Staff Publications

Staff Publications

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    '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.

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Ultratrace LC-MS/MS Analysis of Segmented Calf Hair for Retrospective Assessment of Time of Clenbuterol Administration in Agriforensics
Duvivier, W.F. ; Beek, T.A. van; Meijer, T. ; Peeters, R.J.P. ; Groot, M.J. ; Sterk, S.S. ; Nielen, M.W.F. - \ 2015
Journal of Agricultural and Food Chemistry 63 (2015)2. - ISSN 0021-8561 - p. 493 - 499.
tandem mass-spectrometry - performance liquid-chromatography - beta-agonist residues - equine hair - bovine hair - human urine - cattle - calves - contamination - samples
In agriforensics, time of administration is often debated when illegal drug residues, such as clenbuterol, are found in frequently traded cattle. In this proof-of-concept work, the feasibility of obtaining retrospective timeline information from segmented calf tail hair analyses has been studied. First, an ultraperformance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) hair analysis method was adapted to accommodate smaller sample sizes and in-house validated. Then, longitudinal 1 cm segments of calf tail hair were analyzed to obtain clenbuterol concentration profiles. The profiles found were in good agreement with calculated, theoretical positions of the clenbuterol residues along the hair. Following assessment of the average growth rate of calf tail hair, time of clenbuterol administration could be retrospectively determined from segmented hair analysis data. The data from the initial animal treatment study (n = 2) suggest that time of treatment can be retrospectively estimated with an error of 3–17 days.
Levels of Organochlorine Pesticides in Blood Plasma from Residents of Malaria-Endemic Communities in Chiapas, Mexico
Ruiz-Suarez, L.E. ; Castro-Chan, R.A. ; Rivero-Perez, N.E. ; Trejo-Acevedo, A. ; Guillen-Navarro, G.K. ; Geissen, V. ; Bello-Mendoza, R. - \ 2014
International Journal of Environmental Research and Public Health 11 (2014)10. - ISSN 1660-4601 - p. 10444 - 10460.
southern mexico - exposure - serum - ddt - pollutants - children - samples - women - inhabitants - residues
Organochlorine (OC) pesticides have been extensively used for pest control in agriculture and against malaria vectors in the region of Soconusco, Chiapas, in southern Mexico. Our study aimed to identify whether the inhabitants of four Soconusco communities at different locations (i.e., altitudes) and with different history of use of OC pesticides, have been similarly exposed to residues of these pesticides. In particular, we analyzed the potential relationship between levels of OC pesticides in plasma and the age, gender, and residence of the study population (n = 60). We detected seven pesticides in total (gamma-HCH, beta-HCH, heptachlor, p,p'-DDE, p,p'-DDT, beta-endosulfan, endrin aldehyde). Of these, p,p'-DDE and beta-endosulfan were the most frequently found (in 98% and 38% of the samples, respectively). The low-altitude (60 years) had the highest p,p'-DDE level (56.94 +/- 57.81 mu g/L) of all age groups, while men had higher p,p'-DDE (34.00 +/- 46.76 mu g/L) than women. Our results demonstrate that residents of the Soconusco region are exposed to p,p'-DDE because of high exposure to DDT in the past and current environmental exposure to this DDT-breakdown product.
Genomic relationships computed from either next- generation sequence or array SNP data
Perez Enciso, M. - \ 2014
Journal of Animal Breeding and Genetics 131 (2014)2. - ISSN 0931-2668 - p. 85 - 96.
genetic-variation - complex traits - selection - pig - predictions - genotype - samples - cattle
The use of sequence data in genomic prediction models is a topic of high interest, given the decreasing prices of current next'-generation sequencing technologies (NGS) and the theoretical possibility of directly interrogating the genomes for all causal mutations. Here, we compare by simulation how well genetic relationships (G) could be estimated using either NGS or ascertained SNP arrays. DNA sequences were simulated using the coalescence according to two scenarios: a cattle' scenario that consisted of a bottleneck followed by a split in two breeds without migration, and a pig' model where Chinese introgression into international pig breeds was simulated. We found that introgression results in a large amount of variability across the genome and between individuals, both in differentiation and in diversity. In general, NGS data allowed the most accurate estimates of G, provided enough sequencing depth was available, because shallow NGS (4x) may result in highly distorted estimates of G elements, especially if not standardized by allele frequency. However, high-density genotyping can also result in accurate estimates of G. Given that genotyping is much less noisy than NGS data, it is suggested that specific high-density arrays (similar to 3M SNPs) that minimize the effects of ascertainment could be developed in the population of interest by sequencing the most influential animals and rely on those arrays for implementing genomic selection.
Occurrence of mycotoxins in a total diet study (TDS) for adults and childeren in The Netherlands
Lopez Sanchez, P. ; Rijk, T.C. de; Alewijn, M. ; Sprong, C. ; Castenmiller, J. - \ 2014
mycotoxinen - voedselveiligheid - monsters - voedselproducten - voedselanalyse - mycotoxins - food safety - samples - food products - food analysis
A total diet study (TDS) may be a valuable approach to assess the exposure of consumers to mycotoxins. A TDS study was performed on the risk associated with mycotoxin intake in cooperation with the Dutch National Institute for Public Health and the Environment (RIVM) and the Netherlands Food and Consumer Product Safety Authority (NVWA).
Status quo and future research challenges on organic food quality determination with focus on laboratory methods
Kahl, J. ; Bodroza-Solarov, M. ; Busscher, N. ; Hajslova, J. ; Kneifel, W. ; Kokornaczyk, M.O. ; Ruth, S.M. van; Schulzova, V. ; Stolz, P. - \ 2014
Journal of the Science of Food and Agriculture 94 (2014)13. - ISSN 0022-5142 - p. 2595 - 2599.
wheat-grain leakages - grown winter-wheat - nutritional quality - crystallization patterns - samples - standardization - authentication - definition - validation - products
Organic food quality determination needs multi-dimensional evaluation tools. The main focus is on the authentication as an analytical verification of the certification process. New fingerprinting approaches such as ultra-performance liquid chromatography–mass spectrometry, gas chromatography–mass spectrometry, direct analysis in real time–high-resolution mass spectrometry as well as crystallization with and without the presence of additives seem to be promising methods in terms of time of analysis and detecting organic system-related parameters. For further methodological development, a system approach is recommended, which also takes into account food structure aspects. Furthermore, the authentication of processed organic samples needs more consciousness, hence most of organic food is complex and processed.
Are feldspar SAR protocols appropriate for post-IR IRSL dating?
Kars, R.H. ; Reimann, T. ; Wallinga, J. - \ 2014
Quaternary Geochronology 22 (2014). - ISSN 1871-1014 - p. 126 - 136.
anomalous fading correction - infrared stimulated luminescence - regenerative-dose protocol - k-feldspar - chinese loess - quartz - sediments - samples - deposits - signals
Recently proposed post-infrared infrared stimulated luminescence (post-IR IRSL or pIR) dating protocols have largely overcome problems associated with anomalous fading and have become increasingly important for age determination of Quaternary sediments. Here, we investigate the suitability of the proposed post-IR IRSL protocols for accurate equivalent-dose estimation on K-feldspar extracts. Our research focuses on potential sensitivity changes between the natural signal and the first test dose signal in single-aliquot regenerative dose (SAR) procedures that are not detected and thus not corrected using test-dose responses. For these investigations, we employed the Single Aliquot Regeneration and Added dose (SARA) procedure, which combines equivalent-dose estimation with a dose recovery test. Results indicated that high-temperature preheats (>260 °C for 60 s) may induce a trapping sensitivity change in IRSL signals measured at low temperature (100 °C) after a high temperature preheat. Our results indicate that the SAR protocol is appropriate for equivalent-dose determination using elevated-temperature pIR signals (e.g. pIR at 290 °C or multiple elevated temperature pIR at 250 °C). The SAR protocol may also be appropriate for equivalent-dose determination using low temperature pIR signals, provided that the combination of preheat and measurement temperature
Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles
Zielinska, K. - \ 2014
Environmental Chemistry 11 (2014)1. - ISSN 1448-2517 - p. 72 - 76.
nd-spme - samples - water - adsorption - products - binding - surface
Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid phase poly(dimethylsiloxane) (PDMS). Furthermore, they appear to aggregate at the PDMS–water interface. The total triclosan concentration in the solid phase thus includes both the free and the NP-bound forms. Proper computation of the analyte concentration in the sample medium requires (i) consideration of the speciation of triclosan inside the solid phase and (ii) elimination of the effects of aggregation of NP complexes at the solid phase–bulk medium interface. Possible solutions include application of a protective membrane with pore size smaller than the NP diameter. This allows measurement of the free triclosan concentration, albeit at the cost of longer accumulation times and loss of kinetic information on the triclosan–NP complex.
Determination of T-2/HT-2 toxins in duplicate diets in the Netherlands by GC-MS/MS method development and estimation of human exposure
Jekel, A.A. ; Egmond, H.P. van - \ 2014
World Mycotoxin Journal 7 (2014)3. - ISSN 1875-0710 - p. 267 - 276.
ochratoxin - samples
T-2 and HT-2 toxins (T-2 and HT-2) are important trichothecenes. They have been subject of formal risk assessment by various organisations, including the European Food Safety Authority (EFSA). The EFSA CONTAM Panel recently established a group Tolerable Daily Intake (TDI) of 100 ng/kg body weight/day for the sum of T-2 and HT-2. To assess the actual dietary exposure of Dutch consumers to T-2 and HT-2 a study was conducted in the Netherlands, in which duplicate portions of 24-h diets collected in 2011 were investigated for these toxins. This collection comprised 128 duplicate diets of the adult segment of the Dutch population, divided over a spring and autumn collection period. The diets in the study were homogenised and processed to lyophilised powders. Aliquots of every two of the samples were pooled to test portions that were analysed with a method, based on immunoaffinity chromatography clean-up in combination with GC-MS/MS determination. The method had a limit of quantification of 0.01 mu g/kg original non-lyophilised diet for both T-2 and HT-2. Recoveries ranged from 92-114% for T-2 and from 71-106% for HT-2, determined at levels of addition ranging from 0.1-0.3 mu g/kg. In practically all samples investigated, numerical values for the concentrations of T-2 and HT-2 could be obtained. Exposure estimates of the sum of T-2 and HT-2 in the 2011 study ranged from non-detectable to 18.6 ng/kg body weight/day. In addition limited sets of pooled samples of duplicate diets retained from collections in the period 1976-2004 were analysed for T-2 and HT-2. In all samples the mean and individual intakes of the sum of T-2 and HT-2 of the respondents were below the group TDI of the EFSA CONTAM Panel. From this study it was concluded that no health risks are expected from current exposure of adult Dutch consumers to T-2 and HT-2.
Evaluation of using spot urine to replace 24 h urine sodium and potassium excretions
Hooft Van Huysduynen, E.J.C. ; Hulshof, P.J.M. ; Lee, L. van; Geelen, A. ; Feskens, E.J.M. ; Veer, P. van 't; Woerkum, C.M.J. van; Vries, J.H.M. de - \ 2014
Public Health Nutrition 17 (2014)11. - ISSN 1368-9800 - p. 2505 - 2511.
24-hour - collections - completeness - creatinine - magnesium - calcium - samples - marker - acid
Objective The most accurate method to estimate Na and K intakes is to determine 24 h urinary excretions of these minerals. However, collecting 24 h urine is burdensome. Therefore it was studied whether spot urine could be used to replace 24 h urine samples. Design Participants collected 24 h urine and kept one voiding sample separate. Na, K and creatinine concentrations were analysed in both 24 h and spot urine samples. Also 24 h excretions of Na and K were predicted from spot urine concentrations using the Tanaka and Danish methods. Setting In 2011 and 2012, urine samples were collected and brought to the study centre at Wageningen University, the Netherlands. Subjects Women (n 147) aged 19–26 years. Results According to p-aminobenzoic acid excretions, 127 urine collections were complete. Correlations of Na:creatinine, K:creatinine and Na:K between spot urine and 24 h urine were 0·68, 0·57 and 0·64, respectively. Mean 24 h Na excretion predicted with the Tanaka method was higher (difference 21·2 mmol/d, P
Rapid analysis of Delta-9-tetrahydrocannabinol in hair using direct analysis in real time ambient ionization orbitrap mass spectrometry
Duvivier, W.F. ; Beek, T.A. van; Pennings, E.J.M. ; Nielen, M.W.F. - \ 2014
Rapid Communications in Mass Spectrometry 28 (2014)7. - ISSN 0951-4198 - p. 682 - 690.
synthetic cannabinoids - cocaine - drugs - identification - capabilities - metabolites - validation - samples - abuse
RATIONALE - Forensic hair analysis methods are laborious, time-consuming and provide only a rough retrospective estimate of the time of drug intake. Recently, hair imaging methods using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were reported, but these methods require the application of MALDI matrix and are performed under vacuum. Direct analysis of entire locks of hair without any sample pretreatment and with improved spatial resolution would thus address a need. METHODS - Hair samples were attached to stainless steel mesh screens and scanned in the X-direction using direct analysis in real time (DART) ambient ionization orbitrap MS. The DART gas temperature and the accuracy of the probed hair zone were optimized using ¿-9-tetrahydrocannabinol (THC) as a model compound. Since external contamination is a major issue in forensic hair analysis, sub-samples were measured before and after dichloromethane decontamination. RESULTS - The relative intensity of the THC signal in spiked blank hair versus that of quinine as the internal standard showed good reproducibility (26% RSD) and linearity of the method (R2¿=¿0.991). With the DART hair scan THC could be detected in hair samples from different chronic cannabis users. The presence of THC was confirmed by quantitative liquid chromatography/tandem mass spectrometry. Zones with different THC content could be clearly distinguished, indicating that the method might be used for retrospective timeline assessments. Detection of THC in decontaminated drug user hair showed that the DART hair scan not only probes THC on the surface of hair, but penetrates deeply enough to measure incorporated THC. CONCLUSIONS - A new approach in forensic hair analysis has been developed by probing complete locks of hair using DART-MS. Longitudinal scanning enables detection of incorporated compounds and can be used as pre-screening for THC without sample preparation. The method could also be adjusted for the analysis of other drugs of abuse.
Rapid Mastitis Detection assay on porous nitrocellulose membrane slides
Mujawar, L.H. ; Moers, A.P.H.A. ; Norde, W. ; Amerongen, A. van - \ 2013
Analytical and Bioanalytical Chemistry 405 (2013)23. - ISSN 1618-2642 - p. 7469 - 7476.
microarray technology - protein microarrays - bovine-milk - pathogens - antibody - identification - morphology - samples - chip
We have developed a rapid mastitis detection test based on the immobilization of tag-specific antibody molecules, the binding of double-tagged amplicons, and as a secondary signal a conjugate of black carbon nanoparticles having molecules of a fusion protein of neutrAvidin and alkaline phosphatase at their surface. The antibodies were inkjet printed onto three different nitrocellulose membrane slides, Unisart (Sartorius), FAST (GE Whatman), and Oncyte-Avid (Grace-Biolabs), and the final assay signals on these slides were compared. The blackness of the spots was determined by flatbed scanning and assessment of the pixel gray volume using TotalLab image analysis software. The black spots could be easily read by the naked eye. We successfully demonstrated the detection of specific amplicons from mastitis-causing pathogens in less than 3 h. Using a similar protocol, we also showed that it was possible to detect specific amplicons from four different mastitis-causing pathogens (six strains) on the same pad. The influence of two different printing buffers, phosphate-buffered saline (pH 7.4) and carbonate buffer (pH 9.6), on the functionality of the primary antibodies was also compared.
De voedselveiligheid van Japanse oesters en mosselen in de Waddenzee
Poelman, M. ; Glorius, S.T. ; Gool, A.C.M. van; Linden, A. van der - \ 2013
Aquacultuur 28 (2013)2. - ISSN 1382-2764 - p. 10 - 16.
oesters - crassostrea gigas - mossels - mytilidae - voedselveiligheid - volksgezondheid - monitoring - bemonsteren - monsters - waddenzee - oysters - mussels - food safety - public health - sampling - samples - wadden sea
De laatste decennia is het areaal aan Japanse oesters in de Duitse en Nederlandse Waddenzee toegenomen. Dit leidt tot een zekere mate van concurrentie in ruimte en voedsel tussen onder andere mosselen en oesters. Naast de ecologische effecten zijn er ook directe economische effecten, er wordt inmiddels al dankbaar gebruik gemaakt door bedrijfsmatig oester in de Waddenzee te rapen. Over de voedselveiligheid van deze oesters in het Wad is nog niet veel bekend, reden dus om een monitoring uit te voeren op oesters en als vergelijking mosselen. Dit alles om beter zicht te hebben op de voedselveiligheid van Waddenzee oesters.
Dissecting structural and nucleotide genome-wide variation in inbred Iberian pigs
Esteve-Codina, A. ; Paudel, Y. ; Ferretti, L. ; Megens, H.J.W.C. ; Groenen, M. - \ 2013
BMC Genomics 14 (2013). - ISSN 1471-2164
copy number variation - meat quality traits - positive selection - next-generation - snp discovery - evolution - gene - samples - region - interleukin-2
Background In contrast to international pig breeds, the Iberian breed has not been admixed with Asian germplasm. This makes it an important model to study both domestication and relevance of Asian genes in the pig. Besides, Iberian pigs exhibit high meat quality as well as appetite and propensity to obesity. Here we provide a genome wide analysis of nucleotide and structural diversity in a reduced representation library from a pool (n=9 sows) and shotgun genomic sequence from a single sow of the highly inbred Guadyerbas strain. In the pool, we applied newly developed tools to account for the peculiarities of these data. Results A total of 254,106 SNPs in the pool (79.6 Mb covered) and 643,783 in the Guadyerbas sow (1.47 Gb covered) were called. The nucleotide diversity (1.31x10-3 per bp in autosomes) is very similar to that reported in wild boar. A much lower than expected diversity in the X chromosome was confirmed (1.79x10-4 per bp in the individual and 5.83x10-4 per bp in the pool). A strong (0.70) correlation between recombination and variability was observed, but not with gene density or GC content. Multicopy regions affected about 4% of annotated pig genes in their entirety, and 2% of the genes partially. Genes within the lowest variability windows comprised interferon genes and, in chromosome X, genes involved in behavior like HTR2C or MCEP2. A modified Hudson-Kreitman-Aguadé test for pools also indicated an accelerated evolution in genes involved in behavior, as well as in spermatogenesis and in lipid metabolism. Conclusions This work illustrates the strength of current sequencing technologies to picture a comprehensive landscape of variability in livestock species, and to pinpoint regions containing genes potentially under selection. Among those genes, we report genes involved in behavior, including feeding behavior, and lipid metabolism. The pig X chromosome is an outlier in terms of nucleotide diversity, which suggests selective constraints. Our data further confirm the importance of structural variation in the species, including Iberian pigs, and allowed us to identify new paralogs for known gene families.
Occurrence of the microcystins MC-LW and MC-LF in Dutch surface waters and their contribution to total microcystin toxicity
Faassen, E.J. ; Lurling, M. - \ 2013
Marine Drugs 11 (2013)7. - ISSN 1660-3397 - p. 2643 - 2654.
tandem mass-spectrometry - cyanobacterial toxins - different hydrophobicities - aeruginosa - blooms - nodularin - province - bogoria - samples - china
Microcystins (MCs) are the most frequently found cyanobacterial toxins in freshwater systems. Many MC variants have been identified and variants differ in their toxicity. Recent studies showed that the variants MC-LW and MC-LF might be more toxic than MC-LR, the variant that is most abundant and mostly used for risk assessments. As little is known about the presence of these two variants in The Netherlands, we determined their occurrence by analyzing 88 water samples and 10 scum samples for eight MC variants ((dm-7-)MC-RR, MC-YR, (dm-7-)MC-LR, MC-LY, MC-LW and MC-LF) by liquid chromatography with tandem mass spectrometry detection. All analyzed MC variants were detected, and MC-LW and/or MC-LF were present in 32% of the MC containing water samples. When MC-LW and MC-LF were present, they contributed to nearly 10% of the total MC concentrations, but due to their suspected high toxicity, their average contribution to the total MC toxicity was estimated to be at least 45%. Given the frequent occurrence and possible high toxicity of MC-LW and MC-LF, it seems better to base health risk assessments on the toxicity contributions of different MC variants than on MC-LR concentrations alone
Paling analyses Ecofide
Hoek-van Nieuwenhuizen, M. van - \ 2013
IJmuiden : IMARES (Rapport / IMARES Wageningen UR C196/13) - 13
palingen - european eels - representatieve monstername - monsters - chemische analyse - polychloorbifenylen - organo-tinverbindingen - vet - droge stof - sporenelementen - eels - representative sampling - samples - chemical analysis - polychlorinated biphenyls - organotin compounds - fat - dry matter - trace elements
De opdracht bestond uit het karakteriseren, fileren en homogeniseren tot een mengmonster van de door Ecofide aangeleverde set palingen; het uitvoeren van chemische analyses in het mengmonster en het rapporteren van de resultaten. Dit rapport omvat een korte omschrijving van de toegepaste methoden, een kwaliteitsparagraaf en een presentatie van de resultaten in Exceltabellen.
Towards dating Quaternary sediments using the quartz Violet Stimulated Luminescence (VSL) signal
Ankjaergaard, C. ; Jain, M. ; Wallinga, J. - \ 2013
Quaternary Geochronology 18 (2013). - ISSN 1871-1014 - p. 99 - 109.
regenerative-dose protocol - fine-grained quartz - isothermal tl - chinese loess - k-feldspars - tt-osl - single - components - samples - ages
Quartz optically stimulated luminescence (OSL) dating is widely used to determine the time of deposition and burial of Late Quaternary sediments. Application of the method is usually limited to the past 150,000 years due to early saturation of the OSL signal. Here we explore the potential to date Quaternary sediments using the violet (402 nm) stimulated luminescence (VSL) signal of quartz. We develop and test a new post-blue VSL single aliquot regenerative dose dating protocol, and demonstrate that the VSL signal originates from a deep trap at about 1.9 eV with a thermal lifetime of 1011 years at 10 C, and that this trap is bleachable by sunlight. The VSL signal grows with dose to w6400 Gy, a factor w20 higher than the conventional quartz OSL signal, and with the proposed protocol we recover a known dose of 1000 Gy in three out of four samples. The potential of the VSL protocol for dating Quaternary sediments is highlighted by its successful application to a suite of geological samples ranging in age between 13 and 330 ka. Based on our investigations, we propose that the VSL protocol has the potential to extend the quartz dating range to cover the full Quaternary.
Evaluation of molecular assays for identification Campylobacter fetus species and subspecies and development of a C. fetus specific real-time PCR assay
Graaf-van Bloois, L. van der; Bergen, M.A.P. van; Wal, F.J. van der; Boer, A.G. de; Duim, B. ; Schmidt, T. ; Wagenaar, J.A. - \ 2013
Journal of Microbiological Methods 95 (2013)1. - ISSN 0167-7012 - p. 93 - 97.
polymerase-chain-reaction - 16s ribosomal-rna - amplified fragment - differentiation - venerealis - strains - samples - jejuni - genes - coli
Phenotypic differentiation between Campylobacter fetus (C. fetus) subspecies fetus and C. fetus subspecies venerealis is hampered by poor reliability and reproducibility of biochemical assays. AFLP (amplified fragment length polymorphism) and MLST (multilocus sequence typing) are the molecular standards for C. fetus subspecies identification, but these methods are laborious and expensive. Several PCR assays for C. fetus subspecies identification have been described, but a reliable comparison of these assays is lacking. The aim of this study was to evaluate the most practical and routinely implementable published PCR assays designed for C. fetus species and subspecies identification. The sensitivity and specificity of the assays were calculated by using an extensively characterized and diverse collection of C. fetus strains. AFLP and MLST identification were used as reference. Two PCR assays were able to identify C. fetus strains correctly at species level. The C. fetus species identification target, gene nahE, of one PCR assay was used to develop a real-time PCR assay with 100% sensitivity and 100% specificity, but the development of a subspecies venerealis specific real-time PCR (ISCfe1) failed due to sequence variation of the target insertion sequence and prevalence in other Campylobacter species. None of the published PCR assays was able to identify C. fetus strains correctly at subspecies level. Molecular analysis by AFLP or MLST is still recommended to identify C. fetus isolates at subspecies level.
Results for PCDD/PCDF and dl-PCBs in the first Round of UNEPs Biennial Global Interlaboratory Assessment on Persistent Organic Pollutants
Abalos, M. ; Abad, E. ; Leeuwen, S.P.J. van; Lindström, G. ; Fiedler, H. ; Boer, J. de; Bavel, B. van - \ 2013
TrAC : Trends in Analytical Chemistry 46 (2013). - ISSN 0165-9936 - p. 98 - 109.
international harmonized protocol - dioxin-like pcbs - population characteristics - seal blubber - new-model - chlorobiphenyls - uncertainties - performance - inference - samples
The first worldwide interlaboratory assesment on persistent organic pollutants (POPs) under the Stockholm Convention was organized in the Asian/Pacific, Latin American and African regions during 2009–11. A relatively large number of laboratories reported data for the PCDDs/PCDFs and dioxin-like PCBs, especially in the Asian region. Within the Asian region, several participants used high-resolution GC/high-resolution MS systems optimized for dioxin analysis. The availibility of High-resolution mass spectrometer instrumentation is limited in the Latin America and African regions, although recently several new laboratories for dioxins have started in the Latin American region.
Colorimetry and photoacoustic spectroscopy as suitable tools for direct determination of cocoa powder in confectionary products
Doka, O. ; Pragai, E. ; Bicanic, D.D. ; Kulcsar, R. - \ 2013
European Food Research and Technology 236 (2013)6. - ISSN 1438-2377 - p. 963 - 968.
phenolic content - theobroma-cacao - powders - antioxidant - quantification - polyphenols - mixtures - capacity - samples - beans
Laser photoacoustic spectroscopy (PAS) and colorimetry have been used to rapidly and accurately determine the content of fat-free cocoa solids in dark chocolates. Both techniques are inexpensive and require only a one-time calibration step versus a method capable of absolute concentration measurement (for example HPLC). Once the response of PAS and/or colorimetry has been obtained, the content of fat-free cocoa solids in dark chocolates can be determined directly (i.e. without any sample preparation including the process of extraction) from the calibration curves and the experimentally measured microphone signal (in PAS studies) and colorimetric indices L* and ¿E* (in colorimetric investigations). Both colorimetric indices and PA signals correlate positively with the content of fat-free cocoa solids. The correlation is highly linear over a wide concentration range (25–50 %).
Hair trapping with valerian-treated lure sticks as a tool for genetic wildcat monitoring in low-density habitats
Steyer, K. ; Simon, O. ; Kraus, R.H.S. ; Haase, P. ; Nowak, C. - \ 2013
European Journal of Wildlife Research 59 (2013)1. - ISSN 1612-4642 - p. 39 - 46.
european wildcat - felis-silvestris - domestic cats - population-genetics - living cats - conservation - dna - hybridization - samples - identification
Wildcats are among the most elusive and least investigated carnivores in Central Europe. Here, we propose a hair-trapping method that allows reliable detection of wildcat presence even in low-density habitats. The trap is simple, consisting of a wooden stick with valerian as cat attractant. We performed non-invasive genetic wildcat monitoring in the Kellerwald-Edersee National Park, Germany, between 2007 and 2011. Our results provide the first evidence of wildcat presence in this region. Microsatellite analysis and mtDNA sequencing of hair samples furthermore confirm the existence of at least six individuals (males and females) in the study region. Four individuals were detected over two consecutive years, suggesting the resident status of wildcats in this area. Our results show that the lure stick method releases its full potential when combined with genetic analysis and is a sensitive tool which not only enables the detection of wildcat presence but also provides individual identification, even in recently colonised low-density areas.
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