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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    Expectation management at the local scale: Legal failure of public participation for large urban planning projects
    Hartmann, Thomas ; Straalen, F.M. van; Spit, T.J.M. - \ 2018
    TeMa Journal of Land Use, Mobility and Environment 11 (2018)1. - ISSN 1970-9889 - p. 133 - 145.
    The complex nature of large urban planning projects often results in delays or budget overruns. One of the causes is conflicts of interests between stakeholders. Recent planning failures in projects, due to limited public participation, sparked debates to increase citizen participation in formal planning procedures. This paper investigates how planning law supports public participation in large planning projects that cross municipal borders. The juridical analysis of German and Dutch codified law is based on four elements: literal content, institutional positioning, historical context, and teleological meaning of a legal text. The paper furthermore distinguishes four rationales for participation in planning: support,legitimization, improving plan quality, and education. The analysis shows that these rationales cannot be comprehensively regulated by codified law. Law can enhance the legitimate character of participation, but currently lacks the ability to organize support, improvement of planning, and education at the regional planning level.
    Introduction: Changing environmental conditions, property rights and land use planning
    Straalen, F.M. van; Hartmann, T. ; Sheehan, John - \ 2018
    In: Property rights and climate change / van Straalen, Fennie, Hartmann, Thomas, Sheehan, John, Routledge - ISBN 9781138698000 - p. 1 - 10.
    This introduction presents an overview of the key concepts covered in the subsequent chapters of this book. The book discusses property rights regime reform and challenges the current understanding of property rights regimes and examines the feasibility of a shift in our understanding of property rights to make these environmental changes. It investigates the insurance market and how financial incentives could persuade property owners to act differently in dealing with climate change. Changing environmental conditions – whether triggered by climate change or not – have an impact on land use. This impact can have positive or negative effects. The way land may be used is regulated by public policy, i.e. land use planning. Land use planning can be described as an activity that uses public power to implement and enforce rules about how people may use their property rights over land and buildings.
    Entangled in scales : Multilevel governance challenges for regional planning strategies
    Straalen, F.M. van; Witte, P.A. - \ 2018
    Regional Studies, Regional Science 5 (2018)1. - ISSN 2168-1376 - p. 157 - 163.
    Fuzzy governance - Regionalisation - Scalar problems - The Netherlands

    The academic discourse considers the regional scale as an important planning level to provide for spatial objectives that transcend the boundaries of local authorities. Nonetheless, the problem-solving capacity of the regional planning level is still questioned by both academics and practitioners. This paper studies the tension between formal and informal regional governance and its practical challenges for two cases of Dutch provinces struggling with their position in regional governance networks. These cases entail pan-European development (Trans-European Transport Networks – TEN-T) and regional land development (Bloemendalerpolder). It was found that at the metropolitan scale, formal regional planning powers tend to overrule socially produced regional governance arrangements. Simultaneously, regional planning powers lack support of these socially produced arrangements for their interventions. At the same time, at the supra-regional scale, provinces are a logical stakeholder to fulfil a prominent role in regional governance, but often lack the institutional capacity to act as such. We therefore argue that regional planning authorities need to be granted the power and capacity to take up a more centripetal, intermediate role in governance arrangements. This would provide them more capacity to act in disentangling the difficult practical challenges of scalar problems that many regional governance arrangements currently face.

    Conclusion : The social construction of changing environmental conditions
    Hartmann, Thomas ; Straalen, Fennie van; Sheehan, John - \ 2017
    In: Property Rights and Climate Change CRC Press - ISBN 9781138698000 - p. 182 - 190.

    At the heart of the previous chapters lie the twin issues of change and continuity induced by climate change, and illustrated through theoretical notions of land use planning and practical cases of land use impacted by often unsurprising and yet sometimes unanticipated changing environmental conditions. Even though climate change is an ongoing process that might not yet have reached its climax, we are concerned to judiciously garner trends and then extrapolate how property rights and land use are affected by climate change. Moreover, the book explored ways to deal with - or intervene in - property rights under changing environmental conditions. See, for example, the Old Bar case in Australia and the rolling easement construct in Texas, USA.

    Property rights and climate change : Land-use under changing environmental conditions
    Straalen, F.M. van; Hartmann, Thomas ; Sheehan, John - \ 2017
    Routledge - ISBN 9781315520094 - 208 p.
    Priorities for research in soil ecology
    Eisenhauer, Nico ; Antunes, Pedro M. ; Bennett, Alison E. ; Birkhofer, Klaus ; Bissett, Andrew ; Bowker, Matthew A. ; Caruso, Tancredi ; Chen, Baodong ; Coleman, David C. ; Boer, Wietse de; Ruiter, Peter de; DeLuca, Thomas H. ; Frati, Francesco ; Griffiths, Bryan S. ; Hart, Miranda M. ; Hättenschwiler, Stephan ; Haimi, Jari ; Heethoff, Michael ; Kaneko, Nobuhiro ; Kelly, Laura C. ; Leinaas, Hans Petter ; Lindo, Zoë ; Macdonald, Catriona ; Rillig, Matthias C. ; Ruess, Liliane ; Scheu, Stefan ; Schmidt, Olaf ; Seastedt, Timothy R. ; Straalen, Nico M. van; Tiunov, Alexei V. ; Zimmer, Martin ; Powell, Jeff R. - \ 2017
    Pedobiologia 63 (2017). - ISSN 0031-4056 - p. 1 - 7.
    Aboveground-belowground interactions - Biodiversity–ecosystem functioning - Biogeography - Chemical ecology - Climate change - Ecosystem services - Global change - Microbial ecology - Novel environments - Plant-microbe interactions - Soil biodiversity - Soil food web - Soil management - Soil processes
    The ecological interactions that occur in and with soil are of consequence in many ecosystems on the planet. These interactions provide numerous essential ecosystem services, and the sustainable management of soils has attracted increasing scientific and public attention. Although soil ecology emerged as an independent field of research many decades ago, and we have gained important insights into the functioning of soils, there still are fundamental aspects that need to be better understood to ensure that the ecosystem services that soils provide are not lost and that soils can be used in a sustainable way. In this perspectives paper, we highlight some of the major knowledge gaps that should be prioritized in soil ecological research. These research priorities were compiled based on an online survey of 32 editors of Pedobiologia – Journal of Soil Ecology. These editors work at universities and research centers in Europe, North America, Asia, and Australia. The questions were categorized into four themes: (1) soil biodiversity and biogeography, (2) interactions and the functioning of ecosystems, (3) global change and soil management, and (4) new directions. The respondents identified priorities that may be achievable in the near future, as well as several that are currently achievable but remain open. While some of the identified barriers to progress were technological in nature, many respondents cited a need for substantial leadership and goodwill among members of the soil ecology research community, including the need for multi-institutional partnerships, and had substantial concerns regarding the loss of taxonomic expertise.
    Coping with living in the soil : The genome of the parthenogenetic springtail Folsomia candida
    Faddeeva-Vakhrusheva, Anna ; Kraaijeveld, Ken ; Derks, Martijn F.L. ; Anvar, Seyed Yahya ; Agamennone, Valeria ; Suring, Wouter ; Kampfraath, Andries A. ; Ellers, Jacintha ; Ngoc, Giang Le; Gestel, Cornelis A.M. van; Mariën, Janine ; Smit, Sandra ; Straalen, Nico M. van; Roelofs, Dick - \ 2017
    BMC Genomics 18 (2017). - ISSN 1471-2164 - 14 p.
    Carbohydrate metabolism - Collembola - Gene family expansions - Genome collinearity - Horizontal gene transfer - Hox genes - Intragenomic rearrangement - Palindrome

    Background: Folsomia candida is a model in soil biology, belonging to the family of Isotomidae, subclass Collembola. It reproduces parthenogenetically in the presence of Wolbachia, and exhibits remarkable physiological adaptations to stress. To better understand these features and adaptations to life in the soil, we studied its genome in the context of its parthenogenetic lifestyle. Results: We applied Pacific Bioscience sequencing and assembly to generate a reference genome for F. candida of 221.7 Mbp, comprising only 162 scaffolds. The complete genome of its endosymbiont Wolbachia, was also assembled and turned out to be the largest strain identified so far. Substantial gene family expansions and lineage-specific gene clusters were linked to stress response. A large number of genes (809) were acquired by horizontal gene transfer. A substantial fraction of these genes are involved in lignocellulose degradation. Also, the presence of genes involved in antibiotic biosynthesis was confirmed. Intra-genomic rearrangements of collinear gene clusters were observed, of which 11 were organized as palindromes. The Hox gene cluster of F. candida showed major rearrangements compared to arthropod consensus cluster, resulting in a disorganized cluster. Conclusions: The expansion of stress response gene families suggests that stress defense was important to facilitate colonization of soils. The large number of HGT genes related to lignocellulose degradation could be beneficial to unlock carbohydrate sources in soil, especially those contained in decaying plant and fungal organic matter. Intra- as well as inter-scaffold duplications of gene clusters may be a consequence of its parthenogenetic lifestyle. This high quality genome will be instrumental for evolutionary biologists investigating deep phylogenetic lineages among arthropods and will provide the basis for a more mechanistic understanding in soil ecology and ecotoxicology.

    Reflections on the graph representation of darwinian evolution
    Straalen, Nico van; Gremmen, Bart - \ 2016
    In: Evolution and Transitions in Complexity: The Science of Hierarchical Organization in Nature Springer International Publishing Switzerland - ISBN 9783319438023 - p. 97 - 101.

    The proposal of Jagers op Akkerhuis et al. (Chap. 4) is that Darwinian evolution can better be discussed in terms of a graph-pattern than in terms of population- based frequencies of properties that change from one generation to the next. The authors suggest that the use of a graph-pattern can contribute to resolving current debates about extending and generalizing the concept of evolution, because a graph-pattern allows for detailed discussions of the objects, the relationships, and the patterns that constitute the concept of Darwinian evolution. We raise some questions about the currently suggested graph pattern, which-in our view-may require an additional generation. Furthermore, the use of a minimalistic and abstract graph- pattern raises questions about the links with several biologically relevant evolutionary principles including natural selection, mutation and recombination, development, and genetic drift and genetic bottlenecks. We ask the question whether a graph representation of Darwinian evolution can be extended in such a way that it suffi ciently refl ects this type of biological complexity. This, in our view, presents a challenge for the further development of Jagers op Akkerhuis’ abstract representation of evolutionary theory.

    Gene Family Evolution Reflects Adaptation to Soil Environmental Stressors in the Genome of the Collembolan Orchesella cincta
    Faddeeva-Vakhrusheva, Anna ; Derks, M.F.L. ; Anvar, Seyed Yahya ; Agamennone, Valeria ; Suring, Wouter ; Smit, S. ; Straalen, Nico M. van; Roelofs, Dick - \ 2016
    Genome Biology and Evolution 8 (2016)7. - ISSN 1759-6653 - p. 2106 - 2117.
    Collembola (springtails) are detritivorous hexapods that inhabit the soil and its litter layer. The ecology of the springtail Orchesella cincta is extensively studied in the context of adaptation to anthropogenically disturbed areas. Here, we present a draft genome of an O. cincta reference strain with an estimated size of 286.8 Mbp, containing 20,249 genes. In total, 446 gene families are expanded and 1,169 gene families evolved specific to this lineage. Besides these gene families involved in general biological processes, we observe gene clusters participating in xenobiotic biotransformation. Furthermore, we identified 253 cases of horizontal gene transfer (HGT). Although the largest percentage of them originated from bacteria (37.5%), we observe an unusually high percentage (30.4%) of such genes of fungal origin. The majority of foreign genes are involved in carbohydrate metabolism and cellulose degradation. Moreover, some foreign genes (e.g., bacillopeptidases) expanded after HGT. We hypothesize that horizontally transferred genes could be advantageous for food processing in a soil environment that is full of decaying organic material. Finally, we identified several lineage-specific genes, expanded gene families, and horizontally transferred genes, associated with altered gene expression as a consequence of genetic adaptation to metal stress. This suggests that these genome features may be preadaptations allowing natural selection to act on. In conclusion, this genome study provides a solid foundation for further analysis of evolutionary mechanisms of adaptation to environmental stressors.
    Integration and decentralization: the evolution of Dutch regional land policy
    Straalen, F.M. van; Brink, A. van den; Tatenhove, J.P.M. van - \ 2016
    International Planning Studies 21 (2016)2. - ISSN 1356-3475 - p. 148 - 163.
    The implementation of planning objectives in the public interest depends on the land laws and land policies of a state. Public stakeholders are not only enabled or constrained in their actions by these laws and policies, they also (re)formulate these laws and policies to support their actions. The objective of this paper is to understand how different stakeholders in spatial development processes influence land policy dynamics (both the (re)formulation and the implementation of policies) and vice versa. The paper explores the changes in land policies in the Netherlands, in particular how changes have enabled the regional planning level. The Policy Arrangement Approach is used to analyse the strategic behaviour of agencies and their use of structure in spatial development processes. The findings show that the arrangement rapidly changed from the 1980s onwards, due to changes in the underlying political discourses and the effectuation of these discourses via regulation and instruments. With objectives of decentralization and integration, the national government has enabled the regional planning level to become more active in spatial development processes. Although the provinces were enabled by new laws and policies, this did not significantly change their role within the Dutch planning system.
    Private property in public processes : how public stakeholders strategically interfere in private property rights in the public interest in regional spatial development processes
    Straalen, F.M. van - \ 2014
    Wageningen University. Promotor(en): Adri van den Brink; W.K. Korthals Altes. - Wageningen : Wageningen University - ISBN 9789461739476 - 173
    regionale planning - landschapsplanning - publiek-private samenwerking - grondbeleid - provincies - besluitvorming - betuwe - Nederland - regional planning - landscape planning - public-private cooperation - land policy - provinces - decision making - betuwe - Netherlands
    In planning- en beleidsliteratuur wordt grondbeleidsdynamiek en de invloed van (publieke) actoren op grondbeleid bestudeerd. Desalniettemin, is er nog weinig bekend over de strategieën, interacties en beslissingsmechanismen van actoren, of hoe actoren de grondbeleidsdynamiek beïnvloeden. Het doel van deze thesis is om een bijdrage te leveren aan de wetenschappelijke en maatschappelijke kennis op het vlak van besluitvorming bij actoren, de onderliggende mechanismen, en hoe de keuzes van en interacties tussen actoren grondbeleidsdynamiek beïnvloeden. Concreet wordt aandacht besteed aan de gebiedsontwikkeling bij de vorming van Park Lingezegen en de Bloemendalerpolder.
    Private land ownership as constraint to regional spatial development
    Straalen, F.M. van; Holtslag-Broekhof, S.M. ; Brink, A. van den - \ 2014
    Compulsory purchase for biodiversity conservation in the Netherlands
    Straalen, F.M. van; Korthals Altes, W.K. - \ 2014
    Land Use Policy 38 (2014). - ISSN 0264-8377 - p. 223 - 232.
    land market - policy - plan - law
    Policy instruments are the building blocks of land use policies. Instrumentation of policies relates to values. Compulsory purchase is a direct government instrument that may be an effective way to implement policies of biodiversity conservation and the allocation of land for recreational use. It is, however, in many contexts, politically controversial. The Netherlands’ Government has endorsed policies that involve compulsory purchase in up to 10% of land purchases. This paper reviews if this 10%-ceiling can structure relationships between landowners and government agencies in such a way that it relieves constraints imposed by land availability for biodiversity conservation and the provision of recreational areas. The analysis consists of (1) the background of this 10%-ceiling, (2) the actual procedures of compulsory purchase, by analysis of Royal Decrees, (3) the actual compulsory purchases, and (4) the indirect instrumental effects of the use of this instrument. The paper concludes that the 10%-ceiling does not lift the constraints of land availability, but does influence the relationship between stakeholders, the implementation of biodiversity objectives, and land policy strategies. Nevertheless, compulsory purchase may provide possibilities to acquire land necessary for a consolidated natural area.
    Delivering planning objectives through regional-based land-use planning and land policy instruments: an assessment of recent experiences in the Dutch provincies
    Straalen, F.M. van; Janssen-Jansen, L.B. ; Brink, A. van den - \ 2014
    Environment and Planning C. Government and Policy 32 (2014)3. - ISSN 0263-774X - p. 567 - 584.
    governance - institutions - netherlands - performance - devolution - patterns - rights - city
    This paper evaluates the extent to which the introduction of four new regional planning and land policy instruments in the Netherlands improves the delivery of regional planning objectives. On the basis of case-study research, we identify why and to what extent the Dutch regional authorities—the provinces—have adopted these new instruments and assess whether or not the instruments offer opportunities for improving the delivery of regional planning objectives. The study shows that regional policies and plans are often implemented without consideration of their consequences for national or local planning objectives. As a result, the instruments may not address current policy delivery needs, and may even compound local policy failures. We conclude that the use of such instruments should be accompanied by a more thorough discussion of regional planning tasks and objectives, and a debate on the role of regional authorities within the multilevel governance setting.
    Position at : International Association on Planning, Law and Property Rights
    Straalen, Fennie van - \ 2014
    Property Rights and a Changing Economy
    Straalen, F.M. van - \ 2013
    In: The 7th Conference of the IAAPLPR, Portland, Oregon, 13-15 February 2013. - Portland, Oregon : - p. 659 - 663.
    The interaction between land policy and spatial planning in the Netherlands
    Straalen, Fennie van - \ 2013
    The relationship between land policy and spatial planning; An explanatory history of the interaction of land policy and spatial planning in the Netherlands
    Straalen, F.M. van - \ 2013
    Spatial planning and land policy are inextricably bound up with each other. Land policies can be considered a construct of spatial planning and property relations in land (Davy, 2012). The foundation for this construct is twofold. Land policies are shaped as a result of principles and objectives (discourses) concerning property and land use, as well as the outcomes of planning practices in which land policies are implemented. Additionally, the reverse statement also holds value: changing land policies will have a altered influence on planning processes. To improve the quality and effectiveness of policy implementation in planning processes, insight into the mechanisms behind the (re)shaping and use of policies in planning processes is vital. This paper explores the relationship and interaction between land policy and spatial planning. The objective of the study is to understand the background to and determining factors in the development of land policy as a result of changing discourses and spatial planning processes. The paper discusses the relationship between planning and land policy in the Netherlands. The question is whether or not Dutch land policy is a derivative of the Dutch planning culture? The analytical framework of the study makes use of the structuration theory of Giddens (1984) and the Policy Arrangements Approach of Van Tatenhove et al. (2000). Different land policy documents in recent Dutch history (1950-present) were studied to understand the arrangements (organisation, rules and resources) of land policies and the reasoning behind changes in Dutch land policy. Likewise, planning processes were studied to understand how policy objectives and instruments are used as strategies of stakeholders – both governmental and non-governmental- in planning processes. Finally, the implementation of policy changes in planning practice was investigated. Results of this research show that the perceived control of governmental authorities over planning processes is one of the determining factors in changing land policies. If land policies do not support governmental planning objectives or if other (non-governmental) stakeholders use land policy instruments to their advantage in planning processes, land policies are discussed and if necessary changed. Furthermore, changing discourses, for example as a result of political modernisation or innovation, also spark policy changes. The study also shows a differentiation in governmental choices concerning the implementation of land policy objectives and the application of land policy instruments in planning practices. This means policies leave room for diverse strategies, which simultaneously have effect on the outcome and success of planning projects. Consequently, these outcomes influence the perceived success of land policy objectives, turning into possible new policy changes.
    Unravelling hazards of nanoparticles to earthworms, from gene to population
    Ploeg, M. van der - \ 2013
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Nico van den Brink. - S.l. : s.n. - ISBN 9789461734440 - 192
    aardwormen - lumbricus rubellus - nanotechnologie - blootstelling - ecotoxicologie - earthworms - lumbricus rubellus - nanotechnology - exposure - ecotoxicology

    Nanotechnology is an expeditiously growing field, where engineered nanoparticles are being incorporated in many different applications, from food to waste water treatment (Dekkers et al. 2011; Gottschalk and Nowack 2011; Savage and Diallo 2005). Due to this large scale production and use of nanoparticles, their release into the environment seems inevitable (Crane et al. 2008; Handy et al. 2008a; Oberdörster et al. 2005). Actual exposure levels of nanoparticles under field conditions and the hazards of nanoparticle exposure to the environment are poorly understood, especially for the soil environment (Kahru and Dubourguier 2010; Navarro et al. 2008; Shoults-Wilson et al. 2011a).

    Given the need for better characterization of hazards of engineered nanoparticles to the environment and soil organisms in particular, the aim of the present thesis was to investigate effects of nanoparticle exposure on the earthworm Lumbricus rubellus, as a model organism for soil ecotoxicology, and to contribute to the development of effect markers for engineered nanoparticle exposure in this model.

    The present thesis was divided in different chapters. Chapter 1 provides an introduction to the topic and discusses the importance of research on the hazards of exposure to engineered nanoparticles. Furthermore, the aim and outline of the thesis are presented, with background information on the model organism, effect markers and nanoparticles.

    In chapter 2 effects of exposure to the fullerene C60 (nominal concentrations 0, 15.4 and 154 mg C60/kg soil) on survival and growth during the different life stages of L. rubellus (cocoon, juvenile, subadult and adult), as well as reproduction were quantified. These important individual endpoints for population dynamics were incorporated in a continuous-time life-history model (Baveco and De Roos 1996; De Roos 2008). In this way, effects of C60 exposure on the individual endpoints could be extrapolated to implications for population growth rate and life stage distribution, i.e. the development of the population in terms of number of individuals in the different life stages. These implications at the population level may be more relevant for the ecological impact of C60 than effects on endpoints at the individual level (Klok et al. 2006; Widarto et al. 2004). At the individual level C60 exposure caused significant adverse effects on cocoon production, juvenile growth rate and survival. When these endpoints were used to model effects on the population level, reduced population growth rates with increasing C60 concentrations were observed. Furthermore, a shift in life stage structure was shown for C60 exposed populations, towards a larger proportion of juveniles. This result implies that the lower juvenile growth rate induced by C60 exposure resulted in a larger proportion of juveniles, despite increased mortality among juveniles. Overall, this study implied serious consequences of C60 exposure for L. rubellus earthworm populations, even at the lowest level of exposure tested. Furthermore, it showed that juveniles were more sensitive to C60 exposure than adults.

    To complement the observations made on survival, growth and reproduction described in chapter 2, subsequent investigations on cellular and molecular responses of the earthworms to C60 exposure were performed (chapter 3). A set of established effect markers was used, which reflect different levels of biological organisation in the earthworm and may inform on the toxic mechanisms of adverse effects induced by C60 exposure (Handy et al. 2002; Heckmann et al. 2008). At the molecular level, four specific effect markers were selected, including markers for generic stress (heat shock protein 70 (HSP70) (van Straalen and Roelofs 2006), for oxidative stress (catalase and glutathione-S-transferase (GST) (Kohen and Nyska 2002) and for an immune response (coelomic cytolytic factor-1 (CCF-1) (Olivares Fontt et al. 2002). At the tissue level, histological analyses were used to identify damage to cells and tissues, and indications of inflammation in the tissues. In these investigations, exposure to C60 (0, 15 or 154 mg C60/kg soil) affected gene expression of HSP70 significantly. Gene expression of CCF-1 did not alter in adult earthworms exposed for four weeks, but was significantly down-regulated after lifelong exposure (from cocoon stage to adulthood) of earthworms, already to the lowest C60 exposure level. No significant trends were noted for catalase and glutathione-S-transferase (GST) gene expression or enzyme activity. Tissue samples of the C60 exposed earthworms from both experiments and exposure levels, showed a damaged cuticle with underlying pathologies of epidermis and muscles. Additionally, the gut barrier was not fully intact. However, tissue repair was also observed in these earthworms. In conclusion, this study demonstrated effects of sub-lethal C60 exposure on L. rubellus earthworms, at the level of gene expression and tissue integrity.

    Although tissue injury is generally associated with an inflammatory response, as part of tissue repair (Cikutovic et al. 1999; Goven et al. 1994), the tissue damage observed for the in vivo C60 exposed earthworms in chapter 3 appeareded to occur without accompanying induced immune responses. The CCF-1 gene expression level was reduced in the C60 exposed earthworms, and histological observations did not show infiltration of damaged tissues by immune cells. In order to obtain further insight in mechanisms of effects observed at the molecular and tissue level on immune related parameters, the sensitivity of immune cells (coelomocytes) of L. rubellus earthworms towards exposure to selected nanoparticles was investigated in vitro (chapter 4). To this end, coelomocytes were isolated from unexposed adult L. rubellus earthworms and exposed to C60 in vitro. After exposure, these coelomocytes were tested for cellular viability, phagocytic activity and CCF-1 gene expression levels. The gene expression of CCF-1 was most affected, demonstrating a strong reduction, which indicated immunosuppression. Experiments with NR8383 rat macrophage cells and tri-block copolymer nanoparticles were used to compare sensitivity of the cell types and showed the usefulness of coelomocytes as a test system for nano-immunotoxicity in general. Overall, this study indicated that the absence of an immune response, in case of tissue injuries observed after in vivo C60 exposure, is likely caused by immunosuppression rather than coelomocyte mortality.

    In subsequent investigations, the experiments performed for C60 were also carried out with silver nanoparticles (AgNP), both in vivo and in vitro (chapter 5). Effects of AgNP were assessed in vivo at nominal concentrations of 0, 1.5 (low), 15.4 (medium) and 154 (high) mg Ag/kg soil and compared to effects of silver ions, added as AgNO3 (nominal concentration 15.4 mg Ag/kg soil). In a four week reproduction assay, the high AgNP and AgNO3 treatments had a significant effect on cocoon production and high AgNP exposure also caused a reduction in weight gain of the adult earthworms. No juveniles survived the high AgNP treatment, therefore only F1 earthworms from the other exposure treatments were monitored for survival and growth, until adulthood. These individual endpoints were used to model effects on the population level. The low and medium AgNP as well as the AgNO3 treatments significantly reduced the population growth rate. The high AgNP treatment caused complete failure of the population growth. Furthermore, histological examination of the earthworms from all AgNP exposure treatments demonstrated tissue damage, with injuries mainly at the external barriers, e.g. the cuticle and the gut epithelium. In addition, effects of AgNP exposure were assessed in vitro and a reduction of coelomocyte viability was observed in a concentration-dependent manner, although the EC50 was fourteen times higher compared with that for Ag ions, added as AgNO3. Furthermore, characterisation of the in vivo exposure media implied that AgNP remained present in the soil in single and aggregated state, releasing Ag to the soil pore water up to at least eleven months. The ionic fraction of Ag in soils has been suggested to be bioavailable to organisms and (largely) responsible for the observed AgNP toxicity (Coutris et al. 2012; Koo, et al. 2011; Shoults-Wilson et al. 2011b). In comparison, the AgNO3 seemed to dissolve rapidly, as is also known for this metal salt, and fixation of Ag ions by the soil presumably led to a quick reduction of Ag bioavailability (Atkins and Jones 2000; Coutris et al. 2012; Ratte 1999). This is in line with the observation that effects were more prolonged in the AgNP treatments in comparison with the AgNO3 exposed animals. In conclusion, this study indicated that AgNP exposure may seriously affect earthworm populations, with the ability to cause immunotoxicity, injury to the external barriers of the earthworm body and a reduction in growth, reproduction and juvenile survival.

    Finally, chapter 6 presents a discussion on the findings of the present thesis and provides suggestions for future research.

    Effect of copper exposure on histamine concentrations in the marbled crayfish
    Soedarini, B. ; Klaver, L. ; Giesen, D. ; Roessink, I. ; Widianarko, B. ; Straalen, N.M. van; Gestel, C.A.M. van - \ 2013
    Animal Biology 63 (2013)2. - ISSN 1570-7555 - p. 139 - 147.
    metal bioaccumulation - accumulation - toxicity - metallothionein - hepatopancreas - crustacea - decapoda - kinetics - clarkii - shrimp
    Crustaceans can store excess copper in the hepatopancreas, an organ playing a role in digestive activity as well as in neurosecretory control. Here, we studied the effect of copper exposure on the level of histamine, an indicator of food spoilage in edibl
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