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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    Phase diagram of coacervate complexes containing reversible coordination
    Wang, J. ; Cohen Stuart, M.A. ; Gucht, J. van der - \ 2012
    Macromolecules 45 (2012)21. - ISSN 0024-9297 - p. 8903 - 8909.
    core micelles - polyelectrolyte complexes - polymers - behavior - systems
    Phase separation of coacervate complexes from cationic PDMAEMA [poly(N,N-dimethylaminoethyl methacrylate)] and anionic reversible coordination polymers are studied in the present work. The coordination polymers are formed from zinc and a bis-ligand L2EO4 [1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane] and have variable chain length. The charge mixing ratio and metal-to-ligand ratio, M/L, are varied systematically, and the composition of the two coexisting phases is measured using 1H NMR and ICP-AES. The resulting phase diagram is asymmetric: the coacervate complex phase tolerates an excess of coordination polymer much more than an excess of the homopolymer. Moreover, the coacervate complex tends to choose the right amount of the three components under nonstoichiometric mixing conditions. Both the metal-to-ligand ratio (M/L ˜ 1) and charge ratio (f– ˜ 0.5) in the coacervate phase are around stoichiometry, leaving the excess components in the dilute phase.
    Using chromosome introgression lines to map quantitative trait loci for photosynthesis parameters in rice (Oryza sativa L.) leaves under drought and well-watered field conditions
    Gu, J. ; Yin, X. ; Struik, P.C. ; Stomph, T.J. ; Wang, J. - \ 2012
    Journal of Experimental Botany 63 (2012)1. - ISSN 0022-0957 - p. 455 - 469.
    qtl analysis - upland rice - chlorophyll fluorescence - reproductive-stage - genetic-variation - grain-yield - physiological traits - plant photosynthesis - carbon assimilation - advanced backcross
    Photosynthesis is fundamental to biomass production, but sensitive to drought. To understand the genetics of leaf photosynthesis, especially under drought, upland rice cv. Haogelao, lowland rice cv. Shennong265, and 94 of their introgression lines (ILs) were studied at flowering and grain filling under drought and well-watered field conditions. Gas exchange and chlorophyll fluorescence measurements were conducted to evaluate eight photosynthetic traits. Since these traits are very sensitive to fluctuations in microclimate during measurements under field conditions, observations were adjusted for microclimatic differences through both a statistical covariant model and a physiological approach. Both approaches identified leaf-to-air vapour pressure difference as the variable influencing the traits most. Using the simple sequence repeat (SSR) linkage map for the IL population, 1–3 quantitative trait loci (QTLs) were detected per trait–stage–treatment combination, which explained between 7.0% and 30.4% of the phenotypic variance of each trait. The clustered QTLs near marker RM410 (the interval from 57.3¿cM to 68.4¿cM on chromosome 9) were consistent over both development stages and both drought and well-watered conditions. This QTL consistency was verified by a greenhouse experiment under a controlled environment. The alleles from the upland rice at this interval had positive effects on net photosynthetic rate, stomatal conductance, transpiration rate, quantum yield of photosystem II (PSII), and the maximum efficiency of light-adapted open PSII. However, the allele of another main QTL from upland rice was associated with increased drought sensitivity of photosynthesis. These results could potentially be used in breeding programmes through marker-assisted selection to improve drought tolerance and photosynthesis simultaneously
    A prototype observation system for water resources in South-East Asia
    Menenti, M. ; Jia, L. ; Colin, J. ; Wang, J. ; Shen, X. ; Ueno, K. ; Immerzeel, W. - \ 2010
    In: Proceedings of the ISPRS Technical Commission VIII Symposium on Networking the World with Remote Sensing, Kyoto, Japan, 9-12 August 2010. - - p. 176 - 177.
    Genome-Wide Assessment Of World-Wide Poultry Biodiversity
    Muir, W.M. ; Wong, G.K. ; Zhang, Y. ; Wang, J. ; Groenen, M.A.M. ; Crooijmans, R.P.M.A. ; Megens, H.J.W.C. ; Rattink, A.P. - \ 2008
    Genetic diversity is the key to all genetic progress, past and future. Over the last 10,000 years, poultry was domesticated first from the wild jungle fowl, then in the last 1,000 years into standard breeds. In the last century, those breeds have been further reduced into a few commercially produced types. These lines have since been strongly selected for both growth and egg production among other traits. During this process, genetic variability has been lost at each step. Important issues include: ¿How much variability has been lost¿ and ¿Is there adequate variability to meet future challenges, such as new diseases"? To achieve this goal, a panel of 2551 informative SNPs were genotyped on 2580 individuals including 1440 commercial birds. Allele loss was assessed by determining the relationship with inbreeding, and through the use of SNP ¿weights¿ that correct for ascertainment bias and avoid the need to extrapolate from the inbreeding coefficient. The methods presented are general and could be used to assess loss of biodiversity based on SNP panels. Results indicate that sampled broiler lines of multiple companies have lost between 55%-70% of allelic diversity while sampled layer lines of one commercial layer company have lost between 80%-90% of allelic diversity. However, Insillico crosses among lines show that many of the lost alleles can be found in other lines within the company resulting in true loss across the industry of approximately 50%. However, the alleles lost were primarily those that were rare; it is not known if rare vs. common alleles are more or less likely to be important for response to new challenges. These allele may still exist in standard breeds or wild birds, but the issue remains of how to assess the importance of those alleles to phenotype, and/or how to move them into commercial populations without introducing unwanted alleles.
    Review of the initial validation and characterization of a chicken 3K SNP array.
    Muir, W.M. ; Wong, G.K. ; Zhang, Y. ; Wang, J. ; Groenen, M.A.M. ; Crooijmans, R.P.M.A. ; Zhang, H.M. ; McKay, J. ; McLeod, C.W. ; Okimoto, R. - \ 2008
    Worlds Poultry Science Journal 64 (2008). - ISSN 0043-9339 - p. 219 - 226.
    dierveredeling - genetische bronnen van diersoorten - kippen - pluimvee - biodiversiteit - genetica - genetische kartering - dna - dna-sequencing - genotypen - genetische diversiteit - kippenrassen - single nucleotide polymorphism - animal breeding - animal genetic resources - fowls - poultry - biodiversity - genetics - genetic mapping - dna - dna sequencing - genotypes - genetic diversity - fowl breeds - single nucleotide polymorphism
    In 2004 the chicken genome sequence and more than 2.8 million single nucleotide polymorphisms (SNPs) were reported. This information greatly enhanced the ability of poultry scientists to understand chicken biology, especially with respect to identification of quantitative trait loci (QTL) and genes that control simple and complex traits. To validate and address the quality of the reported SNPs, assays for 3072 SNPS were developed and used to genotype 2576 DNAs isolated from commercial and experimental birds. Over 90% of the SNPs were valid based on the criterion used for segregating, and over 88% had a minor allele frequency of 2% or greater. As the East Lansing (EL) and Wageningen University (WAU) reference panels were genotyped, 1933 SNPs were added to the chicken genetic map, which was used in the second chicken genome sequence assembly. It was also discovered that linkage disequilibrium varied considerably between commercial layers and broilers; with the latter having haplotype blocks averaging 10 to 50 kb in size. Finally, it was estimated that commercial lines have lost 70% or more of their genetic diversity, with the majority of allele loss attributable to the limited number of chicken breeds used.
    High-level production of beta-carotene in Saccharomyces cerevisiae by successive transformation with carotenogenic genes from Xanthophyllomyces dendrorhous
    Verwaal, R. ; Wang, J. ; Meijnen, J.P. ; Visser, H. ; Sandmann, G. ; Berg, J.A. van den; Ooyen, A.J.J. van - \ 2007
    Applied and Environmental Microbiology 73 (2007)13. - ISSN 0099-2240 - p. 4342 - 4350.
    yeast candida-utilis - coenzyme-a reductase - phaffia-rhodozyma - escherichia-coli - biosynthetic-pathway - erwinia-uredovora - hxt5 expression - astaxanthin - lycopene - synthase
    To determine whether Saccharomyces cerevisiae can serve as a host for efficient carotenoid and especially ß-carotene production, carotenogenic genes from the carotenoid-producing yeast Xanthophyllomyces dendrorhous were introduced and overexpressed in S. cerevisiae. Because overexpression of these genes from an episomal expression vector resulted in unstable strains, the genes were integrated into genomic DNA to yield stable, carotenoid-producing S. cerevisiae cells. Furthermore, carotenoid production levels were higher in strains containing integrated carotenogenic genes. Overexpression of crtYB (which encodes a bifunctional phytoene synthase and lycopene cyclase) and crtI (phytoene desaturase) from X. dendrorhous was sufficient to enable carotenoid production. Carotenoid production levels were increased by additional overexpression of a homologous geranylgeranyl diphosphate (GGPP) synthase from S. cerevisiae that is encoded by BTS1. Combined overexpression of crtE (heterologous GGPP synthase) from X. dendrorhous with crtYB and crtI and introduction of an additional copy of a truncated 3-hydroxy-3-methylglutaryl-coenzyme A reductase gene (tHMG1) into carotenoid-producing cells resulted in a successive increase in carotenoid production levels. The strains mentioned produced high levels of intermediates of the carotenogenic pathway and comparable low levels of the preferred end product ß-carotene, as determined by high-performance liquid chromatography. We finally succeeded in constructing an S. cerevisiae strain capable of producing high levels of ß-carotene, up to 5.9 mg/g (dry weight), which was accomplished by the introduction of an additional copy of crtI and tHMG1 into carotenoid-producing yeast cells. This transformant is promising for further development toward the biotechnological production of ß-carotene by S. cerevisiae.
    Groundwater: a global assessment of scale and significance
    Shah, T. ; Bruke, J. ; Vullholth, K. ; Angelica, M. ; Custodio, E. ; Daibes, F. ; Hoogesteger van Dijk, J.D. ; Giordano, M. ; Girman, J. ; Gun, J. van der; Kendy, E. ; Kijne, J. ; Llamas, R. ; Masiyandama, M. ; Margat, J. ; Marin, L. ; Peck, J. ; Rozelle, S. ; Sharma, B. ; Vincent, L.F. ; Wang, J. - \ 2007
    In: Water for food Water for life : a comprehensive Assessment of Water Management in Agriculture / Molden, D., London : Earthscan - ISBN 9781844073962 - p. 395 - 423.
    Exploring worldwide the influence of society on the establishment of national spatial data clearinghouses
    Crompvoets, J.W.H.C. ; Wachowicz, M. ; Bregt, A.K. ; Hofstede, G.J. ; Wang, J. ; Vereijken, P.F.G. ; Man, E. de - \ 2006
    - 15 p.
    Disentangling poverty and biodiversity in the context of rural development: A case study for Pujiang country, China
    Wang, G. ; Wang, J. ; Lu, C. ; Hengsdijk, H. ; Berg, M. van den; Wolf, J. ; Roetter, R.P. ; Keulen, H. van - \ 2005
    The mathematical method of studying the reproduction structure of weeds and its application to Bromus sterilis
    Wang, J. ; Hansen, P.K. ; Christensen, S. ; Qi, G.Z. - \ 2004
    Discrete and Continuous Dynamical Systems. Series B, a journal bridging mathematics and sciences 4 (2004)3. - ISSN 1531-3492 - p. 777 - 788.
    This article discusses the structure of weed reproduction incorporating the application of a mathematical model. This mathematical methodology enables the construction, testing and application of distribution models for the analysis of the structure of weed reproduction and weed ecology. The mathematical model was applied, at the individual level, to the weed species, Bromus sterilis. The application of this method, to the weed under competition, resulted in an analysis of the overall reproduction structure of the weed which follows approximately Gaussian distribution patterns and an analysis of the shoots in the weed plant which follow approximately Sigmoid distribution patterns. It was also discovered that the application of the mathematical distribution models, when applied under specific conditions could, effectively estimate the seed production and total number of shoots in a weed plant. On the average, a weed plant has 3 shoots, with each shoot measuring 90cm in height and being composed of 21 spikelets. Besides the estimations of the total shoots and seed production within the experimental field, one may also apply these mathematical distribution models to estimate the germination rate of the species within the experimental field in following years.
    A genetic variation map for chicken with 2.8 million single-nucleotide polymorphisms: International Chicken Polymorphisms Map Consortium
    Wong, G.K. ; Liu, B. ; Wang, J. ; Crooijmans, R.P.M.A. ; Poel, J.J. van der; Bovenhuis, H. ; Groenen, M.A.M. - \ 2004
    Nature 432 (2004)7018. - ISSN 0028-0836 - p. 717 - 722.
    quantitative trait loci - broiler layer cross - genome - diversity - sequence - mutation - markers - growth - snp
    We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms ( SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds ( a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines - in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases.
    I-flora: a location based service for determining flowers in the Dutch landscape
    Ligtenberg, A. ; Wang, J. ; Vullings, L.A.E. ; Bulens, J.D. - \ 2004
    In: AGILE 2004; 7th conference on geographic information science. - Heraklion (Greece) : Crete University Press - ISBN 9789605241766 - p. 825 - 829.
    Using CA model to obtain insight into mechanism of plant population spread in a controllable system : annual weeds as an example
    Wang, J. ; Kropff, M.J. ; Bastiaans, L. ; Christensen, S. ; Hansen, P.K. - \ 2003
    Ecological Modelling 166 (2003). - ISSN 0304-3800 - p. 277 - 286.
    cellular-automata - metapopulation dynamics - differential-equations - fragmented landscapes - forest dynamics - dispersal - extinction - simulation - geometry - patterns
    Using cellular automata (CA) model, in this article, a mechanistic approach has been conducted to help to insight into spread process of plant population such as annual weed population. A controllable CA model with 25 neighbourhood cells has been built, in which seed dispersal, as a key process of annual weed population dynamics, has been described by Gaussian distribution. The hypothesis that initial configurations affect annual weed population dynamics and control strategies has been tested by simulating. And the results support strongly the hypothesis. Patch, pattern and configuration are important concepts in weed patch management, which have been mathematically defined in this article. The aggregation effects have been found out while simulating, which is subject to patch size, patch density and distribution function of seed dispersal. Perhaps it could partly explain the reason why weeds often distribute in patch. Accordingly, true-patch and generalised patch have been distinguished from each other, which would be practically applicable to weed patch management. Based on this approach to the particular weed-crop system, a new hypothesis has been proposed: in a real controllable weed-crop system, the mean law might hold. If so, algorithm of patch control for long-term weed management could be simplified to control a true-patch only according to its mean density, it is unnecessary to control it according to the density in its each cell. (C) 2003 Elsevier B.V. All rights reserved.
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