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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Building an Artificial Stem Cell Niche: Prerequisites for Future 3D-Formation of Inner Ear Structures—Toward 3D Inner Ear Biotechnology
Groot, Simon C. de; Sliedregt, Karen ; Benthem, Peter Paul G. van; Rivolta, Marcelo N. ; Huisman, Margriet A. - \ 2019
The Anatomical Record (2019). - ISSN 1932-8486
3D - biotechnology - inner ear - stem cell

In recent years, there has been an increased interest in stem cells for the purpose of regenerative medicine to deliver a wide range of therapies to treat many diseases. However, two-dimensional cultures of stem cells are of limited use when studying the mechanism of pathogenesis of diseases and the feasibility of a treatment. Therefore, research is focusing on the strengths of stem cells in the three-dimensional (3D) structures mimicking organs, that is, organoids, or organ-on-chip, for modeling human biology and disease. As 3D technology advances, it is necessary to know which signals stem cells need to multiply and differentiate into complex structures. This holds especially true for the complex 3D structure of the inner ear. Recent work suggests that although other factors play a role, the extracellular matrix (ECM), including its topography, is crucial to mimic a stem cell niche in vitro and to drive stem cells toward the formation of the tissue of interest. Technological developments have led to the investigation of biomaterials that closely resemble the native ECM. In the fast forward moving research of organoids and organs-on-chip, the inner ear has hardly received attention. This review aims to provide an overview, by describing the general context in which cells, matrix and morphogens cooperate in order to build a tissue, to facilitate research in 3D inner ear technology. Anat Rec, 2019.

Erosion of archaeological sites: Quantifying the threat using optically stimulated luminescence and fallout isotopes
Huisman, H. ; Kort, J.W. de; Ketterer, M.E. ; Reimann, T. ; Schoorl, J.M. ; Heiden, M. van der; Soest, Maud van; Egmond, Fenny van - \ 2019
Geoarchaeology: an international journal 34 (2019)4. - ISSN 0883-6353 - p. 478 - 494.
Although visible evidence shows that erosion has damaged many archaeological sites, especially when tilled, there has hitherto been scant attention to its quantitative assessment. Accordingly, the archaeology communities lack insight into whether long‐term threats to the stability and integrity of soils at these sites allow these cultural repositories to be preserved for future human generations. Of the techniques that are available to measure erosion rates, few have been tested on the timescales needed. We selected three archaeological sites with high expected erosion rates. We combined optically stimulated luminescence (OSL) dating with analyses of radioactive fallout isotope distributions to assess erosion patterns and rates. An age–depth representation of OSL single‐aliquot results was developed to determine past erosion, and to identify stable land surfaces on centennial to millennia timescales. Fall‐out isotopes of cesium (Cs) and plutonium (Pu) were suitable for shorter timescales: The 240Pu/239Pu ratios and a correlation between activities of 239+240Pu and 137Cs demonstrated the weapons testing fallout origin of these isotopes in the ~1952–1966 timeframe. Erosion rates in recent decades ranged from 2 to 6 mm/year on the studied sites. Our results indicate that erosion is not only tied to the past, but keeps on threatening archaeological sites.
Fraud vulnerability in the Dutch milk supply chain : Assessments of farmers, processors and retailers
Yang, Y. ; Huisman, W. ; Hettinga, K.A. ; Liu, N. ; Heck, J. ; Schrijver, G.H. ; Gaiardoni, L. ; Ruth, S.M. van - \ 2019
Food Control 95 (2019). - ISSN 0956-7135 - p. 308 - 317.
Dairy supply chain - Fraud factor - Fraud mitigation - Milk adulteration - Organic farm - Vulnerability assessment

Food fraud surfaces regularly, anywhere in the world. Not only the companies involved in food fraud suffer from losses when food fraud occurs, other actors in the supply chain and branch of industry are often painted with the same brush. Milk has been a common fraud target in the past and, therefore, fraud is a concern for companies involved in milk production. In order to manage and prevent fraud in the milk supply chain, a good insight into the vulnerabilities of companies and their supply chain networks is pivotal. The aim of the current study is to understand (a) the fraud vulnerability of the general milk supply chain in the Netherlands and its tiers (farmers, processors, retailers) and (b) the differences in fraud vulnerability of farmers producing organic milk, green intermediate ‘pasture milk’ and conventional milk. The SSAFE food fraud assessment tool was slightly adapted to the milk supply chain and used to examine the fraud vulnerability of the 38 businesses of the three tiers in the study: 30 farmers, 4 milk processors and 4 retailers. Forty-eight fraud factors related to opportunities, motivations and control measures were examined. Subsequently, key fraud factors were identified. The three tier groups showed major similarities in motivation related fraud factors, and large differences in fraud opportunities and controls. There were also differences observed between the organic and non-organic farmers, with organic farmers being slightly more vulnerable than their non-organic counterparts. From this study it appears that the milk supply chain in the Netherlands is low to medium vulnerable to fraud but the key factors contributing to the vulnerability differ between the tiers (farmers, processors, retailers). Management of the fraud risks requires consideration of these differences.

Estuarine fish passes in the northern Netherlands provide contrasting windows of opportunity for migrating fish species (#188)
Huisman, Jeroen - \ 2018
Evergreen – bollen Plantengroei bevorderende rhizobacteriën
Dam, M.F.N. van; Breeuwsma, S.J. ; Huisman, Huei Ming ; Greve, Gerdit ; Wal, A. van der - \ 2018
- 1 p.
Archeologisch onderzoek in de omgeving van het prehistorische vuursteenmijnveld te Rijckholt - St.Geertruid : De resultaten van 2011, 2012 en 2013
Brinkkemper, O. ; Bruinink, A.C. ; Deeben, J. ; Guralnik, B. ; Hoebe, P. ; Huisman, H. ; Kort, J.W. de; Laarman, F. ; Meirvenne, M. van; Orbons, J. ; Os, B. van; Parys, V. van; Schreurs, J. ; Theunissen, L. ; Verhegge, J. ; Versendaal, Alice ; Wallinga, J. - \ 2018
Amersfoort : Rijksdienst voor het Cultureel Erfgoed - ISBN 9789057993022 - 371 p.
Formation of a symbiotic host-microbe interface: the role of SNARE-mediated regulation of exocytosis
Huisman, Rik - \ 2018
Wageningen University. Promotor(en): A.H.J. Bisseling, co-promotor(en): E.H.M. Limpens. - Wageningen : Wageningen University - ISBN 9789463323178 - 158

At the heart of endosymbiosis microbes are hosted inside living cells in specialized membrane compartments that from a host-microbe interface, where nutrients and signal are efficiently exchanged. Such symbiotic interfaces include arbuscules produced by arbuscular mycorrhiza (AM) and organelle-like symbiosomes formed during the rhizobium-legume symbiosis. Also during pathogenic interactions, microbes such as biotrophic fungi and oomycetes are hosted in specialized membrane compartments called haustoria. The formation of such new membrane compartments requires a major reorganization of the host endomembrane system, with a special role for the targeting of secretory/exocytotic vesicles and their cargo to the newly forming interfaces. In this thesis, I studied how exocytotic membrane traffic is regulated to facilitate the formation and maintenance of a host-microbe interface. Therefore, I especially focussed on the role of SNARE (Soluble NSF Attachment Protein Receptor) proteins, as key components of the exocytotic machinery, in symbiotic interface formation.

In Chapter 1, I introduce the different symbioses in which host-microbe interfaces are formed, and the role of the host-microbe interface in these symbioses. Further, I introduce the evolutionary relationship between the different symbioses: AM symbiosis is the most ancient endosymbiosis in plants, which provided the blueprint for different symbioses that evolved later; other symbiotic microbes including rhizobia co-opted the signalling program and adaptations to membrane trafficking required for arbuscule formation, to be hosted inside cells. Finally, I will introduce the symbiosis dedicated SNAREs as key regulators of exocytosis to form a host-microbe interface.

In Chapter 2, we tested the long-standing hypothesis that pathogens make use of the AM symbiotic program to allow the formation of haustoria. To test this, we set up a pathosystem using the biotrophic oomycete Phytophthora palmivora that is able to form haustoria in Medicago truncatula root cells. Using M. truncatula mutants impaired in AM and rhizobium symbioses, we demonstrated that neither the common symbiotic signalling genes, nor symbiosis dedicated regulators of vesicle trafficking are required for haustorium formation. This showed that biotrophic pathogens like P. palmivora, do not hijack the symbiotic program to be accommodated inside plant cells.

In Chapter 3, we identified the t-SNARE SYP132α as a key regulator of both arbuscule and symbiosome formation. During vesicle fusion, a vesicle SNARE (v-SNARE) on the vesicle forms a complex with a target membrane SNAREs (t-SNAREs) on the target membrane. Previous work in our lab identified specific exocytotic v-SNAREs required for arbuscule and symbiosome formation. We identified the t-SNARE counterpart SYP132, and demonstrated that in most dicot plants SYP132 is spliced into two spliceforms; SYP132α and SYP132β. Interestingly, alternative splicing of SYP132 leading to the dominant use of a SYP132α-specific last exon coincides with the accommodation of AM fungi in arbuscule forming root cortex cells and rhizobium bacteria in nodule cells. Using a spliceform-specific RNAi construct, we showed that SYP132α is specifically required for the formation of a stable host-microbe interface in both AM symbiosis and rhizobium symbiosis. Furthermore, we showed that during arbuscular collapse, the two spliceforms localize differently to healthy and degrading arbuscule branches. These results indicated that alternative splicing of SYP132 allows plants to replace a t-SNARE involved in traffic to the plasma membrane with a t-SNARE that is more stringent in its localization to functional arbuscules.

The evolutionary expansion of SNAREs in plants has been hypothesized to have allowed the adaptation of exocytosis to different biological processes. In Chapter 4, we studied what makes the symbiotic SNAREs so special in comparison to their non-symbiotic family members, of which many are also expressed in arbuscule cells. We hypothesized that symbiotic SNAREs define a distinct secretory pathway, that ensures specificity of protein delivery to the host-microbe interface. We show that all tested SYP1 family proteins, and most of the non-symbiotic VAMP72 members, were able to complement the defect in arbuscule formation upon knock-down of their symbiotic counterparts when expressed at sufficient levels. This functional redundancy is in line with the ability of all tested v- and t-SNARE combinations to form SNARE complexes at the peri-arbuscular membrane. This showed that the symbiotic SNAREs do not selectively interact to define a distinct vesicle trafficking pathway, but that their essential role in arbuscule formation can be largely explained by their dominant expression level. Interestingly, the symbiotic t-SNARE SYP132α appeared to occur less in SNARE complexes with v-SNAREs compared to the non-symbiotic syntaxins in the arbuscule cells, suggesting a more strict regulation of symbiotic SNARE complexes at the interface.

Since the alternative splicing of SYP132 does not affect the total transcript levels, we hypothesized that there must be a functional difference between SYP132α and –β, potentially leading to subtle phenotypes that may have gone undetected in the Agrobacterium rhizogenes mediated complementation approach applied in Chapter 4. In Chapter 5, we therefore generated and characterized a stable mutant line in which all SYP132 transcripts are constitutively spliced into the non-symbiotic SYP132β form. Although this mutant is normally colonized by AM fungi, with no effects on arbuscule morphology, it has a severely reduced biomass after mycorrhization. This hints to a yet unknown role for SYP132α to control arbuscule functionality, and offers an explanation for the evolutionary conservation of the SYP132 alternative splicing in dicot plants. Finally, using fluorescent timer fusions to both SYP132 isoforms, we showed that the difference in localization of the two proteins during arbuscular collapse is the result of a different (endocytic) turnover of the two spliceforms at the healthy/functional arbuscule branches, possibly due to a difference in interactions with VAMPs. Together, our data show that, although both SYP132 isoforms can mediate arbuscule formation, SYP132α is functionally different from SYP132β, which may reveal new aspects of the control of nutrient exchange.

In Chapter 6, I discuss the data generated during my thesis research in relation to additional symbiosis dedicated regulators of exocytosis, as well as in relation to other biological processes that depend on specific secretory SNAREs. Following our conclusion that the symbiotic SNAREs do not mark a separate exocytosis pathway, but are functionally different from non-symbiotic SNAREs, I will speculate on the possible scenarios in which symbiosis dedicated SNAREs are specialized for host-microbe interface functionality.

Does a high sugar high fat dietary pattern explain the unequal burden in prevalence of type 2 diabetes in a multi-ethnic population in the Netherlands? The HELIUS study
Huisman, Merel J. ; Soedamah-Muthu, Sabita S. ; Vermeulen, Esther ; Muilwijk, Mirthe ; Snijder, Marieke B. ; Nicolaou, Mary N. ; Valkengoed, Irene G.M. Van - \ 2018
Nutrients 10 (2018)1. - ISSN 2072-6643
HELIUS study - HSHF - Multi-ethnic - T2D - Western dietary pattern
The risk for type 2 diabetes (T2D) in ethnic minorities in Europe is higher in comparison with their European host populations. The western dietary pattern, characterized by high amounts of sugar and saturated fat (HSHF dietary pattern), has been associated with a higher risk for T2D. Information on this association in minority populations is scarce. Therefore, we aimed to investigate the HSHF dietary pattern and its role in the unequal burden of T2D prevalence in a multi-ethnic population in The Netherlands. We included 4694 participants aged 18-70 years of Dutch, South-Asian Surinamese, African Surinamese, Turkish, and Moroccan origin from the HELIUS study. Dutch participants scored the highest on the HSHF dietary pattern, followed by the Turkish, Moroccan, African Surinamese, and South-Asian Surinamese participants. Prevalence ratios (PR) for T2D were then calculated using multivariate cox regression analyses, adjusted for sociodemographic, anthropometric, and lifestyle factors. Higher adherence to an HSHF diet was not significantly related to T2D prevalence in the total study sample (PR 1.04 high versus low adherence, 95% CI: 0.80-1.35). In line, adjustment for HSHF diet score did not explain the ethnic differences in T2D. For instance, the PR of the South-Asian Surinamese vs. Dutch changed from 2.76 (95% CI: 2.05-3.72) to 2.90 (95% CI: 2.11-3.98) after adjustment for HSHF. To conclude, a western dietary pattern high in sugar and saturated fat was not associated with T2D, and did not explain the unequal burden in prevalence of T2D across the ethnic groups.
Differences in fraud vulnerability in various food supply chains and their tiers
Ruth, S.M. van; Luning, P.A. ; Silvis, I.C.J. ; Yang, Y. ; Huisman, W. - \ 2018
Food Control 84 (2018). - ISSN 0956-7135 - p. 375 - 381.
Bananas - Fish - Meat - Milk - Olive oil - Spices
Food fraud results from the interaction of motivated offenders with opportunities, and lack of control measures. The vulnerability to food fraud varies across chain actors (tiers) though, but insights on prime fraud drivers and enablers, as well as chain areas where vulnerabilities might exist are lacking. In the current study the fish, meat, milk, olive oil, organic bananas, and spice supply chains were assessed for their fraud vulnerabilities. The differences and similarities in vulnerabilities across the supply chains, as well as between groups of chain actors were evaluated using the SSAFE food fraud vulnerability assessment tool. Multiple correspondence analysis and agglomerative hierarchical clustering were applied for exploratory data analysis, and differences between chains and actors were assessed by analysis of variance and post-hoc tests. Thirteen fraud factors related to opportunities and motivations scored high across all supply chains indicating their importance as fraud drivers and enablers. Control measures varied considerably across supply chains and actor groups, with technical (hard) controls generally being more in place than managerial (soft) controls. Approximately half of the fraud factors were impacted by the type of commodity chain, and one out of seven of the fraud factors by the actor group. From the current sample group overall fraud vulnerability appeared highest for the spice chain, which was followed by the olive oil, meat, fish, milk and organic banana chains. Among the actor groups, the wholesale/traders group appeared most vulnerable, followed by retailers and processors. The current results provide new insights in the fraud factors determining fraud vulnerability in various supply chains, and the (dis)similarities in fraud vulnerability across supply chains and actor groups which helps to combat future food fraud.
Data from sediment sampling campaign, Sand Motor
Huisman, B.J.A. ; Bart, L. ; Schipper, M.A. de; Meirelles, S. ; Sirks, E.E. ; Tonnon, P.K. ; Zwaag, J. van der; Wijsman, J.W.M. - \ 2017
composition - NeMo project - sampling - Sand Motor - sediment
Sediment sampling data from measurement campaign at the Sand Motor
Kelmond-Beekerveld (gemeente Beek); erosieonderzoek in het kader van het TOPsites project
Huisman, D.J. ; Kort, J.W. de; Derickx, W. ; Heiden, M. van der; Egmond, Fenny van; Reimann, T. ; Schoorl, J.M. ; Soest, M. van; Wallinga, J. - \ 2017
Rijksdienst voor het Cultureel Erfgoed - ISBN 9789057992742 - 92 p.
Nivellering en erosie zijn een algemeen bekend
probleem voor geaccidenteerde terreinen
waarop akkerbouw plaatsvindt. Grond zonder
vegetatie is gevoelig voor erosie, terwijl ploegen
zorgt voor vervlakking en nivellering van reliëfverschillen.
Verschillende tests zijn gedaan, met
name in het buitenland, om de snelheid van
deze nivellering en erosie te karakteriseren.
De resultaten zijn echter niet eenduidig, mede
omdat verschillende tijdschalen worden
gebruikt.
Om beter grip te krijgen op de snelheid van
erosie en nivellering op archeologische vindplaatsen
als gevolg van akkerbouw zijn vijf
locaties uitgezocht. Met opzet is gekozen voor
locaties waarvan de verwachting is dat erosie/
nivellering sterk is, zodat ze kunnen worden
gezien als worst-case scenario. Binnen die groep
is gekozen voor vindplaatsen waar eerder
relevante gegevens zijn verzameld over
degradatie en conservering. Twee (Beek-
Kelmond en Meerssen – Onderste Herkenberg)
liggen in het Limburgse lössgebied; drie andere
(Schouwen, Grote Houw en Tjessens) zijn
terpen/wierden. Op deze locaties worden
verschillende technieken ingezet om erosie en
nivellering door de tijd in kaart te brengen.
Uit het onderzoek op de vroegneolitische
(Lineaire Bandkeramiek) vindplaats Kelmond-
Beekerveld blijkt dat er aanwijzingen zijn voor
van significante erosie, met name op het steilste
deel van de helling. Hoewel het meeste
colluvium op zijn laatst gevormd is tijdens de
late middeleeuwen, zijn er duidelijke aanwijzingen
dat erosie actief was in de afgelopen
decennia, en op dit moment ook nog plaatsvindt.
De snelheid waarop de erosie plaatsvindt is
aanzienlijk; in de afgelopen 50 jaar is enkele
decimeters aan grond verdwenen van de site,
met name rond de hellingknik. De oudere
datering van het colluvium en de aanwezigheid
van een grote concentratie sporen op het steilste
deel van de helling zijn aanwijzingen dat deze
erosie komt na een langere periode van landschappelijke
stabiliteit.
De vergelijking van de maaiveldhoogtes uit
verschillende jaren en de variaties daarin (met
name de vergelijking tussen de twee generaties
van het Actueel Hoogtebestand Nederland)
duiden op erosie, maar deze resultaten op zich
zijn niet overtuigend. De combinatie van 137Cs en
239+240Pu metingen enerzijds en OSL metingen
anderzijds geven wel uitkomsten die geschikt
zijn voor het identificeren en kwantificeren van
erosie en colluviatie.
Veel van de hier geteste methoden bleken niet
geschikt om de erosiesnelheden te meten. In de
meeste gevallen waren ze te onnauwkeurig
(bijvoorbeeld 137Cs oppervlaktekartering), waren
de effecten te onduidelijk (AHN/LIDAR
verschillen) of waren er oncontroleerbare
variaties in de gehaltes van bepaalde tracers.
De tracers 137Cs en 239+240Pu gaven als enige wel
waardes waaraan recente erosie kon worden
afgelezen. De schatting van de snelheden is
gebaseerd op een aantal aannames, waardoor
de schattingen vooral als indicatie moeten
worden gezien. Nader onderzoek naar het
gebruik van deze isotopencombinatie zou de
betrouwbaarheid van de schatting kunnen
verbeteren.
OSL bleek vooral geschikt om erosie en depositie
op tijdschalen van (tientallen) eeuwen te
bepalen. Het is daarmee een goede ondersteunende
techniek – in combinatie met tracers – om
de landschappelijke ontwikkeling en erosiegevoeligheid
van een vindplaats te onderzoeken.
Voor toekomstig onderzoek, waarbij het
schatten van mate van erosie van belang is, is
het aan te raden om een combinatie van 137Cs en
239+240Pu als tracers en OSL als ondersteuning en
landschapsontwikkeling toe te passen. Een extra
voordeel van deze combinatie is dat ze ook een
indicatie kunnen geven van de mate van bioturbatie
op een vindplaats en de timing ervan.
Ten aanzien van het monument zelf kunnen een
aantal aanbevelingen worden gedaan. Uit het
onderzoek blijkt dat er sprake is van stevige
erosie op delen van het terrein. Omdat veel van
de sporen direct onder de bouwvoor liggen, is de
vindplaats zeer kwetsbaar. Eenmaal dieper
ploegen dan de bouwvoor brengt schade en
informatieverlies met zich mee. Een gebruik van
het monument als grasland verdient daarom de
voorkeur.
Erosie-onderzoek op de Grote Houw Oost in het kader van TOPsites
Huisman, D.J. ; Heiden, M. van der; Derickx, W. ; Kort, J.W. de; Reimann, T. ; Schoorl, J.M. ; Thasing, S. ; Egmond, Fenny van; Soest, M. van; Verplanke, P. ; Wallinga, J. - \ 2017
Rijksdienst voor het Cultureel Erfgoed - ISBN 9789057992780
Grote Houw is één van de vier locaties waar in
het kader van het TOPsites project onderzoek is
uitgevoerd naar de snelheid van erosie. Doel was
om te proberen vast te stellen hoe snel op deze
locatie erosie plaatsvindt. Bijkomende doelen
waren (1) om te testen welke methodes het
meest geschikt zijn in een dergelijke context om
erosiesnelheden te meten en (2) om te onderzoeken
in hoeverre erosie schade toebrengt aan
de archeologische vindplaats.
Grote Houw – een terrein van zeer hoge archeologische
waarde – bevat een deel van een
complexe dubbelwierde. De verschillende
methodes die werden getest voor het meten van
de erosiesnelheden gaven variabele resultaten:
• Een vergelijking van de maaiveldhoogtes
volgens AHN1, AHN2 en een nieuwe groundbased
LIDAR opname leverde geen duidelijk
beeld op.
• Met booronderzoek zijn aanwijzingen voor
erosie gevonden in de vorm van variaties in
diktes van de bouwvoor.
• Een intensieve veldkartering leverde een
duidelijk beeld van de vondspreiding in relatie
tot de ligging van de wierde. Er waren echter
geen eenduidige aanwijzingen voor het recent
opploegen van vondstmateriaal.
• Vijf profielputten werden gegraven om de
bodemopbouw te bestuderen – met aandacht
voor de dikte van de bouwvoor en het evt.
aanwezig zijn van colluvium.
• OSL analyses (uit de profielputten) bleken
vooral geschikt om erosie- en sedimentatieprocessen
op langere tijdschalen te
onderzoek. Daarbij was de spreiding aan
dateringen binnen één monster van groter
belang dan een absolute datering. De
metingen gaven een duidelijk beeld van de
ontstaansgeschiedenis van de wierde. Erosie
of colluviumvorming was niet duidelijk aan te
tonen.
• Met metingen van de gehaltes aan 137Cs en
plutonium in het profiel bleek het wel
mogelijk om schattingen van erosiesnelheden
te maken over de periode van ca. 1960
(detonatie van waterstofbommen in de
atmosfeer) tot nu. Schatting is dat gedurende
deze 50 jaar maximaal 2 mm/jaar erosie is
opgetreden.
• De resultaten van 137Cs oppervlaktemetingen
waren op deze locatie niet geschikt om erosie
vast te stellen.
Meerssen – Onderste Herkenberg; erosieonderzoek in het kader van TOPsites
Huisman, D.J. ; Groot, T. de; Kort, J.W. de; Derickx, W. ; Egmond, F.M. van; Heiden, M. van der; Reimann, T. ; Rensink, E. ; Saey, T. ; Schoorl, J.M. ; Parys, V. Van; Soest, M. van; Meirvenne, M. ; Wallinga, J. - \ 2017
Rijksdienst voor het Cultureel Erfgoed - ISBN 9789057992797 - 112 p.
Food fraud vulnerability and its key factors
Ruth, Saskia M. van; Huisman, Wim ; Luning, Pieternel A. - \ 2017
Trends in Food Science and Technology 67 (2017). - ISSN 0924-2244 - p. 70 - 75.
Counterfeiting - Criminology - Food adulteration - Fraud risk - Vulnerability assessment

Background Food fraud prevention and fraud vulnerability reduction are the first steps to combat food fraud and require a recurrent effort throughout the food supply chain. Due to the intentional nature of fraud, it requires different tactics than the common food safety approaches. However, knowledge on what determines food fraud vulnerability is limited. Scope and approach In the current study a new food fraud vulnerability concept is explored. The concept is based on the criminological routine activity theory and key food fraud vulnerability factors are subsequently extracted and identified. Key findings and conclusions Opportunities, motivations and control measures are defined in this concept as the three main elements of food fraud vulnerability. They can be subdivided into technical opportunities, opportunities in time and place, economic drivers, culture and behavior, as well as technical and managerial control measures. They are further detailed in 31 fraud vulnerability factors. Food fraud vulnerability threats may originate from both the external and the internal environment of a business which means that several vulnerability factors need to be considered at multiple environmental levels, i.e. the level of the business itself, its suppliers, its customers, the wider chain and at the (inter)national level. The concept was further developed into a practical food fraud vulnerability self-assessment tool with 50 questions and answering grids. This will be a valuable first step towards fraud prevention and will assist in the global combat on food fraud.

Migration of banks along the Kapuas River, West Kalimantan
Vermeulen, B. ; Huisman, A.K. ; Hoitink, A.J.F. ; Pramulya, M. - \ 2016
In: River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016. - CRC Press/Balkema - ISBN 9781138029132 - p. 1249 - 1253.

In this study we analyse the migration rates along the Kapuas River, West Kalimantan. The migration rates are analysed by digitizing sets of Landsat images. Cloud detection and cloud shadow detection is used to mask the images, then they are combined to obtain water bodies. The difference between images from different years between 1973 and 2013 is used to obtain migration rates. A stream reconaissance was performed along the River to validate the results. The results of the stream reconaissance show good agreement with the Landsat based erosion rates.

Erosion and Errors : Testing the Use of Repeated LIDAR Analyses and Erosion Modelling for the Assessment and Prediction of Erosion of Archaeological Sites?
Huisman, H. ; Heeres, Glenn ; Os, Bertil van; Derickx, Willem ; Schoorl, J.M. - \ 2016
Conservation and Management of Archaeological sites 18 (2016)1-3. - ISSN 1350-5033 - p. 205 - 216.
Slope soil erosion is one of the main threats to archaeological sites. Several methods were applied to establish the erosion rates at archaeological sites. Digital elevation models (DEMs) from three different dates were used. We compared the elevations from these three models to estimate erosion. We also applied the landscape evolution model LAPSUS with the available DEMs as basis. Spatial processing errors and effects of tillage and harvesting practices explain most of the DEM elevation differences between the recordings. Increased DEM resolution does not result in more precise or reliable erosion. The present technological level of landscape evolution modelling makes it possible to indicate areas most vulnerable to soil displacement by surface runoff erosion and tillage. Future research, using sediment and surface dating techniques such as deposit of radionuclides, heavy metals and OSL dating will provide a more accurate estimation of erosion rates and the subsequent impact on archaeological sites.
Heading south or north: novel insights on European silver eel Anguilla anguilla migration in the North Sea : Novel insights on European silver eel Anguilla anguilla migration in the North Sea
Huisman, Jeroen ; Verhelst, Pieterjan ; Verhelst, Pieterjan ; Deneudt, K. ; Goethals, Peter ; Moens, Tom ; Nagelkerke, Leopold A.J. ; Nolting, Carsten ; Reubens, Jan ; Schollema, Peter Paul ; Winter, Hendrik V. ; Mouton, Ans - \ 2016
Marine Ecology Progress Series 554 (2016). - ISSN 0171-8630 - p. 257 - 262.
Conservation - European eel - Marine migration - Telemetry

The European eel Anguilla anguilla L. is a critically endangered fish species that migrates from coastal and freshwater habitats to the Sargasso Sea to spawn. However, the exact migration routes and destination of European eel are still unknown. We are the first to observe southward migrating silver eels in the North Sea. Eels were tagged with acoustic transmitters in 3 different river catchments in Western Europe and swam to the Dutch-Belgian coastal zone during their spawning migration. Therefore, at least part of the Western European population of eels migrates towards the English Channel, in contrast with the Nordic migration route hypothesis. This different migratory route may affect the energy reserve available for spawning and therefore the contribution of these eels to the population. As such, increasing our knowledge of marine eel migrations contributes to the goal of achieving sustainable eel stock management.

Modeling soil processes : Review, key challenges, and new perspectives
Vereecken, H. ; Schnepf, A. ; Hopmans, J.W. ; Javaux, M. ; Or, D. ; Roose, T. ; Vanderborght, J. ; Young, M.H. ; Amelung, W. ; Aitkenhead, M. ; Allison, S.D. ; Assouline, S. ; Baveye, P. ; Berli, M. ; Brüggemann, N. ; Finke, P. ; Flury, M. ; Gaiser, T. ; Govers, G. ; Ghezzehei, T. ; Hallett, P. ; Hendricks Franssen, H.J. ; Heppell, J. ; Horn, R. ; Huisman, J.A. ; Jacques, D. ; Jonard, F. ; Kollet, S. ; Lafolie, F. ; Lamorski, K. ; Leitner, D. ; Mcbratney, A. ; Minasny, B. ; Montzka, C. ; Nowak, W. ; Pachepsky, Y. ; Padarian, J. ; Romano, N. ; Roth, K. ; Rothfuss, Y. ; Rowe, E.C. ; Schwen, A. ; Šimůnek, J. ; Tiktak, A. ; Dam, Jos van; Zee, S.E.A.T.M. van der; Vogel, H.J. ; Vrugt, J.A. ; Wöhling, T. ; Wöhling, T. ; Young, I.M. - \ 2016
Vadose Zone Journal 15 (2016)5. - ISSN 1539-1663 - 57 p.

The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaining in the quality of predictions and several challenges that remain yet to be addressed. First, there is a need to improve exchange of knowledge and experience among the different disciplines in soil science and to reach out to other Earth science communities. Second, the community needs to develop a new generation of soil models based on a systemic approach comprising relevant physical, chemical, and biological processes to address critical knowledge gaps in our understanding of soil processes and their interactions. Overcoming these challenges will facilitate exchanges between soil modeling and climate, plant, and social science modeling communities. It will allow us to contribute to preserve and improve our assessment of ecosystem services and advance our understanding of climate-change feedback mechanisms, among others, thereby facilitating and strengthening communication among scientific disciplines and society. We review the role of modeling soil processes in quantifying key soil processes that shape ecosystem services, with a focus on provisioning and regulating services. We then identify key challenges in modeling soil processes, including the systematic incorporation of heterogeneity and uncertainty, the integration of data and models, and strategies for effective integration of knowledge on physical, chemical, and biological soil processes. We discuss how the soil modeling community could best interface with modern modeling activities in other disciplines, such as climate, ecology, and plant research, and how to weave novel observation and measurement techniques into soil models. We propose the establishment of an international soil modeling consortium to coherently advance soil modeling activities and foster communication with other Earth science disciplines. Such a consortium should promote soil modeling platforms and data repository for model development, calibration and intercomparison essential for addressing contemporary challenges.

A symbiosis-dedicated SYNTAXIN OF PLANTS 13II isoform controls the formation of a stable host-microbe interface in symbiosis
Huisman, Rik ; Hontelez, Jan ; Mysore, Kirankumar S. ; Wen, Jiangqi ; Bisseling, Ton ; Limpens, Erik - \ 2016
New Phytologist 211 (2016)4. - ISSN 0028-646X - p. 1338 - 1351.
Alternative splicing - Arbuscular mycorrhiza (AM) - Arbuscule - Host-microbe interface - N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) - Rhizobium - Symbiosis - Symbiosome

Arbuscular mycorrhizal (AM) fungi and rhizobium bacteria are accommodated in specialized membrane compartments that form a host-microbe interface. To better understand how these interfaces are made, we studied the regulation of exocytosis during interface formation. We used a phylogenetic approach to identify target soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (t-SNAREs) that are dedicated to symbiosis and used cell-specific expression analysis together with protein localization to identify t-SNAREs that are present on the host-microbe interface in Medicago truncatula. We investigated the role of these t-SNAREs during the formation of a host-microbe interface. We showed that multiple syntaxins are present on the peri-arbuscular membrane. From these, we identified SYNTAXIN OF PLANTS 13II (SYP13II) as a t-SNARE that is essential for the formation of a stable symbiotic interface in both AM and rhizobium symbiosis. In most dicot plants, the SYP13II transcript is alternatively spliced, resulting in two isoforms, SYP13IIα and SYP13IIβ. These splice-forms differentially mark functional and degrading arbuscule branches. Our results show that vesicle traffic to the symbiotic interface is specialized and required for its maintenance. Alternative splicing of SYP13II allows plants to replace a t-SNARE involved in traffic to the plasma membrane with a t-SNARE that is more stringent in its localization to functional arbuscules.

Elke Rotterdammer heeft recht op gezondere lucht
Krol, Maarten - \ 2015
Species fluctuations sustained by a cyclic succession at the edge of chaos
Benincà, Elisa ; Ballantine, Bill ; Ellner, Stephen P. ; Huisman, Jef - \ 2015
Proceedings of the National Academy of Sciences of the United States of America 112 (2015)20. - ISSN 0027-8424 - p. 6389 - 6394.
Chaos - Coexistence - Cyclic succession - Rock-paper-scissors dynamics - Rocky intertidal community

Although mathematical models and laboratory experiments have shown that species interactions can generate chaos, field evidence of chaos in natural ecosystems is rare. We report on a pristine rocky intertidal community located in one of the world's oldest marine reserves that has displayed a complex cyclic succession for more than 20 y. Bare rock was colonized by barnacles and crustose algae, they were overgrown by mussels, and the subsequent detachment of the mussels returned bare rock again. These processes generated irregular species fluctuations, such that the species coexisted over many generations without ever approaching a stable equilibrium state. Analysis of the species fluctuations revealed a dominant periodicity of about 2 y, a global Lyapunov exponent statistically indistinguishable from zero, and local Lyapunov exponents that alternated systematically between negative and positive values. This pattern indicates that the community moved back and forth between stabilizing and chaotic dynamics during the cyclic succession. The results are supported by a patch-occupancy model predicting similar patterns when the species interactions were exposed to seasonal variation. Our findings show that natural ecosystems can sustain continued changes in species abundances and that seasonal forcing may push these nonequilibrium dynamics to the edge of chaos.

Growth and development: Close relations of secretion and K+
Huisman, R. ; Bisseling, T. - \ 2015
Nature Plants 1 (2015). - ISSN 2055-026X - 2 p.
Interaction of key regulators of exocytosis with potassium channels enhances both secretion and K+ uptake, making these processes intertwined and jointly coordinated.
Effect of Presymptomatic Body Mass Index and Consumption of Fat and Alcohol on Amyotrophic Lateral Sclerosis
Huisman, M.H.B. ; Seelen, M. ; Doormaal, P.T.C. van; Vries, J.H.M. de - \ 2015
JAMA Neurology 72 (2015)10. - ISSN 2168-6149 - p. 1155 - 1162.
IMPORTANCE Because dietary intakemay influence pathophysiologic mechanisms in sporadic amyotrophic lateral sclerosis (ALS), the association between premorbid dietary intake and the risk of sporadic ALS will provide insight into which mechanisms are possibly involved in ALS pathophogenesis. OBJECTIVE To systematically determine the association between premorbid dietary intake and the risk of sporadic ALS. DESIGN, SETTING, AND PARTICIPANTS A population-based case-control studywas conducted in a general community setting in the Netherlands from January 1, 2006, to September 30, 2011. Analysis was conducted April 1, 2013, to November 15, 2014. All patients with a new diagnosis of possible, probable (laboratory supported), or definite ALS according to the revised El Escorial criteria were included and multiple sources were used to ensure complete case ascertainment. Of 986 eligible patients, 674 gave informed consent and returned a complete questionnaire; 2093 controls randomly selected from the general practitioners’ registers and frequency matched to the patients for sex and age were included. MAIN OUTCOMES AND MEASURES We studied the premorbid intake of nutrients in association with the risk of ALS by using a 199-item food frequency questionnaire adjusted for confounding factors and corrected for multiple comparisons while minimizing recall bias. RESULTS Presymptomatic total daily energy intake in patients, reported as mean (SD), was significantly higher compared with controls (2258 [730] vs 2119 [619] kcal/day; P <.01), and presymptomatic body mass index (calculated as weight in kilograms divided by height in meters squared) was significantly lower in patients (25.7 [4.0] vs 26.0 [3.7]; P = .02). With values reported as odds ratio (95%CI), higher premorbid intake of total fat (1.14; 1.07-1.23; P <.001), saturated fat (1.43; 1.25-1.64; P <.001), trans-fatty acids (1.03; 1.01-1.05; P <.001), and cholesterol (1.08; 1.05-1.12; P <.001) was associated with an increased risk of ALS; higher intake of alcohol (0.91; 0.84-0.99; P = .03) was associated with a decreased risk of ALS. These associations were independent of total energy intake, age, sex, body mass index, educational level, smoking, and lifetime physical activity. No significant associations between dietary intake and survival were found. CONCLUSIONS AND RELEVANCE The combination of independent positive associations of a low premorbid body mass index and a high fat intake together with prior evidence from ALS mouse models transgenic for SOD1 and earlier reports on premorbid body mass index support a role for increased resting energy expenditure before clinical onset of ALS.
Haustorium formation in Medicago truncatula roots infected by Phytophthora palmivora does not involve the common endosymbiotic program shared by AM fungi and rhizobia
Huisman, R.H.J. ; Bouwmeester, K. ; Brattinga, M.A. ; Govers, F. ; Bisseling, A.H.J. ; Limpens, E.H.M. - \ 2015
Molecular Plant-Microbe Interactions 28 (2015)12. - ISSN 0894-0282 - p. 1271 - 1280.
In biotrophic plant-microbe interactions, microbes infect living plant cells where they are hosted in a novel membrane compartment; the host-microbe interface. To create a host-microbe interface, arbuscular mycorrhizal (AM) fungi and rhizobia make use of the same endosymbiotic program. It is a long-standing hypothesis that pathogens make use of plant proteins that are dedicated to mutualistic symbiosis to infect plants and form haustoria. In this report, we developed a Phytophthora palmivora pathosystem to study haustorium formation in Medicago truncatula (Medicago) roots. We show that P. palmivora does not require host genes that are essential for symbiotic infection and host-microbe interface formation to infect Medicago roots and form haustoria. Based on these findings, we conclude that P. palmivora does not hijack the ancient intracellular accommodation program used by symbiotic microbes to form a biotrophic host-microbe interface.
A comparison of rating and dating techniques to estimate the threat of soil erosion to archaeological monuments under agricultural fields
Soest, M. van; Huisman, H. ; Schoorl, J.M. ; Reimann, T. ; Temme, A.J.A.M. ; Wallinga, J. ; Kort, J.W. de; Heiden, M. van der; Os, B. van; Egmond, F. van; Ketteren, M. - \ 2015
For the protection of Dutch archaeological sites against degradation, the TOPsites project is investigating the rate, extent and mitigation of the most important processes involved. One of these processes is soil translocation or soil redistribution. For many Dutch archaeological sites the actual extent and rate of soil erosion is not yet known. In this study different techniques for dating and estimating rates have been compared on three archaeological sites on tilled fields with gentle slopes: (multi-temporal LiDar, profiles and spatial distribution of 137Cs, anthropogenic Pb, and 239+240Pu, and moreover OSL. In addition, the added value of the combination of several of these techniques together will be evaluated. Preliminary results show evidence for colluvium formation (deposition) on two of the sites. Lead contents in a buried soil on one of these sites suggest a subrecent to recent date. 137Cs profiles and spatial mapping, however, do not show clear evidence for recent erosion or re-deposition patterns. These first results suggest that in these agricultural settings with typical Dutch gentle slopes, erosion may only occur in rare, catastrophic, events with local high erosion and re-deposition rates instead of a more or less continuous process with lower rates. Consequently, the impact of ploughing might be limited to mixing of the plough layer, while the effect of damaging soil translocation, for these selected archaeological sites, seems less important. Forthcoming analysis and results of Pu and OSL will provide enough data for further discussion and possible falsification of these preliminary conclusions.
UVb radiation impacts vitamin D3 status but not growth in the nocturnal leopard gecko
Diehl, E. ; Oonincx, D.G.A.B. ; Kik, M.J.L. ; Baines, F.M. ; Hendriks, W.H. ; Bosch, G. - \ 2015
In: Proceedings of the 8th European Zoo Nutrition Conference. - - p. 37 - 37.
Does foraging ecology of terrestrial carnivores impact digestive physiology and metabolism?
Bosch, G. ; Hendriks, W.H. - \ 2015
In: Proceedings of the 8th European Zoo Nutrition Conference. - - p. 23 - 23.
Nutritional value of browse species most fed to zoo animals
Huisman, T.J. ; Hokwerda, J. - \ 2015
dierenwelzijn - dierentuindieren - diervoeding - diergezondheid - planten - voedingswaarde - begraasbare planten of plantendelen - animal welfare - zoo animals - animal nutrition - animal health - plants - nutritive value - browse
Poster met voedingswaarde van begraasbare planten voor dierentuindieren.
Pattern formation at multiple spatial scales drives the resilience of mussel bed ecosystems
Liu, Q. ; Herman, P.M.J. ; Mooij, W.M. ; Huisman, J. ; Scheffer, M. ; Olff, H. ; Koppel, J. van de - \ 2014
Nature Communications 5 (2014). - ISSN 2041-1723
self-organization - trade-offs - dynamics - systems - model
Self-organized complexity at multiple spatial scales is a distinctive characteristic of biological systems. Yet, little is known about how different self-organizing processes operating at different spatial scales interact to determine ecosystem functioning. Here we show that the interplay between self-organizing processes at individual and ecosystem level is a key determinant of the functioning and resilience of mussel beds. In mussel beds, self-organization generates spatial patterns at two characteristic spatial scales: small-scale net-shaped patterns due to behavioural aggregation of individuals, and large-scale banded patterns due to the interplay of between-mussel facilitation and resource depletion. Model analysis reveals that the interaction between these behavioural and ecosystem-level mechanisms increases mussel bed resilience, enables persistence under deteriorating conditions and makes them less prone to catastrophic collapse. Our analysis highlights that interactions between different forms of self-organization at multiple spatial scales may enhance the intrinsic ability of ecosystems to withstand both natural and human-induced disturbances.
Kwetsbaarheid voor voedselfraude in de vleessector
Huisman, W. ; Ruth, S.M. van - \ 2014
Justitiële verkenningen 2014 (2014)2. - ISSN 0167-5850 - p. 28 - 53.
Food fraud is as old as mankind but has advanced in the last decades. Fraud regarding the gross composition of food has progressed in the direction of the addition of unconventional adulterants. Furthermore, consumers are more and more interested in how and where their foods are produced and pay price premiums for organic foods, fair trade, animal welfare considering, and sustainable food products. Since these products are very similar to their conventional counterparts in terms of composition, they provide an additional challenge. The knowledge regarding occurrence, type of meat fraud, causes and damage caused to the sector is limited. There is a need for extensive identification of the vulnerabilities and criminogenic factors. These insights offer leads for detection and prevention. The article deals with a first step into the inventory of these vulnerabilities and factors affecting meat fraud, by assessing fraud risks related to products, companies and the meat supply chain.
Plantes toxiques pour les animauxd de zoo
Huisman, T.R. ; Hokwerda, J. - \ 2014
VHL Animal Management
dierentuindieren - dierenwelzijn - diervoeding - giftige planten - vergiftiging - diergezondheid - zoo animals - animal welfare - animal nutrition - poisonous plants - poisoning - animal health
Poster met een overzicht van planten die giftig zijn voor (dierentuin)dieren.
Le top 12 des groupes d’aliments en zoo-nutrition : un apercu des propriétés principales des groupes d’aliments fréquemment utilisés en zoo-nutrition
Huisman, T.R. ; Hokwerda, J. - \ 2014
VHL Animal Management
dierentuindieren - diervoeding - dierenwelzijn - diergezondheid - zoo animals - animal nutrition - animal welfare - animal health
Een overzicht van de eigenschappen van veel gebruikte voedselgroepen in dierentuinvoeding.
Système d'évaluation des fécès: le score fécal
Huisman, T.R. ; Hokwerda, J. - \ 2014
VHL Animal Management, Animal Welfare Web (DWW)
dierentuindieren - diervoeding - dierenwelzijn - mest - feces - diergezondheid - zoo animals - animal nutrition - animal welfare - manures - faeces - animal health
Kleur, vorm en stevigheid van de uitwerpselen vertellen iets over het dier, het soort voer en de kwaliteit hiervan. Door een goede mest-beoordeling kunnen problemen snel herkend worden. Hoe ziet goede mest van een diersoort er uit? En hoe word de mest beoordeeld?
Le valeurs nutritionnelles des invertebrés : un aperçu du contenu nutritionnel, sur une base matière sèche, des espèces d’invertébrés utilisés comme nourriture
Huisman, T.R. ; Hokwerda, J. - \ 2014
VHL Animal Management, Animal Welfare Web (DWW)
dierentuindieren - diervoeding - dierenwelzijn - diergezondheid - voedingswaarde - ongewervelde dieren - zoo animals - animal nutrition - animal welfare - animal health - nutritive value - invertebrates
Poster met een overzicht van de voedingswaarde van invertebraten.
Sucre et autres nutriments dans les produits alimentaires (fruits et légumes)
Huisman, T.R. ; Hokwerda, J. - \ 2014
VHL Animal Management, Animal Welfare Web (DWW)
dierentuindieren - dierenwelzijn - diergezondheid - diervoeding - zoo animals - animal welfare - animal health - animal nutrition
Overzicht van suikers en andere nutriënten in fruit en groenten.
Uit eten tegen voedselverspilling (interview met o.a. M.H. Zwietering)
Zwietering, Marcel - \ 2014
Search performance and the spatial resource distribution
Huisman, T.J. - \ 2014
Wageningen University. Promotor(en): Herbert Prins, co-promotor(en): Fred de Boer; Frank van Langevelde. - Wageningen : Wageningen University - ISBN 9789461739391 - 100
fauna - dierecologie - migratie - foerageren - telemetrie - diergedrag - fauna - animal ecology - migration - foraging - telemetry - animal behaviour
In de afgelopen decennia heeft het onderzoek naar bewegingspatronen in de ecologie een vlucht genomen. Door de ontwikkeling van alsmaar kleinere gps-transmitters en chips worden tegenwoordig de bewegingsgegevens van een enorm aantal dieren en soorten opgeslagen. Naast deze enorme toename in beschikbare gegevens is er een ontwikkeling geweest in de theoretische modellen die besproken en gebruikt worden in de ecologische literatuur. Al deze ontwikkelingen tezamen vormen de nieuwe subdiscipline van de zogenaamde bewegingsecologie en het onderzoek in dit proefschrift valt precies onder deze noemer.
Randvoorwaarden voor inzet en ondersteuning van de buurtsportcoach in landelijk en gemeentelijk beleid: een beleidsanalyse
Leenaars, K.E.F. ; Huisman, A. ; Wagemakers, A. ; Smit, E. ; Molleman, G. ; Koelen, M.A. - \ 2014
Termination of a toxic Alexandrium bloom with hydrogen peroxide
Burson, A. ; Matthijs, H.C.P. ; Bruijne, W. de; Talens, R. ; Hoogenboom, L.A.P. ; Gerssen, A. ; Visser, P.M. ; Stomp, M. ; Steur, K. ; Scheppingen, Y. van; Huisman, J. - \ 2014
Harmful Algae 31 (2014). - ISSN 1568-9883 - p. 125 - 135.
harmful algal blooms - northern baltic sea - ostenfeldii dinophyceae - water temperature - oxidative stress - shellfish toxins - eutrophication - cyanobacteria - phytoplankton - coastal
The dinoflagellate Alexandrium ostenfeldii is a well-known harmful algal species that can potentially cause paralytic shellfish poisoning (PSP). Usually A. ostenfeldii occurs in low background concentrations only, but in August of 2012 an exceptionally dense bloom of more than 1 million cells L-1 occurred in the brackish Ouwerkerkse Kreek in The Netherlands. The A. ostenfeldii bloom produced both saxitoxins and spirolides, and is held responsible for the death of a dog with a high saxitoxin stomach content. The Ouwerkerkse Kreek routinely discharges its water into the adjacent Oosterschelde estuary, and an immediate reduction of the bloom was required to avoid contamination of extensive shellfish grounds. Previously, treatment of infected waters with hydrogen peroxide (H2O2) successfully suppressed cyanobacterial blooms in lakes. Therefore, we adapted this treatment to eradicate the Alexandrium bloom using a three-step approach. First, we investigated the required H2O2 dosage in laboratory experiments with A. ostenfeldii. Second, we tested the method in a small, isolated canal adjacent to the Ouwerkerkse Kreek. Finally, we brought 50 mg L-1 of H2O2 into the entire creek system with a special device, called a water harrow, for optimal dispersal of the added H2O2. Concentrations of both vegetative cells and pellicle cysts declined by 99.8% within 48 h, and PSP toxin concentrations in the water were reduced below local regulatory levels of 15 µg L-1. Zooplankton were strongly affected by the H2O2 treatment, but impacts on macroinvertebrates and fish were minimal. A key advantage of this method is that the added H2O2 decays to water and oxygen within a few days, which enables rapid recovery of the system after the treatment. This is the first successful field application of H2O2 to suppress a marine harmful algal bloom, although Alexandrium spp. reoccurred at lower concentrations in the following year. The results show that H2O2 treatment provides an effective emergency management option to mitigate toxic Alexandrium blooms, especially when immediate action is required.
Sensing food fraud from analytical chemistry and criminological perspectives
Ruth, S.M. van; Huisman, W. ; Luning, P.A. - \ 2013
voedselveiligheid - authenticiteit - herkomst - analytische scheikunde - forensische wetenschap - food safety - authenticity - provenance - analytical chemistry - forensic science
The joint investigation of analytical opportunities for authentication and understanding the influece of peoples’ motives and agri-food chain context characteristics on fraud, will provide input for a new approach towards fraud risks assessment for food industries and regulators.
Developing an interactive Tool for evaluating sand nourishment strategies along the Holland coast in perspective of benthos, fish nursery and dune quality
Baptist, M.J. ; Wolfshaar, K.E. van de; Huisman, B.J.A. ; Groot, A.V. de; Boer, W. de; Ye, Q. - \ 2012
Den Burg : IMARES (Rapport / IMARES Wageningen UR C083/12) - 38
kustbeheer - zandsuppletie - versterking - duinen - nadelige gevolgen - geologische sedimentatie - vissen - aquatische ecologie - noordzee - coastal management - sand suppletion - reinforcement - dunes - adverse effects - geological sedimentation - fishes - aquatic ecology - north sea
Sand nourishments can affect the coastal ecosystem in various ways. Direct effects are the burial of benthic species under a layer of sand. In the direct vicinity, suffocation of benthos can occur due to the settling of a plume of suspended sediment particles. A plume of fine particles may also increase turbidity and thereby affect primary production and the foraging success of filter-feeding benthos and fish. Indirect effects are habitat change, such as altered morphology and sedimentology. It was tested by investigating whether it is possible to optimise nourishment configuration, location and timing, to: - minimise the impact on benthos, - increase nursery area and/or quality, and - enhance dune quality.
Endocytic accommodation of microbes in plants
Huisman, R. ; Ovchinnikova, E. ; Bisseling, T. ; Limpens, E.H.M. - \ 2012
In: Endocytosis in plants / Šamaj, J., Berlin Heidelberg : Springer Verlag - ISBN 9783642324635 - p. 271 - 295.
Plants host many different microbes within their cells. These endosymbiotic relationships are characterized by the formation of new specialized membrane compartments inside the plant cells in which the microbes live and where nutrients and signals are efficiently exchanged. Such symbiotic interfaces include arbuscules produced by arbuscular mycorrhiza (AM), organelle-like symbiosomes formed during the rhizobium-legume symbiosis, and haustoria produced by biotrophic fungi and oomycetes. The formation and maintenance of such new membrane compartments require a major reorganization of the host endomembrane system. In the last decade, much progress has been made in understanding how arbuscules, symbiosomes, and haustoria are formed. In this chapter, we will summarize the recent developments in each field, with a major focus on the AM and rhizobial endosymbiosis. It has become clear that rhizobia have co-opted a signalling pathway as well as a cellular mechanism to make the interface membrane compartment from the ancient and most successful AM symbiosis. Both AM symbiosis and rhizobium symbiosis depend on the secretion of lipo-chito-oligosaccharides that trigger a symbiotic signalling cascade, which is required for both arbuscule and symbiosome formation. In both interactions a shared specific exocytosis pathway is recruited to facilitate the formation of the symbiotic interface resulting in a membrane compartment with distinct protein composition. Given the structural similarity of haustoria to arbuscules, similar mechanisms are envisioned to be involved in the formation of a haustorium.
Nutritional value of invertebrates : an overview of the nutritional content of invertebrate species for use as feed
Stichter, M. ; Huisman, T.R. - \ 2012
dierentuindieren - diervoeding - dierenwelzijn - ongewervelde dieren - acheta domesticus - sprinkhanen - diergezondheid - zoo animals - animal nutrition - animal welfare - invertebrates - acheta domesticus - locusts - animal health
Poster giving an overview of the nutritional content of invertebrate species for use as feed.
Soil properties in artificial dwelling mounds under grassland and arable land
Meuwissen, M.N.J. ; Sonneveld, M.P.W. ; Huisman, D.J. ; Schoorl, J.M. - \ 2012
In: Final programme and abstract book /2nd International landscape archeology Berlin, 6-9 June 2012. - - p. 86 - 86.
Stopping tillage and converting arable land into grassland is often seen to be the best management practice to preserve shallow archaeological remains: It stops physical disturbance and minimizes erosion. However, pedoturbation by soil fauna, which strongly depends on the type of land use, is often neglected. Therefore land use is a key element in order to preserve archaeological remains. Plans to protect artificial dwelling mounds (“terps”) in the province of Friesland in the North of the Netherlands by converting arable land to grassland triggered a research project on the influence of land use on pedoturbation. Fieldwork was done on locations with continuous arable land and locations with continuous grassland. The research focussed on i) to which depth the soil horizons are affected by mechanical agricultural practices and soil fauna and ii) the percentage of the different soil horizons that is disturbed. As was expected soils under arable land will show a strongly homogenised plough layer, whereas the soil layers below are less disturbed. Soils under grassland are in general less homogenised but the depth to which pedoturbation occurs is deeper. The results of the fieldwork are also used in the LAPSUS model to simulate the effect of land use on the elevation profile of the artificial dwelling mounds. Especially soil translocation by tillage negatively affects the archaeological preservation. Consequently, the quantification of both tillage erosion rates and rates of pedoturbation form an important input for the land use decision making.
Effects of phenolic compounds on adventitious root formation and oxidative decarboxylation of applied indoleacetic acid in Malus 'Jork 9'
Klerk, G.J.M. de; Guan, H. ; Huisman, P. ; Marinova, S. - \ 2011
Plant Growth Regulation 63 (2011)2. - ISSN 0167-6903 - p. 175 - 185.
Stem slices (1-mm thick) cut from apple microshoots were cultured on a modified Murashige-Skoog medium with indole-3-acetic acid (IAA) or α-naphthaleneacetic acid (NAA), and increasing concentrations of various phenolic compounds. Both auxins were added at a concentration suboptimal for rooting. Indole-3-acetic acid is metabolized through oxidation and conjugation but NAA through conjugation only; which might have affected the results. With IAA, all tested orthodiphenols, paradiphenols and triphenols promoted adventitious root formation from the stem slices. Ferulic acid (FA, a methylated orthodiphenol) had the largest effect and increased the number of adventitious roots from 0.9 to 5.8. With NAA there was little or no promotion after addition of phenolics. Phloroglucinol (a triphenol) and FA were examined in detail. Their effects on the dose–response curve of IAA and the timing of their action indicated that both acted as antioxidants protecting IAA from decarboxylation and the tissue from oxidative stress. Experiments with carboxyl-labelled IAA showed that IAA was massively decarboxylated by the slices and that decarboxylation was strongly reduced by phenolics. Decarboxylation was to a great extent attributable to the wound response and did not occur to such an extent in non-wounded plant tissues. In shoots, FA promoted little rooting. Slices were cultured on top of the medium and shoots were stuck into the medium. Possibly, the anaerobic conditions in the medium near the basal part of the stem of shoots reduced the wound response and consequently decarboxylation of IAA. The monophenolic compound salicylic acid (SA) promoted IAA decarboxylation. Accordingly, SA reduced rooting when added during the initial days of the rooting process (the period during which auxin enhances rooting), and promoted outgrowth of root primordia later on (the period during which auxin inhibits rooting).
Le score de condition physique
Huisman, T.R. ; Hokwerda, J. - \ 2011
VHL Animal Management
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - lichaamsgewicht - lichaamsafmetingen - zoo animals - animal welfare - animal nutrition - animal health - body weight - body measurements
Poster over de Body Condition Score (BCS). De BCS gaat uit van uiterlijke kenmerken van dieren, waaraan je kunt aflezen of ze te zwaar of te licht zijn.
Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - lichaamsgewicht - lichaamsafmetingen - zoo animals - animal welfare - animal nutrition - animal health - body weight - body measurements
Poster over de Body Condition Score (BCS). De BCS gaat uit van uiterlijke kenmerken van dieren, waaraan je kunt aflezen of ze te zwaar of te licht zijn.
Answers quiz Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - bouw (dier) - lichaamsgewicht - lichaamsafmetingen - zoo animals - animal welfare - animal nutrition - animal health - conformation - body weight - body measurements
Poster met quiz Body Condition Score. Er worden verschillende Body Condition Scores beschreven. Het is de bedoeling de juiste score bij het juiste dier te plaatsen.
Antwoorden quiz Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - lichaamsgewicht - lichaamsafmetingen - zoo animals - animal welfare - animal nutrition - animal health - body weight - body measurements
Poster met antwoorden op de quiz Body Condition Score: de juiste scores zijn nu bij de verschillende dieren geplaatst.
Quiz mestscore
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - dierlijke meststoffen - diergezondheid - zoo animals - animal welfare - animal nutrition - animal manures - animal health
Poster met quiz mestscore: Welke diersoort en welke mestscore hoort bij welke mest?
Antwoorden op de quiz mestscore
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - dierlijke meststoffen - zoo animals - animal welfare - animal nutrition - animal health - animal manures
Poster met antwoorden op de quiz mestscore: de diersoort en mestscore zijn nu bij de verschillende soorten mest geplaatst.
Planten giftig voor (dierentuin) dieren
Hillen, R. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - giftige planten - vergiftiging - diergezondheid - zoo animals - animal welfare - animal nutrition - poisonous plants - poisoning - animal health
Poster met een overzicht van planten die giftig zijn voor (dierentuin)dieren.
Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - zoo animals - animal welfare - animal nutrition - animal health
Poster on the Body Condition Score (BCS) as a tool to visually assess whether the animal is overweight or too thin.
Quiz Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - zoo animals - animal welfare - animal nutrition - animal health
Poster with a quiz on Body Condition Scores. Different Body Condition Scores are described. The goal is to give each animal the correct score.
Answers quiz Body Condition Score
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - diergezondheid - zoo animals - animal welfare - animal nutrition - animal health
Poster with answers to the quiz Body Condition Score (BCS). The correct scores are given to each animal.
Fecal scoring system
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - feces - excreten - diergezondheid - zoo animals - animal welfare - animal nutrition - faeces - excreta - animal health
Poster on the assessment of feces of different animals. Colour, shape and solidity of excrement say something about an animal, the kind of food it gets and the quality of the food.
Quiz fecal scoring system
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - feces - excreten - diergezondheid - zoo animals - animal welfare - animal nutrition - faeces - excreta - animal health
Poster with a quiz on fecal scoring. Which animal species and which fecal score belong to the feces shown?
Answers quiz fecal scoring system
Vijgeboom, W. ; Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - feces - excreten - diergezondheid - zoo animals - animal welfare - animal nutrition - faeces - excreta - animal health
Poster with answers to the quiz on fecal scoring. The correct animal species and fecal score are given for the feces shown.
Plants poisonous to zoo animals
Huisman, T.R. - \ 2011
dierentuindieren - dierenwelzijn - diervoeding - giftige planten - diergezondheid - zoo animals - animal welfare - animal nutrition - poisonous plants - animal health
Poster giving an overview of plants that are poisonous to zoo animals.
"Roofdiervoeding" meer spiegelen aan de natuur?
Huisman, T.R. - \ 2011
zoo animals - animal nutrition - animal welfare - carnivores - animal behaviour - animal health - teaching materials
Dierentuinvoeding: knelpunten en aanpak
Huisman, T.R. - \ 2011
zoo animals - animal welfare - animal nutrition - food composition - animal behaviour - animal health - teaching materials
BCS als hulpmiddel : docentendag dierentuinvoedingscursus 8 februari 2011
Huisman, T.R. - \ 2011
zoo animals - animal nutrition - animal welfare - animal health - body condition - monitoring - teaching materials
Varying disease-mediated selection at different life-history stages of Atlantic salmon in fresh water
Eyto, E. de; McGinnity, P. ; Huisman, J. ; Coughlan, J. ; Consuegra, S. ; Megens, H.J.W.C. - \ 2011
Evolutionary Applications 4 (2011)6. - ISSN 1752-4563 - p. 749 - 762.
major histocompatibility complex - class-i locus - salar l. - genetic-variation - pathogen resistance - balancing selection - natural-selection - wild populations - local adaptation - climate-change
Laboratory studies on associations between disease resistance and susceptibility and major histocompatibility (MH) genes in Atlantic salmon Salmo salar have shown the importance of immunogenetics in understanding the capacity of populations to fight specific diseases. However, the occurrence and virulence of pathogens may vary spatially and temporally in the wild, making it more complicated to predict the overall effect that MH genes exert on fitness of natural populations and over several life-history stages. Here we show that MH variability is a significant determinant of salmon survival in fresh water, by comparing observed and expected genotype frequencies at MH and control microsatellite loci at parr and migrant stages in the wild. We found that additive allelic effects at immunogenetic loci were more likely to determine survival than dominance deviation, and that selection on certain MH alleles varied with life stage, possibly owing to varying pathogen prevalence and/or virulence over time. Our results highlight the importance of preserving genetic diversity (particularly at MH loci) in wild populations, so that they have the best chance of adapting to new and increased disease challenges as a result of projected climate warming and increasing aquaculture
Biotechnology based processes for arsenic removal
Huisman, J. ; Olde Weghuis, M. ; Gonzalez-Contreras, P.A. - \ 2011
The regulations for arsenic control have become strict. Therefore, better technologies to remove arsenic from bleeds and effluents are desired. In addition, no single solution is suitable for all cases. The properties of the process streams and the storage facilities are major factors determining the selection of a certain technology. In this paper, two technologies are described. What these technologies have in common is that they are based on high-rate engineered bioreactors that allow optimal control, efficient resource use, and predictable and reliable process performance. One technology (Arsenoteq) converts arsenic to corodite, which is most suitable for storage under oxidising conditions. The other technology (Thioteq) operates under reducing conditions and produces arsenic sulphide (As2S3, orpiment) with 61 mass% arsenic. The first technology is suitable for medium to high (> 1000 mg/L) concentrations of arsenic in acidic process streams, whereas the latter is ideal for effluent treatment up to <5000 mg/L of arsenic. The residual arsenic concentration that can be obtained with the latter method is <0.1 mg/L.
Bioscorodite crystallization for arsenic removal
Gonzalez-Contreras, P.A. ; Huisman, J. ; Weijma, J. ; Buisman, C.J.N. - \ 2011
In: Proceedings of 6th European Metallurgical Conference, June 26-29, 2011, Düsseldorf, Germany. - - p. 1751 - 1762.
In the bio-scorodite process, arsenic is precipitated as crystalline iron arsenate, i.e. scorodite (FeAsO4·2H2O). This is a more economic and more environmentally friendly method for arsenic immobilization than the chemical production of iron- or calcium arsenate, as fewer chemicals are needed. Moreover, scorodite is an attractive medium for arsenic control and immobilization because it is stable, compact and has a very low solubility. Therefore it is regarded as the most ideal form for long-term arsenic storage. We have demonstrated that bio-crystallization of arsenic into scorodite crystals is possible with the aid of microorganisms. The operational conditions of the bio-scorodite process allow for a fast growth of the microorganisms and facilitate the crystallization of scorodite, avoiding the precipitation of other iron oxides or amorphous iron arsenates. The bio-scorodite process brings several advantages compared to chemical crystallization such as the lower required temperature (70°C), the control of supersaturation by biological oxidation and no need for crystal parents or seeds to begin the crystallization. Arsenic concentrations are removed to ppm level with starting concentrations ranging from 1000 to 2000 mg L-1. The produced bioscorodite crystals are very similar to the scorodite mineral found in nature. By control of the iron feed and the pH, the production of other iron precipitates is avoided. The latter facilitates easy separation of the solid product. Based on their highly crystalline nature, the biogenic scorodite crystals seem very suitable for safe disposal. At present the research has started with the continuous production of scorodite in bioreactors. The follow-up challenges are focused on the selection of a suitable reactor configuration.
Resonance of plankton communities with temperature fluctuations
Beninca, E. ; Dakos, V. ; Nes, E.H. van; Huisman, J. ; Scheffer, M. - \ 2011
American Naturalist 178 (2011)4. - ISSN 0003-0147 - p. E85 - E95.
colored environmental noise - predator-prey system - food-web - population-dynamics - sustained oscillations - extinction risk - chaos - time - phytoplankton - variability
The interplay between intrinsic population dynamics and environmental variation is still poorly understood. It is known, however, that even mild environmental noise may induce large fluctuations in population abundances. This is due to a resonance effect that occurs in communities on the edge of stability. Here, we use a simple predator-prey model to explore the sensitivity of plankton communities to stochastic environmental fluctuations. Our results show that the magnitude of resonance depends on the timescale of intrinsic population dynamics relative to the characteristic timescale of the environmental fluctuations. Predator-prey communities with an intrinsic tendency to oscillate at a period T are particularly responsive to red noise characterized by a timescale of [Formula: see text]. We compare these theoretical predictions with the timescales of temperature fluctuations measured in lakes and oceans. This reveals that plankton communities will be highly sensitive to natural temperature fluctuations. More specifically, we demonstrate that the relatively fast temperature fluctuations in shallow lakes fall largely within the range to which rotifers and cladocerans are most sensitive, while marine copepods and krill will tend to resonate more strongly with the slower temperature variability of the open ocean
Modeling of desorption of Alfalfa (Medicago sativa) stems and leaves.
ArabHosseini, A. ; Huisman, W. ; Müller, J. - \ 2011
Industrial Crops and Products 34 (2011)3. - ISSN 0926-6690 - p. 1550 - 1555.
moisture sorption isotherms - temperature - equations - dryer
The equilibrium moisture content of agricultural products is necessary to optimize drying process and helps to keep the quality of the product during the period of storage. The main aim of this research was to find the best model which could define well, the exchange of moisture between alfalfa (Medicago sativa) and the surrounding air. The desorption isotherms of alfalfa (stem and leaf) were determined separately by using the saturated salt solutions method at three temperatures (25, 50 and 70 °C) within a range of 5–90% relative humidity. Experimental curves of desorption isotherms were fitted to modified equations of Henderson, Halsey, Oswin and Chung-Pfost as well as the GAB model and then evaluated visually by using residual plots and also by some statistical error parameters. The modified Halsey model was found to be the most suitable for describing the relationship between equilibrium moisture content, relative humidity and temperature.
Meerjarige tuinbouwsamenwerking met Indonesië beëindigd: HORTIN, terugblik op een succesvolle samenwerking
Everaarts, A.P. ; Huisman, W. - \ 2011
Berichten buitenland 37 (2011)1/2. - ISSN 0920-0975 - p. 6 - 7.
tuinbouw - samenwerking - ontwikkelingsprogramma's - indonesië - horticulture - cooperation - development programmes - indonesia
Eind november 2010 werd in Jakarta de tweede fase van het programma Horticultural Research co-operation between Indonesia and The Netherlands (HORTIN) afgesloten. De eerste fase liep van 2003 tot en met 2006. De samenwerking in de eerste fase concentreerde zich op onderzoek. Tijdens de tweede fase (2007-2010) lag de nadruk op co-innovatie en ontwikkeling in de hele keten, van productie tot afzet van tuinbouwproducten, in nauwe samenwerking met bedrijven uit het mkb.
Effect of Drying on the Color of Tarragon (Artemisia dracunculus L.) Leaves
ArabHosseini, A. ; Padhye, S. ; Huisman, W. ; Boxtel, A.J.B. van; Müller, J. - \ 2011
Food Bioprocess Technology 4 (2011)7. - ISSN 1935-5130 - p. 1281 - 1287.
thermal kinetics - puree - degradation - quality
The effect of drying conditions on the color of tarragon (Artemisia dracunculus L.) leaves was studied. Tarragon leaves were dried at temperatures of 40 to 90 °C with a constant airflow of 0.6 m/s. The samples were collected at 7%, 10%, 20%, and 30% moisture content wet basis for evaluation of the color change. The color parameters of fresh and dried leaves were measured by a colorimeter. The individual parameters of L*a*b* and L*C*h° color systems were evaluated and h° proved to be the best parameter to monitor color change. The smallest change of the color parameters was observed at 40 °C, in which temperature was low, and also at 90 °C, when drying time was short. The biggest change occurred at the temperatures of 50 to 70 °C. Most of the color change happened before the material reaches 35% moisture content. The combination of drying time and temperature defines the change of color.
Modeling of the equilibrium moisture content (EMC) of Miscanthus (Miscanthus x giganteus)
ArabHosseini, A. ; Huisman, W. ; Muller, J. - \ 2010
Biomass and Bioenergy 34 (2010)4. - ISSN 0961-9534 - p. 411 - 416.
sorption isotherms - equations - crop
The desorption isotherms of miscanthus, Miscanthus x giganteus (stems and leaves) were determined separately by using the saturated salt solutions method at three temperatures (25, 50 and 70 degrees C) within a range from 5 to 90% relative humidity. Experimental curves of desorption isotherms were fitted to Modified Henderson, Modified Halsey, Modified Oswin and Modified Chung-Pfost models and evaluated by Residual Sum of Squares (RSS), Standard Error Estimation (SEE) and Mean Relative Deviation (MAD) methods. The Modified Oswin model was found to be the most suitable for describing the correlation between equilibrium moisture content, relative humidity and temperature.
Diverging affinity of tospovirus RNA silencing suppressor proteins, NSs, for various RNA duplex molecules
Schnettler, E. ; Hemmes, J.C. ; Huisman, R. ; Goldbach, R.W. ; Prins, M.W. ; Kormelink, R.J.M. - \ 2010
Journal of Virology 84 (2010)21. - ISSN 0022-538X - p. 11542 - 11554.
spotted-wilt-virus - double-stranded-rna - antiviral immunity - interfering rna - drosophila-melanogaster - viral suppressors - in-vivo - gene - plant - cells
The tospovirus NSs protein was previously shown to suppress the antiviral RNA silencing mechanism in plants. Here the biochemical analysis of NSs proteins from different tospoviruses, using purified NSs or NSs containing cell extracts, is described. The results showed that all tospoviral NSs proteins analyzed exhibited affinity to small double-stranded RNA molecules, i.e., small interfering RNAs (siRNAs) and micro-RNA (miRNA)/miRNA* duplexes. Interestingly, the NSs proteins from tomato spotted wilt virus (TSWV), impatiens necrotic spot virus (INSV), and groundnut ringspot virus (GRSV) also showed affinity to long double-stranded RNA (dsRNA), whereas tomato yellow ring virus (TYRV) NSs did not. The TSWV NSs protein was shown to be capable of inhibiting Dicer-mediated cleavage of long dsRNA in vitro. In addition, it suppressed the accumulation of green fluorescent protein (GFP)-specific siRNAs during coinfiltration with an inverted-repeat-GFP RNA construct in Nicotiana benthamiana. In vivo interference of TSWV NSs in the miRNA pathway was shown by suppression of an enhanced GFP (eGFP) miRNA sensor construct. The ability to stabilize miRNA/miRNA* by different tospovirus NSs proteins in vivo was demonstrated by increased accumulation and detection of both miRNA171c and miRNA171c* in tospovirus-infected N. benthamiana. All together, these data suggest that tospoviruses interfere in the RNA silencing pathway by sequestering siRNA and miRNA/miRNA* molecules before they are uploaded into their respective RNA-induced silencing complexes. The observed affinity to long dsRNA for only a subset of the tospoviruses studied is discussed in light of evolutional divergence and their ancestral relation to the animal-infecting members of the Bunyaviridae
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 33 (november – december) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 32 (september – oktober) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 31 (juli – augustus) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 30 (mei – juni) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 29 (maart – april) )
Landelijk onderzoek naar teken en de ziekte van Lyme
Takken, W. ; Vliet, A.J.H. van; Huisman, M. - \ 2010
Wageningen : Wageningen Universiteit (Nieuwsbrief # 28 (januari – februari) )
Onderwijsproject "Animal Welfare Quality Management"
Huisman, T.J. ; Reijd, P. van der; Hopster, H. ; Miedema, S. ; Ooijen, M. ; Pompe, V.M.M. ; Verheijen, C. ; Ophorst, S. ; Brandt, H. van den; Knobbe, L. ; Bos, J. ; Koenis, I. - \ 2010
dierenwelzijn - agrarisch onderwijs - onderwijsprogramma's - kwaliteitszorg - animal welfare - agricultural education - education programmes - quality management
Poster met informatie over het onderwijsproject "Animal Welfare Quality Management": introductie, beoogde resultaten, aanpak en resultaten per mei 2008.
"Met kennis beter doen" ook uitgangspunt bij dierentuinvoeding
Huisman, T.J. ; Polet, J.J. ; Spit, L. ; Kuperus, S. - \ 2010
dierentuindieren - dierenwelzijn - diervoeding - dierentuinen - lesmaterialen - zoo animals - animal welfare - animal nutrition - zoological gardens - teaching materials
Voeding is bepalend voor gezondheid en welzijn van dieren. Theoretische kennis over voeding in alle geledingen van de dierentuinorganisatie draagt bij aan de communicatie hierover. Dit leidt tot meer uitwisseling tussen praktijk en theorie en betere acceptatie van voedingsvoorschriften.
Dierentuinvoeding
Huisman, T. - \ 2010
onderwijsmethoden - dierentuindieren - diervoeding - dierenwelzijn - lesmaterialen - teaching methods - zoo animals - animal nutrition - animal welfare - teaching materials
Factsheet met informatie over het KIGO project over dierentuinvoeding.
Is there chaos out there? : analysis of complex dynamics in plankton communities
Benincà, E. - \ 2010
Wageningen University. Promotor(en): Marten Scheffer; J. Huisman, co-promotor(en): K. Jöhnk; Egbert van Nes. - [S.l. : S.n. - ISBN 9789085858126 - 169
plankton - waterorganismen - veranderingen in de bevolking - populatiedichtheid - populatiedynamica - chaos - wiskundige modellen - populatiebiologie - plankton - aquatic organisms - population change - population density - population dynamics - chaos - mathematical models - population biology
Species often show irregular fluctuations in their population abundances. Traditionally, ecologists have thought that external processes (e.g., variability in weather conditions) are the main drivers of these ups and downs. However, recent theoretical work suggests that fluctuations in natural populations may also be driven by internal mechanisms (e.g., the interplay between species). In this thesis I use a combination of time series analysis and modeling to provide more insight into the question to which extent such internally generated chaos might drive the population dynamics of plankton communities under controlled as well as natural conditions. In short, this thesis demonstrates in theory and experiment that species in plankton communities may rise and fall forever in a chaotic way. This result challenges the traditional view that nature is at equilibrium and that only externally driven processes may disturb this equilibrium.
Effects of exercise on l-carnitine and lipid metabolism in African catfish (Clarias gariepinus) fed different dietary l-carnitine and lipid levels
Ozorio, R.O.A. ; Ginneken, V.J.T. van; Bessa, R.J.B. ; Verstegen, M.W.A. ; Verreth, J.A.J. ; Huisman, E.A. - \ 2010
The British journal of nutrition 103 (2010)8. - ISSN 0007-1145 - p. 1139 - 1150.
trout oncorhynchus-mykiss - bream pagrus-major - high-fat diets - salmo-salar l - rainbow-trout - growth-performance - exhaustive exercise - nutritional supplements - intermediary metabolism - swimming performance
African catfish (Clarias gariepinus) were fed four isonitrogenous diets (34 % crude protein), each containing one of two lipid (100 or 180 g/kg) and two l-carnitine (15 or 1000 mg/kg) levels. After 81 d of feeding, thirty-two fish (body weight 32 g) from each dietary group were randomly selected, sixteen fish were induced to a 3-h swim (speed of 1.5 body length (BL)/s), while the other sixteen fish were kept under resting condition. Fish fed 1000 mg l-carnitine accumulated 3.5 and 5 times more l-carnitine in plasma and muscle, respectively, than fish fed the 15 mg l-carnitine. Muscle l-carnitine content was significantly lower in exercised fish than in rested fish. High dietary lipid level (fish oil) led to an increase in muscle n-3 PUFA content and a decrease in SFA and MUFA content. In liver, the increase in dietary lipid level resulted in an increased levels of both n-6 and n-3 PUFA. l-carnitine supplementation significantly decreased n-3 PUFA content. Exercise decreased n-3 PUFA in both muscle and liver. Plasma lactate and lactate dehydrogenase, normally associated with increased glycolytic processes, were positively correlated with exercise and inversely correlated with dietary l-carnitine level. l-carnitine supplementation reduced significantly the RQ from 0.72 to 0.63, and an interaction between dietary l-carnitine and lipid was observed (P <0.03). Our results indicate that an increase in fatty acids (FA) intake may promote FA oxidation, and both carnitine and exercise might influence the regulation of FA oxidation selectivity.
Coupled predator-prey oscillations in a chaotic food web
Benincà, E. ; Johnk, K.D. ; Heerkloss, R. ; Huisman, J. - \ 2009
Ecology Letters 12 (2009)12. - ISSN 1461-023X - p. 1367 - 1378.
wavelet analysis - time-series - ecological dynamics - populations - abundance - models - cycles - synchronization - biodiversity - competition
Coupling of several predator-prey oscillations can generate intriguing patterns of synchronization and chaos. Theory predicts that prey species will fluctuate in phase if predator-prey cycles are coupled through generalist predators, whereas they will fluctuate in anti-phase if predator-prey cycles are coupled through competition between prey species. Here, we investigate predator-prey oscillations in a long-term experiment with a marine plankton community. Wavelet analysis of the species fluctuations reveals two predator-prey cycles that fluctuate largely in anti-phase. The phase angles point at strong competition between the phytoplankton species, but relatively little prey overlap among the zooplankton species. This food web architecture is consistent with the size structure of the plankton community, and generates highly dynamic food webs. Continued alternations in species dominance enable coexistence of the prey species through a non-equilibrium 'killing-the-winner' mechanism, as the system shifts back and forth between the two predator-prey cycles in a chaotic fashion.
Investigating Neolithic land use in Swifterbant (NL) using micromorphological techniques
Huisman, D.J. ; Jongmans, A.G. ; Raemaekers, D.C.M. - \ 2009
Catena 78 (2009)3. - ISSN 0341-8162 - p. 185 - 197.
In the Swifterbant area in The Netherlands, a complete Neolithic landscape is preserved, buried in a wetland environment. A dozen sites (dating from ca. 4300-4000 cal. BC) on levees of a former creek system are characterized by a black layer containing large amounts of carbonized plant remains, burnt bone, flint and pottery. These sites are usually interpreted as occupation sites with accumulated refuse of a society in transition from a Mesolithic to a Neolithic lifestyle (hunting and herding), in an area that was too wet for crops. In the context of a new research campaign in the area, we investigated the site- and land-use on two locations (S2 and S4) using micromorphological techniques. On S2, the soil matrix in the archaeological horizon has a heterogeneous, non-sedimentary appearance due to the ubiquitous presence of rounded and subrounded aggregates. These aggregates indicate that the sediment was disturbed after deposition, but it is unclear by what human activity. This disturbance is not restricted to the archaeological site horizon, but extends also into the under- and overlying layers. On S4, three layers can be distinguished. Only the lower and central parts are usually regarded as archaeological layers. The lower layer shows thorough mixing of the (partly decalcified) groundmass and the incorporation of anthropogenic materials (carbonized plant remains, burnt bone, etc.). Most probably, the thorough mixing is a result of tillage. The central layer consists of thinly laminated phytoliths and carbonized plant remains with ample fragments of (burnt) bone, angular sediment clods and some dog coprolites. Mineral sediments are absent. Apparently, the layer was formed by human activities that resulted in a massive accumulation of burnt organic materials and anthropogenic debris. The preservation of the microlayering formed by phytoliths and carbonized is remarkable, since trampling would have deformed or disturbed the layering. The surprising conclusion therefore has to be that this location was not the main settlement area-as was implicitly thought until now. Rather, the area should be interpreted as a location where specific activities resulted in the accumulation of burnt plant material, e.g. a waste dump. The upper layer again has indications of anthropogenic soil disturbance. Samples from the basin adjacent to the levee site show sediments that are deformed by trampling. The transition of the site to the channel shows no signs of trampling, but rather interfingering of site layers with channel sediments. Lack of trampling in the central zone of S4 and the adjacent channel shore is at odds with the classical interpretation that the site represents a settlement area. The black layers that up till now were thought to encompass a complete settlement, could very well be a very prominent part of larger sites with remains of human activities during the Neolithic
Energieproducerende Kas levert vooral kennis op (interview met Feije de Zwart)
Jagers op Akkerhuis, F. ; Zwart, H.F. de - \ 2009
Vakblad voor de Bloemisterij 64 (2009)5. - ISSN 0042-2223 - p. 44 - 45.
tuinbouwbedrijven - kassen - energie - onderzoek - glastuinbouw - semi-gesloten kassen - market gardens - greenhouses - energy - research - greenhouse horticulture - semi-closed greenhouses
Het onderzoek naar de Energieproducerende Kas bij Hydro Huisman is afgerond. Het blijkt mogelijk om met een kas energie te verzamelen en te gebruiken voor klimaatregeling. Momenteel is het systeem echter nog niet rendabel, al heeft het onderzoek ook praktisch bruikbare inzichten opgeleverd
Interannual variability in species composition explained as seasonally entrained chaos
Dakos, V. ; Beninca, E. ; Nes, E.H. van; Philippart, C.J.M. ; Scheffer, M. ; Huisman, J. - \ 2009
Proceedings of the Royal Society. B: Biological Sciences 276 (2009)1669. - ISSN 0962-8452 - p. 2871 - 2880.
predator-prey system - competitive-exclusion - phytoplankton biomass - marine-phytoplankton - plankton dynamics - food webs - models - stability - patterns - daphnia
The species composition of plankton, insect and annual plant communities may vary markedly from year to year. Such interannual variability is usually thought to be driven by year-to-year variation in weather conditions. Here we examine an alternative explanation. We studied the effects of regular seasonal forcing on a multi-species predator–prey model consisting of phytoplankton and zooplankton species. The model predicts that interannual variability in species composition can easily arise without interannual variability in external conditions. Seasonal forcing increased the probability of chaos in our model communities, but squeezed these irregular species dynamics within the seasonal cycle. As a result, the population dynamics had a peculiar character. Consistent with long-term time series of natural plankton communities, seasonal variation led to a distinct seasonal succession of species, yet the species composition varied from year to year in an irregular fashion. Our results suggest that interannual variability in species composition is an intrinsic property of multi-species communities in seasonal environments
The ecological stoichiometry of toxins produced by harmful cyanobacteria: an experimental test of the carbonnutrient balance hypothesis
Waal, D.B. van de; Verspagen, J.M.H. ; Lürling, M.F.L.L.W. ; Donk, E. van; Visser, P.M. ; Huisman, J. - \ 2009
Ecology Letters 12 (2009)2. - ISSN 1461-023X - p. 1326 - 1335.
limited microcystis-aeruginosa - planktothrix-agardhii - inorganic carbon - growth-rate - light - nitrogen - phytoplankton - population - metabolism - blooms
The elemental composition of primary producers reflects the availability of light, carbon and nutrients in their environment. According to the carbon-nutrient balance hypothesis, this has implications for the production of secondary metabolites. To test this hypothesis, we investigated a family of toxins, known as microcystins, produced by harmful cyanobacteria. The strain Microcystis aeruginosa HUB 5-2-4, which produces several microcystin variants of different N:C stoichiometry, was cultured in chemostats supplied with various combinations of nitrate and CO2. Excess supply of both nitrogen and carbon yielded high cellular N:C ratios accompanied by high cellular contents of total microcystin and the nitrogen-rich variant microcystin-RR. Comparable patterns were found in Microcystis-dominated lakes, where the relative microcystin-RR content increased with the seston N:C ratio. In total, our results are largely consistent with the carbon-nutrient balance hypothesis, and warn that a combination of rising CO2 and nitrogen enrichment will affect the microcystin composition of harmful cyanobacteria
Local positive feedback and the persistence and recovery of fringe Avicennia marina (Forssk.) Vierh. mangroves
Huisman, T.J. ; Langevelde, F. van; Boer, W.F. de - \ 2009
Wetlands Ecology and Management 17 (2009)6. - ISSN 0923-4861 - p. 601 - 611.
early-life history - early growth - ecosystems - restoration - australia - establishment - regeneration - propagules - patterns - forests
While mangrove restoration efforts are reasonably successful, failure often occurs in high wave energy situations. Due to differences in wave energy, seedling mortality rates vary strongly with position on the intertidal flat between high water spring and high water neap elevations. However, a local positive feedback can be present between the pneumatophores of adult mangroves and the survival of mangrove seedlings to trigger recovery. In this study, a mangrove population of Avicennia marina is modelled to determine the effects of seedling mortality and local positive feedback on mangrove recovery. The model uses life history data and dispersal to simulate population dynamics. The mangrove range limits are determined by high water spring and high water neap levels. The results indicate that within these limits mangrove populations with life-history parameter values as derived from literature are indeed capable of fast growth under conditions with low seedling mortality. Local positive feedback has then a small positive influence on population recovery after mangrove loss. If, however, mortality rates increase, such as in high wave energy situations, the importance of a positive feedback increases. The model shows that a positive feedback may, given high seedling mortality rates, be an important factor for mangrove recovery. While a positive feedback may enable mangrove persistence in unfavourable conditions, destruction of adult mangroves can remove the positive feedback, which would render the system uninhabitable and practically prohibits reforestation of such areas. The model results and the presence of positive feedbacks and their importance for population dynamics in harsh conditions indicate that investigating and understanding possible feedbacks could be crucial for successful restoration efforts
Omgaan met digitale nationale beleidskaarten
Vullings, L.A.E. ; Blok, C. ; Vonk, G.A. ; Heusden, M. van; Huisman, A. ; Linge, J.M. van; Keijzer, S. ; Oldengarm, J. ; Bulens, J.D. - \ 2009
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 141) - 44
kaarten - interpretatie - overheidsbeleid - nederland - geografische informatiesystemen - visualisatie - maps - interpretation - government policy - netherlands - geographical information systems - visualization
In dit werkdocument worden de resultaten besproken van een casestudy die onderdeel is van het project GeO3 - Omgaan met onzekerheid binnen Ruimtelijke Ordening. De directie Platteland van het ministerie van LNV heeft bij het publiceren van het meerjarenprogramma van Agenda Vitaal Platteland geen digitale viewer gepubliceerd omdat men bang was voor verkeerde interpretatie van de digitale kaarten. In dit project is gekeken naar methoden en cartografische oplossingen om voortaan zonder angst voor misinterpretaties digitale nationale beleidskaarten te kunnen verspreiden. De oplossing is gezocht in het opstellen van een handreiking, zodat kaarten ook daadwerkelijk weergeven wat er bedoeld is door de maker.
Citric acid wastewater as electron donor for biological sulfate reduction
Stams, A.J.M. ; Huisman, J. ; Garcia Encina, P.A. ; Muyzer, G. - \ 2009
Applied Microbiology and Biotechnology 83 (2009)5. - ISSN 0175-7598 - p. 957 - 963.
sp-nov. - lactosphaera-pasteurii - ruminococcus-palustris - citrate metabolism - reducing bacteria - comb-nov - gen-nov - reactor - veillonella - reclassification
Citrate-containing wastewater is used as electron donor for sulfate reduction in a biological treatment plant for the removal of sulfate. The pathway of citrate conversion coupled to sulfate reduction and the microorganisms involved were investigated. Citrate was not a direct electron donor for the sulfate-reducing bacteria. Instead, citrate was fermented to mainly acetate and formate. These fermentation products served as electron donors for the sulfate-reducing bacteria. Sulfate reduction activities of the reactor biomass with acetate and formate were sufficiently high to explain the sulfate reduction rates that are required for the process. Two citrate-fermenting bacteria were isolated. Strain R210 was closest related to Trichococcus pasteurii (99.5% ribosomal RNA (rRNA) gene sequence similarity). The closest relative of strain S101 was Veillonella montepellierensis with an rRNA gene sequence similarity of 96.7%. Both strains had a complementary substrate range
De energieproducerende kas bij Hydro Huisman
Zwart, Feije de - \ 2009
greenhouses - protected cultivation - energy conservation - cogeneration - greenhouse horticulture - energy saving
Modeling of thin layer drying of tarragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Huisman, W. ; Boxtel, A.J.B. van; Mueller, J. - \ 2009
Industrial Crops and Products 29 (2009)1. - ISSN 0926-6690 - p. 53 - 59.
sweet-potato slices - bay leaves - hot air - parameters
The drying behavior of tarragon leaves as well as chopped plants were evaluated at air temperatures ranging from 40 to 90 °C, at various air relative humidities and a constant air velocity of 0.6 m/s. The experimental data was fitted to a number of thin layer drying equations. The equations were classified to select the more relevant one. Three equations were selected and the coefficients of the equations were compared by three statistical parameters as residual sum of squares, standard error of estimate and mean relative deviation. The effect of temperature on the coefficients of the three selected equations was evaluated by nonlinear regression. The results show that higher temperature cause shorter drying time. Separated leaves have shorter drying time compared to chopped plants. Although the Diffusion approach equation showed the best fit, the Page equation was selected, since it had almost a similar performance but the equation is simpler with two parameters instead of three. Then a function was derived describing the relationship between the two parameter values and drying temperature.
The timescale of phenotypic plasticity and its impact on competition in fluctuating environments
Stomp, M. ; Dijk, M.A. van; Overzee, H.M.J. van; Wortel, M.T. ; Sigon, C.A.M. ; Egas, M. ; Hoogveld, H. ; Gons, H.J. ; Huisman, J. - \ 2008
American Naturalist 172 (2008)5. - ISSN 0003-0147 - p. E169 - E185.
complementary chromatic adaptation - fresh-water picocyanobacteria - phototrophic microorganisms - marine synechococcus - variable environment - selective advantage - inducible defenses - experimental tests - baltic sea - light
Although phenotypic plasticity can be advantageous in fluctuating environments, it may come too late if the environment changes fast. Complementary chromatic adaptation is a colorful form of phenotypic plasticity, where cyanobacteria tune their pigmentation to the prevailing light spectrum. Here, we study the timescale of chromatic adaptation and its impact on competition among phytoplankton species exposed to fluctuating light colors. We parameterized a resource competition model using monoculture experiments with green and red picocyanobacteria and the cyanobacterium Pseudanabaena, which can change its color within approximately 7 days by chromatic adaptation. The model predictions were tested in competition experiments, where the incident light color switched between red and green at different frequencies (slow, intermediate, and fast). Pseudanabaena (the flexible phenotype) competitively excluded the green and red picocyanobacteria in all competition experiments. Strikingly, the rate of competitive exclusion was much faster when the flexible phenotype had sufficient time to fully adjust its pigmentation. Thus, the flexible phenotype benefited from its phenotypic plasticity if fluctuations in light color were relatively slow, corresponding to slow mixing processes or infrequent storms in their natural habitat. This shows that the timescale of phenotypic plasticity plays a key role during species interactions in fluctuating environments.
Evaluation of vaccination strategies against infection with feline immunodeficiency virus (FIV) based on recombinant viral vectors expressing FIV Rev and OrfA
Huisman, W. ; Schrauwen, E.J.A. ; Tijhaar, E. ; Süzer, Y. ; Pas, S.D. ; Amerongen, G. van; Sutter, G. ; Rimmelzwaan, G.F. ; Osterhaus, A.D.M.E. - \ 2008
Veterinary Immunology and Immunopathology 126 (2008)3-4. - ISSN 0165-2427 - p. 332 - 338.
cytotoxic t-lymphocytes - semliki-forest-virus - envelope glycoprotein - protective immunity - subunit vaccines - rhesus macaques - 89.6p challenge - animal-model - tat protein - replication
In recent years it has become clear that cell-mediated immunity is playing a role in the control of lentivirus infections. In particular, cytotoxic T lymphocyte responses have been associated with improved outcome of infection, especially those directed against the regulatory proteins like Rev and Tat, which are expressed early after infection. Therefore, there is considerable interest in lentiviral vaccine candidates that can induce these types of immune responses. In the present study, we describe the construction and characterisation of expression vectors based on recombinant Semliki Forest virus system and modified vaccinia virus Ankara for the expression of feline immunodeficiency virus (FIV) accessory proteins Rev and OrfA. These recombinant viral vectors were used to immunize cats using a prime-boost regimen and the protective efficacy of this vaccination strategy was assessed after challenge infection of immunized cats with FIV.
Chaos in a long-term experiment with a plankton community
Beninca, E. ; Huisman, J. ; Heerkloss, R. ; Jöhnk, K.D. ; Branco, P. ; Nes, E.H. van; Scheffer, M. ; Ellner, S.P. - \ 2008
Nature 451 (2008). - ISSN 0028-0836 - p. 822 - 825.
time-series - dynamics - cycles - phytoplankton - oscillations - models
Mathematical models predict that species interactions such as competition and predation can generate chaos1, 2, 3, 4, 5, 6, 7, 8. However, experimental demonstrations of chaos in ecology are scarce, and have been limited to simple laboratory systems with a short duration and artificial species combinations9, 10, 11, 12. Here, we present the first experimental demonstration of chaos in a long-term experiment with a complex food web. Our food web was isolated from the Baltic Sea, and consisted of bacteria, several phytoplankton species, herbivorous and predatory zooplankton species, and detritivores. The food web was cultured in a laboratory mesocosm, and sampled twice a week for more than 2,300 days. Despite constant external conditions, the species abundances showed striking fluctuations over several orders of magnitude. These fluctuations displayed a variety of different periodicities, which could be attributed to different species interactions in the food web. The population dynamics were characterized by positive Lyapunov exponents of similar magnitude for each species. Predictability was limited to a time horizon of 15¿30 days, only slightly longer than the local weather forecast. Hence, our results demonstrate that species interactions in food webs can generate chaos. This implies that stability is not required for the persistence of complex food webs, and that the long-term prediction of species abundances can be fundamentally impossible.
Energieproducerende Kas nog niet volledig benut
Zwart, H.F. de; Noort, F.R. van - \ 2008
Vakblad voor de Bloemisterij 63 (2008)3. - ISSN 0042-2223 - p. 38 - 40.
kassen - potplanten - energie - energieterugwinning - innovaties - nuttig gebruik - productiemogelijkheden - glastuinbouw - kastechniek - greenhouses - pot plants - energy - energy recovery - innovations - utilization - production possibilities - greenhouse horticulture - greenhouse technology
De Energieproducerende Kas by Hydro Huisman laat zien dat het concept werkt, maar dat een schaduwminnende potplantenteelt niet de beste teelt is voor een hoge netto-energieproductie. Een lichtminnend groentegewas en een lichtere kas zou een betere energieproductie hebben laten zien. Teelttechnisch gezien zijn de ervaringen overwegend positief
Het topsysteem van de ondergrond: Een reactievat. Deelrapport 5. Bruikbaarheid van reactiviteitsgegevens voor herleiden conserverend vermogen van de bodem m.b.t. archeologisch erfgoed
Klein, J. ; Griffioen, J. ; Huisman, D.J. ; Alterra - Centrum Landschap, - \ 2007
Utrecht : TNO-RACM - 25 p.
An airtight paddy storage system for small-scale farmers in Sri Lanka
Adhikarinayake, T.B. ; Müller, J. ; Oostdam, J.W.M. ; Huisman, W. ; Richards, P. - \ 2007
AMA: Agricultural Mechanization in Asia, Africa and Latin America 38 (2007)3. - ISSN 0084-5841 - p. 48 - 55.
The farmers in Sri Lanka's dry zone are the main contributors to the paddy production in the country. However, due to various reasons, they face difficulties in obtaining a reasonable income for their produce at harvesting time. According to the survey carried out in the paddy producing regions, it was found that one possible solution to reduce this problem is to enable the farmers to sell their produce at a time when prices are higher than at harvest time. To enable the farmers to keep their paddy on-farm for some time with a minimum loss of quality and quantity, some reliable and affordable storage facility has to be developed. To achieve this, an airtight storage system of 2.5 tons was developed by a four-step approach, which consists of: preliminary study to investigate the actual need, definition of the core problem, definition of the main function to be fulfilled by the designed system and finally, assessment of applicable working principles, to achieve a viable solution of the problem. This paper describes in detail the steps in the approach to achieve an efficient and inexpensive system acceptable to the farmers.
Tussenrapportage energie en teelt in de energieproducerende kas
Zwart, H.F. de; Noort, F. van; Bakker, J.C. - \ 2007
Wageningen : Wageningen UR Glastuinbouw (Nota / Wageningen UR Glastuinbouw 491) - 35
kassen - energie - energieterugwinning - productiemogelijkheden - transmissie - potplanten - gewaskwaliteit - glastuinbouw - greenhouses - energy - energy recovery - production possibilities - transmission - pot plants - crop quality - greenhouse horticulture
Tussenrapportage van de gewaskwaliteit in de energieproducerende kas bij Hydro Huisman om Huissen. Een lichtminnend groentegewas en een lichtere kas zou een betere energieproductie hebben laten zien. Vanuit teelttechnisch oogpunt zijn de ervaringen overwegend positief. Er is een behoorlijke teeltversnelling zichtbaar en de plantkwaliteit is voor de meeste beproefde soorten gelijk of wat beter. Voor een enkele soort is de kwaliteit wat minder
Onderzoek Energie Producerende Kas Stef Huisman - Bergerden (Huissen)
Noort, F.R. van; Zwart, H.F. de - \ 2007
kassen - energie - energiebehoud - teelt onder bescherming - glastuinbouw - greenhouses - energy - energy conservation - protected cultivation - greenhouse horticulture
Onderzoek van de Energieproducerende kas: nieuwe teeltmogelijkheden en bevindingen
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