Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

    We have a manual that explains all the features 

    Current refinement(s):

    Records 1 - 20 / 144

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Simultaneous quantification of ergot and tropane alkaloids in bread in the Netherlands by LC-MS/MS
    Veršilovskis, Aleksandrs ; Mulder, Patrick P.J. ; Pereboom-de Fauw, Diana P.K.H. ; Stoppelaar, Joyce de; Nijs, Monique de - \ 2020
    Food Additives & Contaminants Part B-Surveillance 13 (2020)3. - ISSN 1939-3210 - p. 215 - 223.
    bread - Ergot alkaloids - LC-MS/MS - quantification - survey - tropane alkaloids

    Atropine and scopolamine are tropane alkaloids (TAs), which are regulated for cereal-based foods for children in the EU. For ergot alkaloids (EAs) in cereals and cereal-based food harmonised legislation is not yet established. A fast and straightforward method, which employs extraction by acidified water/methanol followed by ultra-filtration prior to analysis by LC-MS/MS, was validated in bread for 20 EAs and six TAs. LOQs for individual alkaloids ranged from 0.3 to 1.2 µg kg−1, while recoveries ranged from 65% to 94% and repeatability from 3.4% to 17%. A survey was conducted in the Netherlands on 40 retail samples of bread (wheat, rye, wheat-rye, multi-grain) collected in 2014 and 2018. TAs, including atropine and scopolamine, were not detected. Eighteen different EAs were detected and total levels varied between −1. Since EAs were detected in a wide concentration range, it is recommended to monitor their occurrence in bread more regularly.

    Nucleus-specific expression in the multinuclear mushroom-forming fungus Agaricus bisporus reveals different nuclear regulatory programs
    Gehrmann, Thies ; Pelkmans, Jordi F. ; Ohm, Robin A. ; Vos, Aurin M. ; Sonnenberg, Anton S.M. ; Baars, Johan J.P. ; Wösten, Han A.B. ; Reinders, Marcel J.T. ; Abeel, Thomas - \ 2018
    Proceedings of the National Academy of Sciences of the United States of America 115 (2018)17. - ISSN 0027-8424 - p. 4429 - 4434.
    fungi - heterokaryon - Nuclear-specific expression - quantification - RNA-seq
    Many fungi are polykaryotic, containing multiple nuclei per cell. In the case of heterokaryons, there are different nuclear types within a single cell. It is unknown what the different nuclear types contribute in terms of mRNA expression levels in fungal heterokaryons. Each cell of the mushroom Agaricus bisporus contains two to 25 nuclei of two nuclear types originating from two parental strains. Using RNA-sequencing data, we assess the differential mRNA contribution of individual nuclear types and its functional impact. We studied differential expression between genes of the two nuclear types, P1 and P2, throughout mushroom development in various tissue types. P1 and P2 produced specific mRNA profiles that changed through mushroom development. Differential regulation occurred at the gene level, rather than at the locus, chromosomal, or nuclear level. P1 dominated mRNA production throughout development, and P2 showed more differentially up-regulated genes in important functional groups. In the vegetative mycelium, P2 up-regulated almost threefold more metabolism genes and carbohydrate active enzymes (cazymes) than P1, suggesting phenotypic differences in growth. We identified widespread transcriptomic variation between the nuclear types of A. bisporus. Our method enables studying nucleus-specific expression, which likely influences the phenotype of a fungus in a polykaryotic stage. Our findings have a wider impact to better understand gene regulation in fungi in a heterokaryotic state. This work provides insight into the transcriptomic variation introduced by genomic nuclear separation.
    The Material practices of quantification: Measuring ‘deprivation’ in the Amsterdam Neighbourhood Policy
    Wilde, Mandy de; Franssen, Thomas - \ 2016
    Critical Social Policy 36 (2016)4. - ISSN 0261-0183 - p. 489 - 510.
    actor-network theory - evaluation - governmentality - quantification - social policy
    The use of indicators and indexes in social policy, as part of evidence-based policy, is understood by governmentality scholars as ‘techniques of governance’. However, we know very little about how the process of quantification is enacted in the material practices that constitute social policy itself. In this article we focus on a particular quantified object: the ‘Normal Amsterdam Level’ (NAP), used in an Amsterdam Neighbourhood Policy programme. We follow the NAP from its birth, to its life and its afterlife. We show that the qualification ‘deprived’ calls forth a whole set of problematic arrangements which are lost in a process of quantification. We understand the NAP as a generative device that actively assembles and arranges the world. These assemblages are rendered ‘hard’ through semiotic, statistical and visual techniques that produce facts about targeted neighbourhoods in relation to a city-wide average, thus serving as evidence and legitimisation for policy interventions.
    Single particle ICP-MS combined with a data evaluastion tool as a routine techique for the analysis of nanoparticles in complex matrices
    Peters, R.J.B. ; Herrera-Rivera, Z. ; Undas, A.K. ; Lee, M.K. van der; Marvin, H.J.P. ; Bouwmeester, H. ; Weigel, S. - \ 2015
    Journal of Analytical Atomic Spectrometry 30 (2015). - ISSN 0267-9477 - p. 1274 - 1285.
    inductively-coupled plasma - field-flow fractionation - mass spectrometry - quantitative-determination - silver nanoparticles - gold nanoparticles - chicken meat - food - quantification - nanomaterials
    Detection and characterization of nanoparticles (NPs) in complex media as consumer products, food and toxicological test media is an essential part of understanding the potential benefits and risks of the application of nanoparticles. Single particle ICP-MS (spICP-MS) was studied as a screening tool for the detection and characterization of nanoparticles in complex matrices such as food and biological tissues. A data evaluation tool was created for the calculation of particle size, concentration and size distribution from the raw data. spICP-MS measurements were carried out on a standard quadrupole instrument as well as on a sector-field instrument. Performance characteristics were determined for four types of NPs. For the quadrupole instrument the size detection limits were 20 nm (Au and Ag), 50 (TiO2) and 200 nm (SiO2). For the sector-field instrument size detection limits are lower, 10 nm (Au). Concentration detection limits ranged from 1 ng L-1 for 60 nm Au NPs to 0.1 µg L-1 for 500 nm SiO2 particles. The dynamic range of spICP-MS is limited to two orders of magnitude and as a consequence sample dilution is often required. The precision of the method was found to be
    Uncertainty in the future change of extreme precipitation over the Rhine basin: the role of internal climate variability
    Pelt, S.C. van; Beersma, J.J. ; Buishand, T.A. ; Hurk, B.J.J.M. van den; Schellekens, J. - \ 2015
    Climate Dynamics 44 (2015)7. - ISSN 0930-7575 - p. 1789 - 1800.
    klimaatverandering - neerslag - hydrologie van stroomgebieden - risicoanalyse - rijn - climatic change - precipitation - catchment hydrology - risk analysis - river rhine - local precipitation - change simulations - model - temperature - quantification - frequency - ensemble - version - gcm
    Future changes in extreme multi-day precipitation will influence the probability of floods in the river Rhine basin. In this paper the spread of the changes projected by climate models at the end of this century (2081–2100) is studied for a 17-member ensemble of a single Global Climate Model (GCM) and results from the Coupled Model Intercomparison Project Phase 3 (CMIP3) ensemble. All climate models were driven by the IPCC SRES A1B emission scenario. An analysis of variance model is formulated to disentangle the contributions from systematic differences between GCMs and internal climate variability. Both the changes in the mean and characteristics of extremes are considered. To estimate variances due to internal climate variability a bootstrap method was used. The changes from the GCM simulations were linked to the local scale using an advanced non-linear delta change approach. This approach uses climate responses of the GCM to transform the daily precipitation of 134 sub-basins of the river Rhine. The transformed precipitation series was used as input for the hydrological Hydrologiska Byråns Vattenbalansavdelning model to simulate future river discharges. Internal climate variability accounts for about 30 % of the total variance in the projected climate trends of average winter precipitation in the CMIP3 ensemble and explains a larger fraction of the total variance in the projected climate trends of extreme precipitation in the winter half-year. There is a good correspondence between the direction and spread of the changes in the return levels of extreme river discharges and extreme 10-day precipitation over the Rhine basin. This suggests that also for extreme discharges a large fraction of the total variance can be attributed to internal climate variability.
    Vaccination of cattle only is sufficient to stop FMDV transmission in mixed populations of sheep and cattle
    Bravo De Rueda, C. ; Dekker, A. ; Eblé, P.L. ; Jong, M. de - \ 2015
    Epidemiology and Infection 143 (2015)11. - ISSN 0950-2688 - p. 2279 - 2286.
    mouth-disease virus - basic reproduction ratio - between-pen transmission - emergency vaccination - infectious-diseases - quantification - eradication - protection - reduction - exposure
    We quantified the transmission of foot-and-mouth disease virus in mixed cattle-sheep populations and the effect of different vaccination strategies. The (partial) reproduction ratios (R) in groups of non-vaccinated and vaccinated cattle and/or sheep were estimated from (published) transmission experiments. A 4 × 4 next-generation matrix (NGM) was constructed using these estimates. The dominant eigenvalue of the NGM, the R for a mixed population, was determined for populations with different proportions of cattle and sheep and for three different vaccination strategies. The higher the proportion of cattle in a mixed cattle-sheep population, the higher the R for the mixed population. Therefore the impact of vaccination of the cattle is higher. After vaccination of all animals R = 0·1 independent of population composition. In mixed cattle-sheep populations with at least 14% of cattle, vaccination of cattle only is sufficient to reduce R to <1.
    Transmission of Actinobacillus pleuropneumoniae among weaned piglets on endemically infected farms
    Tobias, T.J. ; Bouma, A. ; Broek, J. van den; Nes, A. van; Daemen, A.J.J.M. ; Wagenaar, J.A. ; Stegeman, J.A. ; Klinkenberg, D. - \ 2014
    Preventive Veterinary Medicine 117 (2014)1. - ISSN 0167-5877 - p. 207 - 214.
    between-pen transmission - acquired colostral antibodies - within-pen - airborne transmission - pigs - serotype-2 - virus - herd - quantification - colonization
    Clinical outbreaks due to Actinobacillus pleuropneumoniae occur recurrently, despite the wide-scale use of antimicrobials or vaccination. Therefore, new approaches for the prevention and control of these outbreaks are necessary. For the development of alternative measures, more insight into the transmission of the bacterium on farms is necessary. The aim of this cohort study was to quantify transmission of A. pleuropneumoniae amongst weaned piglets on farms. We investigated three possible transmission routes: (i) indirect transmission by infected piglets within the same compartment, (ii) transmission by infected pigs in adjacent pens and (iii) transmission by direct contact within pens. Additionally, we evaluated the effect of independent litter characteristics on the probability of infection. Two farms participated in our study. Serum and tonsil brush samples were collected from sows pre-farrowing. Serum was analysed for antibodies against Apx toxins and Omp. Subsequently, tonsil brush samples were collected from all piglets from these dams (N = 542) in three cohorts, 3 days before weaning and 6 weeks later. Tonsil samples were analysed by qPCR for the presence of the apxIVA gene of A. pleuropneumoniae. Before weaning, 25% of the piglets tested positive; 6 weeks later 47% tested positive. Regression and stochastic transmission models were used to assess the contribution of each of the three transmission routes and to estimate transmission rates. Transmission between piglets in adjacent pens did not differ significantly from that between non-adjacent pens. The transmission rate across pens was estimated to be 0.0058 day(-1) (95% CI: 0.0030-0.010), whereas the transmission rate within pens was ten times higher 0.059 day(-1) (95% CI: 0.048-0.072). Subsequently, the effects of parity and serological response of the dam and litter age at weaning on the probability of infection of pigs were evaluated by including these into the regression model. A higher dam ApxII antibody level was associated with a lower probability of infection of the pig after weaning; age at weaning was associated with a higher probability of infection of the pig after weaning. Finally, transmission rate estimates were used in a scenario study in which the litters within a compartment were mixed across pens at weaning instead of raising litter mates together in a pen. The results showed that the proportion of infected piglets increased to 69% if litters were mixed at weaning, indicating that farm management measures may affect spread of A. pleuropneumoniae. (C) 2014 Elsevier B.V. All rights reserved.
    Metabolic flux phenotype of tobacco hairy roots engineered for increased geraniol production
    Masakapalli, S.K. ; Ritala, A. ; Dong, L.M. ; Krol, A.R. van der; Oksman-Caldentey, K.M. ; Ratcliffe, R.G. ; Sweetlove, L.J. - \ 2014
    Phytochemistry 99 (2014). - ISSN 0031-9422 - p. 73 - 85.
    heterotrophic arabidopsis cells - central carbon metabolism - alkaloid biosynthesis - mevalonate pathway - mass-spectrometry - synthase - networks - plants - quantification - expression
    The goal of this study was to characterise the metabolic flux phenotype of transgenic tobacco (Nicotiana tabacum) hairy roots engineered for increased biosynthesis of geraniol, an intermediate of the terpenoid indole alkaloid pathway. Steady state, stable isotope labelling was used to determine flux maps of central carbon metabolism for transgenic lines over-expressing (i) plastid-targeted geraniol synthase (pGES) from Valeriana officinalis, and (ii) pGES in combination with plastid-targeted geranyl pyrophosphate synthase from Arabidopsis thaliana (pGES + pGPPS), as well as for wild type and control-vector-transformed roots. Fluxes were constrained by the redistribution of label from [1-C-13]-, [2-C-13]- or [C-13(6)]glucose into amino acids, sugars and organic acids at isotopic steady state, and by biomass output fluxes determined from the fractionation of [U-C-14]glucose into insoluble polymers. No significant differences in growth and biomass composition were observed between the lines. The pGES line accumulated significant amounts of geraniol/geraniol glycosides (151 +/- 24 ng/mg dry weight) and the de nova synthesis of geraniol in pGES was confirmed by C-13 labelling analysis. The pGES + pGPPS also accumulated geraniol and geraniol glycosides, but to lower levels than the pGES line. Although there was a distinct impact of the transgenes at the level of geraniol synthesis, other network fluxes were unaffected, reflecting the capacity of central metabolism to meet the relatively modest.demand for increased precursors in the transgenic lines. It is concluded that re-engineering of the terpenoid indole alkaloid pathway will only require simultaneous manipulation of the steps producing the pathway precursors that originate in central metabolism in tissues engineered to produce at least an order of magnitude more geraniol than has been achieved so far. (C) 2013 Elsevier Ltd. All rights reserved.
    Adventitious presence of transgenic events in the maize supply chain in Peru: A case study
    Santa-Maria, M.C. ; Lajo-Morgan, G. ; Guardia, L. - \ 2014
    Food Control 41 (2014)1. - ISSN 0956-7135 - p. 96 - 101.
    genetically-modified organisms - reference molecules - quantification - quantitation - crops
    Cultivation and trade of transgenic or genetically modified organisms (GMO) and commodities has become widespread worldwide. In particular, production of transgenic crops has seen an accelerated growth along with a complex regulatory process. Current Peruvian legislation prohibits import of transgenic seeds and cultivation of transgenic crops in National territory but allows import of GMO-derived products and commodities. In addition, there is legislation that mandates the labeling of food products containing transgenic ingredients but the labeling threshold is still under discussion and the enforcement of this law is on hold. In this context, we evaluated adventitious presence of transgenic events in locally traded yellow maize using PCR- and immuno-based detection methods. Our results indicated that contamination during the distribution system of lots derived from non-transgenic maize was unavoidable and generally below 1.0% (w/w). Transgenic event MON810 was found in truck-loads of nationally grown maize. In general, frequencies of GMO-derived targets in whole-grain lots were 2.2% (GMO content >= 1%), 16.4% (GMO content 0.9%), 65.1% (GMO content
    Angiopoietin-like 4 Stimulates STAT3-mediated iNOS Expression and Enhances Angiogenesis to Accelerate Wound Healing in Diabetic Mice
    Chong, H.C. ; Goh, C.Q. ; Gounko, N.V. ; Luo, B. ; Wang, X. ; Kersten, A.H. - \ 2014
    Molecular Therapy 22 (2014)9. - ISSN 1525-0016 - p. 1593 - 1604.
    nitric-oxide synthase - solid human tumors - international consensus - growth-factors - foot ulcers - repair - cells - quantification - methodology - mechanisms
    Impaired wound healing is a major source of morbidity in diabetic patients. Poor outcome has, in part, been related to increased inflammation, poor angiogenesis, and deficiencies in extracellular matrix components. Despite the enormous impact of these chronic wounds, effective therapies are lacking. Here, we showed that the topical application of recombinant matricellular protein angiopoietin-like 4 (ANGPTL4) accelerated wound reepithelialization in diabetic mice, in part, by improving angiogenesis. ANGPTL4 expression is markedly elevated upon normal wound injury. In contrast, ANGPTL4 expression remains low throughout the healing period in diabetic wounds. Exogenous ANGPTL4 modulated several regulatory networks involved in cell migration, angiogenesis, and inflammation, as evidenced by an altered gene expression signature. ANGPTL4 influenced the expression profile of endothelial-specific CD31 in diabetic wounds, returning its profile to that observed in wild-type wounds. We showed ANGPTL4-induced nitric oxide production through an integrin/JAK/STAT3-mediated upregulation of inducible nitric oxide synthase (iNOS) expression in wound epithelia, thus revealing a hitherto unknown mechanism by which ANGPTL4 regulated angiogenesis via keratinocyte-to-endothelial-cell communication. These data show that the replacement of ANGPTL4 may be an effective adjunctive or new therapeutic avenue for treating poor healing wounds. The present finding also confirms that therapeutic angiogenesis remains an attractive treatment modality for diabetic wound healing.
    Validation of a qualitative screening method for pesticides in fruits and vegetables by gas chromatography quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization
    Portoles, T. ; Mol, J.G.J. ; Sancho, J.V. ; Lopez, F.J. ; Hernandez, F. - \ 2014
    Analytica Chimica Acta 838 (2014). - ISSN 0003-2670 - p. 76 - 85.
    residue analysis - transformation products - multiclass pesticides - waste-water - identification - food - quantification - elucidation - extraction - advantages
    A wide-scope screening method was developed for the detection of pesticides in fruit and vegetables. The method was based on gas chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer with an atmospheric pressure chemical ionization source (GC-(APCI)QTOF MS). A non-target acquisition was performed through two alternating scan events: one at low collision energy and another at a higher collision energy ramp (MSE). In this way, both protonated molecule and/or molecular ion together with fragment ions were obtained in a single run. Validation was performed according to SANCO/12571/2013 by analysing 20 samples (10 different commodities in duplicate), fortified with a test set of 132 pesticides at 0.01, 0.05 and 0.20 mg kg-1. For screening, the detection was based on one diagnostic ion (in most cases the protonated molecule). Overall, at the 0.01 mg kg-1 level, 89% of the 2620 fortifications made were detected. The screening detection limit for individual pesticides was 0.01 mg kg-1 for 77% of the pesticides investigated. The possibilities for identification according to the SANCO criteria, requiring two ions with a mass accuracy =±5 ppm and an ion-ratio deviation =±30%, were investigated. At the 0.01 mg kg-1 level, identification was possible for 70% of the pesticides detected during screening. This increased to 87% and 93% at the 0.05 and 0.20 mg kg-1 level, respectively. Insufficient sensitivity for the second ion was the main reason for the inability to identify detected pesticides, followed by deviations in mass accuracy and ion ratios.
    Use of electron ionization and atmospheric pressure chemical ionization in gas chromatography coupled to time-of-flight mass spetrometry for screening and identification of organic pollutants in waters
    Portoles, T. ; Mol, J.G.J. ; Sancho, J.V. ; Hernandez, F. - \ 2014
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1339 (2014). - ISSN 0021-9673 - p. 145 - 153.
    urban waste-water - pesticide-residues - ms analysis - qtof-ms - tof-ms - contaminants - metabolites - quantification - elucidation - vegetables
    A new approach has been developed for multiclass screening of organic contaminants in water based on the use of gas chromatography coupled to hybrid quadrupole high-resolution time-of-flight mass spectrometry with atmospheric pressure chemical ionization (GC–(APCI)QTOF MS). The soft ionization promoted by the APCI source allows effective and wide-scope screening based on the investigation of the molecular ion and/or protonated molecule. This is in contrast to electron ionization (EI) where ionization typically results in extensive fragmentation, and diagnostic ions and/or spectra need to be known a priori to facilitate detection of the analytes in the raw data. Around 170 organic contaminants from different chemical families were initially investigated by both approaches, i.e. GC-(EI)TOF and GC-(APCI)QTOF, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and a notable number of pesticides and relevant metabolites. The new GC–(APCI)QTOF MS approach easily allowed widening the number of compounds investigated (85 additional compounds), with more pesticides, personal care products (UV filters, musks), polychloronaphthalenes (PCNs), antimicrobials, insect repellents, etc., most of them considered as emerging contaminants. Both GC-(EI)TOF and GC-(APCI)QTOF methodologies have been applied, evaluating their potential for a wide-scope screening in the environmental field.
    Ninety-day oral toxicity studies on two genetically modified maize MON810 varieties in Wistar Han RCC rats (EU 7th Framework Programme project GRACE)
    Zeljenkova, D. ; Ambrusova, K. ; Bartusova, M. ; Kebis, A. ; Kovriznych, J. ; Krivosikova, Z. ; Kuricova, M. ; Liskova, A. ; Rollerova, E. ; Spustova, V. ; Szabova, E. ; Tulinska, J. ; Wimmerova, S. ; Levkut, M. ; Revajova, V. ; Sevcikova, Z. ; Schmidt, K. ; Schmidtke, J. ; Paz, J.L. La; Corujo, M. ; Pia, M. ; Kleter, G.A. ; Kok, E.J. ; Sharbati, J. ; Hanish, C. ; Einspanier, R. ; Adel-Patient, K. ; Wal, J.M. ; Spök, A. ; Pöting, A. ; Kohl, C. ; Wilhelm, R. ; Schiemann, J. ; Steinberg, P. - \ 2014
    Archives of Toxicology 88 (2014)12. - ISSN 0340-5761 - p. 2289 - 2314.
    soybean trypsin-inhibitors - bacillus-thuringiensis - proteins - quantification
    The GMO Risk Assessment and Communication of Evidence (GRACE; www.grace-fp7.eu) project is funded by the European Commission within the 7th Framework Programme. A key objective of GRACE is to conduct 90-day animal feeding trials, animal studies with an extended time frame as well as analytical, in vitro and in silico studies on genetically modified (GM) maize in order to comparatively evaluate their use in GM plant risk assessment. In the present study, the results of two 90-day feeding trials with two different GM maize MON810 varieties, their near-isogenic non-GM varieties and four additional conventional maize varieties are presented. The feeding trials were performed by taking into account the guidance for such studies published by the EFSA Scientific Committee in 2011 and the OECD Test Guideline 408. The results obtained show that the MON810 maize at a level of up to 33 % in the diet did not induce adverse effects in male and female Wistar Han RCC rats after subchronic exposure, independently of the two different genetic backgrounds of the event.
    Comparison of Fecal Methanogenic Archaeal Community Between Erhualian and Landrace Pigs Using Denaturing Gradient Gel Electrophoresis and Real-Time PCR Analysis
    Su, Y. ; Smidt, H. ; Zhu, W.Y. - \ 2014
    Journal of Integrative Agriculture 13 (2014)6. - ISSN 2095-3119 - p. 1340 - 1348.
    16s ribosomal-rna - methanobrevibacter-smithii - human gut - diversity analysis - mcra gene - quantification - populations - bacterial - methane - prevalence
    Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis (DGGE) with two primer pairs (344fGC/519r and 519f/915rGC) and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE profiles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no significant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs; however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A (mcrA) gene fragments amplified with real-time PCR showed all samples possessed a single peak at 82°C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase (including diet factor) other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.
    Estimation of the transmission of foot-and-mouth disease virus from infected sheep to cattle
    Bravo De Rueda, C. ; Jong, M.C.M. de; Eble, P.L. ; Dekker, A. - \ 2014
    Veterinary Research 45 (2014). - ISSN 0928-4249 - 11 p.
    between-pen transmission - basic reproduction ratio - swine-fever virus - emergency vaccination - subclinical infection - within-pen - pigs - quantification - excretion - epidemic
    The quantitative role of sheep in the transmission of foot-and-mouth disease virus (FMDV) is not well known. To estimate the role of sheep in the transmission of FMDV, a direct contact transmission experiment with 10 groups of animals each consisting of 2 infected lambs and 1 contact calf was performed. Secretions and excretions (oral swabs, blood, urine, faeces and probang samples) from all animals were tested for the presence of FMDV by virus isolation (VI) and/or RT-PCR. Serum was tested for the presence of antibodies against FMDV. To estimate FMDV transmission, the VI, RT-PCR and serology results were used. The partial reproduction ratio R0 p i.e. the average number of new infections caused by one infected sheep introduced into a population of susceptible cattle, was estimated using either data of the whole infection chain of the experimental epidemics (the transient state method) or the final sizes of the experimental epidemics (the final size method). Using the transient state method, R0 p was estimated as 1.0 (95% CI 0.2 - 6.0) using virus isolation results and 1.4 (95% CI 0.3 - 8.0) using RT-PCR results. Using the final size method, R0 p was estimated as 0.9 (95% CI 0.2 - 3.0). Finally, R0 p was compared to the R0’s obtained in previous transmission studies with sheep or cattle only. This comparison showed that the infectivity of sheep is lower than that of cattle and that sheep and cattle are similarly susceptible to FMD. These results indicate that in a mixed population of sheep and cattle, sheep play a more limited role in the transmission of FMDV than cattle.
    Physical and Sensory Characterizations of Oral Coatings of Oil/Water Emulsions
    Camacho, S. ; Riel, V. van; Graaf, C. de; Velde, F. van de; Stieger, M.A. - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)25. - ISSN 0021-8561 - p. 5789 - 5795.
    custard desserts - perception - tongue - fat - quantification - difference - retention - papillae - texture - cavity
    The physical and sensory properties of oil coatings on the tongue formed by five oil/water emulsions varying in oil content were investigated. A total of 20 subjects processed orally each emulsion for 30 s in triplicate. In vivo fluorescence measurements at the front and back of the anterior tongue were made to quantify the oil fraction deposited at different time points. Calibration lines relating fluorescence intensity to oil fraction were determined using pig tongues at 37.5 °C to mimic oral conditions. The oil fraction on the tongue increased linearly with an increasing oil content of the emulsions. The oil fraction deposited at the back of the anterior tongue was 1.5–2.0× larger than at the front. The intensity of sensory attributes describing after-feel perception was related to the oil fraction by Weber–Fechner’s law. This study uses in vivo fluorescence to study food behavior in the mouth and unravel new insights in after-feel perception of emulsions.
    Long-term acclimation of anaerobic sludges for high-rate methanogenesis from LCFA
    Silva, S.A. ; Cavaleiro, A.J. ; Pereira, M.A. ; Stams, A.J.M. ; Alves, M.M. ; Sousa, D.Z. - \ 2014
    Biomass and Bioenergy 67 (2014). - ISSN 0961-9534 - p. 297 - 303.
    chain fatty-acids - oleic-acid - oxidizing bacteria - methane production - waste-water - digestion - lipids - quantification - hybridization - accumulation
    Inhibition of methanogens by long chain fatty acids (LCFA) and the low numbers of LCFA-degrading bacteria are limitations to exploit biogas production from fat-rich wastewaters. Generally reactors fail due to excessive LCFA accumulation onto the sludge. Here, long-term acclimation and bioaugmentation with a LCFA-degrading coculture were hypothesized as strategies to enhance methanogenic conversion of these compounds. Anaerobic sludges previously exposed to LCFA for more than 100 days converted a specific biomass-associated substrate of (3.2 ± 0.1) kg·kg-1 with very short lag phases (
    Increasing protein intake modulates lipid metabolism in healthy young men and women consuming a high-fat hypercaloric diet 1-3
    Rietman, A. ; Schwarz, J. ; Blokker, B.A. ; Siebelink, E. ; Kok, F.J. ; Afman, L.A. ; Tome, D. ; Mensink, M.R. - \ 2014
    The Journal of Nutrition 144 (2014)8. - ISSN 0022-3166 - p. 1174 - 1180.
    energy-expenditure - hepatic steatosis - adipose-tissue - liver fat - quantification - disease - rats - homeostasis - accurate - insulin
    The objective of this study was to evaluate the effect of increasing protein intake, at the expense of carbohydrates, on intrahepatic lipids (IHLs), circulating triglycerides (TGs), and body composition in healthy humans consuming a high-fat, hypercaloric diet. A crossover randomized trial with a parallel control group was performed. After a 2-wk run-in period, participants were assigned to either the control diet [n = 10; 27.8 energy percent (en%) fat, 16.9 en% protein, 55.3 en% carbohydrates] for 4 wk or a high-fat, hypercaloric diet (n = 17; >2 MJ/d) crossover trial with 2 periods of 2 wk, with either high-protein (HP) (37.7 en% fat, 25.7 en% protein, 36.6 en% carbohydrates) or normal-protein (NP) (39.4 en% fat, 15.4 en% protein, 45.2 en% carbohydrates) content. Measurements were performed after 2 wk of run-in (baseline), 2 wk of intervention (period 1), and 4 wk of intervention (period 2). A trend toward lower IHL and plasma TG concentrations during the HP condition compared with the NP condition was observed (IHL: 0.35 ± 0.04% vs. 0.51 ± 0.08%, P = 0.08; TG: 0.65 ± 0.03 vs. 0.77 ± 0.05 mmol/L, P = 0.07, for HP and NP, respectively). Fat mass was significantly lower (10.6 ± 1.72 vs. 10.9 ± 1.73 kg; P = 0.02) with the HP diet than with the NP diet, whereas fat-free mass was higher (55.7 ± 2.79 vs. 55.2 ± 2.80 kg; P = 0.003). This study indicated that an HP, high-fat, hypercaloric diet affects lipid metabolism. It tends to lower the IHL and circulating TG concentrations and significantly lowers fat mass and increases fat-free mass compared with an NP, high-fat, hypercaloric diet. This trail was registered at www.clinicaltrails.gov as NCT01354626.
    Two-step enzymatic fingerprinting of sugar beet pectin
    Remoroza, C.A. ; Broxterman, S.E. ; Gruppen, H. ; Schols, H.A. - \ 2014
    Carbohydrate Polymers 108 (2014). - ISSN 0144-8617 - p. 338 - 347.
    galacturonic acid distribution - aspergillus-niger - esterified oligogalacturonides - endopolygalacturonase - quantification - degradation - oligomers - enzymes - lyase
    A two-step enzymatic fingerprinting method was introduced to analyze a highly methylesterified and acetylated sugar beet pectin having a degree of methylesterification (DM) of 62 and acetylation of 30. A cocktail of pectolytic enzymes, including endo-polygalacturonase II (endo-PGII) and pectin lyase (PL), was used for the first digestion. The endo-PGII and PL resistant pectin fragments were isolated and subjected to a second digestion using fungal pectin methylesterase and endo-PGII. After the two sequential digestions, 78% of the total GalA residues present in the parental pectin were recovered as mono- and oligomers, which were used to quantitatively describe the parental SBP. For this reason, the descriptive parameters degree of blockiness (DBabs), degree of hydrolysis by PG (DHPG) and degree of hydrolysis by PL (DHPL) were established for both digestions. The first digestion revealed the presence of short blocks of nonesterified GalA residues and blocks of partly methylesterified and acetylated GalA residues in the parental SBP, in addition to blocks of highly methylesterified and acetylated GalA residues. The second digestion revealed the presence of blocks of methylesterified, partly methylesterified and/or acetylated GalA residues in a sequence not to be degradable by neither endo-PGII nor by PL. The acetyl groups were present in an blockwise manner. Application of the method to two differently prepared DM 50 SBPs showed that the two pectins differ in the ratio of blocks of nonesterified and blocks of partly methylesterified and acetylated GalA residues.
    Descriptive parameters for revealing substitution patterns of sugar beet pectins using pectolytic enzymes
    Remoroza, C.A. ; Buchholt, H.C. ; Gruppen, H. ; Schols, H.A. - \ 2014
    Carbohydrate Polymers 101 (2014). - ISSN 0144-8617 - p. 1205 - 1215.
    aspergillus-niger - mass-spectrometry - acetyl groups - endopolygalacturonase - homogalacturonans - quantification - esterification - degradation - oligomers - methyl
    Enzymatic fingerprinting was applied to sugar beet pectins (SBPs) modified by either plant or fungal pectin methyl esterases and alkali catalyzed de-esterification to reveal the ester distributions over the pectin backbone. A simultaneous pectin lyase (PL) treatment to the commonly used endo-polygalacturonase (endo-PG) degradation showed to be effective in degrading both high and low methylesterified and/or acetylated homogalaturonan regions of SBP simultaneously. Using LC-HILIC–MS/ELSD, we studied in detail all the diagnostic oligomers present, enabling us to discriminate between differently prepared sugar beet pectins having various levels of methylesterification and acetylation. Furthermore, distinction between commercially extracted and de-esterified sugar beet pectin having different patterns of substitution was achieved by using novel descriptive pectin parameters. In addition to DBabs approach for nonmethylesterified sequences degradable by endo-PG, the “degree of hydrolysis” (DHPG) representing all partially saturated methylesterified and/or acetylated galacturonic acid (GalA) moieties was introduced as a new parameter. Consequently, the description DHPL has been introduced to quantify all esterified unsaturated GalA oligomers.
    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

     
    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.