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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Phenotypic Variation of Cell Wall Composition and Stem Morphology in Hemp (Cannabis sativa L.): Optimization of Methods
Petit, Jordi ; Gulisano, Agata ; Dechesne, Annemarie ; Trindade, Luisa M. - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Cannabis sativa - cell wall - fiber quality - genetic diversity - hemp - phenotyping methods - stem morphology

The growing demands for sustainable fibers have stimulated the study of genetic diversity in the quality of hemp fiber (Cannabis sativa L.). Nevertheless, the lack of high-throughput phenotyping methods that are suited for the analysis of hemp fiber, hampers the analysis of many accessions, and consequently the breeding for this complex trait. In the present report, we developed and optimized the throughput of five methods to study the diversity in hemp fiber quality including cell wall extraction, biochemical composition of cell wall polysaccharides, quantification of lignin, quantification of crystalline polysaccharides and morphology of the stems. Six hemp accessions contrasting for cell wall properties were used to assess the throughput and suitability of these methods for genetic studies. The methods presented revealed to be highly repeatable, with low coefficients of variation between technical replicates. With these methods we were able to detect significant phenotypic variation in cell wall composition and stem morphology between the six accessions. In addition, the throughput of the methods has been upgraded to a level that enables their use for phenotyping cell wall traits in breeding programs. The cell wall extraction was optimized to extract enough material for the complete characterization of the cell wall of hemp while reducing the time for the entire analysis. The throughput of the stem morphological analysis was improved by decreasing the timing of fixation, infiltration, and embedding of mature and dry hemp stems. Notwithstanding, our methods already have the potential to phenotype large number of accessions in a relatively short period of time. Our methods will enable exploration of genetic diversity of fiber quality and will contribute to the development of new hemp varieties with advanced quality of fibers.

Multi-host disease management: The why and the how to include wildlife
Portier, Julien ; Ryser-Degiorgis, Marie Pierre ; Hutchings, Mike R. ; Monchâtre-Leroy, Elodie ; Richomme, Céline ; Larrat, Sylvain ; Poel, Wim H.M. Van Der; Dominguez, Morgane ; Linden, Annick ; Santos, Patricia Tavares ; Warns-Petit, Eva ; Chollet, Jean Yves ; Cavalerie, Lisa ; Grandmontagne, Claude ; Boadella, Mariana ; Bonbon, Etienne ; Artois, Marc - \ 2019
BMC Veterinary Research 15 (2019)1. - ISSN 1746-6148
Coordination - Decision-making framework - Emerging infectious diseases - Europe - Integrated management - Policy making - Proportionate management - Risk assessment - Wildlife - Zoonosis

In recent years, outbreaks caused by multi-host pathogens (MHP) have posed a serious challenge to public and animal health authorities. The frequent implication of wildlife in such disease systems and a lack of guidelines for mitigating these diseases within wild animal populations partially explain why the outbreaks are particularly challenging. To face these challenges, the French Ministry of Agriculture launched a multi-disciplinary group of experts that set out to discuss the main wildlife specific concepts in the management of MHP disease outbreaks and how to integrate wildlife in the disease management process. This position paper structures the primary specific concepts of wildlife disease management, as identified by the working group. It is designed to lay out these concepts for a wide audience of public and/or animal health officers who are not necessarily familiar with wildlife diseases. The group's discussions generated a possible roadmap for the management of MHP diseases. This roadmap is presented as a cycle for which the main successive step are: step 1-descriptive studies and monitoring; step 2-risk assessment; step 3-management goals; step 4-management actions and step 5-assessment of the management plan. In order to help choose the most adapted management actions for all involved epidemiological units, we integrated a decision-making framework (presented as a spreadsheet). This tool and the corresponding guidelines for disease management are designed to be used by public and health authorities when facing MHP disease outbreaks. These proposals are meant as an initial step towards a harmonized transboundary outbreak response framework that integrates current scientific understanding adapted to practical intervention.

Evidence of trained immunity in a fish: Conserved features in cArp macrophages
Petit, Jules ; Embregts, Carmen W.E. ; Forlenza, Maria ; Wiegertjes, Geert F. - \ 2019
The Journal of Immunology 203 (2019)1. - ISSN 0022-1767 - p. 216 - 224.

Trained immunity is a form of innate immune memory best described in mice and humans. Clear evidence of the evolutionary conservation of trained immunity in teleost fish is lacking. Given the evolutionary position of teleosts as early vertebrates with a fully developed immune system, we hypothesize that teleost myeloid cells show features of trained immunity common to those observed in mammalian macrophages. These would at least include the ability of fish macrophages to mount heightened responses to a secondary stimulus in a nonspecific manner. We established an in vitro model to study trained immunity in fish by adapting a well-described culture system of head kidney-derived macrophages of common carp. A soluble NOD-specific ligand and a soluble b-glucan were used to train carp macrophages, after which cells were rested for 6 d prior to exposure to a secondary stimulus. Unstimulated trained macrophages displayed evidence of metabolic reprogramming as well as heightened phagocytosis and increased expression of the inflammatory cytokines il6 and tnf-a. Stimulated trained macrophages showed heightened production of reactive oxygen and nitrogen species as compared with the corresponding stimulated but untrained cells. We discuss the value of our findings for future studies on trained immunity in teleost fish.

The complex interactions between flowering behavior and fiber quality in hemp
Salentijn, Elma M.J. ; Petit, Jordi ; Trindade, Luisa M. - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Cannabis sativa - Fiber development - Flowering-time - Hemp - Phenology - Sex determination - Short-day plant

Hemp, Cannabis sativa L., is a sustainable multipurpose fiber crop with high nutrient and water use efficiency and with biomass of excellent quality for textile fibers and construction materials. The yield and quality of hemp biomass are largely determined by the genetic background of the hemp cultivar but are also strongly affected by environmental factors, such as temperature and photoperiod. Hemp is a facultative short-day plant, characterized by a strong adaptation to photoperiod and a great influence of environmental factors on important agronomic traits such as “flowering-time” and “sex determination.” This sensitivity of hemp can cause a considerable degree of heterogeneity, leading to unforeseen yield reductions. Fiber quality for instance is influenced by the developmental stage of hemp at harvest. Also, male and female plants differ in stature and produce fibers with different properties and quality. Next to these causes, there is evidence for specific genotypic variation in fiber quality among hemp accessions. Before improved hemp cultivars can be developed, with specific flowering-times and fiber qualities, and adapted to different geographical regions, a better understanding of the molecular mechanisms controlling important phenological traits such as “flowering-time” and “sex determination” in relation to fiber quality in hemp is required. It is well known that genetic factors play a major role in the outcome of both phenological traits, but the major molecular factors involved in this mechanism are not characterized in hemp. Genome sequences and transcriptome data are available but their analysis mainly focused on the cannabinoid pathway for medical purposes. Herein, we review the current knowledge of phenotypic and genetic data available for “flowering-time,” “sex determination,” and “fiber quality” in short-day and dioecious crops, respectively, and compare them with the situation in hemp. A picture emerges for several controlling key genes, for which natural genetic variation may lead to desired flowering behavior, including examples of pleiotropic effects on yield quality and on carbon partitioning. Finally, we discuss the prospects for using this knowledge for the molecular breeding of this sustainable crop via a candidate gene approach.

Modulation of innate immunity in carp : Diverse approaches to ß-glucanmediated responses
Petit, Jules - \ 2019
Wageningen University. Promotor(en): G.F. Wiegertjes; M. Forlenza. - Wageningen : Wageningen University - ISBN 9789463439466 - 202
An early β-glucan bath during embryo development increases larval size of Nile tilapia
Jesus, Raphael B. de; Petit, Jules ; Pilarski, Fabiana ; Wiegertjes, Geert F. ; Koch, João Fernando A. ; Oliveira, Carlos A.F. de; Zanuzzo, Fábio S. - \ 2019
Aquaculture Research 50 (2019)7. - ISSN 1355-557X - p. 2012 - 2014.
fish larvae - growth performance - hatching - immunostimulant - prebiotics
Studies Into β-Glucan Recognition in Fish Suggests a Key Role for the C-Type Lectin Pathway
Petit, Jules ; Bailey, Erin C. ; Wheeler, Robert T. ; Oliveira, Carlos A.F. de; Forlenza, Maria ; Wiegertjes, Geert F. - \ 2019
Frontiers in Immunology 10 (2019). - ISSN 1664-3224 - 1 p.
C-type lectin-like domain - CTLD - Cyprinidae - primary macrophage - RNAseq analysis - teleost - transcriptome analysis - β-glucan

Immune-modulatory effects of β-glucans are generally considered beneficial to fish health. Despite the frequent application of β-glucans in aquaculture practice, the exact receptors and downstream signalling remains to be described for fish. In mammals, Dectin-1 is a member of the C-type lectin receptor (CLR) family and the best-described receptor for β-glucans. In fish genomes, no clear homologue of Dectin-1 could be identified so far. Yet, in previous studies we could activate carp macrophages with curdlan, considered a Dectin-1-specific β-(1,3)-glucan ligand in mammals. It was therefore proposed that immune-modulatory effects of β-glucan in carp macrophages could be triggered by a member of the CLR family activating the classical CLR signalling pathway, different from Dectin-1. In the current study, we used primary macrophages of common carp to examine immune modulation by β-glucans using transcriptome analysis of RNA isolated 6 h after stimulation with two different β-glucan preparations. Pathway analysis of differentially expressed genes (DEGs) showed that both β-glucans regulate a comparable signalling pathway typical of CLR activation. Carp genome analysis identified 239 genes encoding for proteins with at least one C-type Lectin Domains (CTLD). Narrowing the search for candidate β-glucan receptors, based on the presence of a conserved glucan-binding motif, identified 13 genes encoding a WxH sugar-binding motif in their CTLD. These genes, however, were not expressed in macrophages. Instead, among the β-glucan-stimulated DEGs, a total of six CTLD-encoding genes were significantly regulated, all of which were down-regulated in carp macrophages. Several candidates had a protein architecture similar to Dectin-1, therefore potential conservation of synteny of the mammalian Dectin-1 region was investigated by mining the zebrafish genome. Partial conservation of synteny with a region on the zebrafish chromosome 16 highlighted two genes as candidate β-glucan receptor. Altogether, the regulation of a gene expression profile typical of a signalling pathway associated with CLR activation and, the identification of several candidate β-glucan receptors, suggest that immune-modulatory effects of β-glucan in carp macrophages could be a result of signalling mediated by a member of the CLR family.

Data from: Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe
González Muñoz, N. ; Sterck, F.J. ; Torres-Ruiz, J.M. ; Petit, Giai ; Cochard, Hervé ; Arx, G. von; Lintunen, Anna ; Caldeira, Maria C. ; Capdeville, G. ; Copini, P. ; Gebauer, Roman ; Grönlund, Leila ; Hölttä, Teemu ; Lobo-do-Vale, Raquel L. ; Peltoniemi, M. ; Stritih, A. ; Urban, Josef ; Delzon, S. - \ 2018
hydraulic safety - hydraulic efficiency - phenotypic variability - drought - species distribution
Transcriptome analysis reveals several b-glucan recognition pathways in carp macrophages
Petit, J. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2018
Studying metabolic pathways in macrophages of carp
Wentzel, A.S. ; Petit, J. ; Boer, V.C.J. de; Forlenza, M. ; Wiegertjes, G. - \ 2018
The role of fibers in poultry and swine nutrition’
Vries, Sonja de - \ 2018
Training the immune system to become as healthy as a fish
Petit, J. ; Embregts, C.W.E. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2018
Training carp macrophages: establishment of an in vitro screening model for trained immunity in teleost fish
Petit, J. ; Embregts, C.W.E. ; Forlenza, M. ; Wiegertjes, G. - \ 2018
Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
Karp, Daniel S. ; Chaplin-Kramer, Rebecca ; Meehan, Timothy D. ; Martin, Emily A. ; Declerck, Fabrice ; Grab, Heather ; Gratton, Claudio ; Hunt, Lauren ; Larsen, Ashley E. ; Martínez-Salinas, Alejandra ; O’Rourke, Megan E. ; Rusch, Adrien ; Poveda, Katja ; Jonsson, Mattias ; Rosenheim, Jay A. ; Schellhorn, Nancy A. ; Tscharntke, Teja ; Wratten, Stephen D. ; Zhang, Wei ; Iverson, Aaron L. ; Adler, Lynn S. ; Albrecht, Matthias ; Alignier, Audrey ; Angelella, Gina M. ; Zubair Anjum, Muhammad ; Avelino, Jacques ; Batáry, Péter ; Baveco, Johannes M. ; Bianchi, Felix J.J.A. ; Birkhofer, Klaus ; Bohnenblust, Eric W. ; Bommarco, Riccardo ; Brewer, Michael J. ; Caballero-López, Berta ; Carrière, Yves ; Carvalheiro, Luísa G. ; Cayuela, Luis ; Centrella, Mary ; Ćetković, Aleksandar ; Henri, Dominic Charles ; Chabert, Ariane ; Costamagna, Alejandro C. ; La Mora, Aldo De; Kraker, Joop De; Desneux, Nicolas ; Diehl, Eva ; Diekötter, Tim ; Dormann, Carsten F. ; Eckberg, James O. ; Entling, Martin H. ; Fiedler, Daniela ; Franck, Pierre ; Veen, F.J.F. van; Frank, Thomas ; Gagic, Vesna ; Garratt, Michael P.D. ; Getachew, Awraris ; Gonthier, David J. ; Goodell, Peter B. ; Graziosi, Ignazio ; Groves, Russell L. ; Gurr, Geoff M. ; Hajian-Forooshani, Zachary ; Heimpel, George E. ; Herrmann, John D. ; Huseth, Anders S. ; Inclán, Diego J. ; Ingrao, Adam J. ; Iv, Phirun ; Jacot, Katja ; Johnson, Gregg A. ; Jones, Laura ; Kaiser, Marina ; Kaser, Joe M. ; Keasar, Tamar ; Kim, Tania N. ; Kishinevsky, Miriam ; Landis, Douglas A. ; Lavandero, Blas ; Lavigne, Claire ; Ralec, Anne Le; Lemessa, Debissa ; Letourneau, Deborah K. ; Liere, Heidi ; Lu, Yanhui ; Lubin, Yael ; Luttermoser, Tim ; Maas, Bea ; Mace, Kevi ; Madeira, Filipe ; Mader, Viktoria ; Cortesero, Anne Marie ; Marini, Lorenzo ; Martinez, Eliana ; Martinson, Holly M. ; Menozzi, Philippe ; Mitchell, Matthew G.E. ; Miyashita, Tadashi ; Molina, Gonzalo A.R. ; Molina-Montenegro, Marco A. ; O’Neal, Matthew E. ; Opatovsky, Itai ; Ortiz-Martinez, Sebaastian ; Nash, Michael ; Östman, Örjan ; Ouin, Annie ; Pak, Damie ; Paredes, Daniel ; Parsa, Soroush ; Parry, Hazel ; Perez-Alvarez, Ricardo ; Perović, David J. ; Peterson, Julie A. ; Petit, Sandrine ; Philpott, Stacy M. ; Plantegenest, Manuel ; Plećaš, Milan ; Pluess, Therese ; Pons, Xavier ; Potts, Simon G. ; Pywell, Richard F. ; Ragsdale, David W. ; Rand, Tatyana A. ; Raymond, Lucie ; Ricci, Benoît ; Sargent, Chris ; Sarthou, Jean-Pierre ; Saulais, Julia ; Schäckermann, Jessica ; Schmidt, Nick P. ; Schneider, Gudrun ; Schüepp, Christof ; Sivakoff, Frances S. ; Smith, Henrik G. ; Stack Whitney, Kaitlin ; Stutz, Sonja ; Szendrei, Zsofia ; Takada, Mayura B. ; Taki, Hisatomo ; Tamburini, Giovanni ; Thomson, Linda J. ; Tricault, Yann ; Tsafack, Noelline ; Tschumi, Matthias ; Valantin-Morison, Muriel ; Trinh, Mai Van; Werf, Wopke Van Der; Vierling, Kerri T. ; Werling, Ben P. ; Wickens, Jennifer B. ; Wickens, Victoria J. ; Woodcock, Ben A. ; Wyckhuys, Kris ; Xiao, Haijun ; Yasuda, Mika ; Yoshioka, Akira - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)33. - ISSN 0027-8424 - p. E7863 - E7870.
The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe
González-Muñoz, N. ; Sterck, F. ; Torres-Ruiz, J.M. ; Petit, G. ; Cochard, H. ; Arx, G. von; Lintunen, A. ; Caldeira, M.C. ; Capdeville, G. ; Copini, P. ; Gebauer, R. ; Grönlund, L. ; Hölttä, T. ; Lobo-do-Vale, R. ; Peltoniemi, M. ; Stritih, A. ; Urban, J. ; Delzon, S. - \ 2018
PLoS ONE 13 (2018)5. - ISSN 1932-6203
Many studies have reported that hydraulic properties vary considerably between tree species, but little is known about their intraspecific variation and, therefore, their capacity to adapt to a warmer and drier climate. Here, we quantify phenotypic divergence and clinal variation for embolism resistance, hydraulic conductivity and branch growth, in four tree species, two angiosperms (Betula pendula, Populus tremula) and two conifers (Picea abies, Pinus sylvestris), across their latitudinal distribution in Europe. Growth and hydraulic efficiency varied widely within species and between populations. The variability of embolism resistance was in general weaker than that of growth and hydraulic efficiency, and very low for all species but Populus tremula. In addition, no and weak support for a safety vs. efficiency trade-off was observed for the angiosperm and conifer species, respectively. The limited variability of embolism resistance observed here for all species except Populus tremula, suggests that forest populations will unlikely be able to adapt hydraulically to drier conditions through the evolution of embolism resistance.
Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe
Petit, Giai ; Arx, Georg von; Kiorapostolou, Natasa ; Lechthaler, Silvia ; Prendin, Angela Luisa ; Anfodillo, Tommaso ; Caldeira, Maria C. ; Cochard, Hervé ; Copini, Paul ; Crivellaro, Alan ; Delzon, Sylvain ; Gebauer, Roman ; Gričar, Jožica ; Grönholm, Leila ; Hölttä, Teemu ; Jyske, Tuula ; Lavrič, Martina ; Lintunen, Anna ; Lobo-do-Vale, Raquel ; Peltoniemi, Mikko ; Peters, Richard L. ; Robert, Elisabeth M.R. ; Roig Juan, Sílvia ; Senfeldr, Martin ; Steppe, Kathy ; Urban, Josef ; Camp, Janne Van; Sterck, Frank - \ 2018
New Phytologist 218 (2018)4. - ISSN 0028-646X - p. 1383 - 1392.
Allocation - Climate change - Functional balance - Leaf area - Plant architecture - Sapwood - Structural balance - Xylem
Trees scale leaf (AL) and xylem (AX) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in AL: AX balance in response to climate conditions, but whether trees of different species acclimate in AL: AX in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of AL vs AX in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, AL and AX change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of AL vs AX with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance.
Increased oxygen radicals and phagocytosis, and altered immune response dynamics in trained carp macrophages
Petit, J. ; Embregts, C.W.E. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2017
Increased immune activities in "trained" common carp macrophages
Petit, J. ; Embregts, C.W.E. ; Wentzel, A.S. ; Forlenza, M. ; Wiegertjes, G. - \ 2017
- 1 p.
Intramuscular DNA vaccination of juvenile carp against spring viremia of carp virus induces full protection and Establishes a Virus-Specific B and T Cell Response
Embregts, Carmen W.E. ; Rigaudeau, Dimitri ; Veselỳ, Tomáš ; Pokorová, Dagmar ; Lorenzen, Niels ; Petit, Jules ; Houel, Armel ; Dauber, Malte ; Schütze, Heike ; Boudinot, Pierre ; Wiegertjes, Geert F. ; Forlenza, Maria - \ 2017
Frontiers in Immunology 8 (2017). - ISSN 1664-3224 - 16 p.
B cells - DNA vaccination - Rhabdovirus - Spring viremia of carp virus - T cells

Although spring viremia of carp virus (SVCV) can cause high mortalities in common carp, a commercial vaccine is not available for worldwide use. Here, we report a DNA vaccine based on the expression of the SVCV glycoprotein (G) which, when injected in the muscle even at a single low dose of 0.1 μg DNA/g of fish, confers up to 100% protection against a subsequent bath challenge with SVCV. Importantly, to best validate vaccine efficacy, we also optimized a reliable bath challenge model closely mimicking a natural infection, based on a prolonged exposure of carp to SVCV at 15°C. Using this optimized bath challenge, we showed a strong age-dependent susceptibility of carp to SVCV, with high susceptibility at young age (3 months) and a full resistance at 9 months. We visualized local expression of the G protein and associated early inflammatory response by immunohistochemistry and described changes in the gene expression of pro-inflammatory cytokines, chemokines, and antiviral genes in the muscle of vaccinated fish. Adaptive immune responses were investigated by analyzing neutralizing titers against SVCV in the serum of vaccinated fish and the in vitro proliferation capacity of peripheral SVCV-specific T cells. We show significantly higher serum neutralizing titers and the presence of SVCV-specific T cells in the blood of vaccinated fish, which proliferated upon stimulation with SVCV. Altogether, this is the first study reporting on a protective DNA vaccine against SVCV in carp and the first to provide a detailed characterization of local innate as well as systemic adaptive immune responses elicited upon DNA vaccination that suggest a role not only of B cells but also of T cells in the protection conferred by the SVCV-G DNA vaccine.

Effect of the middle lamella biochemical composition on the non-linear behaviour of technical fibres of hemp under tensile loading using strain mapping
Fuentes, C.A. ; Willekens, P. ; Petit, J. ; Thouminot, C. ; Müssig, J. ; Trindade, L.M. ; Vuure, A.W. Van - \ 2017
Composites Part A: Applied Science and Manufacturing 101 (2017). - ISSN 1359-835X - p. 529 - 542.
A. Biocomposite - A. Natural fibres - B. Fibre deformation - Strain mapping
This manuscript describes the effects of alterations in biochemical composition on structural morphology and the mechanical behaviour of technical fibres of hemp used for composite applications. First, the strength and apparent Young's modulus distribution of technical fibres of hemp of 96 hemp samples, corresponding to 32 different hemp accessions cultivated in 3 locations, were analysed using Weibull distribution. From these, 2 samples (one with high and one with low fibre strength) were selected for further analysis. Next, full-field strain measurement at the micro-scale during tensile loading via digital image correlation analysis was used for evaluating both, the stress-strain behaviour at a global scale and the local mechanical behaviour heterogeneity at a micro-scale, along a technical fibre of hemp. The analysis reveals 2 typical types of tensile stress-strain curves, and a complex and very irregular pattern of strain concentrations, which are associated to the technical fibre strength. The non-linear behaviour of the stress-strain curve is explained by the development of shear strain at the elementary fibre (botanically defined as the individual cell) interphases. Micro tomography and biochemical analysis of the technical fibre microstructure showed that alterations in cell wall composition, in particular substitution of pectin, leads to changes in the non-linear behaviour of technical fibres of hemp under tensile loading.
Genomic and transcriptomic approaches to study immunology in cyprinids : What is next?
Petit, Jules ; David, Lior ; Dirks, Ron ; Wiegertjes, Geert F. - \ 2017
Developmental and Comparative Immunology 75 (2017). - ISSN 0145-305X - p. 48 - 62.
Carp - Cyprinidae - Immunity - NGS - Polyploidy - Whole genome duplication

Accelerated by the introduction of Next-Generation Sequencing (NGS), a number of genomes of cyprinid fish species have been drafted, leading to a highly valuable collective resource of comparative genome information on cyprinids (Cyprinidae). In addition, NGS-based transcriptome analyses of different developmental stages, organs, or cell types, increasingly contribute to the understanding of complex physiological processes, including immune responses. Cyprinids are a highly interesting family because they comprise one of the most-diversified families of teleosts and because of their variation in ploidy level, with diploid, triploid, tetraploid, hexaploid and sometimes even octoploid species. The wealth of data obtained from NGS technologies provides both challenges and opportunities for immunological research, which will be discussed here. Correct interpretation of ploidy effects on immune responses requires knowledge of the degree of functional divergence between duplicated genes, which can differ even between closely-related cyprinid fish species. We summarize NGS-based progress in analysing immune responses and discuss the importance of respecting the presence of (multiple) duplicated gene sequences when performing transcriptome analyses for detailed understanding of complex physiological processes. Progressively, advances in NGS technology are providing workable methods to further elucidate the implications of gene duplication events and functional divergence of duplicates genes and proteins involved in immune responses in cyprinids. We conclude with discussing how future applications of NGS technologies and analysis methods could enhance immunological research and understanding.

Conservation of macrophage polarization in fish
Wentzel, A.S. ; Petit, J. ; Fink, I.R. ; Forlenza, M. ; Wiegertjes, G. - \ 2016
Macrophages of higher vertebrates can express a range of activation states, with the extremes termed M1 and M2. Neither the evolutionary conservation of these activation states, nor the exact microbial and/or cytokine stimulants involved, have been examined in detail in lower vertebrates. We have shown that macrophages of teleost fish, including carp, have the ability to polarize into activation states typical of classical (M1) and alternative (M2) extremes upon stimulation with LPS, or exogenous cAMP, respectively. Upon this polarization, carp macrophages display functional profiles and several molecular markers that indicate the M1-M2 dichotomy could be an intrinsic property of macrophages which arose early in evolution. Owing to the more recent discoveries of IFN-y and lL-4/IL-13-like cytokines in teleost fish, we now can also study cytokine-dependent polarization of carp macrophages. Interferon-y amplifies LPS-induced polarisation into M1-like profiles of carp macrophages, including the induction of nitric oxide. Strikingly, IL-4/IL-13 appears to increase levels of arginase along with an activation profile that at least partly overlaps with that of cAMP-induced M2 macrophages. Thus, the chief macrophage M1 and M2 activation states appear to operate under the guidance of primordially conserved principles.
Increased oxygen but not nitrogen radicals in trained carp macrophages
Petit, J. ; Wentzel, A.S. ; Wiegertjes, G. - \ 2016
Allometric trajectories and "stress" : A quantitative approach
Anfodillo, Tommaso ; Petit, Giai ; Sterck, Frank ; Lechthaler, Silvia ; Olson, Mark E. - \ 2016
Frontiers in Plant Science 7 (2016). - ISSN 1664-462X - 6 p.
Fitness - Morphospace - Operationalization - Plasticity - Scaling

The term "stress" is an important but vague term in plant biology. We show situations in which thinking in terms of "stress" is profitably replaced by quantifying distance from functionally optimal scaling relationships between plant parts. These relationships include, for example, the often-cited one between leaf area and sapwood area, which presumably reflects mutual dependence between sources and sink tissues and which scales positively within individuals and across species. These relationships seem to be so basic to plant functioning that they are favored by selection across nearly all plant lineages.Within a species or population, individuals that are far from the common scaling patterns are thus expected to perform negatively. For instance, "too little" leaf area (e.g., due to herbivory or disease) per unit of active stem mass would be expected to incur to low carbon income per respiratory cost and thus lead to lower growth. We present a framework that allows quantitative study of phenomena traditionally assigned to "stress," without need for recourse to this term. Our approach contrasts with traditional approaches for studying "stress," e.g., revealing that small "stressed" plants likely are in fact well suited to local conditions. We thus offer a quantitative perspective to the study of phenomena often referred to under such terms as "stress," plasticity, adaptation, and acclimation.

Osmolality and non-structural carbohydrate composition in the secondary phloem of trees across a latitudinal gradient in Europe
Lintunen, Anna ; Paljakka, Teemu ; Jyske, Tuula ; Peltoniemi, Mikko ; Sterck, Frank ; Arx, Georg Von; Cochard, Hervé ; Copini, Paul ; Caldeira, Maria C. ; Delzon, Sylvain ; Gebauer, Roman ; Grönlund, Leila ; Kiorapostolou, Natasa ; Lechthaler, Silvia ; Lobo-Do-Vale, Raquel ; Peters, Richard L. ; Petit, Giai ; Prendin, Angela L. ; Salmon, Yann ; Steppe, Kathy ; Urban, Josef ; Juan, Sílvia Roig ; Robert, Elisabeth M.R. ; Hölttä, Teemu - \ 2016
Frontiers in Plant Science 7 (2016)JUNE2016. - ISSN 1664-462X
Hexose - Osmotic concentration - Phloem water content - Pinitol - Raffinose - Starch - Sucrose

Phloem osmolality and its components are involved in basic cell metabolism, cell growth, and in various physiological processes including the ability of living cells to withstand drought and frost. Osmolality and sugar composition responses to environmental stresses have been extensively studied for leaves, but less for the secondary phloem of plant stems and branches. Leaf osmotic concentration and the share of pinitol and raffinose among soluble sugars increase with increasing drought or cold stress, and osmotic concentration is adjusted with osmoregulation. We hypothesize that similar responses occur in the secondary phloem of branches. We collected living bark samples from branches of adult Pinus sylvestris, Picea abies, Betula pendula and Populus tremula trees across Europe, from boreal Northern Finland to Mediterranean Portugal. In all studied species, the observed variation in phloem osmolality was mainly driven by variation in phloem water content, while tissue solute content was rather constant across regions. Osmoregulation, in which osmolality is controlled by variable tissue solute content, was stronger for Betula and Populus in comparison to the evergreen conifers. Osmolality was lowest in mid-latitude region, and from there increased by 37% toward northern Europe and 38% toward southern Europe due to low phloem water content in these regions. The ratio of raffinose to all soluble sugars was negligible at mid-latitudes and increased toward north and south, reflecting its role in cold and drought tolerance. For pinitol, another sugar known for contributing to stress tolerance, no such latitudinal pattern was observed. The proportion of sucrose was remarkably low and that of hexoses (i.e., glucose and fructose) high at mid-latitudes. The ratio of starch to all non-structural carbohydrates increased toward the northern latitudes in agreement with the build-up of osmotically inactive C reservoir that can be converted into soluble sugars during winter acclimation in these cold regions. Present results for the secondary phloem of trees suggest that adjustment with tissue water content plays an important role in osmolality dynamics. Furthermore, trees acclimated to dry and cold climate showed high phloem osmolality and raffinose proportion.

Long-lived effects of administering β-glucans : Indications for trained immunity in fish
Petit, Jules ; Wiegertjes, Geert F. - \ 2016
Developmental and Comparative Immunology 64 (2016). - ISSN 0145-305X - p. 93 - 102.
Fish - Immune-stimulation - Innate immunity - Teleost - Trained immunity - β-glucans

Over the past decades, it has become evident that immune-modulation of fish with β-glucans, using injection, dietary or even immersion routes of administration, has stimulating but presumed short-lived effects on both intestinal and systemic immunity and can increase protection against a subsequent pathogenic challenge. Although the exact effects can be variable depending on, among others, fish species and administration route, the immune-stimulating effects of β-glucans on the immune system of fish appear to be universal. This review provides a condensed update of the most recent literature describing the effects of β-glucans on the teleost fish immune system. We shortly discuss possible mechanisms influencing immune-stimulation by β-glucans, including microbial composition of the gut, receptor recognition and downstream signalling. Of interest, in mammalian monocytes, β-glucans are potent inducers of trained immunity. First, we screened the literature for indications of this phenomenon in fish. Criteria that we applied include indications for at least one out of three features considered characteristic of trained immunity; (i) providing protection against a secondary infection in a T- and B-lymphocyte independent manner, (ii) conferring increased resistance upon re-infection and, (iii) relying on key roles for innate immune cell types such as natural killer cells and macrophages. We conclude that several indications exist that support the notion that the innate immune system of teleost fish can be trained. Second, we screened the literature for indications of long-lived effects on innate immunity of fish after administering β-glucans, a criterion which could help to identify key roles for macrophages on resistance to infection. We discuss whether β-glucans, as well-known immune-stimulants, are able to train the immune system of fish and argue in favour of further studies designed to specifically investigate this phenomenon in fish.

Sugar and acid interconversion in tomato fruits based on biopsy sampling of locule gel and pericarp tissue
Schouten, R.E. ; Woltering, E.J. ; Tijskens, L.M.M. - \ 2016
Postharvest Biology and Technology 111 (2016). - ISSN 0925-5214 - p. 83 - 92.
This study deals with quantifying sugar and acids levels important for the perceived taste of tomatoes (Solanum lycopersicum). Sugar and acids levels were measured repeatedly on the same tomato using tissue samples obtained with a biopsy needle in combination with HPLC protocols. Biopsies of pericarp and locular gel tissue from tomatoes differing in position in the truss, from mature green to ripe red, were taken from a beef- (‘Licorossa’), a cocktail- (‘Lucino’) and a cherry type (‘Petit Sweet’) cultivar. Tomatoes were stored up to three weeks at three temperatures (12, 19 and 24.5 °C) and biopsy samples were taken every few days. A model regarding the most important processes that interconvert sugars and acids (glycolysis, TCA cycle and gluconeogenesis (GNG)) is proposed. Results of the model calibration showed more breakdown of hexoses in red tomatoes and more conversion of malate into hexoses in green tomatoes. More hexose turnover was found in locular gel than in pericarp tissue. GNG was more important in the cherry type cultivar due to faster hexose and malate breakdown. In the round type cultivar malate levels were higher due to faster citrate breakdown and slower malate breakdown. Starch and sucrose levels did not significantly affect postharvest sugar and acid development. Molecular markers that quantify the kinetic parameters of the model might be important to develop genotypes with better taste performance.
Evidence for trained immunity in fish
Petit, J. ; Forlenza, M. ; Wiegertjes, G. - \ 2015
Dominance in domestic dogs : A quantitative analysis of its behavioural measures
Borg, J.A.M. Van Der; Schilder, M.B.H. ; Vinke, C.M. ; Vries, Han De; Petit, Odile - \ 2015
PLoS ONE 10 (2015)8. - ISSN 1932-6203 - 18 p.

A dominance hierarchy is an important feature of the social organisation of group living animals. Although formal and/or agonistic dominance has been found in captive wolves and free-ranging dogs, applicability of the dominance concept in domestic dogs is highly debated, and quantitative data are scarce. Therefore, we investigated 7 body postures and 24 behaviours in a group of domestic dogs for their suitability as formal status indicators. The results showed that high posture, displayed in most dyadic relationships, and muzzle bite, displayed exclusively by the highest ranking dogs, qualified best as formal dominance indicators. The best formal submission indicator was body tail wag, covering most relationships, and two low postures, covering two-thirds of the relationships. In addition, both mouth lick, as included in Schenkel's active submission, and pass under head qualified as formal submission indicators but were shown almost exclusively towards the highest ranking dogs. Furthermore, a status assessment based on changes in posture displays, i.e., lowering of posture (LoP) into half-low, low, low-on-back or on-back, was the best status indicator for most relationships as it showed good coverage (91% of the dyads), a nearly linear hierarchy (h' = 0.94, p

Evidence for innate immune memory in fish
Petit, J. ; Wiegertjes, G. - \ 2015
Evaluation of tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) hairy roots for the production of geraniol, the first committed step in terpenoid indole alkaloid pathway
Ritala, A. ; Dong, L. ; Imseng, N. ; Seppanen-Laakso, T. ; Vasilev, N. ; Krol, A.R. van der; Rischer, H. ; Maaheimo, H. ; Virkki, A. ; Brandli, J. ; Schillberg, S. ; Eibl, R. ; Bouwmeester, H.J. ; Oksman-Caldentey, K.M. - \ 2014
Journal of Biotechnology 176 (2014). - ISSN 0168-1656 - p. 20 - 28.
catharanthus-roseus - isoprenoid biosynthesis - plastidial pathways - essential oils - key enzyme - monoterpene - cultures - synthase - cells - bioreactors
The terpenoid indole alkaloids are one of the major classes of plant-derived natural products and are well known for their many applications in the pharmaceutical, fragrance and cosmetics industries. Hairy root cultures are useful for the production of plant secondary metabolites because of their genetic and biochemical stability and their rapid growth in hormone-free media. Tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) hairy roots, which do not produce geraniol naturally, were engineered to express a plastidtargeted geraniol synthase gene originally isolated from Valeriana officinalis L. (VoGES). A SPME-GC–MS screening tool was developed for the rapid evaluation of production clones. The GC–MS analysis revealed that the free geraniol content in 20 hairy root clones expressing VoGES was an average of 13.7 g/g dry weight (DW) and a maximum of 31.3 g/g DW. More detailed metabolic analysis revealed that geraniol derivatives were present in six major glycoside forms, namely the hexose and/or pentose conjugates of geraniol and hydroxygeraniol, resulting in total geraniol levels of up to 204.3 g/g DW following deglycosylation. A benchtop-scale process was developed in a 20-L wave-mixed bioreactor eventually yielding hundreds of grams of biomass and milligram quantities of geraniol per cultivation bag.
Evolution of uni- and bifactorial sexual compatibility systems in fungi
Nieuwenhuis, B.P.S. ; Billiard, S. ; Vuilleumier, S. ; Petit, E. ; Hood, M.E. ; Giraud, T. - \ 2013
Heredity 111 (2013)6. - ISSN 0018-067X - p. 445 - 455.
mating-type locus - schizophyllum-commune - microbotryum-violaceum - wood-decay - cryptococcus-neoformans - transposable elements - self-incompatibility - tilletia-indica - ustilago-maydis - gene
Mating systems, that is, whether organisms give rise to progeny by selfing, inbreeding or outcrossing, strongly affect important ecological and evolutionary processes. Large variations in mating systems exist in fungi, allowing the study of their origin and consequences. In fungi, sexual incompatibility is determined by molecular recognition mechanisms, controlled by a single mating-type locus in most unifactorial fungi. In Basidiomycete fungi, however, which include rusts, smuts and mushrooms, a system has evolved in which incompatibility is controlled by two unlinked loci. This bifactorial system probably evolved from a unifactorial system. Multiple independent transitions back to a unifactorial system occurred. It is still unclear what force drove evolution and maintenance of these contrasting inheritance patterns that determine mating compatibility. Here, we give an overview of the evolutionary factors that might have driven the evolution of bifactoriality from a unifactorial system and the transitions back to unifactoriality. Bifactoriality most likely evolved for selfing avoidance. Subsequently, multiallelism at mating-type loci evolved through negative frequency-dependent selection by increasing the chance to find a compatible mate. Unifactoriality then evolved back in some species, possibly because either selfing was favoured or for increasing the chance to find a compatible mate in species with few alleles. Owing to the existence of closely related unifactorial and bifactorial species and the increasing knowledge of the genetic systems of the different mechanisms, Basidiomycetes provide an excellent model for studying the different forces that shape breeding systems.
Genetic diversity of Vietnamese domestic chicken populations as decision-making support for conservation strategies
Pham, H.T.M. ; Berthouly-Salazar, C. ; Crooijmans, R.P.M.A. - \ 2013
Animal Genetics 44 (2013)5. - ISSN 0268-9146 - p. 509 - 521.
multilocus genotype data - breeds - program - microsatellites - construction - resources - inference - software - ecotypes - alleles
The aims of this study were to assess the genetic diversity of 17 populations of Vietnamese local chickens (VNN) and one Red Jungle Fowl population, together with six chicken populations of Chinese origin (CNO), and to provide priorities supporting the conservation of genetic resources using 20 microsatellites. Consequently, the VNN populations exhibited a higher diversity than did CNO populations in terms of number of alleles but showed a slightly lower observed heterozygosity. The VNN populations showed in total seven private alleles, whereas no CNO private alleles were found. The expected heterozygosity of 0.576 in the VNN populations was higher than the observed heterozygosity of 0.490, leading to heterozygote deficiency within populations. This issue could be partly explained by the Wahlund effect due to fragmentation of several populations between chicken flocks. Molecular analysis of variance showed that most of genetic variation was found within VNN populations. The Bayesian clustering analysis showed that VNN and CNO chickens were separated into two distinct groups with little evidence for gene flow between them. Among the 24 populations, 13 were successfully assigned to their own cluster, whereas the structuring was not clear for the remaining 11 chicken populations. The contributions of 24 populations to the total genetic diversity were mostly consistent across two approaches, taking into account the within- and between-populations genetic diversity and allelic richness. The black H'mong, Lien Minh, Luong Phuong and Red Jungle Fowl were ranked with the highest priorities for conservation according to Caballero and Toro's and Petit's approaches. In conclusion, a national strategy needs to be set up for Vietnamese chicken populations, with three main components: conservation of high-priority breeds, within-breed management with animal exchanges between flocks to avoid Wahlund effect and monitoring of inbreeding rate.
LED ligt gevoelig (Confrontatie Nico van der Houwen en Tom Dueck)
Petit, R. ; Dueck, T.A. - \ 2010
Groenten en Fruit Magazine 2010 (2010)7/8. - ISSN 1879-7318 - p. 34 - 35.
tuinbouw - kunstmatige verlichting - kunstlicht - energie - duurzaamheid (durability) - glastuinbouw - energiebesparing - horticulture - artificial lighting - artificial light - energy - durability - greenhouse horticulture - energy saving
De led-lamp beroerde een gevoelige snaar bij glastuinders in Nederland. Een duurzame lamp, energiezuinig, minder lichtuitstoot. Maar ook al wil iedereen dat het een succes wordt, daarmee ben je er nog niet. Tegenvallers hebben de tuinbouw nu led-moe gemaakt.
Land cover change in Europe between 1950 and 2000 determined employing aerial photography
Gerard, F. ; Bugar, G. ; Gregor, M. ; Halada, L. ; Hazeu, G.W. ; Huitu, H. ; Köhler, H.R. ; Kolar, J. ; Luque, S. ; Mücher, C.A. ; Olschofsky, K. ; Petit, S. ; Pino, J. ; Smith, G. ; Thomson, A. ; Wachowicz, M. ; Bezák, P. ; Brown, N. ; Boltiziar, M. ; Badts, E. de; Feranec, J. ; Halabuk, A. ; Manchester, S. ; Mojse, M. ; Petrovic, F. ; Pons, X. ; Roda, F. ; Roscher, M. ; Sustera, J. ; Tuominen, S. ; Wadsworth, R. ; Ziese, H. - \ 2010
Progress in Physical Geography 34 (2010)2. - ISSN 0309-1333 - p. 183 - 205.
BIOPRESS (‘Linking Pan-European Land Cover Change to Pressures on Biodiversity’), a European Commission funded ‘Global Monitoring for Environment and Security’ project, produced land cover change information (1950—2000) for Europe from aerial photographs and tested the suitability of this for monitoring habitats and biodiversity. The methods and results related to the land cover change work are summarized. Changes in land cover were established through 73 window and 59 transect samples distributed across Europe. Although the sample size was too small and biased to fully represent the spatial variability observed in Europe, the work highlighted the importance of method consistency, the choice of nomenclature and spatial scale. The results suggest different processes are taking place in different parts of Europe: the Boreal and Alpine regions are dominated by forest management; abandonment and intensification are mainly encountered in the Mediterranean; urbanization and drainage are more characteristic of the Continental and Atlantic regions.
Bluetongue control in Europe - New challenges and achievements
Makoschey, B. ; Maclachlan, J. ; Wuijckhuise, L. van; Kirschvink, N. ; Pozzo, F. Dal; Petit, H. ; Kaandorp-Huber, C. ; Rijn, P.A. van; Sellal, E. ; Oura, C.A.L. - \ 2009
Berliner und Münchener Tierärztliche Wochenschrift 122 (2009)7-8. - ISSN 0005-9366 - p. 320 - 324.
Historical analysis of the effectiveness of AKST systems in promoting innovation
Dreyfus, F. ; Plencovich, C. ; Petit, M. ; Akca, H. ; Dogheim, S. ; Ishii-Eitman, M. ; Kingamkono, R. ; Jiggins, J.L.S. ; Keith, D. - \ 2008
In: Agriculture at a Crossroads: The IAASTD Global Report / McIntyre, B.D., Herren, H.R., Wakhungu, J., Watson, R.T., Washington, DC : Island Press - ISBN 9781597265393
Land use functions — a multifunctionality approach to assess the impact of land use changes on land use sustainability
Pérez-Soba, M. ; Petit, S. ; Jones, L. ; Bertrand, N. ; Briquel, V. ; Omodei-Zorini, L. ; Contini, C. ; Helming, K. ; Farrington, J. ; Tinacci Mossello, M. ; Wascher, D. ; Kienast, F. ; Groot, R.S. de - \ 2008
In: Sustainability Impact Assessment of land use changes / Helming, K., Pérez-Soba, M., Tabbush, P., Berlin : Springer - ISBN 9783540786474 - p. 375 - 404.
The dramatic changes in land use observed in Europe in the last fifty years have generally resulted in improvement of human welfare and economic development. On the other hand, they have caused serious environmental problems. There is therefore a need for approaches that help to understand in an integrative way the economic, environmental and societal impacts that land use changes have on sustainability. Sustainability Impact Assessment (SIA), which assesses the impact of policies on sustainability, addresses this challenge. SIA partly builds on the concept of the multifunctionality of land which helps to deal with the complexity of interactions between different land uses, their temporal and spatial changes, and finally how policies might steer those changes towards sustainability. Following this need for true integration of economic, environmental and societal issues across policy areas at a meaningful spatial scale, an interdisciplinary team in the SENSOR project has developed an innovative conceptual framework to assess the impact of policies on land sustainability at various levels of spatial aggregation i.e. the Land Use Functions (LUFs) framework. LUFs are the goods and services provided by the different land uses that summarise the most relevant economic, environmental and societal issues of a region. The LUFs framework integrates the changes observed in a large set of impact indicators into nine Land Use Functions (LUFs), which are balanced among the three pillars of sustainability. The LUFs framework makes it possible for policy makers, scientists and stakeholders to identify at a glance those functions of the land which are hindered or enhanced under various scenarios of land use change, and makes it possible to explore the trade-offs between them. The LUFs framework allows therefore the building of assessment across disciplines, sectors and the three sustainability dimensions. It has proved to be very helpful for the systematisation of relevant sustainability indicators within SENSOR and is intended to be further used in other projects as a tool for Sustainability Impact Assessment. The rationale leading to the LUFs concept, its definition and the conceptual framework is described in this chapter. We conclude that the concept of LUFs allows users to make explicit the analytical links between multifunctional land use and sustainable development, and therefore to look at multifunctionality as a way towards sustainability.
Land Use Functions - an approach to integrate economic, environmental and societal impacts of land use change
Pérez-Soba, M. ; Petit, S. ; Jones, L. ; Betrand, N. ; Briquel, V. ; Omodei-Zorini, L. ; Contini, C. ; Helming, K. ; Farington, J. ; Tinacci Mossello, M. ; Wascher, D.M. ; Kienast, F. ; Groot, R.S. de - \ 2008
Reference material for radionuclides in sediment IAEA-384 (Fangataufa Lagoon sediment)
Povinec, P.P. ; Pham, M.K. ; Sanchez-Cabeza, J.A. ; Barci-Funel, G. ; Bojanowski, R. ; Boshkova, T. ; Burnett, W.C. ; Carvalho, F. ; Chapeyron, B. ; Cunha, I.L. ; Dahlgaard, H. ; Galabov, N. ; FiField, L.K. ; Gastaud, J. ; Geering, J.J. ; Gomez, I.F. ; Green, N. ; Hamilton, T. ; Ibanez, F.L. ; Ibn Majah, M. ; John, M. ; Kanisch, G. ; Kenna, T.C. ; Kloster, M. ; Korun, M. ; Liong Wee Kwong, L. ; Rosa, J. la; Lee, S.H. ; Levy-Palomo, I. ; Malatova, M. ; Maruo, Y. ; Mitchell, P. ; Murciano, I.V. ; Nelson, R. ; Nouredine, A. ; Oh, J.S. ; Origioni, B. ; Petit, G. le; Petterson, H.B.L. ; Reineking, A. ; Smedley, P.A. ; Suckow, A. ; Struijs, T.D.B. van der; Voors, P.I. ; Yoshimizu, K. ; Wyse, E. - \ 2007
Journal of Radioanalytical and Nuclear Chemistry 273 (2007)2. - ISSN 0236-5731 - p. 383 - 393.
certified reference material - pacific-ocean - irish sea - seawater - water - pu
A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides (40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides in the environment, as well as for the development and validation of analytical methods and for training purposes. The material is available from IAEA in 100 g units.
Fungal bio-treatment of spruce wood with Trametes versicolor for pitch control: Influence on extractive contents, pulping process parameters, paper quality and effluent toxicity
Beek, T.A. van; Kuster, B. ; Claassen, F.W. ; Tienvieri, T. ; Bertaud, F. ; Lennon, G. ; Petit-Concil, M. ; Sierra-Alvarez, R. - \ 2007
Bioresource Technology 98 (2007)2. - ISSN 0960-8524 - p. 302 - 311.
white-rot fungi - mills - detoxification - chromatography - degradation
Lipophilic low molar-mass constituents in wood chips for the paper industry result in low quality pulp, pitch deposition, and effluent toxicity. New biotechnological solutions such as fungal pre-treatment of wood chips can reduce pitch problems. This laboratory-scale study focuses on the potential and limitations of a fungal bio-treatment of Norway spruce chips with the white-rot fungus Trametes versicolor. Different fungal treatment conditions were compared. A 4-week fungal treatment reduced the concentration of resin acids and triglycerides by 40% and 100%, respectively, but neither lowered the energy requirements of the TMP process nor significantly affected the morphological fiber characteristics and the physical pulp properties. The pre-treatment led to slightly poorer optical properties. The Trametes versicolor fungal treatment contributed to a less toxic effluent and improved the biodegradability. A treatment of 2-3 weeks appears optimal
Aerial photo interpretation and derived statistics from 59 samples distributed across Europe
Gerard, F. ; Thompson, A. ; Manchester, S. ; Smith, G. ; Wadsworth, R. ; Swetnam, S. ; Petit, S. ; Gregor, M. ; Luque, S. ; Huitu, H. ; Köhler, H.R. ; Olschofsky, K. ; Hazeu, G.W. ; Mücher, C.A. ; Halada, L. ; Bugár, G. ; Pino, J. - \ 2006
In: Land Cover Change in Europe from the 1950'ies to 2000 / Köhler, R., Olschofsky, K., Gerard, F., Hamburg : University of Hamburg, World Forestry Institute - ISBN 8089088465 - 364 p.
Spatial impact of conservation sites (Natura 2000) on land cover changes
Mücher, S. ; Gerard, F. ; Olschofsky, K. ; Hazeu, G.W. ; Luque, S. ; Pino, J. ; Gregor, M. ; Wachowicz, M. ; Halada, L. ; Tompo, E. ; Kohler, R. ; Petit, S. ; Smith, G. ; Kolar, J. - \ 2006
In: Proceedings of the second workshop of the EARSeL SIG on remote sensing of land use & land cover; application & development, Bonn (Germany), September 28-30, 2006. - Bonn (Germany) : EARSeL - ISBN 3000205187 - p. 386 - 393.
Assessing the risk of impact of farming intensification on calcareous grasslands in Europe: a quantitative implementation of the MIRABEL framework
Petit, S. ; Elbersen, B.S. - \ 2006
Ambio 35 (2006)6. - ISSN 0044-7447 - p. 297 - 303.
species richness - biodiversity - conservation - nitrogen - landscapes - quality - balance - land - uk
Intensification of farming practices is still a major driver of biodiversity loss in Europe, despite the implementation of policies that aim to reverse this trend. A conceptual framework called MIRABEL was previously developed that enabled a qualitative and expert-based assessment of the impact of agricultural intensification on ecologically valuable habitats. We present a quantitative update of the previous assessment that uses newly available pan-European spatially explicit data on pressures and habitats at risk. This quantitative assessment shows that the number of calcareous grasslands potentially at risk of eutrophication and overgrazing is rapidly increasing in Europe. Decreases in nitrogen surpluses and stocking densities that occurred between 1990 and 2000 have rarely led to values that were below the ecological thresholds. At the same time, a substantial proportion of calcareous grassland that has so far experienced low values for indicators of farming intensification has faced increases between 1990 and 2000 and could well become at high risk from farming intensification in the near future. As such, this assessment is an early warning signal, especially for habitats located in areas that have traditionally been farmed extensively. When comparing the outcome of this assessment with the previous qualitative MIRABEL assessment, it appears that if pan-European data are useful to assess the intensity of the pressures, more work is needed to identify regional variations in the response of biodiversity to such pressures. This is where a qualitative approach based on regional expertise should be used to complement data-driven assessments.
The environmental impacts of the production of concentrated feed: the case of pig feed in Bretagne
Werf, H.M.G. ; Petit, J. ; Sanders, J. - \ 2005
Agricultural Systems 83 (2005)2. - ISSN 0308-521X - p. 153 - 177.
Pig production systems often depend to a large extent on concentrated feed imported from outside the farm. This study used the Life Cycle Assessment (LCA) method to assess major environmental impacts associated with the production and on-farm delivery of concentrated feed for pigs. Feed composition was based on average data for Bretagne (France) in 1998 and on published data for wheat-based, maize-based and co-product based feeds. As crop and feed production practices in Bretagne are similar to those in most of western Europe, we conclude that the results of this study apply more largely for western Europe. Depending on feed composition and fertilisation practise for crop-based feed ingredients, the production and delivery of one kg of feed for finishing pigs will produce a eutrophication potential between 3.8 and 9.3 g PO4-equivalents, a global warming potential between 472 and 792 g CO2-equivalents, an acidification potential between 3.0 and 6.3 g SO2-equivalents, a terrestrial ecotoxicity potential between 0.4 and 8.7 g 1,4-dichlorobenzene-equivalents, an energy use between 3.3 and 6.1 MJ, and land use between 1.44 and 2.07 m2 year. These impacts are mainly due to the production of crop-based ingredients. The contribution of transport processes was substantial for climate change, acidification and energy use. A feed containing mainly co-products had higher energy use and lower terrestrial ecotoxicity than feeds consisting mainly of non-processed crop-based ingredients. Hypotheses with respect to the fertilisation practices for the feed's main ingredients have a major effect on its impact values. The effect of uncertainty concerning the emissions of N2O, NH3, and NO3 was very large for climate change, and large for acidification and eutrophication. The environmental burdens associated with the production and delivery of pig feed can be decreased by: optimising the fertilisation of its crop based ingredients, using more locally produced feed ingredients, reducing concentrations of Cu and Zn in the feed, and using wheat-based rather than maize-based feeds.
Gerard, F. ; Gregor, M. ; Wachowicz, M. ; Olschofsky, K. ; Smith, G. ; Luque, S. ; Brems, E. ; Bugar, G. ; Hazeu, G.W. ; Janssens, E. ; Kohler, R. ; Kolar, J. ; Manchester, S. ; Mücher, C.A. ; Oszlanyi, J. ; Petit, S. ; Pino, J. ; Pons, X. ; Rocher, M. ; Sustera, J. ; Thomson, A. ; Tuominen, S. ; Halada, L. ; Hresko, J. ; Wadsworth, R. ; Wyatt, B. ; Ziese, H. - \ 2005
A long-term biodiversity, ecosystem and awareness research network; modelling and forecasting
Watt, A. ; Gelan, A. ; Courbaud, B. ; Topping, C.J. ; Klok, C. ; Maes, D. ; Bogusz, D. ; Framstad, E. ; Skov, F. ; Waetzold, F. ; Matteucci, G. ; Deffuant, G. ; Haberl, H. ; Tóth, J. ; Heizlar, J. ; Krause, K. ; Halada, L. ; Drechsler, M. ; Luoto, M. ; Petit, S. ; Dullinger, S. ; Marañon, T. ; Parr, T. ; Dirnböck, T. ; Tappeiner, U. ; Grandin, U. - \ 2005
[S.l.] : ALTER-Net (WP R6 Deliverable 2005-01) - 49 p.
The landscape ecology of the Atlantic mountains
Bunce, R.G.H. ; Petit, S. - \ 2005
- p. 1 - 10.
Increased and altered fragrance of tobacco plants after metabolic engineering using three monoterpene synthases from lemon
Lücker, J. ; Schwab, W. ; Hautum, B. van; Blaas, J. ; Plas, L.H.W. van der; Bouwmeester, H.J. ; Verhoeven, H.A. - \ 2004
Plant Physiology 134 (2004)1. - ISSN 0032-0889 - p. 510 - 519.
s-linalool synthase - biosynthetic-pathway - volatile compounds - nicotiana-tabacum - gene-expression - floral scents - flowers - transformation - emission - clarkia
Wild-type tobacco (Nicotiana tabacum) plants emit low levels of terpenoids, particularly from the flowers. By genetic modification of tobacco cv Petit Havana SR1 using three different monoterpene synthases from lemon (Citrus limon L. Burm. f.) and the subsequent combination of these three into one plant by crossings, we show that it is possible to increase the amount and alter the composition of the blend of monoterpenoids produced in tobacco plants. The transgenic tobacco plant line with the three introduced monoterpene synthases is emitting -pinene, limonene, and -terpinene and a number of side products of the introduced monoterpene synthases, from its leaves and flowers, in addition to the terpenoids emitted by wild-type plants. The results show that there is a sufficiently high level of substrate accessible for the introduced enzymes
Metabolic engineering of monoterpende biosysnthesis: two step production of (+)-trans-Isopiperitenol by tobacco
Lücker, J. ; Schwab, W. ; Franssen, M.C.R. ; Plas, L.H.W. van der; Bouwmeester, H.J. ; Verhoeven, H.A. - \ 2004
The Plant Journal 39 (2004)1. - ISSN 0960-7412 - p. 135 - 145.
peppermint mentha-piperita - functional expression - limonene enantiomers - linalool synthase - cdna isolation - s-linalool - plants - mint - (-)-limonene - cloning
Monoterpenoid biosynthesis in tobacco was modified by introducing two subsequent enzymatic activities targeted to different cell compartments. A limonene-3-hydroxylase (lim3h) cDNA was isolated from Mentha spicata L. 'Crispa'. This cDNA was used to re-transform a transgenic Nicotiana tabacum'Petit Havana' SR1 (tobacco) line expressing three Citrus limon L. Burm. f. (lemon) monoterpene synthases producing (+)-limonene, gamma-terpinene and (-)-beta-pinene as their main products. The targeting sequences of these synthases indicate that they are probably localized in the plastids, whereas the sequence information of the P450 hydroxylase indicates targeting to the endoplasmatic reticulum. Despite the different location of the enzymes, the introduced P450 hydroxylase proved to be functional in the transgenic plants as it hydroxylated (+)-limonene, resulting in the emission of (+)-trans-isopiperitenol. Some further modifications of the (+)-trans-isopiperitenol were also detected, resulting in the additional emission of 1,3,8-p-menthatriene, 1,5,8-p-menthatriene, p-cymene and isopiperitenone.
The capsid of infectious bursal disease virus contains several small peptides arising from the maturation process of pVP2
Costa, B. Da; Chevalier, C. ; Henry, C. ; Huet, J.C. ; Petit, S. ; Lepault, J. ; Boot, H. ; Delmas, B. - \ 2002
Journal of Virology 76 (2002). - ISSN 0022-538X - p. 2393 - 2402.
The capsid proteins VP2 and VP3 of infectious bursal disease virus, a birnavirus, are derived from the processing of a large polyprotein: NH2-pVP2-VP4-VP3-COOH. Although the primary cleavage sites at the pVP2-VP4 and VP4-VP3 junctions have been identified, the proteolytic cascade involved in the processing of this polyprotein is not yet fully understood, particularly the maturation of pVP2. By using different approaches, we showed that the processing of pVP2 (residues 1 to 512) generated VP2 and four small peptides (residues 442 to 487, 488 to 494, 495 to 501, and 502 to 512). We also showed that in addition to VP2, at least three of these peptides (residues 442 to 487, 488 to 494, and 502 to 512) were associated with the viral particles. The importance of the small peptides in the virus cycle was assessed by reverse genetics. Our results showed that the mutants lacking the two smaller peptides were viable, although the virus growth was affected. In contrast, deletions of the domain 442 to 487 or 502 to 512 did not allow virus recovery. Several amino acids of the peptide 502 to 512 appeared essential for virus viability. Substitutions of the P1 and/or P1" position were engineered at each of the cleavage sites (P1-P1": 441-442, 487-488, 494-495, 501-502, and 512-513). Most substitutions at the pVP2-VP4 junction (512-513) and at the final VP2 maturation cleavage site (441-442) were lethal. Mutations of intermediate cleavage sites (487-488, 494-495, and 501-502) led to viable viruses showing different but efficient pVP2 processing. Our data suggested that while peptides 488 to 494 and 495 to 501 play an accessory role, peptides 442 to 487 and 502 to 512 have an unknown but important function within the virus cycle.
General principles of monitoring land cover change based on two case studies in Britain and Denmark
Brandt, J.J.E. ; Bunce, R.G.H. ; Howard, D.C. ; Petit, S. - \ 2002
Landscape and Urban Planning 62 (2002)1. - ISSN 0169-2046 - p. 37 - 51.
monitoring - landschapsecologie - Denemarken - Groot-Brittannië
There is a well-established need to monitor land use and ecological change so that appropriate policies for the maintenance and enhancement of biodiversity can be developed. By building such exercises around sound scientific principles the reliabilityof the results can be quantified and policy makers can have confidence that they are genuinely independent. This paper describes two case studies of the development of such systems, the Small Biotope project of Denmark and the Countryside Survey project of Great Britain. These systems illustrate the problems involved in studies at the landscape level and the way satisfactory results can be achieved. Monitoring is considered to be effectively repeated surveillance and needs especially strict protocols toseparate real change from the artefacts of sampling. The lessons to be learnt from these studies are summarised as a number of guidelines.
Chloroplast DNA variation of oaks in western Central Europe and genetic consequences of human influences
König, A.O. ; Ziegenhagen, B. ; Dam, B.C. van; Csaikl, U.M. ; Coart, E. ; Degen, B. ; Burg, K. ; Vries, S.M.G. de; Petit, R.J. - \ 2002
Forest Ecology and Management 156 (2002)1-3. - ISSN 0378-1127 - p. 147 - 166.
biodiversiteit - biogeografie - eik - genetica - ontbossing - populatiebiologie - Europa - België - Nederland - Luxemburg - Duitsland - Tsjechië - Oostenrijk
Oak chloroplast DNA (cpDNA) variation was studied in a grid-based inventory in western Central Europe, including Belgium, The Netherlands, Luxembourg, Germany, the Czech Republic, and the northern parts of Upper and Lower Austria. A total of 2155 trees representing 426 populations of Quercus robur L. and Q. petraea (Matt.) Liebl. were screened for polymorphism in up to four PCR-amplified cpDNA fragments. Eleven haplotypes belonging to four lineages were detected; these lineages were formerly restricted to glacial refugia in the Iberian Peninsula, the Apennine Peninsula and the Balkan Peninsula. The haplotypes originating from the Apennines are particularly well represented in the study region, but there is also a significant contribution from the other refugia, which explain the high overall level of cpDNA diversity. The strong human impact in western Central Europe during the past centuries, which has resulted in the clearance of most forests, was followed by reforestation, sometimes involving seed transfers. Despite this strong human impact, broad geographic patterns of lineages and haplotypes could still be detected. To evaluate further the consequences of the former human activities on the present day oak cpDNA genetic structure, four regions where increasingly strong human impact was anticipated (ranging from hilly regions in southern Germany to roadsides plantations in The Netherlands) were selected. There, a comparison of the levels of intrapopulation cpDNA diversity and spatial structuring was made. Over the whole area, within stand diversity was significantly higher in Q. robur than in Q. petraea (h[sub]S = 0.24 vs. 0.16). Since total diversity is identical for both species, this results in a significantly lower level of fixation for Q.robur than for Q. petraea (G[sub]ST = 0.68 vs. 0.79). The analyses also reveal a decrease of fixation with increasing human impact on oak populations. The Dutch roadside plantations (Q. robur) exhibit a very low level of fixation (GST = 0.28) as comparedto Q. petraea in southern Germany (GST=0.91). The significance of the spatial genetic structure was tested using geostatistical methods. For the complete data set, a strong spatial genetic structure is confirmed, with higher than average genetic similarities between populations distant from up to 270 km, whereas there is no spatial structure in the roadside plantations in The Netherlands or in the northern German lowlands. These results should help to differentiate introduced from autochthonous populations, and provide a framework for the identification of the geographic origin of seed lots.
Identification of refugia and post-glacial colonisation routes of European white oaks based on chloroplast DNA and fossil pollen evidence
Petit, R.J. ; Brewer, S. ; Bordács, S. ; Burg, K. ; Cheddadi, R. ; Coart, E. ; Cottrell, J. ; Csaikl, U.M. ; Dam, B.C. van; Deans, J.D. ; Espinel, S. ; Fineschi, S. ; Finkeldey, R. ; Glaz, I. ; Goicoechea, P.G. ; Jensen, J.S. ; König, A.O. ; Lowe, A.J. ; Madsen, S.F. ; Mátyás, G. ; Munro, R.C. ; Popescu, F. ; Slade, D. ; Tabbener, H. ; Vries, S.G.M. de; Ziegenhagen, B. ; Beaulieu, J.L. de; Kremer, A. - \ 2002
Forest Ecology and Management 156 (2002)1-3. - ISSN 0378-1127 - p. 49 - 74.
biodiversiteit - biogeografie - eik - genetica - palynologie - populatiebiologie - Europa
The geographic distribution throughout Europe of each of 32 chloroplast DNA variants belonging to eight white oak species sampled from 2613 populations is presented. Clear-cut geographic patterns were revealed by the survey. These distributions, together with the available palynological information, were used to infer colonisation routes out of the glacial period refugia. In western Europe in particular, movements out of the Iberian and the Italian Peninsulas can be clearly identified. Separate refugia are also present in eastern Balkans, whereas further west in this peninsula similarities with Italy were evident. Movements resulting in the exchange of haplotypes between refugia both during the present interglacial and probably also during earlier glacial cycles were therefore inferred. The consequences of these past exchanges is that phylogenetically divergent haplotypes have sometimes followed very similar colonisation routes, limiting somewhat the phylogeographic structure. Cases of geographic disjunction in the present-day distribution of haplotypes are also apparent and could have been induced by the existence of rapid climatic changes at the end of the glacial period (specifically the Younger Dryas cold period), which resulted in range restriction following an early warm period during which oak first expanded from its primary refugia. This cold phase was followed by a new period of expansion at the outset of the Holocene, involving in some cases `secondary' refugia. It is expected that these short climate oscillations would have led to a partial reshuffling of haplotype distribution. Early association between haplotypes and oak species are also suggested by the data, although extensive introgression among species has ultimately largely blurred the pattern. This implies that colonisation routes may have been initially constrained by the ecological characteristics of the species hosting each chloroplast variant. We suggest for instance that two oak species distributed in the north of the Iberian Peninsula (Quercus petraea and Q. pubescens) are recent post-glacial immigrants there. When considered together, conclusions on the location of glacial period refugia and the colonisation routes derived from molecular information and fossil pollen data appear to be both largely compatible and complementary.
Chloroplast DNA variation in European white oaks phylogeography and patterns of diversity based on data from over 2600 populations
Petit, R.J. ; Csaikl, U.M. ; Bordács, S. ; Burg, K. ; Coart, E. ; Cottrell, J. ; Dam, B.C. van; Deans, J.D. ; Dumolin-LapOgue, S. ; Fineschi, S. ; Finkeldey, R. ; Gillies, A. ; Glaz, I. ; Goicoechea, P.G. ; Jensen, J.S. ; König, A.O. ; Lowe, A.J. ; Madsen, S.F. ; Mátyás, G. ; Munro, R.C. ; Olalde, M. ; Pemonge, M.H. ; Popescu, F. ; Slade, D. ; Tabbener, H. ; Taurchini, D. ; Vries, S.G.M. de; Ziegenhagen, B. ; Kremer, A. - \ 2002
Forest Ecology and Management 156 (2002)1-3. - ISSN 0378-1127 - p. 5 - 26.
biodiversiteit - biogeografie - eik - genetica - populatiebiologie - Europa
A consortium of 16 laboratories have studied chloroplast DNA (cpDNA) variation in European white oaks. A common strategy for molecular screening, based on restriction analysis of four PCR-amplified cpDNA fragments, was used to allow comparison among the different laboratories. A total of 2613 oak populations (12,214 individual trees from eight species) were sampled from 37 countries, and analysed with the four fragments. They belong to eight related oak species: Quercus robur, Q. petraea, Q. pubescens, Q. frainetto, Q. faginea, Q. pyrenaica, Q. canariensis and Q. macranthera. During this survey, 45 chloroplast variants were detected and are described together with their phylogenetic relationships, but several of these haplotypes were pooled when there were some risks of confusion across laboratories during the survey, and finally 32 remained that were mapped and used in diversity analyses. A strong phylogeographic structure is apparent from the data, where related haplotypes have broadly similar geographic distributions. In total, six cpDNA lineages are identified, which have distinct geographic distributions, mainly along a longitudinal gradient. Most haplotypes found in northern Europe are also present in the south, whereas the converse is not true, suggesting that the majority of mutations observed were generated prior to postglacial recolonisation, corroborating the conclusions of earlier studies. The description of a new western European lineage constitutes a major finding, compared to earlier phylogenetic treatments. Although the eight oak species studied systematically share cpDNA variants when in sympatry, they partition cpDNA diversity differently, as a consequence of their different ecology and life history attributes. Regional differences in levels of differentiation also exist (either species-specific or general); these seem to be related to the intensity of past and present management of the forests across Europe but also to the level of fragmentation of the range within these regions.
Metabolic engineering of monoterpene biosynthesis in plants
Lücker, J. - \ 2002
Wageningen University. Promotor(en): L.H.W. van der Plas; H.A. Verhoeven; H.J. Bouwmeester. - S.l. : S.n. - ISBN 9789058087171 - 158
nicotiana - petunia - citrus limon - monoterpenen - biosynthese - genetische modificatie - metabolisme - transgene planten - plantenfysiologie - nicotiana - petunia - citrus limon - monoterpenes - biosynthesis - genetic engineering - metabolism - transgenic plants - plant physiology

Monoterpenes are a large group of compounds that belong to the terpenoid family of natural compounds in plants. They are small, volatile, lipophilic substances of which around one thousand different structures have been identified. Monoterpenes are involved in plant-insect, plant-microorganism and plant-plant interactions. Many monoterpenes, such as menthol, carvone, limonene and linalool, are of commercial interest as they are commonly used in foods, beverages, perfumes and cosmetics and in many cleaning products. In flowers they also contribute to the characteristic scent. Monoterpene synthases and subsequent modifying enzymes such as cytochrome P450 hydroxylases, dehydrogenases, reductases and isomerases are responsible for the production of the variety of different carbon skeletons of monoterpenes that are found in nature. In this thesis the use of genetic engineering to introduce or alter the production of monoterpenes by plants was explored.

Initially, as described in Chapter 2, S -linalool synthase from Clarkia breweri was introduced in Petunia plants regulated by a constitutive promoter. Expression was obtained in all tissues analysed, but formation of linalool was restricted to leaves, sepals, corollas, stems and ovaries, and could not be detected in nectaries, roots, pollen and style. Although it was expected that the formation of linalool would result in an alteration of the scent of the plants, no linalool was detected in the headspace. Instead, all the S -linalool produced was efficiently converted by an endogenous glucosyltransferase present in the petunia tissues to the non-volatile S -linalyl-b-D-glucopyranoside. These results showed that genetic engineering of plants for monoterpene biosynthesis is possible, but that it can lead to unexpected conversions of the produced metabolites by endogenous enzyme activities.

In order to obtain new monoterpene synthases for the genetic engineering of plants, a cDNA library was made of the fruit peel of lemon, a plant species producing many different monoterpenes. From this library four different monoterpene synthases were obtained as described in Chapter 3, which together showed to be responsible for more than 90% of the total number of components present in lemon oil. The product specificity of the enzymes could be analysed after heterologous expression in Escherichia coli . Two of the four cDNA-encoded enzymes were producing (+)-limonene, the main component present in lemon. One cDNA-encoded enzyme was mainly producing (-)-b-pinene and the fourth cDNA-encoded enzyme was mainly producingg-terpinene. The latter two enzymes were both producing traces of multiple side products as well. Also other properties of the heterologously expressed enzymes were determined, which are described in Chapter 3.

Three monoterpene synthases responsible for the production of different main products were chosen for the genetic engineering of Nicotiana tabacum 'Petit Havana' SR1, described in Chapter 4. The wild type of this tobacco variety produces one monoterpene, linalool that is only emitted from the flowers. After the transformation with the three monoterpene synthases and subsequent crossings, a plant was obtained that emitted all the three main products of the three introduced monoterpene synthases in addition to the endogenous linalool in the flowers. The levels of limonene,b-pinene andg-terpinene emitted from the leaves and flowers of the plant were higher than the level of the endogenous monoterpene. Also the side products of the monoterpene synthases were detected. The extensive modification of the volatile profile of the tobacco plants that we obtained indicates that there is a sufficient amount of substrate available to the introduced enzymes.

In Chapter 5 the transgenic tobacco plant emitting the products of three monoterpene synthases, was used in a subsequent transformation experiment in order to modify the already introduced pathway. A second step in the pathway was introduced by transformation of the plant material with a limonene-3-hydroxylase isolated from spearmint, which is supposed to be localised in the endoplasmatic reticulum (ER) in the cytosol of the plant cells, while the primarily introduced monoterpene synthases were most likely localised in the plastids in the transgenic plants. The introduction of the cytochrome P450 monoterpene hydroxylase and the resulting formation of the hydroxylated product of (+)-limonene, (+)- trans -isopiperitenol demonstrates that there is intracellular trafficking of limonene from the plastids to the ER in the cytosol. That this trafficking mechanism would be present in plants normally producing these hydroxylated monoterpenes could be expected, but that it is apparently also present in plants not specialised for the production of these compounds is an exciting discovery. Apart from the production and subsequent emission of high further oxidised conversion product isopiperitenone was detected. In addition, an increase in the p -cymene level and the formation of the new products 1,3,8- p -menthatriene and 1,5,8- p -menthatriene were detected. The occurrence of these latter two products and the increase of the p -cymene level could be a consequence of the metabolic engineering of the biosynthetic route into a cell compartment not adapted to the production of these compounds. Endogenous enzymes and pH differences were suggested to be the main cause the formation of these products.

Chapter 6 discusses the various strategies followed for the metabolic engineering of monoterpene biosynthesis in this thesis and by other groups. Functional implications are discussed such as ecological and physiological consequences of the new metabolites for the transgenic plants. The commercial aspects and interesting opportunities for further research are also discussed.

Ondersteuning productontwikkeling Petit Buffet. deel 1. Ondersteuning opzet productielijn Petit Buffet
Aalberts, C.H.J. ; Schelvis-Smit, A.A.M. ; Gouda, J.W.M. - \ 1999
Unknown Publisher (RAPPORT C020/99)
MIRABEL. Model for Integrated Review and Assessment of Biodiversity in European Landscapes
Petit, S. ; Wyatt, B.K. ; Firbank, L.G. ; Howard, D. ; Bunce, R.G.H. ; Hill, M.O. ; Swetman, R.D. ; Bull, K.R. ; Morton, D. ; Cooper, J. ; Foppen, R.P.B. - \ 1998
Monkswood : Institute of Terrestrial Ecology
Boekbespreking: Agricultural policy formation in the European Community: The birth of milk quotas and CAP reform, M. Petit et al.
Oskam, A.J. - \ 1987
Tijdschrift voor sociaalwetenschappelijk onderzoek van de landbouw 2 (1987). - ISSN 0921-481X - p. 197 - 199.
Ovariole development in workers of Myrmica rubra Linnaeus (Hymenoptera: Formicidae) and its relation to age-polyethism
Minkenberg, O.P.J.M. ; Petit, M. - \ 1985
Annales de la Société royale zoologique de Belgique 115 (1985). - p. 29 - 43.
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