus sp. and Trichoderma reesei for protein production on a commercial scale. Besides many cellulases, a large number of hemicellulases (particularly xylanases and arabinofuranosidases) and esterases (acetyl xylan esterases and ferulic acid esterases) encoding genes have also been identified in the C1 genome. Many of these extracellular enzymes have been selectively expressed in C1 and then purified and characterized. Four arabinofuranosidases, two acetyl xylan esterases, two ferulic acid esterases, an α-glucuronidase and four xylanases have been purified and characterized. All these enzymes were found to be active towards arabinoxylans, demonstrating the high potential of C1 as a producer of hemicellulolytic enzymes.  相似文献   

Automated crop plant counting from very high-resolution aerial imagery     

Valente  João  Sari  Bilal  Kooistra  Lammert  Kramer  Henk  Mücher  Sander 《Precision Agriculture》2020,21(6):1366-1384

Precision Agriculture - Knowing before harvesting how many plants have emerged and how they are growing is key in optimizing labour and efficient use of resources. Unmanned aerial vehicles (UAV)...  相似文献   

The synergistic effect of combining woodlands and green veining for biodiversity     

Carla J. Grashof-Bokdam  J. Paul Chardon  Claire C. Vos  Ruud P. B. Foppen  Michiel WallisDeVries  Marja van der Veen  Henk A. M. Meeuwsen 《Landscape Ecology》2009,24(8):1105-1121

Combining nature reserves with small semi-natural elements (green veining) may improve the persistence of plant and animal species in fragmented landscapes. A better understanding of this synergy is essential to improve species diversity in the European Natura 2000 sites and in green veining elements. To test this hypothesis, we investigated the relationship between the occurrence of 40 forest plant and animal species in 1,000 km grid cells in the Netherlands and the spatial cohesion of the surrounding large woodlands and small woody elements. Two types of synergy were found. First, nine species were more often present if there was more cohesion of large elements; small elements enhanced this effect. Second, 11 other species were more often present when there was more cohesion of small elements; large elements enhanced this effect. Eight species showed both effects, indicating two-way synergy. The remaining 12 species preferred landscapes dominated by either large or small elements, or displayed no positive relationship whatsoever to woody elements. Species showing synergy often had a low dispersal capacity; the type of synergy seemed to be related to their habitat preference. These results imply that species diversity could be improved by integrating different policy instruments used for nature reserves and green veining. Using a zoning principle where green veins surround and connect nature reserves, the different spatial and habitat preferences of species can be secured. In this way a coherent network could become reality.  相似文献