Relations between organic carbon and methylmercury in humic rich surface waters from Svartberget catchment in northern Sweden     

Catharina Pettersson  Kevin Bishop  Ying -Hua Lee  Bert Allard 《Water, air, and soil pollution》1995,80(1-4):971-979

Monthly sampling of a mire outlet and two tributaries, one of them originating in the mire, on the Svartberget catchment in northern Sweden was performed during one year. The concentration of total organic carbon (TOC) in the three waters was fairly high (10–40 mg/l). Methylmercury (MeHg) was analysed in the original water sample (MeHg-whl) and in the humic fraction (MeHg-hum). The MeHg-hum increased with increasing concentration of humic substances (HS; measured as absorbance at 254 nm) in the water. A seasonal variation of the MeHg-hum/TOC ratio was superimposed on a negative relationship to the water flow, which indicates that the methylation is a slow process which results in a rapid drainage of the storage during periods of high flow. A minimum of the MeHg-whl/TOC ratio observed during the spring flood was followed by a slow increase during the rest of the year.  相似文献   

Tree species selection for land rehabilitation in Ethiopia: from fragmented knowledge to an integrated multi-criteria decision approach   总被引：1，自引：1，他引：0  

Bert Reubens  Clara Moeremans  Jean Poesen  Jan Nyssen  Sarah Tewoldeberhan  Steve Franzel  Jozef Deckers  Caleb Orwa  Bart Muys 《Agroforestry Systems》2011,82(3):303-330

Dryland regions worldwide are increasingly suffering from losses of soil and biodiversity as a consequence of land degradation. Integrated conservation, rehabilitation and community-based management of natural resources are therefore of vital importance. Local planting efforts should focus on species performing a wide range of functions. Too often however, unsuitable tree species are planted when both ecological suitability for the targeted area or preferences of local stakeholders are not properly taken into account during selection. To develop a decision support tool for multi-purpose species selection, first information needs to be pooled on species-specific ranges, characteristics and functions for a set of potentially valuable species. In this study such database has been developed for the highly degraded northern Ethiopian highlands, using a unique combination of information sources, and with particular attention for local ecological knowledge and preferences. A set of candidate tree species and potentially relevant criteria, a flexible input database with species performance scores upon these criteria, and a ready-to-use multi-criteria decision support tool are presented. Two examples of species selection under different scenarios have been worked out in detail, with highest scores obtained for Cordia africana and Dodonaea angustifolia, as well as Eucalyptus spp., Acacia abyssinica, Acacia saligna, Olea europaea and Faidherbia albida. Sensitivity to criteria weights, and reliability and lack of knowledge on particular species attributes remain constraints towards applicability, particularly when many species are jointly evaluated. Nonetheless, the amount and diversity of the knowledge pooled in the presented database is high, covering 91 species and 45 attributes.  相似文献   

Effects of an anthelmintic treatment programme on sheep productivity in the Middle Atlas,Morocco     

Khalid Khallaayoune  Bert E. Stromberg 《Tropical animal health and production》1992,24(3):129-134

Summary This study evaluated the production advantages of the strategic anthelmintic treatment of both lambs and ewes in an area endemic for gastro-intestinal nematodes, lungworms and liver flukes. The liver fluke infections were generally chronic. The lambs were treated with albendazole (SmithKline Beecham), fenbendazole (Hoechst Roussel) or a vitamin supplement and their weight gains were followed over the next 7 months. The control group, which received a vitamin supplement only, gained 6·67 kg from July to January. The group that received fenbendazole, an anthelmintic with no activity against liver flukes, gained 10·42 kg over the study period. The third group which received albendazole, an anthelmintic with efficacy against liver flukes, gained 13·07 kg over the same period. Lamb deaths apparently due to liver flukes were 12, 4, and zero for the control, fenbendazole and albendazole groups, respectively. Similar advantages were observed in the ewes. Deaths were 16, 8, and zero in the control, fenbendazole and albendazole groups, respectively. The lambing rate in the control groupswas significantly lower than that in either of the 2 treated groups. The number of services per conception was significantly lower in the albendazole treated group than that in either of the other groups. These studies demonstrated the advantages of anthelmintic treatment in sheep in a helminth endemic area. While removing gastro-intestinal nematodes and lungworms improved production, the additional removal of liver flukes enhanced production gains as well as reducing deaths.

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Resumen Este estudio evaluó las ventajas de un tratamiento estratégico en corderos y ovejas en un área endémica de parásitos gastrointestinales, pulmonares y hepáticos. La infección con fasciola era crónica. Los corderos fueron tratados con albendazole (Smithkline Beecham), fenbendazole (Hoechst Roussel) o un suplemento vitamínico; el peso fue consignado durante 7 meses seguidos. El grupo control que recibió el suplemento vitamínico, ganó 6·67 kg desde julio hasta enero. El grupo que recibió fenbendazole, antihelmíntico sin acción contra la fasciola, ganó 10·42 kg durante el período de estudio. El tercer grupo que recibió albendazole, un antihelmíntico eficaz contra la fascioliasis, ganó 13·7 kg durante el mismo período. La mortalidad de los corderos aparentemente debida a fascioliasis fue de 12 animales, 4 animales y cero animales, en el grupo control, en el tratado con fenbendazole y en el tratado con albendazole, respectivamente. En ovéjas, las ventajas fueron similares. La mortalidad por fascioliasis fue de 16 animales, 8 animales y cero animales, en el grupo control, en el tratado con fenbendazole y en el tratado con albendazole, respectivamente. La tasa de pariciones en el grupo control, fue significativamente más baja, que aquella de los grupos tratados. El número de servicios por concepción fue menor en el grupo tratado con albendazole. Estos estudios demostraron, la ventaja de los tratamientos antihelmínticos en ovejas en áreas endémicas. Mientras que el tratamiento contra parásitos gastrointestinales y pulmonares mejoró la producción, el tratamiento contra fasciola mejoró las ganancias de peso y redujo las muertes.

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Résumé Cette étude évalue les avantages en matière de production d’une stratégie de traitements anthelminthiques des brebis et des agneaux dans une zone endémique pour les nématodes gastro-intestinaux, les Fasciola et les strongles pulmonaires. Les infections à Fasciola ont généralement un caractère chronique. Les agneaux ont été traités soit à l’albendazole (SmithKline, Beecham) ou au fenbendazole (Hoechst Roussel) ou avec un complément vitaminé. Leur gain de poids ont été suivis pendant les sept mois suivants. Le groupe des témoins qui n’a re?u qu’un complément vitaminé a gagné 6,67 kg de juillet à janvier. Celui traité au fenbendazole, anthelminthique dépourvu d’activité contre les douves a progressé de 10,42 kg pendant la période d’étude. Le troisième groupe a été traité à l’albendazole, produit actif contre les Fasciola. Il a gagné quant à lui 13,07 kg au cours du même laps de temps. La mortalité des agneaux, due apparemment aux douves a été pour les groupes témoins et fenbendazole et albendazole respectivement de 12,4 et zéro. Des avantages identiques ont été observés pour les brebis dont la mortalité a été de 16,8 et zéro respectivement pour les lots témoins et fenbendazole et albendazole. Le taux d’agnelage dans le groupe témoin a été significativement plus bas que celui de l’un et de l’autre des deux groupes traités. Le nombre d’accouplements par conception était significativement plus bas dans le lot traité à l’albendazole que dans n’importe lequel des autres lots. Ces facteurs confirment les avantages d’un traitement anthelminthique chez les ovins vivants dans une région de parasitisme endémique. Tandis que la production est améliorée par la suppression des nématodes gastro-intestinaux et des strongles pulmonaires, la disparition complémentaire des douves accro?t les gains de production au même titre qu’elle réduit la mortalité.

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This work was supported in part by the International Foundation for Science (Stockholm).  相似文献   

Foaming properties of wheat gliadin     

Thewissen BG  Celus I  Brijs K  Delcour JA 《Journal of agricultural and food chemistry》2011,59(4):1370-1375

We studied gliadin solubility, surface tension and foam behavior, and the presence of different gliadin types in gliadin aqueous solutions and foams as a function of pH. Gliadin has excellent foaming properties only at neutral and alkaline pH. Its solubility is minimal near neutral pH, while almost complete at acidic and alkaline pH. Surface tensions of gliadin solutions are minimal around neutral pH, higher at alkaline pH, and highest at acidic pH, which corresponds well with their respective foaming properties. Foams at acidic and alkaline pH values are enriched in γ-gliadin, while foams at pH 8.0 have a similar distribution of α- and γ-gliadins. Thus, γ-gliadin predominantly contributes to the foaming properties of gliadin. The poor foaming properties of gliadin at pH 2.0 improve in the presence of 0.25 and 1.0% NaCl. It follows that the presence of positively charged amino acid residues hinders the formation of stable foam at acidic pH.  相似文献   

Kinetics of heat-induced polymerization of gliadin     

Lagrain B  Rombouts I  Brijs K  Delcour JA 《Journal of agricultural and food chemistry》2011,59(5):2034-2039

The kinetics of heat-induced polymerization of gliadin, that is, a mixture of monomeric wheat storage proteins, was studied using a model system. Samples were heated at pH 6.0 and 8.0 at 110, 120, and 130 °C for up to 240 min, and their extractabilities were compared under nonreducing and reducing (with 1% dithiothreitol) conditions. Extraction media were sodium dodecyl sulfate (SDS) containing buffer (pH 6.8, SDS buffer) and/or 70% ethanol. Gliadin cross-linking mainly resulted from intermolecular disulfide (SS) bond formation. At higher temperatures and, preferably, alkaline pH, intramolecular SS bonds in gliadin underwent β-elimination reactions, leading to the formation of dehydroalanine (DHA) and free sulfhydryl (SH) groups. The latter interchanged rapidly with SS bonds, leading to intermolecular SS bonds and gliadin extractability loss. When free SH groups had been formed, gliadin extractability in SDS buffer decreased following first-order reaction kinetics, the reaction rate constant of which increased with temperature and pH. Furthermore, the extractabilities of α- and γ-gliadin in 70% ethanol decreased according to first-order reaction kinetics. ω-Gliadin extractability was much less affected. Under the experimental conditions, gliadin polymerization through SH-SS interchange occurred much more rapidly than β-elimination of cystine.  相似文献   

DAXX/ATRX, MEN1, and mTOR pathway genes are frequently altered in pancreatic neuroendocrine tumors     

Jiao Y  Shi C  Edil BH  de Wilde RF  Klimstra DS  Maitra A  Schulick RD  Tang LH  Wolfgang CL  Choti MA  Velculescu VE  Diaz LA  Vogelstein B  Kinzler KW  Hruban RH  Papadopoulos N 《Science (New York, N.Y.)》2011,331(6021):1199-1203

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Long unfolded linkers facilitate membrane protein import through the nuclear pore complex   总被引：1，自引：0，他引：1  

Meinema AC  Laba JK  Hapsari RA  Otten R  Mulder FA  Kralt A  van den Bogaart G  Lusk CP  Poolman B  Veenhoff LM 《Science (New York, N.Y.)》2011,333(6038):90-93

Active nuclear import of soluble cargo involves transport factors that shuttle cargo through the nuclear pore complex (NPC) by binding to phenylalanine-glycine (FG) domains. How nuclear membrane proteins cross through the NPC to reach the inner membrane is presently unclear. We found that at least a 120-residue-long intrinsically disordered linker was required for the import of membrane proteins carrying a nuclear localization signal for the transport factor karyopherin-α. We propose an import mechanism for membrane proteins in which an unfolded linker slices through the NPC scaffold to enable binding between the transport factor and the FG domains in the center of the NPC.  相似文献   

Retraction     

Petersen CC  Brecht M  Hahn TT  Sakmann B 《Science (New York, N.Y.)》2004,306(5693):54

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Passively Aerated Composting of Straw-Rich Pig Manure: Effect of Compost Bed Porosity     

Adrie Veeken  Vinnie de Wilde  Bert Hamelers 《Compost science & utilization》2013,21(2):114-128

Straw-rich manure from organic pig farming systems can be composted in passively aerated systems as the high application of straw results in a compost bed with good structure and porosity. The passively aerated composting process was simulated in one-dimensional reactors of 2 m³ for straw-rich manure with compost bed densities of 1100, 700 and 560 kg m^?3. Temperature profiles over the reactor height were monitored online and ammonia emissions were measured periodically. The composition of the compost bed over the reactor height was determined at the end of the composting process. The composting process strongly depends on the density of the compost bed. At a density of 1100 kg.m^?3, the porosity of the bed is too low to initiate natural convection, and aerobic degradation fails and anaerobic conditions may lead to emissions of methane and odorous compounds. At a density of 560 kg.m^?3, the porosity of the bed is high and the high rate of natural convection will keep the temperature low thereby preventing the removal of pathogens and weeds. Best results were observed at a density of 700 kg.m^?3 for which aerobic degradation and drying were adequate and temperatures were high enough to kill pathogens and weeds. On basis of the Ergun equation, which describes the airflow in porous media with internal heat generation, this corresponds to a compost bed permeability of 7×10^?8 m². It was also shown that it is possible to compost animal manures with a low C/N ratio without significant emissions of ammonia. This can be established by trapping the initial ammonia emissions in a straw filter, which is placed on top of the compost bed. Ammonia absorbed in the straw filter and in the compost bed were removed by nitrification and denitrification. The passively aerated composting system results in a compost bed which is highly heterogeneous with respect to temperature, oxygen level and its composition. It is proposed that in this way a highly diverse microbial community in the compost bed is established which can perform various microbial conversions. The extensive composting system is most promising for on-farm production of an organic fertilizer from straw-rich manure, since the costs of the process and the level of ammonia emissions were low.  相似文献   

Is humane slaughter of fish possible for industry?   总被引：4，自引：1，他引：4  

Hans van de Vis  Steve Kestin  David Robb  Jörg Oehlenschläger  Bert Lambooij  Werner Münkner  Holmer Kuhlmann  Karin Kloosterboer  Margarita Tejada  Almudena Huidobro  Håkon Otterå  Bjørn Roth  Nils Kristian Sørensen  Leif Akse  Hazel Byrne  & Paul Nesvadba 《Aquaculture Research》2003,34(3):211-220

Abstract The objective was to evaluate industrial and research slaughter methods for Atlantic salmon (Salmo salar), gilt‐head seabream (Sparus auratus) and eel (Anguilla anguilla) with respect to welfare and quality. As a general term of reference, an optimal slaughter method should render fish unconscious until death without avoidable excitement, pain or suffering prior to killing. For Atlantic salmon, commercial slaughter methods (carbon dioxide stunning followed by gill cutting, and gill cutting alone) are not in conformity with the general term of reference, as the fish are not rendered unconscious immediately and possibly experience stress. Evaluation of automated percussive stunning remained unconclusive. More research should enable us to ascertain whether loss of consciousness is instantaneous. Electrical stunning can be humane if applied properly. However, because flesh of electrostunned fish was characterized by occasional bloodspots, optimization of the electrical parameters is required. Prototypes for percussive and electrical stunning of salmon have been recently developed. This implies that humane slaughter of salmon is feasible for industry. For gilt‐head seabream, neither aphyxia in air nor transfer of the fish to an ice slurry were considered to be humane: the methods did not induce immediate brain dysfunction and vigorous attempts to escape occurred. Percussive and electrical stunning can be in conformity with the general term of reference. However, conditions for stunning whole batches of seabream have not been established. Quality of the fish slaughtered by percussive stunning was similar to that obtained by the industrial method, i.e. immersion in an ice slurry. Further work is required to establish optimal stunning conditions and to develop prototypes. For eel, desliming in a salt‐bath followed by evisceration, electrical stunning performed under the conditions prescribed by the German legislation, and live chilling and freezing were not considered to be humane. In contrast, it was established that a 10–20 kg batch of eels in fresh water could be rendered unconscious immediately and until death by applying electricity in combination with nitrogen gas. The conditions used were 0.64 A dm^?2 for 1 s, followed by 0.17 A dm^?2 combined with nitrogen flushing for 5 min. A preliminary assessment of flesh quality suggests that it may be improved by application of the latter method, compared with the salt bath. The results clearly indicated that humane slaughter of eels is possible in practice.  相似文献