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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Promoting Social Accountability for Equitable Fisheries Within Beach Management Units in Lake Victoria (Kenya)
Etiegni, Christine ; Kooy, Michelle ; Irvine, Kenneth - \ 2019
Conservation and Society 17 (2019)1. - ISSN 0972-4923 - p. 63 - 72.
accountability, co-management, decentralisation, fisheries, power, Lake Victoria, Kenya
The decentralisation of resource management through co-management assumes that the devolution of power benefits resource users. This assumption is often premised on the democratic election of leaders within resource user organisations. In this article, we investigate the validity of co-management assumptions about who benefits from a devolution of decision-making power through a case study analysis of political equity in fisherfolk organisations of Beach Management Units (BMUs) in Lake Victoria (Kenya). From the analysis of the distribution of political power, we identify how, where, and for whom greater accountability can work to address the current political inertia of fisherfolk, who form a majority of the BMU membership. We also identify the relationships between the empowerment of fisherfolk, the accountability of the BMU leaders, and the distribution of political power determining decision making in co-management. We conclude with identifying how other mechanisms of social accountability beyond elections can improve accountability of elected leaders of resource users for improved co-management outcomes.
Introduction: Exclusion and Struggles for Co-Decision : from Part III - Exclusion and Struggles for Co-Decision
Vos, J.M.C. ; Perreault, Tom ; Boelens, R.A. - \ 2018
In: Water Justice / Boelens, R., Perreault, T., Vos, J., Cambridge : Cambridge University Press - ISBN 9781107179080 - p. 188 - 192.
Water justice is often sought in “good water governance.” Yet, what “good governance” means is not something that can be straightforwardly decided or linearly implemented: different stakeholders hold different power positions, have conflicting interests and deploy different valuation languages regarding water, land and livelihoods. Deliberative policy-making processes, including local communities’ participation in decision-making, are often presented as the tool to help craft inclusive, democratic water governance arrangements. However, here, a fundamental but commonly neglected or actively suppressed question is, “who participates in whose project”? Although water governance is about institutional configurations, regulations and policy-making and implementation, it is also about capabilities, powers and social struggle over access to resources, setting the agenda and discursively framing problems. Water justice, then, is not something that can easily be crafted through tinkering with governance arrangements, but requires struggles and continuous renegotiation as part of larger battles for justice and democracy. Water injustices often imply exclusion of vulnerable groups from access to clean water and affordable services, but also from representation in water-control decision-making. This exclusion can be based on gender, race, caste, class, ethnicity, religion, or political affiliation. Maria Rusca, Cecilia Alda-Vidal, and Michelle Kooy (Chapter 11) provide clear examples of this in their chapter on drinking water in Kampala. Joyeeta Gupta (Chapter 14) contends that privatizing irrigation water services may often exclude smallholders. Climate Justice Climate change also causes major distributive injustices. Droughts and floods tend to affect the poor more severely than the relatively rich (Adger, 2001; Ikeme, 2003; IPCC 2014; Ribot, 2010; Schneider and Lane, 2006). Skewed vulnerabilities in relation to effects of climate change lead to asymmetrical impacts (Gardiner and Hartzell-Nichols, 2012). This is even more unfair and imbalanced considering that the poor’s share in emission of greenhouse gases is much less than the gigantic emissions by the rich. A report commissioned by the World Bank (2008) estimates the impacted populations killed or left homeless per region by seven common chronic and sudden disasters that are increasingly related to climate change: droughts, extreme temperatures, floods, landslides, tidal surges and wind storms. Already millions of people are affected by floods in Southern and Eastern Asia and droughts in South America, South Asia and East Africa. Likewise, health effects of climate change affect the poor disproportionally (Costello et al., 2009)
Socio-hydrology and hydrosocial analysis: toward dialogues across disciplines
Wesselink, Anna ; Kooy, Michelle ; Warner, Jeroen - \ 2017
Wiley Interdisciplinary Reviews: Water 4 (2017)2. - ISSN 2049-1948
In this study, we review the ways in which water has recently been conceptualized by both natural and social scientists as either hydro-social or socio-hydrological. We do this in order to discuss whether and how they can be compatible, in order to enable dialogue across disciplines that seek to address the ecological and social challenges related to the complex human/water interactions. Through our review, we document the emergence of these specific terminologies, identify how these terms—and the conceptualizations they represent—relate to each other, and suggest what opportunities there are for building further interdisciplinary approaches to understanding water and society. Specifically, we review the recent rise in socio-hydrology amongst natural scientists/hydrologists to put this in discussion with a much longer tradition in social sciences of seeing water as both natural and social. We identify what the paradigms are in both conceptualizations in order to assess what their respective focus is, and what they omit. Our purpose is not to judge competing claims. Rather we want to assess the knowledge claims made in both paradigms: what can we learn when we employ these different approaches, what different rationales for action do they suggest, and what scope exists for collaboration. We conclude that there is scope in combining both approaches without a need to antagonistically question their respective fundamental assumptions, and playing to the strengths of each: the rich case study narratives produced by hydrosocial research can be the basis for the conceptual and quantitative modeling of socio-hydrology.
Effects of N fertilization on trichome density, leaf size and artemisinin production in artemisia annua leaves
Bilkova, I. ; Kjaer, A. ; Kooy, F. van der; Lommen, W.J.M. - \ 2016
Acta Horticulturae 1125 (2016). - ISSN 0567-7572 - p. 369 - 375.
Glandular trichomes - Leaf area - Malaria - Microscopy - Nitrogen - Trichomes

Artemisia annua is currently the only economically viable source of the antimalarial compound artemisinin. Synthesis of artemisinin takes place in glandular trichomes, primarily on the leaves from where artemisinin is extracted. It is not well understood why yields and concentrations of artemisinin vary across crops in relation to external conditions and agricultural practices. We therefore studied the diverse processes underlying artemisinin synthesis in A. annua crops, focussing on effects of |nitrogen fertilization on processes involved in formation of leaves and trichomes, and production of artemisinin in the individual leaves. In two field experiments, effects of nitrogen application levels (0, 75, 175, 400 kg N ha-1) on leaves from a selected position at the main stem and a primary branch were studied. Measurements during part of the life cycle of the leaves included: area and dry weight per leaf, trichome density on the abaxial (lower) leaf side, trichome size, and artemisinin concentration. Results showed that effects of N fertilization were generally small, but in line with the hypothesis that at low N levels individual leaves remain smaller but have higher trichome densities. These trends were especially clear in the branch leaves. The total |number of trichomes per leaf usually increased with increase in N application up to at least 175 kg N ha-1. Within a leaf position, effects of N application on artemisinin concentration in the leaf dry mass were similar to effects on percentage of leaf area covered by trichomes. The total quantity of artemisinin produced per (abaxial) trichome varied, but seemed to decrease linearly with increase in N level. There were no systematic linear or quadratic responses to N application in the total quantity of artemisinin per leaf. The reduction in artemisinin concentration in the leaf mass at higher N levels was therefore caused by increased dry weights per leaf.

Development for Children, or Children for Development? Examining Children's Participation in School-Led Total Sanitation Programmes
Joshi, Deepa ; Kooy, Michelle ; Ouden, Vincent van den - \ 2016
Development and Change 47 (2016)5. - ISSN 0012-155X - p. 1125 - 1145.

The Community-Led Total Sanitation (CLTS) approach is said to have radically revolutionized a poorly performing sanitation sector. The claims of CLTS programmes successfully stopping practices of open defecation have only recently begun to be critically reviewed: scholars and practitioners are questioning the sustainability and scrutinizing the participatory nature of this approach. This article builds on these analyses to draw attention to the School-Led Total Sanitation (SLTS) programme which promotes the role of children as sanitation change agents to ‘trigger’ a shift of behaviour in their peers and elders in school and surrounding environments. The article reviews the active role of children in SLTS in the context of how ‘participation’ is structured in demand-led sanitation approaches, as well as in relation to children's rights to participation in developmental projects in general. Reviewing the arguments supporting SLTS in practitioner literature and drawing on observations from SLTS case studies in Ghana, the authors notice a significant contradiction in the concept of children's participation as premised in SLTS initiatives and as outlined in the child rights agenda. These findings expose inherent tensions in SLTS between children's rights, participation and the role of children as sanitation change agents. They build on existing critiques of participation as coercion within demand-led sanitation approaches that have ‘gone global’.

Effecten van militaire en civiele helikopters op vogels op het Kooijhoekschor
Smit, C.J. ; Schermer, D.S. - \ 2015
Den Burg : IMARES (Rapport C156/15) - 111
vogels - helikopters - militaire activiteiten - diergedrag - invloeden - menselijke invloed - noord-holland - birds - helicopters - military activities - animal behaviour - influences - human impact
Het Maritiem Vliegkamp De Kooy en de civiele medegebruiker van het vliegveld, Den Helder Airport, zijn gelegen op korte afstand van de Waddenzee. Bij de nadering of bij het vertrek van het vliegveld moet, afhankelijk van de windrichting, in de helft van de gevallen op relatief geringe hoogte over de Waddenzee worden gevlogen. Het vliegveld wordt vooral gebruikt ten behoeve van helikopterverkeer. Den Helder Airport gebruikt het vliegveld vooral voor het vervoer van offshore-arbeiders van en naar olie- en gasplatforms op het Nederlands Continentaal Plat. De groep Maritieme Helikopters is de belangrijkste gebruiker vanuit het Ministerie van Defensie. De 12 hier gestationeerde NH90 helikopters hebben De Kooy als thuisbasis. Ook het onderhoud aan deze helikopters vindt hier plaats. Het vliegkamp wordt vooral gebruikt voor trainingsvluchten. De effecten van de uitbreiding van civiel helikopterverkeer op vogels zijn de afgelopen jaren gemonitord. Tijdens deze onderzoeken zijn ook steeds de effecten van militair vliegverkeer meegenomen. Er is na 2006 echter vrijwel geen onderzoek uitgevoerd op de minder intensief gebruikte aan- en afvliegroute via het Kooijhoekschor. Doel van het in deze rapportage beschreven deelonderzoek was de effecten van militair vliegverkeer op deze route nauwkeuriger in kaart te brengen en te actualiseren. Primaire doel van het in deze rapportage beschreven onderzoek was het bepalen van het effect van vliegbewegingen met militaire helikopters op wad- en watervogels op de locatie Kooijhoekschor, gelegen aan de rand van het Balgzand, ten zuidoosten van het Maritiem Vliegkamp De Kooy. Daarbij is vooral gekeken of overvliegende helikopters vogels doen opvliegen, hoe vaak dit gebeurt en beoordeeld of dit wellicht negatieve effecten voor vogels kan hebben.
Survey van watervogels in het Malzwin, 2013 - 2014
Smit, C.J. ; Meijboom, A. - \ 2015
Den Burg : IMARES (Rapport / IMARES Wageningen UR C101/15) - 47
watervogels - vogels - karteringen - waddenzee - militaire gebieden - waterfowl - birds - surveys - wadden sea - military areas
Het Ministerie van Defensie streeft ernaar dat militaire activiteiten in het Waddengebied een zo gering mogelijk effect op natuurwaarden hebben. Dit geldt ook voor oefeningen met militaire helikopters in de omgeving van Marinevliegkamp De Kooy. Door het Ministerie wordt dan ook gezocht naar mogelijkheden om de noodzakelijk geachte activiteiten te concentreren in een relatief beschut gelegen gebied waar effecten op natuurwaarden zo klein mogelijk zijn. Eén van deze gebieden is een locatie in het Malzwin, ten noorden van het Balgzand. In deze rapportage wordt aan de hand van een reeks maandelijkse tellingen aangegeven welke vogelsoorten in welke aantallen in dit gebied aanwezig zijn.
Kinetic and structural analysis of two transferase domains inPasteurella multocida hyaluronan synthase
Kooy, F.K. ; Beeftink, H.H. ; Eppink, M.H.M. ; Tramper, J. ; Eggink, G. ; Boeriu, C.G. - \ 2014
Journal of Molecular Catalysis. B, Enzymatic 102 (2014). - ISSN 1381-1177 - p. 138 - 145.
blood-group-b - enzymological characterization - conformational-changes - n-acetylglucosamine - crystal-structure - group-a - glycosyltransferase - polypeptide - mechanism - substrate
Pasteurella multocida hyaluronan synthase (PmHAS) encompasses two transferase domains that elongatea growing hyaluronan (HA) oligosaccharide chain by addition of either GlcNAc or GlcUA residues froma corresponding UDP-sugar. Initial velocity studies of single-step elongations were conducted for bothdomains by independently varying the concentrations of the HA oligosaccharide and the UDP-sugar.Two-substrate models were discriminated by their goodness-of-fit parameters and by dead-end inhi-bition studies. A mechanistic shift from a steady-state ordered bi-bi to rapid equilibrium ordered bi-bimechanism was observed at the NAc-site between the HA6and HA8elongation. This shift was invokedby a minor reduction in turnover number kcat. Both NAc- and UA-transferase domains follow a sequentialkinetic mechanism, most likely an ordered one in which the UDP-sugar donor binds first, followed bythe HA oligosaccharide. After transfer of the sugar moiety, both products are released, first the elongatedHA oligosaccharide and then the UDP sugar. This mechanism was visualized with a structural model ofPmHAS that presented two flexible loops, one in each transferase domain; these loops form a bridgeabove the active site.
Production methods for hyaluronan
Boeriu, C.G. ; Springer, J. ; Kooy, F.K. ; Broek, L.A.M. van den; Eggink, G. - \ 2013
International Journal of Carbohydrate Chemistry 2013 (2013). - ISSN 1687-9341 - 14 p.
Hyaluronan is a polysaccharide with multiple functions in the human body being involved in creating flexible and protective layers in tissues and in many signalling pathways during embryonic development, wound healing, inflammation, and cancer. Hyaluronan is an important component of active pharmaceutical ingredients for treatment of, for example, arthritis and osteoarthritis, and its commercial value far exceeds that of other microbial extracellular polysaccharides. Traditionally hyaluronan is extracted from animal waste which is a well-established process now. However, biotechnological synthesis of biopolymers provides a wealth of new possibilities. Therefore, genetic/metabolic engineering has been applied in the area of tailor-made hyaluronan synthesis. Another approach is the controlled artificial (in vitro) synthesis of hyaluronan by enzymes. Advantage of using microbial and enzymatic synthesis for hyaluronan production is the simpler downstream processing and a reduced risk of viral contamination. In this paper an overview of the different methods used to produce hyaluronan is presented. Emphasis is on the advancements made in the field of the synthesis of bioengineered hyaluronan.
Structural and functional evidence for two separate oligosaccharide binding sites of Pasteurellamultocida hyaluronan synthase
Kooy, F.K. ; Beeftink, H.H. ; Eppink, M.H.M. ; Tramper, J. ; Eggink, G. ; Boeriu, C.G. - \ 2013
Advances in Enzyme Research 1 (2013)4. - ISSN 2328-4846 - p. 97 - 111.
Pasteurella multocida hyaluronan synthase (PmHAS) is a bi-functional glycosyltransferase, containing a ß1,3-glucuronyltransferase and ß1,4-N-acetylglucosaminetransferase domain. PmHAS catalyzes the elongation of hyaluronan (HA) through the sequential addition of single monosaccharides to the non-reducing end of the hyaluronan chain. Research is focused on the relation between the length of the HA oligo- saccharide and the single-step elongation ki- netics from HA4 up to HA9. It was found that the turnover number kcat increased with length to maximum values of 11 and 14 s-1 for NAc- and UA-transfer, respectively. Interestingly, the spe- cificity constant kcat/KM increased with polymer length from HA5 to HA7 to a value of 44 mM-1·s-1, indicating an oligosaccharide binding site with increasing specificity towards a heptasaccha- ride at the UA domain. The value of kcat/KM re- mained moderately constant around 8 mM-1·s-1 for HA4, HA6, and HA8, indicating a binding site with significantly lower binding specificity at the NAc domain than at the UA domain. These find- ings are further corroborated by a structural homology model of PmHAS, revealing two dis- tinct sites for binding of oligosaccharides of different sizes, one in each transferase domain. Structural alignment studies between PmHAS and glycosyltransferases of the GT-A fold showed significant similarity in the binding of the UDP-sugars and the orientation of the ac- ceptor substrate. These similarities in substrate orientation in the active site and in essential amino acid residues involved in substrate bind- ing were utilized to localize the two HA oligo- saccharide binding sites.
Monitoring van effecten van vliegbewegingen bij Den Helder Airport in 2011. Met aanvullende waarnemingen in een vergelijkbare situatie op Borkum
Smit, C.J. - \ 2012
Den Burg : IMARES (Rapport / IMARES Wageningen UR C109/12) - 41
vogels - helikopters - luchttransport - milieueffect - natura 2000 - waddenzee - noord-holland - birds - helicopters - air transport - environmental impact - wadden sea
Naar aanleiding van verzoeken tot uitbreiding van het aantal vliegbewegingen met civiele helikopters van en naar Den Helder Airport is in 2003 en 2004 onderzoek uitgevoerd naar de mogelijke effecten van deze vliegbewegingen. Dit onderzoek was nodig omdat een deel van de vliegbewegingen, bij de nadering of bij het vertrek van vliegveld De Kooy, op vrij geringe hoogte wordt uitgevoerd boven het Natura 2000 gebied Waddenzee. De uitgevoerde waarnemingen in 2011 concentreerden zich op de omgeving van het Kuitje, het deel van het Balgzand waar de meeste vliegbewegingen plaatsvinden en waar ook het vaakst effecten van vliegbewegingen zijn waargenomen.
Enzymatic production of hyaluronan oligo- and polysaccharides
Kooy, F.K. - \ 2010
Wageningen University. Promotor(en): Gerrit Eggink; Hans Tramper, co-promotor(en): Carmen Boeriu. - [S.l. : S.n. - ISBN 9789085856481 - 174
hyaluronzuur - derivaten - oligosacchariden - polysacchariden - industriële microbiologie - industriële enzymen - hyaluronic acid - derivatives - oligosaccharides - polysaccharides - industrial microbiology - industrial enzymes
Hyaluronan oligo- and polysaccharides are abundant in the human body. Depending on the chain length, hyaluronan is an important structural component or is involved in influencing cell responses during embryonic development, healing processes, inflammation and cancer. Due to these diverse roles of hyaluronan, there are multiple applications already in use or in development, such as supplementation of fluid in eyes and joints, cosmetic tissue augmentation, enhancing wound healing, tissue engineering, cancer treatment, controlled drug release and targeted drug delivery. State-of-the-art hyaluronan production techniques include bacterial fermentation to produce long hyaluronan polymers with a small chain length distribution and in vitro enzymatic systems to produce hyaluronan oligosaccharides of one chain length. Both production strategies make use of hyaluronan synthase (HAS), an enzyme that elongates UDP-glucuronic acid (UDP-GlcUA) and UDP-N-acetylglucosamine (UDP-GlcNAc) into hyaluronan.

The main question in hyaluronan production today is how the chain length of the products can be controlled. Since most production processes use hyaluronan synthases, the aim of this thesis was to elucidate the polymerization mechanism of Pasteurella multocida hyaluronan synthase (PmHAS) from a biochemical point of view. In addition, the acquired knowledge is used for improving the control on hyaluronan chain length in polymerization reactions using PmHAS. Valuable information important for production processes on the intrinsic properties of the enzyme, such as substrate affinity, can be obtained by kinetic studies using single-step elongations. Kinetic studies also provide insights on how polymerization is achieved and, combined with structural studies, the identification of amino acid residues that are important for polymerization. This knowledge can be used for improving the hyaluronan synthesis performance of the enzyme.

Kinetic studies require purified substrates in quantities of mg-scale. Hyaluronan (HA) oligosaccharides were obtained through stepwise hyaluronan cleavage using hyaluronidase and consecutive separation of the reaction mixture by flash-chromatography (Chapter 2). The enzymatic hydrolysis was optimized by experimental design studies with pH, enzyme concentration and reaction time as parameters. Empirical models were developed for the yield of each individual target HA oligosaccharide using the results from a central composite design. Selective production of short HA oligomers (HA ≤ 10) or longer oligosaccharides (HA > 10) was made possible through implementation of the reaction conditions indicated by the empirical models. Separated HA oligomers were characterized by a combination of anion exchange chromatography and matrix-assisted laser desorption/ionization mass spectrometry with time-off-flight analysis. Using these techniques, the desired quantities of purified target HA oligosaccharides (n = 4, 6, 8 and 10) were obtained and used in further studies.

Besides the single-step elongations assessed in kinetic studies, full polymerization studies with both UDP-sugars available were used to investigate the influence of substrate concentrations on the chain length distribution of the hyaluronan products. In order to quantify all oligosaccharides formed during PmHAS polymerization in μl-scale reactions, HA templates consisting of a fluorophore-labeled HA tetrasaccharide (HA4) were generated (Chapter 3). A fast, simple and sensitive assay was developed based on fluorophore-assisted carbohydrate electrophoresis (FACE) that was used for quantification and characterization of PmHAS polymerization products.

The individual β1,3-glucuronyl-transferase (UA-transferase) and β1,4-N-acetylglucosamine-transferase (NAc-transferase) activities of PmHAS were investigated separately using kinetic studies, where the reaction of an HA oligosaccharide was followed with, respectively, UDP-GlcUA or UDP-GlcNAc in single-step elongations. In Chapter 4, the influence of HA oligosaccharide length (n = 4, 5, 6, 7, 8 and 9) on the polymerization reaction was investigated by one-substrate kinetics, varying only the HA oligosaccharide concentration at saturating UDP-sugar concentration. These reactions followed Michaelis Menten kinetics, although HA oligosaccharides may become inhibiting at elevated concentrations above 6 mM. The observed kcat values increased with increasing HA oligosaccharide length to a constant value at HA6 and HA7. The specificity constant kcat/Km values for HA oligosaccharides in the UA-transferase domain increased at increasing oligosaccharide length, whereas in the NAc-transferase domain kcat/Km values were constant at a low value. This indicates that there are two separate oligosaccharide binding sites of different lengths, one in each transferase domain of PmHAS. In Chapter 4, it was demonstrated that the chain-lenght distribution in PmHAS polymerization reactions can be decreased, and thus improved, by using saturating concentrations of both HA oligosaccharides and UDP-sugars.

Chapter 5 describes two-substrate kinetic studies, where in single-step elongations both HA oligosaccharide and one of the UDP-sugars were varied, to investigate the polymerization mechanism of each individual transferase domain in PmHAS. Dead-end inhibition studies and goodness-of-fit parameters were used to distinguish between two-substrate models. From this analysis follows that both transferase domains elongate the UDP-sugar through a sequential mechanism, which is most likely an ordered one. In this proposed mechanism, the UDP-sugar is first bound followed by binding of the HA oligosaccharide, after which first the elongated HA oligosaccharide and then UDP is released. Large differences between Km values for UDP-GlcNAc and UDP-GlcUA, also found in Class I HAS enzymes, suggest that UDP-GlcNAc concentration is involved in the regulation of HAS activity and thus the chain length of hyaluronan products.

Structural studies were used to evaluate the results obtained with kinetic studies. In Chapter 4, a structural homology model of PmHAS was built based on crystal structure K4CP chondroitin polymerase in E. coli, which has a high sequence identity of 62% and high sequence homology of 78% with PmHAS. The active sites of PmHAS are structurally related to other glycosyltransferases and this provided information on where the oligosaccharide binding sites could be located. These putative oligosaccharide binding sites differ in size, as was predicted by kinetic studies (Chapter 4). Furthermore, structural similarities between PmHAS, α1,3-galactosyltransferase (α3GT) and β1,4-galactosyltransferase (β4Gal-T1) demonstrated that PmHAS contains in each transferase domain one flexible loop that forms a bridge over the active site. In crystal structures of α3GT and β4Gal-T1, these flexible loops have been shown to change conformation upon binding the UDP-sugar. Based on similarities in kinetic mechanisms and structures between PmHAS, α3GT and β4Gal-T1, it is likely that the flexible loops in PmHAS follow a similar conformational change, which makes the proposed ordered mechanism the only possible mechanism (Chapter 5).

In Chapter 6, the knowledge on the PmHAS polymerization mechanism gained in earlier chapters is reviewed and used to create new insights in the polymerization mechanism of Class I HAS enzymes. Both Class I HASs and PmHAS are used in hyaluronan production, and, therefore, the differences and similarities are discussed in Chapter 6. During hyaluronan production, there are many different aspects, such as intrinsic properties of the enzyme, cell metabolism and fermentation reaction conditions, that influence hyaluronan chain length and yield (Chapter 6). Moreover, hyaluronan production systems that are able to produce hyaluronan of desired length are discussed in Chapter 6 and a personal view of how these systems can be improved is presented.
In vitro synthesis of heparosan using recombinant Pasteurella multocida heparosan synthase PmHS2
Chavaroche, A.A.E. ; Springer, J. ; Kooy, F.K. ; Boeriu, C.G. ; Eggink, G. - \ 2010
Applied Microbiology and Biotechnology 85 (2010)6. - ISSN 0175-7598 - p. 1881 - 1891.
molecular-weight heparins - hyaluronan synthase - chemoenzymatic synthesis - capsular polysaccharide - identification - streptococcus - biosynthesis - acid - glycosyltransferases - polymers
In vertebrates and bacteria, heparosan the precursor of heparin is synthesized by glycosyltransferases via the stepwise addition of UDP-N-acetylglucosamine and UDP-glucuronic acid. As heparin-like molecules represent a great interest in the pharmaceutical area, the cryptic Pasteurella multocida heparosan synthase PmHS2 found to catalyze heparosan synthesis using substrate analogs has been studied. In this paper, we report an efficient way to purify PmHS2 and to maintain its activity stable during 6 months storage at -80¿°C using His-tag purification and a desalting step. In the presence of 1 mM of each nucleotide sugar, purified PmHS2 synthesized polymers up to an average molecular weight of 130 kDa. With 5 mM of UDP-GlcUA and 5 mM of UDP-GlcNAc, an optimal specific activity, from 3 to 6 h of incubation, was found to be about 0.145 nmol/µg/min, and polymers up to an average of 102 kDa were synthesized in 24 h. In this study, we show that the chain length distribution of heparosan polymers can be controlled by change of the initial nucleotide sugar concentration. It was observed that low substrate concentration favors the formation of high molecular weight heparosan polymer with a low polydispersity while high substrate concentration did the opposite. Similarities in the polymerization mechanism between PmHS2, PmHS1, and PmHAS are discussed
Quantification and characterization of enzymatically produced hyaluronan with fluorophore-assisted carbohydrate electrophoresis
Kooy, F.K. ; Muyuan Ma, ; Beeftink, H.H. ; Eggink, G. ; Tramper, J. ; Boeriu, C.G. - \ 2009
Analytical Biochemistry 384 (2009)2. - ISSN 0003-2697 - p. 329 - 336.
polyacrylamide-gel electrophoresis - synthase - oligosaccharides - microanalysis - acid - fragments - sulfate - assay - face
Hyaluronan (HA) is a polysaccharide with high-potential medical applications, depending on the chain length and the chain length distribution. Special interest goes to homogeneous HA oligosaccharides, which can be enzymatically produced using Pasteurella multocida hyaluronan synthase (PmHAS). We have developed a sensitive, simple, and fast method, based on fluorophore-assisted carbohydrate electrophoresis (FACE), for characterization and quantification of polymerization products. A chromatographic pure fluorescent template was synthesized from HA tetrasaccharide (HA4) and 2-aminobenzoic acid. HA4-fluor and HA4 were used as template for PmHAS-mediated polymerization of nucleotide sugars. All products, fluorescent and nonfluorescent, were analyzed with gel electrophoresis and quantified using lane densitometry. Comparison of HA4- and HA4-fluor-derived polymers showed that the fluorophore did not negatively influence the PmHAS-mediated polymerization. Only even-numbered oligosaccharide products were observed using HA4-fluor or HA4 as template. The fluorophore intensity was linearly related to its concentration, and the limit of detection was determined to be 7.4 pmol per product band. With this assay, we can now differentiate oligosaccharides of size range DP2 (degree of polymerization 2) to approximately DP400, monitor the progress of polymerization reactions, and measure subtle differences in polymerization rate. Quantifying polymerization products enables us to study the influence of experimental conditions on HA synthesis
Family in modern city environment 1967
Kooy, G.A. ; Kloeze, J.W. te - \ 2007
sociology - family life
Contacts with relatives / visiting parents, parents-in-law, brothers and sisters / financial support of parents and parents-in-law / opinion on relatives, being excessively fond of relatives, asking relatives for help / importance of friends / mothers-in-law. Background variables: basic characteristics/ place of birth/ residence/ household characteristics/ characteristics of parental family/household/ occupation/employment/ education/ religion/ consumption of durables
Marriage in the Netherlands, 1967
Kooy, G.A. - \ 2007
sociology - family life - interpersonal relations - religion - work - sexual behaviour - marriage
Detailed background data on marriage and family / religion and occupation / satisfaction with job / household and mutual friends / perceptions of partner / personal worries / relationships with mutual friends / self description / personal problems / opinions on financial matters / socio-cultural and recreational activities of both partners / sexual relationship / relations with family / mutual relationship and the solving of mutual problems / reasons for divorce. Background variables: basic characteristics/ residence/ household characteristics/ occupation/employment/ education/ social class/ religion
Development of two assays to measure hyaluronan synthase activity
Kooy, F.K. ; Ma, M. ; Beeftink, H.H. ; Eggink, G. ; Boeriu, C.G. - \ 2007
Controlled enzymatic production of oligosaccharide templates for hyaluronan synthesis
Boeriu, C.G. ; Boswinkel, G. ; Kooy, F.K. ; Boer, E. - \ 2007
Controlled biosynthesis of glycoseaminoglycan polymers
Kooy, F.K. ; Beeftink, H.H. ; Boeriu, C.G. ; Eggink, G. ; Tramper, J. - \ 2006
In: 11th Netherlands Biotechnology Congress "Colourful Biotechnology: Red, White and Blue" , Ede, The Netherlands, 16-17 March 2006. - Ede : - p. 122 - 122.
Natural variation in toxicity of wheat: potential for selection of nontoxic varieties for celiac disease patients
Spaenij-Dekking, L. ; Kooy-Winkelaar, Y. ; Veelen, P. van; Drijfhout, J.W. ; Jonker, H.H. ; Soest, L.J.M. van; Smulders, M.J.M. ; Bosch, H.J. ; Gilissen, L.J.W.J. ; Koning, F. de - \ 2005
Gastroenterology 129 (2005)3. - ISSN 0016-5085 - p. 797 - 806.
t-cell recognition - tissue transglutaminase - prolyl endopeptidase - gliadin peptides - interferon-gamma - cereal toxicity - alpha-gliadin - in-vivo - gluten - epitopes
Background & Aims: Celiac disease (CD) is an intestinal disorder caused by T-cell responses to peptides derived from the gluten proteins present in wheat. Such peptides have been found both in the gliadin and glutenin proteins in gluten. The only cure for CD is a lifelong gluten-free diet. It is unknown, however, if all wheat varieties are equally harmful for patients. We investigated whether wheat varieties exist with a natural low number of T-cell¿stimulatory epitopes. Methods: Gluten proteins present in public databases were analyzed for the presence of T-cell¿stimulatory sequences. In addition, wheat accessions from diploid (AA, SS/BB, and DD genomes), tetraploid (AABB), and hexaploid (AABBDD) Triticum species were tested for the presence of T-cell¿stimulatory epitopes in gliadins and glutenins by both T-cell and monoclonal antibody¿based assays. Results: The database analysis readily identified gluten proteins that lack 1 or more of the known T-cell¿stimulatory sequences. Moreover, both the T-cell¿ and antibody-based assays showed that a large variation exists in the amount of T-cell¿stimulatory peptides present in the wheat accessions. Conclusions: Sufficient genetic variation is present to endeavor the selection of wheat accessions that contain low amounts of T-cell¿stimulatory sequences. Such materials may be used to select and breed wheat varieties suitable for consumption by CD patients, contributing to a well-balanced diet and an increase in their quality of life. Such varieties also may be useful for disease prevention in individuals at risk.
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