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191.
Gerard H. Ros Ellis Hoffland Erwin J.M. Temminghoff 《Soil biology & biochemistry》2009,41(6):1029-1039
Extractable Organic N (EON) or Dissolved Organic Nitrogen (DON) pools are often analyzed to predict N mineralisation, N leaching, and to evaluate agricultural (nutrient) management practices. Size and characteristics of both pools, however, are strongly influenced by methodology. Quantifying the influence of methodology can increase the accuracy of soil tests to predict N mineralisation, improve model simulations, and can help to quantify the contribution of the EON and DON pools to soil N cycling. We estimated the relative impact of methodological, management, and environmental factors on EON and DON, using a meta-analysis approach based on 127 studies. Our results indicate that the EON and DON pools are neither similar in size nor controlled by the same factors. The influence of factors controlling EON generally decreased in the order of methodology (Δ10-2400%), followed by environment (Δ11-270%) and management (Δ16-77%). DON concentrations were primarily controlled by management factors: different land use and fertilisation caused a variation of 37-118%. Seasonal variations in DON concentrations were generally smaller than variations in EON, suggesting that high mineralisation and sorption rates buffer DON. The large range in EON as affected by different methodology emphasizes the importance of using appropriate and standardized methods for the determination of EON. The determination of DON can be useful to estimate leaching losses. EON, however, can be used to assess the impact of soil management practices on the turnover rate of labile soil organic matter pools. 相似文献
192.
Bart van de Vossenberg Marcel Westenberg Ian Adams Olga Afanasenko Ani Besheva Margriet Boerma James Choiseul Toos Dekker Kerstin Flath Marga van Gent-Pelzer Kurt Heungens Anatolii Karelov Ilona Kibildiene Jaroslaw Przetakiewicz Alexandra Schlenzig Vera Yakovleva Gerard van Leeuwen 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(3):757-766
An international test performance study (TPS) was organised to generate validation data for three molecular Synchytrium endobioticum tests: van den Boogert et al. (European Journal of Plant Pathology 113, 47–57, 2005), and van Gent-Pelzer et al. (European Journal of Plant Pathology, 126, 129-133, 2010) for the detection of S. endobioticum, and the pathotype 1(D1) identification test described by Bonants et al. (European Journal of Plant Pathology, 143, 495-506, 2015). Two TPS rounds were organised focussing on different test matrices, i.e. round 1: warted potato tissue, and round 2: resting spore suspensions. When using the tests for detection and identification of S. endobioticum in warted potato tissue, no significant differences were observed for diagnostic sensitivity, diagnostic specificity, overall accuracy, analytical sensitivity and robustness. When using the tests for detection and identification of S. endobioticum in resting spore suspensions, the van den Boogert and van Gent-Pelzer tests significantly outperform the Bonants test for diagnostic sensitivity and diagnostic specificity. For overall accuracy and analytical sensitivity, the van Gent-Pelzer significantly outperforms the van den Boogert and Bonants tests and is regarded as the test of choice when identifying S. endobioticum from resting spores. Tests regarded fit for purpose for routine testing of wart material and resting spore suspensions are proposed for the update of EPPO standard PM7/28(1) Synchytrium endobioticum. 相似文献
193.
Nigussie Haregeweyn Jean Poesen Jan Nyssen Gerard Govers Gert Verstraeten Joris de Vente Jozef Deckers Jan Moeyersons Mitiku Haile 《CATENA》2008
In Tigray-northern Ethiopia, lack of sediment yield data and appropriate methodologies for predicting sediment yield have contributed to poor planning resulting in rapid sedimentation in reservoirs and storage capacity loss. The objectives of this study were: (1) to assess the spatial variability of absolute sediment yield (SY) and area-specific sediment yield (SSY) and to identify their controlling factors for 11 representative catchments and (2) to develop models to predict sediment yield. We quantified sediment yield from reservoir sediment surveys and studied the role of bio-physical characteristics of the catchments and their interactions in controlling SY and SSY variability. 相似文献
194.
195.
Tonie E Rocke Jordan Mencher Susan R Smith Arthur M Friedlander Gerard P Andrews Laurie A Baeten 《Journal of zoo and wildlife medicine》2004,35(2):142-146
Black-footed ferrets (Mustela nigripes) are highly susceptible to sylvatic plague, caused by the bacterium Yersinia pestis, and this disease has severely hampered efforts to restore ferrets to their historic range. A study was conducted to assess the efficacy of vaccination of black-footed ferrets against plague using a recombinant protein vaccine, designated F1-V, developed by personnel at the U.S. Army Medical Research Institute of Infectious Diseases. Seven postreproductive black-footed ferrets were immunized with the vaccine, followed by two booster immunizations on days 23 and 154; three control black-footed ferrets received a placebo. After the second immunization, antibody titers to both F1 and V antigen were found to be significantly higher in vaccinates than controls. On challenge with 7,800 colony-forming units of virulent plague by s.c. injection, the three control animals died within 3 days, but six of seven vaccinates survived with no ill effects. The seventh vaccinate died on day 8. These results indicate that black-footed ferrets can be immunized against plague induced by the s.c. route, similar to fleabite injection. 相似文献
196.
197.
L. Ayalew J. L. Frchette R. Malo C. Beauregard 《Canadian journal of veterinary research》1973,37(4):356-361
Nematode populations is stabled ewes of the Rimouski region were studied by means of fecal worm egg counts, fecal culture of larvae, and worm counts at necropsy. It was found that during the winter strongyle egg counts were low, Trichostrongylus eggs being most numerous, The stronglye egg counts increased following lambing and reached peak in June. Ostertagia spp was the principal contributor to this “spring-rise”, with substantial contribution from Trichostrongylus and Haemonchus contortus. The bulk of adult worm populations in winter, however, was made up of Trichostrongylus, whereas the great majority of the populations of Ostertagia spp, H. contortus and Nematodirus spp were inhibited in development at the fourth larval stage. All the worms recovered at necropsy in spring were adults, coinciding with the “spring-rise”. 相似文献
198.
Penning LC Vrieling HE Brinkhof B Riemers FM Rothuizen J Rutteman GR Hazewinkel HA 《Veterinary immunology and immunopathology》2007,120(3-4):212-222
For a proper determination of relative mRNA expression levels with real-time quantitative PCR (Q-PCR) internal standards, such as the expression of reference genes, are of utmost importance. For cats, in contrast to dogs, no validation of reference genes has been published. Our goal was to evaluate frequently used reference genes for the analysis of relative mRNA levels from feline tissues in a SYBR Green-based Q-PCR protocol. First, primers were optimized on mRNA-derived cDNA from liver and kidney tissues of randomly chosen (healthy and diseased) cats. Then, the expression variation and stability of each reference gene within a specific tissue was determined. Dental roots and crowns, heart (left ventricle), renal, liver, lung, and mammary gland tissues from 3 to 11 cats of different breeds, sexes, ages, and disease status were included in this study. Averaging relative stabilities over these six tissues revealed the usefulness of each tested gene as reference gene. In order to compensate for the expression variation of a reference gene within a specific tissue, as much as six reference genes (e.g. RPL17, RPL30, RPS7, YWHAZ, and HPRT) were required to obtain highly reliable data in cat tissues. The optimal set of reference genes depended on the tissue analyzed and should, ideally, be selected and evaluated at the start of each experimental condition. A comparison with a similar evaluation in dogs revealed three issues: (i) most ribosomal genes are suitable in both species; (ii) good non-ribosomal reference genes differ; (iii) more feline than canine reference genes are required for proper analysis. 相似文献
199.
Mortier L Daeseleire E Huyghebaert G Grijspeerdt K Van Peteghem C 《Journal of agricultural and food chemistry》2005,53(4):905-911
A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the quantitative determination of diclazuril in poultry tissues and feed is presented. A simple clean up with an organic solvent was carried out. A reversed-phase C(18) column was used for the high-performance liquid chromatography (HPLC) to separate the analyte with a gradient of acetonitrile and water as mobile phase. The precursor ions produced by electrospray negative ionization were selected for collisional dissociation. Validation of the methods was performed based on Commission Decision 2002/657/EC (Off. J. Eur. Communities 2002, L221, 8-36). For the detection of diclazuril in poultry meat, the decision limit was found to be 0.5 microg/kg. An animal experiment was set up in which 70 chickens were held for 6 weeks. From day 22 until day 32, they were fed feed containing 730 microg/kg diclazuril. From day 33 until day 42, every day six chickens were slaughtered, and breast, thigh, and liver were analyzed. Average steady-state concentrations of 94, 135, and 722 microg/kg in breast, thigh, and liver were obtained, respectively. Nine days after withdrawal of the medicated feed, diclazuril was still present in the different sample types. 相似文献
200.
We present some aspects of the methods of extraction and analysis of drugs; a number of other techniques exist (immunologic, radioactive, microbiologic methods). The generla method which is described, liquid-liquid extraction in relation to pH and to solvents, and analysis by chromatographic methods is presently one of the most efficient and most frequently employed tools, which permits the analyst to resolve most of the problems which arise. 相似文献