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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Tri-trophic interactions: bridging species, communities and ecosystems
Abdala-Roberts, Luis ; Puentes, Adriana ; Finke, Deborah L. ; Marquis, Robert J. ; Montserrat, Marta ; Poelman, Erik H. ; Rasmann, Sergio ; Sentis, Arnaud ; Dam, Nicole M. van; Wimp, Gina ; Mooney, Kailen ; Björkman, Christer - \ 2019
Ecology Letters 22 (2019)12. - ISSN 1461-023X - p. 2151 - 2167.
abiotic forcing - arthropod behaviour - ecosystem effects - food web - indirect defence - trophic cascade

A vast body of research demonstrates that many ecological and evolutionary processes can only be understood from a tri-trophic viewpoint, that is, one that moves beyond the pairwise interactions of neighbouring trophic levels to consider the emergent features of interactions among multiple trophic levels. Despite its unifying potential, tri-trophic research has been fragmented, following two distinct paths. One has focused on the population biology and evolutionary ecology of simple food chains of interacting species. The other has focused on bottom-up and top-down controls over the distribution of biomass across trophic levels and other ecosystem-level variables. Here, we propose pathways to bridge these two long-standing perspectives. We argue that an expanded theory of tri-trophic interactions (TTIs) can unify our understanding of biological processes across scales and levels of organisation, ranging from species evolution and pairwise interactions to community structure and ecosystem function. To do so requires addressing how community structure and ecosystem function arise as emergent properties of component TTIs, and, in turn, how species traits and TTIs are shaped by the ecosystem processes and the abiotic environment in which they are embedded. We conclude that novel insights will come from applying tri-trophic theory systematically across all levels of biological organisation.

The shufflon of IncI1 plasmids is rearranged constantly during different growth conditions
Brouwer, Mike ; Jurburg, Stephanie ; Harders, Frank ; Kant, Arie ; Mevius, Dik ; Roberts, Adam P. ; Bossers, Alex - \ 2019
Wageningen University & Research
PRJEB30618 - ERP113093 - Escherichia coli
One of the factors that can affect conjugation of IncI1 plasmids, amongst others, is the genetic region known as the shufflon. This multiple inversion system modifies the pilus tip proteins used during conjugation, thus affecting the affinity for different recipient cells. Although recombination is known to occur in in vitro conditions, little is known about the regulation and the extend of recombination that occurs. To measure the recombination of the shufflon, we have amplified the entire shufflon region and sequenced the amplicons using nanopore long-read sequencing. This method was effective to determine the order of the segments of the shufflon and allow for the analysis of the shufflon variants that are present in a heterogeneous pool of templates. Analysis was performed over different growth phases and after addition of cefotaxime. Furthermore, analysis was performed in different E. coli host cells to determine if recombination is likely to be influenced. Recombination of the shufflon was constantly ongoing in all conditions that were measured, although no differences in the amount of different shufflon variants or the rate at which novel variants were formed could be found. As previously reported, some variants were abundant in the population while others were scarce. This leads to the conclusion that the shufflon is continuously recombining at a constant rate, or the method used here was not sensitive enough to detect differences in this rate. For one of the plasmids, the host cell appears to have an effect on the specific shufflon variants that were formed which were not predominant in another host, indicating that host factors may be involved. As previously reported, the pilV-A and pilV-A’ ORFs are formed at higher frequencies than other pilV ORFs. These results demonstrate that the recombination that occurs within the shufflon is not random. While any regulation of the shufflon affected by these in vitro conditions could not be revealed, the method of amplifying large regions for long-read sequencing for the analysis of multiple inversion systems proved effective.
Nature of Amorphous Hydrophilic Block Affects Self-Assembly of an Artificial Viral Coat Polypeptide
Willems, Lione ; Westerveld, Larissa Van; Roberts, Stefan ; Weitzhandler, Isaac ; Calcines Cruz, Carlos ; Hernandez-Garcia, Armando ; Chilkoti, Ashutosh ; Mastrobattista, Enrico ; Oost, John Van Der; Vries, Renko De - \ 2019
Biomacromolecules 20 (2019)10. - ISSN 1525-7797 - p. 3641 - 3647.

Consensus motifs for sequences of both crystallizable and amorphous blocks in silks and natural structural analogues of silks vary widely. To design novel silklike polypeptides, an important question is therefore how the nature of either the crystallizable or the amorphous block affects the self-assembly and resulting physical properties of silklike polypeptides. We address herein the influence of the amorphous block on the self-assembly of a silklike polypeptide that was previously designed to encapsulate single DNA molecules into rod-shaped viruslike particles. The polypeptide has a triblock architecture, with a long N-terminal amorphous block, a crystallizable midblock, and a C-terminal DNA-binding block. We compare the self-assembly behavior of a triblock with a very hydrophilic collagen-like amorphous block (GXaaYaa)132 to that of a triblock with a less hydrophilic elastin-like amorphous block (GSGVP)80. The amorphous blocks have similar lengths and both adopt a random coil structure in solution. Nevertheless, atomic force microscopy revealed significant differences in the self-assembly behavior of the triblocks. If collagen-like amorphous blocks are used, there is a clear distinction between very short polypeptide-only fibrils and much longer fibrils with encapsulated DNA. If elastin-like amorphous blocks are used, DNA is still encapsulated, but the polypeptide-only fibrils are now much longer and their size distribution partially overlaps with that of the encapsulated DNA fibrils. We attribute the difference to the more hydrophilic nature of the collagen-like amorphous block, which more strongly opposes the growth of polypeptide-only fibrils than the elastin-like amorphous blocks. Our work illustrates that differences in the chemical nature of amorphous blocks can strongly influence the self-assembly and hence the functionality of engineered silklike polypeptides.

Exploring the munchies: An online survey of users’ experiences of cannabis effects on appetite and the development of a Cannabinoid Eating Experience Questionnaire
Roberts, Carl A. ; Jager, Gerry ; Christiansen, Paul ; Kirkham, Tim C. - \ 2019
Journal of Psychopharmacology 33 (2019)9. - ISSN 0269-8811 - 11 p.
Appetite - cannabinoids - cannabis - munchies - survey

Background: Cannabis intoxication is commonly reported to increase appetite and enhance appreciation of food (the ‘munchies’). These effects are attributed to activation of the endocannabinoid system. However, the psychological changes that underlie these phenomena are under-researched. We report here the results of an extensive online survey of cannabis users with an exploratory Cannabinoid Eating Experience Questionnaire (CEEQ). Method: Frequent cannabis users completed a 46-item questionnaire about their eating behaviour under the influence of cannabis. An English-speaking sample (n=591) provided data for the initial exploratory validation of the scale. A second Dutch-language survey (n=163) was used for confirmatory factor analysis. Test-retest reliability was based on a third English-speaking sample (n=40) who completed the revised, 28-item CEEQ twice across 2 weeks. Results: Principal components analysis provided a two-factor solution. Factor 1 (hedonic) comprised 14 items that related primarily to the enjoyment and altered sensory aspects of eating. Factor 2 (appetitive) comprised a further 14 items related to motivational factors that instigate or promote eating. The two-factor structure was supported by confirmatory factor analysis. Both the hedonic and appetitive subscales had good internal reliability (α=0.92 for each subscale, in two independent samples). Good test-retest reliability was obtained for the revised 28-item questionnaire (ps<.01 for Total CEEQ and each subscale). Conclusion: The Cannabinoid Eating Experience Questionnaire provided a valid, reliable assessment of the psychological features of cannabis-induced alterations to appetite. Our data confirm that cannabis principally influences the motivational factors that lead to the initiation of eating and the hedonic factors implicated in maintaining eating.

Management of Malnutrition in Older Patients—Current Approaches, Evidence and Open Questions
Volkert, Dorothee ; Beck, Anne Marie ; Cederholm, Tommy ; Cereda, Emanuele ; Cruz-Jentoft, Alfonso ; Goisser, Sabine ; Groot, Lisette de; Großhauser, Franz ; Kiesswetter, Eva ; Norman, Kristina ; Pourhassan, Maryam ; Reinders, Ilse ; Roberts, Helen C. ; Rolland, Yves ; Schneider, Stéphane M. ; Sieber, Cornel C. ; Thiem, Ulrich ; Visser, Marjolein ; Wijnhoven, Hanneke A.H. ; Wirth, Rainer - \ 2019
Journal of Clinical Medicine 8 (2019)7. - ISSN 2077-0383 - 16 p.
Malnutrition is widespread in older people and represents a major geriatric syndrome with multifactorial etiology and severe consequences for health outcomes and quality of life. The aim of the present paper is to describe current approaches and evidence regarding malnutrition treatment and to highlight relevant knowledge gaps that need to be addressed. Recently published guidelines of the European Society for Clinical Nutrition and Metabolism (ESPEN) provide a summary of the available evidence and highlight the wide range of different measures that can be taken—from the identification and elimination of potential causes to enteral and parenteral nutrition—depending on the patient’s abilities and needs. However, more than half of the recommendations therein are based on expert consensus because of a lack of evidence, and only three are concern patient-centred outcomes. Future research should further clarify the etiology of malnutrition and identify the most relevant causes in order to prevent malnutrition. Based on limited and partly conflicting evidence and the limitations of existing studies, it remains unclear which interventions are most effective in which patient groups, and if specific situations, diseases or etiologies of malnutrition require specific approaches. Patient-relevant outcomes such as functionality and quality of life need more attention, and research methodology should be harmonised to allow for the comparability of studies.
Convergent evolution of hetero-oligomeric cellulose synthesis complexes in mosses and seed plants
Li, Xingxing ; Speicher, Tori L. ; Dees, Dianka C.T. ; Mansoori, Nasim ; McManus, John B. ; Tien, Ming ; Trindade, Luisa M. ; Wallace, Ian S. ; Roberts, Alison W. - \ 2019
The Plant Journal (2019). - ISSN 0960-7412
cell wall - cellulose - cellulose synthase - cellulose synthesis complex - convergent evolution - Physcomitrella patens

In seed plants, cellulose is synthesized by rosette-shaped cellulose synthesis complexes (CSCs) that are obligate hetero-oligomeric, comprising three non-interchangeable cellulose synthase (CESA) isoforms. The moss Physcomitrella patens has rosette CSCs and seven CESAs, but its common ancestor with seed plants had rosette CSCs and a single CESA gene. Therefore, if P. patens CSCs are hetero-oligomeric, then CSCs of this type evolved convergently in mosses and seed plants. Previous gene knockout and promoter swap experiments showed that PpCESAs from class A (PpCESA3 and PpCESA8) and class B (PpCESA6 and PpCESA7) have non-redundant functions in secondary cell wall cellulose deposition in leaf midribs, whereas the two members of each class are redundant. Based on these observations, we proposed the hypothesis that the secondary class A and class B PpCESAs associate to form hetero-oligomeric CSCs. Here we show that transcription of secondary class A PpCESAs is reduced when secondary class B PpCESAs are knocked out and vice versa, as expected for genes encoding isoforms that occupy distinct positions within the same CSC. The class A and class B isoforms co-accumulate in developing gametophores and co-immunoprecipitate, suggesting that they interact to form a complex in planta. Finally, secondary PpCESAs interact with each other, whereas three of four fail to self-interact when expressed in two different heterologous systems. These results are consistent with the hypothesis that obligate hetero-oligomeric CSCs evolved independently in mosses and seed plants and we propose the constructive neutral evolution hypothesis as a plausible explanation for convergent evolution of hetero-oligomeric CSCs.

Inducible Fibril Formation of Silk-Elastin Diblocks
Willems, Lione ; Roberts, Stefan ; Weitzhandler, Isaac ; Chilkoti, Ashutosh ; Mastrobattista, Enrico ; Oost, John Van Der; Vries, Renko De - \ 2019
ACS Omega 4 (2019)5. - ISSN 2470-1343 - p. 9135 - 9143.

Silk-elastin block copolymers have such physical and biological properties that make them attractive biomaterials for applications ranging from tissue regeneration to drug delivery. Silk-elastin block copolymers that only assemble into fibrils at high concentrations can be used for a template-induced fibril assembly. This can be achieved by additionally including template-binding blocks that promote high local concentrations of polymers on the template, leading to a template-induced fibril assembly. We hypothesize that template-inducible silk-fibril formation, and hence high critical concentrations for fibril formation, requires careful tuning of the block lengths, to be close to a critical set of block lengths that separates fibril forming from nonfibril forming polymer architectures. Therefore, we explore herein the impact of tuning block lengths for silk-elastin diblock polypeptides on fibril formation. For silk-elastin diblocks ESm-SQn, in which the elastin pentamer repeat is ES = GSGVP and the crystallizable silk octamer repeat is SQ = GAGAGAGQ, we find that no fibril formation occurs for n = 6 but that the n = 10 and 14 diblocks do show concentration-dependent fibril formation. For n = 14 diblocks, no effect is observed of the length m (with m = 40, 60, 80) of the amorphous block on the lengths of the fibrils. In contrast, for the n = 10 diblocks that are closest to the critical boundary for fibril formation, we find that long amorphous blocks (m = 80) oppose the growth of fibrils at low concentrations, making them suitable for engineering template-inducible fibril formation.

Improving environmental risk assessments of chemicals: Steps towards evidence-based ecotoxicology
Martin, Olwenn V. ; Adams, Julie ; Beasley, Amy ; Belanger, Scott ; Breton, Roger L. ; Brock, Theo C.M. ; Buonsante, Vito A. ; Galay Burgos, Malyka ; Green, John ; Guiney, Patrick D. ; Hall, Tilghman ; Hanson, Mark ; Harris, Meagan J. ; Henry, Tala R. ; Huggett, Duane ; Junghans, Marion ; Laskowski, Ryszard ; Maack, Gerd ; Moermond, Caroline T.A. ; Panter, Grace ; Pease, Anita ; Poulsen, Veronique ; Roberts, Mike ; Rudén, Christina ; Schlekat, Christian E. ; Schoeters, Ilse ; Solomon, Keith R. ; Staveley, Jane ; Stubblefield, Bill ; Sumpter, John P. ; Warne, Michael S.J. ; Wentsel, Randall ; Wheeler, James R. ; Wolff, Brian A. ; Yamazaki, Kunihiko ; Zahner, Holly ; Ågerstrand, Marlene - \ 2019
Environment International 128 (2019). - ISSN 0160-4120 - p. 210 - 217.
Chemical safety - Decision-making - Ecological risk assessment - Ecotoxicology - Environmental risk assessment - Evidence-based
Growth rings of Brazil nut trees (Bertholletia excelsa) as a living record of historical human disturbance in Central Amazonia
Caetano Andrade, Victor L. ; Flores, Bernardo M. ; Levis, Carolina ; Clement, Charles R. ; Roberts, Patrick ; Schöngart, Jochen - \ 2019
PLoS ONE 14 (2019)4. - ISSN 1932-6203

The Brazil nut tree (Bertholletia excelsa) is an iconic and economically valuable species that dominates vast swathes of the Amazon Basin. This species seems to have been an important part of human subsistence strategies in the region from at least the Early Holocene, and its current distribution may be a legacy of past human settlement. Because B. excelsa is a long-lived pioneer tree it requires natural or human disturbances to increase light availability in the understory for a successful establishment. However, it remains unclear how the long-term population dynamics of this species have been shaped by pre-colonial and post-colonial human practices. Here, we use tree-ring analyses to look at changes in growing conditions over the past 400 years in a Brazil nut tree population in Central Amazonia. We identify changes in tree recruitment and growth rates associated not only with regional climatic variability, but also major political and socio-economic activities recorded by historical documents in the vicinity of Manaus. We demonstrate that the expansion of a post-colonial political center (Manaus) from the middle of the 18 th century onwards coincided with a reduction in recruitment of B. excelsa. We argue that this hiatus suggests the interruption of indigenous management practices, probably due to the collapse of pre-Columbian societies. A second recruitment pulse, and unprecedented cycles of growth release and suppression, aligns with a shift to modern exploitation of the forest into the 20 th century. Our findings shed light on how past histories of human-forest interactions can be revealed by the growth rings of trees in Amazonia. Future interdisciplinary analysis of these trees should enable more detailed investigation of how human forest management has changed in this part of the world, through pre-colonial, colonial, and industrial periods of human activity, with potential implications for conservation.

The shufflon of IncI1 plasmids is rearranged constantly during different growth conditions
Brouwer, Michael S.M. ; Jurburg, Stephanie D. ; Harders, Frank ; Kant, Arie ; Mevius, Dik J. ; Roberts, Adam P. ; Bossers, Alex - \ 2019
Plasmid 102 (2019). - ISSN 0147-619X - p. 51 - 55.

One of the factors that can affect conjugation of IncI1 plasmids, amongst others, is the genetic region known as the shufflon. This multiple inversion system modifies the pilus tip proteins used during conjugation, thus affecting the affinity for different recipient cells. Although recombination is known to occur in in vitro conditions, little is known about the regulation and the extent of recombination that occurs. To measure the recombination of the shufflon, we have amplified the entire shufflon region and sequenced the amplicons using nanopore long-read sequencing. This method was effective to determine the order of the segments of the shufflon and allow for the analysis of the shufflon variants that are present in a heterogeneous pool of templates. Analysis was performed over different growth phases and after addition of cefotaxime. Furthermore, analysis was performed in different E. coli host cells to determine if recombination is likely to be influenced. Recombination of the shufflon was constantly ongoing in all conditions that were measured, although no differences in the amount of different shufflon variants or the rate at which novel variants were formed could be found. As previously reported, some variants were abundant in the population while others were scarce. This leads to the conclusion that the shufflon is continuously recombining at a constant rate, or that the method used here was not sensitive enough to detect differences in this rate. For one of the plasmids, the host cell appeared to have an effect on the specific shufflon variants that were formed which were not predominant in another host, indicating that host factors may be involved. As previously reported, the pilV-A and pilV-A' ORFs are formed at higher frequencies than other pilV ORFs. These results demonstrate that the recombination that occurs within the shufflon is not random. While any regulation of the shufflon affected by these in vitro conditions could not be revealed, the method of amplifying large regions for long-read sequencing for the analysis of multiple inversion systems proved effective.

What agricultural practices are most likely to deliver “sustainable intensification” in the UK?
Dicks, Lynn V. ; Rose, David C. ; Ang, Frederic ; Aston, Stephen ; Birch, A.N.E. ; Boatman, Nigel ; Bowles, Elizabeth L. ; Chadwick, David ; Dinsdale, Alex ; Durham, Sam ; Elliott, John ; Firbank, Les ; Humphreys, Stephen ; Jarvis, Phil ; Jones, Dewi ; Kindred, Daniel ; Knight, Stuart M. ; Lee, Michael R.F. ; Leifert, Carlo ; Lobley, Matt ; Matthews, Kim ; Midmer, Alice ; Moore, Mark ; Morris, Carol ; Mortimer, Simon ; Murray, T.C. ; Norman, Keith ; Ramsden, Stephen ; Roberts, Dave ; Smith, Laurence G. ; Soffe, Richard ; Stoate, Chris ; Taylor, Bryony ; Tinker, David ; Topliff, Mark ; Wallace, John ; Williams, Prysor ; Wilson, Paul ; Winter, Michael ; Sutherland, William J. - \ 2019
Food and Energy Security 8 (2019)1. - ISSN 2048-3694

Sustainable intensification is a process by which agricultural productivity is enhanced whilst also creating environmental and social benefits. We aimed to identify practices likely to deliver sustainable intensification, currently available for UK farms but not yet widely adopted. We compiled a list of 18 farm management practices with the greatest potential to deliver sustainable intensification in the UK, following a well-developed stepwise methodology for identifying priority solutions, using a group decision-making technique with key agricultural experts. The list of priority management practices can provide the focal point of efforts to achieve sustainable intensification of agriculture, as the UK develops post-Brexit agricultural policy, and pursues the second Sustainable Development Goal, which aims to end hunger and promote sustainable agriculture. The practices largely reflect a technological, production-focused view of sustainable intensification, including for example, precision farming and animal health diagnostics, with less emphasis on the social and environmental aspects of sustainability. However, they do reflect an integrated approach to farming, covering many different aspects, from business organization and planning, to soil and crop management, to landscape and nature conservation. For a subset of 10 of the priority practices, we gathered data on the level of existing uptake in English and Welsh farms through a stratified survey in seven focal regions. We find substantial existing uptake of most of the priority practices, indicating that UK farming is an innovative sector. The data identify two specific practices for which uptake is relatively low, but which some UK farmers find appealing and would consider adopting. These practices are: prediction of pest and disease outbreaks, especially for livestock farms; staff training on environmental issues, especially on arable farms.

The diverse economy: feminism, Capitalocentrism and postcapitalist futures
McKinnon, Katherine ; Dombroski, Kelly ; Morrow, Oona - \ 2018
In: Handbook on the International Political Economy of Gender / Elias, Juanita, Roberts, Adrienne, Edward Elgar (Social and Political Science 2018 ) - ISBN 9781783478835 - p. 335 - 350.
Feminist economic geography has been a rich site for exploring issues of political economy and gender. In this chapter the authors explore the contributions of feminist economic geographers to rethinking economy. Diverse economies thinking reveals diversity in existing economic practices, broadening our view of what is important and viable economic activity. This includes recognizing and valuing care work and the household, and recognizing diversity in forms of economic transactions, labour and enterprise through which people around the world secure their livelihoods. Alternative markets, unpaid work and noncapitalist enterprises all come into view as vital parts of our economy. Community economies scholarship begins by rethinking ‘the economy’ and the discourses that shape expectations of how globalization and capitalism function. Building on the work of J.K. Gibson-Graham, the diverse economies framework informs the work of others in the ‘Community Economies Collective’ and the ‘Community Economies Research Network’.
Risk assessment paradigm for glutamate
Roberts, Ashley ; Lynch, Barry ; Rietjens, Ivonne M.C.M. - \ 2018
Annals of Nutrition & Metabolism 73 (2018)Suppl 5. - ISSN 0250-6807 - p. 53 - 64.
Acceptable daily intake - Glutamate - Macronutrient - Risk assessment

Background: Re-evaluation of the use of glutamic acid and glutamate salts (referred to as glutamate hereafter) by the European Food Safety Authority (EFSA) proposed a group acceptable daily intake (ADI) of 30 mg/kg body weight (bw)/day. Summary: This ADI is below the normal dietary intake, while even intake of free glutamate by breast-fed babies can be above this ADI. In addition, the pre-natal developmental toxicity study selected by EFSA, has never been used by regulatory authorities worldwide for the safety assessment of glutamate despite it being available for nearly 40 years. Also, the EFSA ignored that toxicokinetic data provide support for eliminating the use of an uncertainty factor for interspecies differences in kinetics. Key Messages: A 3-generation reproductive toxicity study in mice that includes extensive brain histopathology, provides a better point of departure showing no effects up to the highest dose tested of 6,000 mg/kg bw/day. Furthermore, kinetic data support use of a compound-specific uncertainty factor of 25 instead of 100. Thus, an ADI of at least 240 mg/kg bw/day would be indicated. In fact, there is no compelling evidence to indicate that the previous ADI of "not specified" warrants any change.

Introduction and summary of the 2018 dietary glutamate workshop
Cynober, Luc ; Fernstrom, John D. ; Koletzko, Berthold ; Rietjens, Ivonne M.C.M. ; Roberts, Ashley ; Tennant, David R. ; Tomé, Daniel ; Vorhees, Charles V. - \ 2018
Annals of Nutrition & Metabolism 73 (2018)Suppl 5. - ISSN 0250-6807 - 4 p.
Amino acid - European food safety authority - Glutamate - Risk assessment - Toxicology

The 2018 Dietary Glutamate Workshop was organized and sponsored by the International Glutamate Technical Committee to provide a platform for a broad expert discussion on all relevant aspects of glutamate metabolism and safety in human nutrition. The participants reached a consensus with previous safety evaluations conducted by the global expert bodies, but contradicted the 2017 re-evaluation of dietary glutamates by the European Food Safety Authority, which proposed a group acceptable daily intake (ADI) of 30 mg/kg body weight per day. The participants of the Workshop concluded that the present knowledge on metabolism, kinetics, developmental and general toxicity of dietary glutamates did not warrant a change in the previous ADI of "not specified."

Negative hydrostatic pressure is an unnoticed but significant source of contamination in tissue culture
Askari, N. ; Klerk, G.J. de - \ 2018
In: Proceedings of the 2017 Annual Meeting of the International Plant Propagators' Society. - International Society for Horticultural Science (Acta Horticulturae ) - ISBN 9789462612099 - p. 85 - 87.
Plants are characterized by a negative hydrostatic pressure, brought about by transpiration and by capillary activity of xylem vessels (Taiz and Zeiger, 2010). Because of this, a stem that is being cut sucks up what is nearby. Often this is air but it may also be liquid. The diameter of the xylem vessels is 50-100 μm, so when the liquid contains bacteria (that are typically 0.5-5.0 μm), they will enter deeply into the tissue (Askari et al., 2014; De Klerk et al., 2014). To our knowledge, this alleged source of contamination has never been examined.
Plant Desiccation Tolerance: A Survival Strategy with Exceptional Prospects for Climate‐Smart Agriculture
Hilhorst, H.W.M. ; Farrant, Jill M. - \ 2018
In: Annual Plant Reviews Online / Roberts, Jerry, Wiley - ISBN 9781119312994 - 27 p.
Drought is one of the main threats to agriculture worldwide because most of our staple crops are not very tolerant to dehydration stress. Some 135 species of angiosperms, however, are extremely tolerant of severe drought. These so‐called resurrection plants are desiccation tolerant because they can withstand drying to water contents below 0.1 gram water per gram dry weight and remain viable for extended periods of time, similar to most seeds. Indeed, recent research has shown that mechanisms of desiccation tolerance of different species, be it vegetative tissues or seeds, utilise the same basic ingredients, including anti‐oxidants, chaperone proteins, and specific carbohydrates. However, there is species‐specific behaviour, related to habitat, e.g. in cell wall properties and the manner in which photo‐oxidative damage is prevented upon drying. Crop plants produce desiccation‐tolerant seeds and, hence, possess the genomic information required for desiccation tolerance, but this is exclusively expressed in the seeds. Elucidation of the mechanisms of desiccation tolerance may enable the ‘release’ of this characteristic in the leaves, stems, and roots.
Plant domestication decreases both constitutive and induced chemical defences by direct selection against defensive traits
Moreira, Xoaquín ; Abdala-Roberts, Luis ; Gols, Rieta ; Francisco, Marta - \ 2018
Scientific Reports 8 (2018)1. - ISSN 2045-2322

Studies reporting domestication effects on plant defences have focused on constitutive, but not on induced defences. However, theory predicts a trade-off between constitutive (CD) and induced defences (ID), which intrinsically links both defensive strategies and argues for their joint consideration in plant domestications studies. We measured constitutive and induced glucosinolates in wild cabbage (Brassica oleracea ssp. oleracea) and two domesticated varieties (B. oleracea var. acephala and B. oleracea var. capitata) in which the leaves have been selected to grow larger. We also estimated leaf area (proxy of leaf size) to assess size-defence trade-offs and whether domestication effects on defences are indirect via selection for larger leaves. Both CD and ID were lower in domesticated than in wild cabbage and they were negatively correlated (i.e. traded off) in all of the cabbage lines studied. Reductions in CD were similar in magnitude for leaves and stems, and CD and leaf size were uncorrelated. We conclude that domestication of cabbage has reduced levels not only constitutive defences but also their inducibility, and that reductions in CD may span organs not targeted by breeding. This reduction in defences in domesticated cabbage is presumably the result of direct selection rather than indirect effects via trade-offs between size and defences.

Development and analysis of the Soil Water Infiltration Global database
Rahmati, Mehdi ; Weihermüller, Lutz ; Vanderborght, Jan ; Pachepsky, Yakov A. ; Mao, Lili ; Sadeghi, Seyed Hamidreza ; Moosavi, Niloofar ; Kheirfam, Hossein ; Montzka, Carsten ; Looy, Kris Van; Toth, Brigitta ; Hazbavi, Zeinab ; Yamani, Wafa Al; Albalasmeh, Ammar A. ; Alghzawi, M.Z. ; Angulo-Jaramillo, Rafael ; Antonino, Antônio Celso Dantas ; Arampatzis, George ; Armindo, Robson André ; Asadi, Hossein ; Bamutaze, Yazidhi ; Batlle-Aguilar, Jordi ; Béchet, Béatrice ; Becker, Fabian ; Blöschl, Günter ; Bohne, Klaus ; Braud, Isabelle ; Castellano, Clara ; Cerdà, Artemi ; Chalhoub, Maha ; Cichota, Rogerio ; Císlerová, Milena ; Clothier, Brent ; Coquet, Yves ; Cornelis, Wim ; Corradini, Corrado ; Coutinho, Artur Paiva ; Oliveira, Muriel Bastista De; Macedo, José Ronaldo De; Durães, Matheus Fonseca ; Emami, Hojat ; Eskandari, Iraj ; Farajnia, Asghar ; Flammini, Alessia ; Fodor, Nándor ; Gharaibeh, Mamoun ; Ghavimipanah, Mohamad Hossein ; Ghezzehei, Teamrat A. ; Giertz, Simone ; Hatzigiannakis, Evangelos G. ; Horn, Rainer ; Jiménez, Juan José ; Jacques, Diederik ; Keesstra, Saskia Deborah ; Kelishadi, Hamid ; Kiani-Harchegani, Mahboobeh ; Kouselou, Mehdi ; Jha, Madan Kumar ; Lassabatere, Laurent ; Li, Xiaoyan ; Liebig, Mark A. ; Lichner, Lubomír ; López, María Victoria ; Machiwal, Deepesh ; Mallants, Dirk ; Mallmann, Micael Stolben ; Oliveira Marques, Jean Dalmo De; Marshall, Miles R. ; Mertens, Jan ; Meunier, Félicien ; Mohammadi, Mohammad Hossein ; Mohanty, Binayak P. ; Pulido-Moncada, Mansonia ; Montenegro, Suzana ; Morbidelli, Renato ; Moret-Fernández, David ; Moosavi, Ali Akbar ; Mosaddeghi, Mohammad Reza ; Mousavi, Seyed Bahman ; Mozaffari, Hasan ; Nabiollahi, Kamal ; Neyshabouri, Mohammad Reza ; Ottoni, Marta Vasconcelos ; Ottoni Filho, Theophilo Benedicto ; Pahlavan-Rad, Mohammad Reza ; Panagopoulos, Andreas ; Peth, Stephan ; Peyneau, Pierre Emmanuel ; Picciafuoco, Tommaso ; Poesen, Jean ; Pulido, Manuel ; Reinert, Dalvan José ; Reinsch, Sabine ; Rezaei, Meisam ; Roberts, Francis Parry ; Robinson, David ; Rodrigo-Comino, Jesüs ; Rotunno Filho, Otto Corrêa ; Saito, Tadaomi ; Suganuma, Hideki ; Saltalippi, Carla ; Sándor, Renáta ; Schütt, Brigitta ; Seeger, Manuel ; Sepehrnia, Nasrollah ; Sharifi Moghaddam, Ehsan ; Shukla, Manoj ; Shutaro, Shiraki ; Sorando, Ricardo ; Stanley, Ajayi Asishana ; Strauss, Peter ; Su, Zhongbo ; Taghizadeh-Mehrjardi, Ruhollah ; Taguas, Encarnación ; Teixeira, Wenceslau Geraldes ; Vaezi, Ali Reza ; Vafakhah, Mehdi ; Vogel, Tomas ; Vogeler, Iris ; Votrubova, Jana ; Werner, Steffen ; Winarski, Thierry ; Yilmaz, Deniz ; Young, Michael H. ; Zacharias, Steffen ; Zeng, Yijian ; Zhao, Ying ; Zhao, Hong ; Vereecken, Harry - \ 2018
Earth System Science Data 10 (2018)3. - ISSN 1866-3508 - p. 1237 - 1263.

In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements (∼76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76ĝ€% of the experimental sites with agricultural land use as the dominant type (∼40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in ∗.xlsx and ∗.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it.

Data challenges and opportunities for environmental management of North Sea oil and gas decommissioning in an era of blue growth
Murray, Fiona ; Needham, Katherine ; Gormley, Kate ; Rouse, Sally ; Coolen, Joop W.P. ; Billett, David ; Dannheim, Jennifer ; Birchenough, Silvana N.R. ; Hyder, Kieran ; Heard, Richard ; Ferris, Joseph S. ; Holstein, Jan M. ; Henry, Lea-Anne ; Mcmeel, Oonagh ; Calewaert, Jan-Bart ; Roberts, J.M. - \ 2018
Marine Policy 97 (2018). - ISSN 0308-597X - p. 130 - 138.
Maritime industries routinely collect critical environmental data needed for sustainable management of marine ecosystems, supporting both the blue economy and future growth. Collating this information would provide a valuable resource for all stakeholders. For the North Sea, the oil and gas industry has been a dominant presence for over 50 years that has contributed to a wealth of knowledge about the environment. As the industry begins to decommission its offshore structures, this information will be critical for avoiding duplication of effort in data collection and ensuring best environmental management of offshore activities. This paper summarises the outcomes of a Blue Growth Data Challenge Workshop held in 2017 with participants from: the oil and gas industry; the key UK regulatory and management bodies for oil and gas decommissioning; open access data facilitators; and academic and research institutes. Here, environmental data collection and archiving by oil and gas operators in the North Sea are described, alongside how this compares to other offshore industries; what the barriers and opportunities surrounding environmental data sharing are; and how wider data sharing from offshore industries could be achieved. Five primary barriers to data sharing were identified: 1) Incentives, 2) Risk Perception, 3) Working Cultures, 4) Financial Models, and 5) Data Ownership. Active and transparent communication and collaboration between stakeholders including industry, regulatory bodies, data portals andacademic institutions will be key to unlocking the data that will be critical to informing responsible decommissioning decisions for offshore oil and gas structures in the North Sea.
Detecting macroecological patterns in bacterial communities across independent studies of global soils
Ramirez, Kelly S. ; Knight, Christopher G. ; Hollander, Mattias de; Brearley, Francis Q. ; Constantinides, Bede ; Cotton, Anne ; Creer, Si ; Crowther, Thomas W. ; Davison, John ; Delgado-Baquerizo, Manuel ; Dorrepaal, Ellen ; Elliott, David R. ; Fox, Graeme ; Griffiths, Robert I. ; Hale, Chris ; Hartman, Kyle ; Houlden, Ashley ; Jones, David L. ; Krab, Eveline J. ; Maestre, Fernando T. ; McGuire, Krista L. ; Monteux, Sylvain ; Orr, Caroline H. ; Putten, Wim H. van der; Roberts, Ian S. ; Robinson, David A. ; Rocca, Jennifer D. ; Rowntree, Jennifer ; Schlaeppi, Klaus ; Shepherd, Matthew ; Singh, Brajesh K. ; Straathof, Angela L. ; Bhatnagar, Jennifer M. ; Thion, Cécile ; Heijden, Marcel G.A. van der; Vries, Franciska T. de - \ 2018
Nature Microbiology 3 (2018). - ISSN 2058-5276 - p. 189 - 196.
The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential ‘indicator’ taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.
Analysing the impacts of air quality policies on ecosystem services; a case study for Telemark, Norway
Hein, L. ; White, L. ; Miles, A. ; Roberts, P. - \ 2018
Journal of Environmental Management 206 (2018). - ISSN 0301-4797 - p. 650 - 663.
Air pollution - Ecosystem services - Nitrogen deposition - Norway
There is an increasing interest in considering the effects of air pollution on ecosystem services supply in order to enhance cost-benefit analyses of air pollution policies. This paper presents a generic, conceptual approach that can be used to link atmospheric deposition of air pollutants to ecosystem services supply and societal benefits. The approach is applied in a case study in the Telemark county of Norway. First, we examine the potential effects of four European air quality policy scenarios on N deposition in the ecosystems of this county. Second, we analyse the subsequent impacts on the supply of three ecosystem services: carbon sequestration, timber production and biodiversity. Changes in the supply of the first two services are analysed in both physical and monetary units, biodiversity effects are only analysed in physical terms. The scenarios derive from work conducted in the context of the European National Emissions Ceilings Directive. In the 2010 base case the benefits of carbon sequestration are estimated at 13 million euro per year and the value of timber harvesting at 2.9 million euro per year. Under the examined policy scenarios aiming to reduce nitrogen emissions the societal benefits resulting from these two ecosystem services in Telemark are found to be reduced; the scenarios have little effect on terrestrial biodiversity. Such results cannot be scaled up, individual ecosystem services respond differently to changes in air pollution depending upon type of pollutant, type of ecosystem, type of service, and the magnitude of change. The paper further presents an analysis of the uncertainties that need to be considered in linking air pollution and ecosystem services including those in deposition rates, ecosystem responses, human responses and in the values of ecosystem services. Our conceptual approach is also useful for larger scale analysis of air pollution effects on ecosystem services, for example at national or potentially European scale.
Dimensions of biodiversity loss : Spatial mismatch in land-use impacts on species, functional and phylogenetic diversity of European bees
Palma, Adriana De; Kuhlmann, Michael ; Bugter, Rob ; Ferrier, Simon ; Hoskins, Andrew J. ; Potts, Simon G. ; Roberts, Stuart P.M. ; Schweiger, Oliver ; Purvis, Andy - \ 2017
Diversity and Distributions 23 (2017)12. - ISSN 1366-9516 - p. 1435 - 1446.
agricultural intensification - land-use conversion - non-random species loss - pollinator diversity
Aim: Agricultural intensification and urbanization are important drivers of biodiversity change in Europe. Different aspects of bee community diversity vary in their sensitivity to these pressures, as well as independently influencing ecosystem service provision (pollination). To obtain a more comprehensive understanding of human impacts on bee diversity across Europe, we assess multiple, complementary indices of diversity. Location: One Thousand four hundred and forty six sites across Europe. Methods: We collated data on bee occurrence and abundance from the published literature and supplemented them with the PREDICTS database. Using Rao's Quadratic Entropy, we assessed how species, functional and phylogenetic diversity of 1,446 bee communities respond to land-use characteristics including land-use class, cropland intensity, human population density and distance to roads. We combined these models with statistically downscaled estimates of land use in 2005 to estimate and map—at a scale of approximately 1 km2—the losses in diversity relative to semi-natural/natural baseline (the predicted diversity of an uninhabited grid square, consisting only of semi-natural/natural vegetation). Results: We show that—relative to the predicted local diversity in uninhabited semi-natural/natural habitat—half of all EU27 countries have lost over 10% of their average local species diversity and two-thirds of countries have lost over 5% of their average local functional and phylogenetic diversity. All diversity measures were generally lower in pasture and higher-intensity cropland than in semi-natural/natural vegetation, but facets of diversity showed less consistent responses to human population density. These differences have led to marked spatial mismatches in losses: losses in phylogenetic diversity were in some areas almost 20 percentage points (pp.) more severe than losses in species diversity, but in other areas losses were almost 40 pp. less severe. Main conclusions: These results highlight the importance of exploring multiple measures of diversity when prioritizing and evaluating conservation actions, as species-diverse assemblages may be phylogenetically and functionally impoverished, potentially threatening pollination service provision.
Managing laying hen flocks with intact beaks
Niekerk, T.G.C.M. van - \ 2017
In: Achieving sustainable production of eggs / Roberts, Juliet R., Cambridge : Burleigh Dodds Science Publishing Limited - ISBN 9781786760807
Worldwide, the majority of laying hens are beak trimmed to prevent injurious pecking. However, a ban on beak treatments has come into force in some countries, while others are discussing instituting such a ban. European legislation also prohibits beak treatment of organic flocks. When beak trimming is not practiced, farmers face the challenge of preventing injurious pecking behaviour in their flocks. Many environmental factors have been identified as affecting the onset and severity of feather pecking, and good management of these factors can prevent the onset of feather pecking or help to prevent escalation once feather pecking starts. In this chapter we review types of feather pecking and consider the origins of the behaviour. We then offer detailed discussion of management techniques for the prevention of feather pecking, during both rearing and the laying period.
Data from: Mass-flowering crops dilute pollinator abundance in agricultural landscapes across Europe
Holzschuh, A. ; Dainese, Matteo ; González-Varo, Juan P. ; Riedinger, V. ; Mudri-Stojnić, Sonja ; Rundlöf, M. ; Scheper, J.A. ; Wickens, J.B. ; Wickens, V.J. ; Bommarco, R. ; Kleijn, D. ; Potts, S.G. ; Roberts, Stuart P.M. ; Smith, H.G. ; Vilà, Montserrat ; Vujic, A. ; Steffan-Dewenter, I. - \ 2016
agricultural intensification
Mass-flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi-natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape-scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator-dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator-supporting practices in agricultural landscapes.
Valuing a Statistical Life Year in Relation to Clean Air
Hein, Lars ; Roberts, Pete ; Gonzalez, Lucia - \ 2016
Journal of environmental assessment policy and management 18 (2016)4. - ISSN 1464-3332
air pollution - cost-benefit analysis - Europe - policy - VOLY

Environmental cost-benefit analysis is increasingly used to support the formulation of European air quality policies. In these analyses, typically around three-quarters of the societal benefits of cleaner air are related to monetised increases in statistical life expectancy. However, the literature presents widely diverging estimates for the value of a statistical life year (a 'VOLY'). This paper presents a review of studies aimed at establishing a VOLY as used in European air quality policies and it examines the factors that cause the variations in VOLY estimates. We discuss the implications of our findings for European air quality policies and also present a novel approach to analyse the VOLY. We have labelled our approach the 'maximum societal revenue VOLY' (MSR-VOLY), and postulate that this approach may be particularly useful in the context of natural capital accounting.

Investigating Transfer of Large Chromosomal Regions Containing the Pathogenicity Locus Between Clostridium difficile Strains
Brouwer, Mike ; Mullany, P. ; Allan, E. ; Roberts, P. - \ 2016
In: Clostridium dfficile Springer (Methods in Molecular Biology ) - ISBN 9781493963591 - p. 215 - 222.
The genomes of all sequenced Clostridium difficile isolates contain multiple mobile genetic elements. The chromosomally located pathogenicity locus (PaLoc), encoding the cytotoxins TcdA and TcdB, was previously hypothesized to be a mobile genetic element; however, mobility was not demonstrated. Here we describe the methods used to facilitate and detect the transfer of the PaLoc from a toxigenic strain into non-toxigenic strains of C. difficile. Although the precise mechanism of transfer has not yet been elucidated, a number of controls are described which indicate transfer occurs via a cell-to-cell-mediated conjugation-like transfer mechanism. Importantly, transfer of the PaLoc was shown to occur on large chromosomal fragments of variable sizes, indicating that homologous recombination is likely to be responsible for the insertion events
High Resolution Model Intercomparison Project (HighResMIP v1.0) for CMIP6
Haarsma, Reindert J. ; Roberts, Malcolm J. ; Vidale, Pier Luigi ; Senior, Catherine A. ; Bellucci, Alessio ; Bao, Qing ; Chang, Ping ; Corti, Susanna ; Fučkar, Neven S. ; Hazeleger, Wilco - \ 2016
Geoscientific Model Development 9 (2016)11. - ISSN 1991-959X - p. 4185 - 4208.

Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest both the possibility of significant changes in large-scale aspects of circulation as well as improvements in small-scale processes and extremes. However, such high-resolution global simulations at climate timescales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centres and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other model intercomparison projects (MIPs). Increases in high-performance computing (HPC) resources, as well as the revised experimental design for CMIP6, now enable a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal-resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950-2050, with the possibility of extending to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulations. HighResMIP thereby focuses on one of the CMIP6 broad questions, "what are the origins and consequences of systematic model biases?", but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.

Monty Roberts’ public demonstrations : Preliminary report on the heart rate and heart rate variability of horses undergoing training during live audience events
Loftus, Loni ; Marks, Kelly ; Jones-McVey, Rosie ; Gonzales, Jose L. ; Fowler, Veronica L. - \ 2016
Animals 6 (2016)9. - ISSN 2076-2615
Heart rate - Heart rate variability - Horse training - Live demonstration - Monty roberts

Effective training of horses relies on the trainer’s awareness of learning theory and equine ethology, and should be undertaken with skill and time. Some trainers, such as Monty Roberts, share their methods through the medium of public demonstrations. This paper describes the opportunistic analysis of beat-to-beat (RR) intervals and heart rate variability (HRV) of ten horses being used in Monty Roberts’ public demonstrations within the United Kingdom. RR and HRV was measured in the stable before training and during training. The HRV variables standard deviation of the RR interval (SDRR), root mean square of successive RR differences (RMSSD), geometric means standard deviation 1 (SD1) and 2 (SD2), along with the low and high frequency ratio (LF/HF ratio) were calculated. The minimum, average and maximum RR intervals were significantly lower in training (indicative of an increase in heart rate as measured in beats-per-minute) than in the stable (p = 0.0006; p = 0.01; p = 0.03). SDRR, RMSSD, SD1, SD2 and the LF/HF ratio were all significantly lower in training than in the stable (p = 0.001; p = 0.049; p = 0.049; p = 0.001; p = 0.01). When comparing the HR and HRV of horses during Join-up® to overall training, there were no significant differences in any variable with the exception of maximum RR which was significantly lower (p = 0.007) during Join-up®, indicative of short increases in physical exertion (canter) associated with this training exercise. In conclusion, training of horses during public demonstrations is a low-moderate physiological, rather than psychological stressor for horses. The physiological stress responses observed within this study were comparable or less to those previously reported in the literature for horses being trained outside of public audience events. Furthermore, there is no evidence that the use of Join-up® alters HR and HRV in a way to suggest that this training method negatively affects the psychological welfare of horses.

Mass-flowering crops dilute pollinator abundance in agricultural landscapes across Europe
Holzschuh, Andrea ; Dainese, Matteo ; González-Varo, Juan P. ; Mudri-Stojnić, Sonja ; Riedinger, Verena ; Rundlöf, Maj ; Scheper, Jeroen ; Wickens, Jennifer B. ; Wickens, Victoria J. ; Bommarco, Riccardo ; Kleijn, David ; Potts, Simon G. ; Roberts, Stuart P.M. ; Smith, Henrik G. ; Vilà, Montserrat ; Vujić, Ante ; Steffan-Dewenter, Ingolf - \ 2016
Ecology Letters 19 (2016)10. - ISSN 1461-023X - p. 1228 - 1236.
Agri-environment schemes - Agricultural intensification - Biofuels - Crop pollination - Ecosystem services - Field boundaries - Landscape composition - Non-crop habitats - Semi-natural habitats - Spillover

Mass-flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi-natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape-scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator-dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator-supporting practices in agricultural landscapes.

Oligocene termite nests with in situ fungus gardens from the rukwa rift basin, Tanzania, support a paleogene african origin for insect agriculture
Roberts, Eric M. ; Todd, Christopher N. ; Aanen, Duur K. ; Nobre, Tania ; Hilbert-Wolf, Hannah L. ; O'Connor, Patrick M. ; Tapanila, Leif ; Mtelela, Cassy ; Stevens, Nancy J. - \ 2016
PLoS ONE 11 (2016)6. - ISSN 1932-6203

Based on molecular dating, the origin of insect agriculture is hypothesized to have taken place independently in three clades of fungus-farming insects: the termites, ants or ambrosia beetles during the Paleogene (66-24 Ma). Yet, definitive fossil evidence of fungus-growing behavior has been elusive, with no unequivocal records prior to the late Miocene (7-10 Ma). Here we report fossil evidence of insect agriculture in the form of fossil fungus gardens, preserved within 25 Ma termite nests from southwestern Tanzania. Using these well-dated fossil fungus gardens, we have recalibrated molecular divergence estimates for the origins of termite agriculture to around 31 Ma, lending support to hypotheses suggesting an African Paleogene origin for termite-fungus symbiosis; perhaps coinciding with rift initiation and changes in the African landscape.

Data from: Local and landscape-level floral resources explain effects of wildflower strips on wild bees across four European countries
Scheper, J.A. ; Bommarco, R. ; Holzschuh, A. ; Potts, S.G. ; Riedinger, V. ; Roberts, S.P.M. ; Rundlöf, M. ; Smith, H.G. ; Steffan-Dewenter, I. ; Wickens, J.B. ; Wickens, V.J. ; Kleijn, D. - \ 2015
agri-environment - ecosystem services - flower strips - field boundaries - floral resources - landscape context - pollinators
1. Growing evidence for declines in wild bees calls for the development and implementation of effective mitigation measures. Enhancing floral resources is a widely accepted measure for promoting bees in agricultural landscapes, but effectiveness varies considerably between landscapes and regions. We hypothesize that this variation is mainly driven by a combination of the direct effects of measures on local floral resources and the availability of floral resources in the surrounding landscape. 2. To test this, we established wildflower strips in four European countries, using the same seed mixture of forage plants specifically targeted at bees. We used a before–after control–impact approach to analyse the impacts of wildflower strips on bumblebees, solitary bees and Red List species and examined to what extent effects were affected by local and landscape-wide floral resource availability, land-use intensity and landscape complexity. 3. Wildflower strips generally enhanced local bee abundance and richness, including Red-listed species. Effectiveness of the wildflower strips increased with the local contrast in flower richness created by the strips and furthermore depended on the availability of floral resources in the surrounding landscape, with different patterns for solitary bees and bumblebees. Effects on solitary bees appeared to decrease with increasing amount of late-season alternative floral resources in the landscape, whereas effects on bumblebees increased with increasing early-season landscape-wide floral resource availability. 4. Synthesis and applications. Our study shows that the effects of wildflower strips on bees are largely driven by the extent to which local flower richness is increased. The effectiveness of this measure could therefore be enhanced by maximizing the number of bee forage species in seed mixtures, and by management regimes that effectively maintain flower richness in the strips through the years. In addition, for bumblebees specifically, our study highlights the importance of a continuous supply of food resources throughout the season. Measures that enhance early-season landscape-wide floral resource availability, such as the cultivation of oilseed rape, can benefit bumblebees by providing the essential resources for colony establishment and growth in spring. Further research is required to determine whether, and under what conditions, wildflower strips result in actual population-level effects.
Inferring social structure from temporal data
Psorakis, Ioannis ; Voelkl, Bernhard ; Garroway, C.J. ; Radersma, Reinder ; Aplin, L.M. ; Crates, R.A. ; Culina, Antica ; Farine, D.R. ; Firth, J.A. ; Hinde, C.A. ; Kidd, Lindall R. ; Milligan, Nicole D. ; Roberts, Stephen J. ; Verhelst, Brecht ; Sheldon, Ben C. - \ 2015
Behavioral Ecology and Sociobiology 69 (2015)5. - ISSN 0340-5443 - p. 857 - 866.
Flocks - Gathering events - Great tits - Group detection - Social networks

Social network analysis has become a popular tool for characterising the social structure of populations. Animal social networks can be built either by observing individuals and defining links based on the occurrence of specific types of social interactions, or by linking individuals based on observations of physical proximity or group membership, given a certain behavioural activity. The latter approaches of discovering network structure require splitting the temporal observation stream into discrete events given an appropriate time resolution parameter. This process poses several non-trivial problems which have not received adequate attention so far. Here, using data from a study of passive integrated transponder (PIT)-tagged great tits Parus major, we discuss these problems, demonstrate how the choice of the extraction method and the temporal resolution parameter influence the appearance and properties of the retrieved network and suggest a modus operandi that minimises observer bias due to arbitrary parameter choice. Our results have important implications for all studies of social networks where associations are based on spatio-temporal proximity, and more generally for all studies where we seek to uncover the relationships amongst a population of individuals that are observed through a temporal data stream of appearance records.

Testing projected wild bee distributions in agricultural habitats: predictive power depends on species traits and habitat type
Marshall, L. ; Carvalheiro, L.G. ; Aguirre-Gutierrez, J. ; Bos, M. ; Groot, G.A. de; Kleijn, D. ; Potts, S.G. ; Reemer, M. ; Roberts, S.P.M. ; Scheper, J.A. ; Biesmeijer, J.C. - \ 2015
Ecology and Evolution 5 (2015)19. - ISSN 2045-7758 - p. 4426 - 4436.
Species distribution models (SDM) are increasingly used to understand the factors that regulate variation in biodiversity patterns and to help plan conservation strategies. However, these models are rarely validated with independently collected data and it is unclear whether SDM performance is maintained across distinct habitats and for species with different functional traits. Highly mobile species, such as bees, can be particularly challenging to model. Here, we use independent sets of occurrence data collected systematically in several agricultural habitats to test how the predictive performance of SDMs for wild bee species depends on species traits, habitat type, and sampling technique. We used a species distribution modeling approach parametrized for the Netherlands, with presence records from 1990 to 2010 for 193 Dutch wild bees. For each species, we built a Maxent model based on 13 climate and landscape variables. We tested the predictive performance of the SDMs with independent datasets collected from orchards and arable fields across the Netherlands from 2010 to 2013, using transect surveys or pan traps. Model predictive performance depended on species traits and habitat type. Occurrence of bee species specialized in habitat and diet was better predicted than generalist bees. Predictions of habitat suitability were also more precise for habitats that are temporally more stable (orchards) than for habitats that suffer regular alterations (arable), particularly for small, solitary bees. As a conservation tool, SDMs are best suited to modeling rarer, specialist species than more generalist and will work best in long-term stable habitats. The variability of complex, short-term habitats is difficult to capture in such models and historical land use generally has low thematic resolution. To improve SDMs’ usefulness, models require explanatory variables and collection data that include detailed landscape characteristics, for example, variability of crops and flower availability. Additionally, testing SDMs with field surveys should involve multiple collection techniques.
Local and landscape-level floral resources explain effects of wildflower strips on wild bees across four European countries
Scheper, J.A. ; Bommarco, R. ; Holzschuh, A. ; Potts, S.G. ; Riedinger, V. ; Roberts, S.P.M. ; Rundlöf, M. ; Smith, H.G. ; Steffan-Dewenter, I. ; Wickens, J.B. ; Wickens, V.J. ; Kleijn, D. - \ 2015
Journal of Applied Ecology 52 (2015)5. - ISSN 0021-8901 - p. 1165 - 1175.
1.Growing evidence for declines in wild bees calls for the development and implementation of effective mitigation measures. Enhancing floral resources is a widely accepted measure for promoting bees in agricultural landscapes, but effectiveness varies considerably between landscapes and regions. We hypothesize that this variation is mainly driven by a combination of the direct effects of measures on local floral resources and the availability of floral resources in the surrounding landscape. 2.To test this, we established wildflower strips in four European countries, using the same seed mixture of forage plants specifically targeted at bees. We used a before–after control–impact approach to analyse the impacts of wildflower strips on bumblebees, solitary bees and Red List species and examined to what extent effects were affected by local and landscape-wide floral resource availability, land-use intensity and landscape complexity. 3.Wildflower strips generally enhanced local bee abundance and richness, including Red-listed species. Effectiveness of the wildflower strips increased with the local contrast in flower richness created by the strips and furthermore depended on the availability of floral resources in the surrounding landscape, with different patterns for solitary bees and bumblebees. Effects on solitary bees appeared to decrease with increasing amount of late-season alternative floral resources in the landscape, whereas effects on bumblebees increased with increasing early-season landscape-wide floral resource availability. 4.Synthesis and applications. Our study shows that the effects of wildflower strips on bees are largely driven by the extent to which local flower richness is increased. The effectiveness of this measure could therefore be enhanced by maximizing the number of bee forage species in seed mixtures, and by management regimes that effectively maintain flower richness in the strips through the years. In addition, for bumblebees specifically, our study highlights the importance of a continuous supply of food resources throughout the season. Measures that enhance early-season landscape-wide floral resource availability, such as the cultivation of oilseed rape, can benefit bumblebees by providing the essential resources for colony establishment and growth in spring. Further research is required to determine whether, and under what conditions, wildflower strips result in actual population-level effects.
Habitat complexity reduces parasitoid foraging efficiency, but does not prevent orientation towards learned host plant odours
Kruidhof, H.M. ; Roberts, A.L. ; Magdaraog, P.M. ; Muñoz, D. ; Gols, R. ; Vet, L.E.M. ; Hoffmeister, T.S. ; Harvey, J.A. - \ 2015
Oecologia 179 (2015)2. - ISSN 0029-8549 - p. 353 - 361.
It is well known that many parasitic wasps use herbivore-induced plant odours (HIPVs) to locate their inconspicuous host insects, and are often able to distinguish between slight differences in plant odour composition. However, few studies have examined parasitoid foraging behaviour under (semi-)field conditions. In nature, food plants of parasitoid hosts are often embedded in non-host-plant assemblages that confer both structural and chemical complexity. By releasing both naïve and experienced Cotesia glomerata females in outdoor tents, we studied how natural vegetation surrounding Pieris brassicae-infested Sinapis arvensis and Barbarea vulgaris plants influences their foraging efficiency as well as their ability to specifically orient towards the HIPVs of the host plant species on which they previously had a positive oviposition experience. Natural background vegetation reduced the host-encounter rate of naïve C. glomerata females by 47 %. While associative learning of host plant HIPVs 1 day prior to foraging caused a 28 % increase in the overall foraging efficiency of C. glomerata, it did not reduce the negative influence of natural background vegetation. At the same time, however, females foraging in natural vegetation attacked more host patches on host-plant species on which they previously had a positive oviposition experience. We conclude that, even though the presence of natural vegetation reduces the foraging efficiency of C. glomerata, it does not prevent experienced female wasps from specifically orienting towards the host-plant species from which they had learned the HIPVs.
Response to an emerging vector-borne disease: Surveillance and preparedness for Schmallenberg virus.
Roberts, H.C. ; Elbers, A.R.W. ; Conraths, F.J. ; Holsteg, M. ; Hoereth-Boentgen, D. ; Gethmann, J. ; Schaik, G. van - \ 2014
Preventive Veterinary Medicine 116 (2014)4. - ISSN 0167-5877 - p. 341 - 349.
serotype 8 - bluetongue - netherlands - cattle - europe - seroprevalence - model - spp.
Surveillance for new emerging animal diseases from a European perspective is complicated by the non-harmonised approach across Member States for data capture, recording livestock populations and case definitions. In the summer of 2011, a new vector-borne Orthobunyavirus emerged in Northern Europe and for the first time, a coordinated approach to horizon scanning, risk communication, data and diagnostic test sharing allowed EU Member States to develop early predictions of the disease, its impact and risk management options. There are many different systems in place across the EU for syndromic and scanning surveillance and the differences in these systems have presented epidemiologists and risk assessors with concerns about their combined use in early identification of an emerging disease. The emergence of a new disease always will raise challenging issues around lack of capability and lack of knowledge; however, Schmallenberg virus (SBV) gave veterinary authorities an additional complex problem: the infection caused few clinical signs in adult animals, with no indication of the possible source and little evidence about its spread or means of transmission. This paper documents the different systems in place in some of the countries (Germany and the Netherlands) which detected disease initially and predicted its spread (to the UK) and how information sharing helped to inform early warning and risk assessment for Member States. Microarray technology was used to identify SBV as a new pathogen and data from the automated cattle milking systems coupled with farmer-derived data on reporting non-specific clinical signs gave the first indications of a widespread issue while the UK used meteorological modelling to map disease incursion. The coordinating role of both EFSA and the European Commission were vital as are the opportunities presented by web-based publishing for disseminating information to industry and the public. The future of detecting emerging disease looks more positive in the light of this combined approach in the EU.
Global, regional, and national incidence and mortality for HIV, tuberculosis, and malaria during 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013
Murray, C.J. ; Ortblad, K.F. ; Guinovart, C. ; Lim, S.S. ; Wolock, T.M. ; Roberts, D.A. ; Dansereau, E.A. ; Geleijnse, J.M. - \ 2014
The Lancet 384 (2014)9947. - ISSN 0140-6736 - p. 1005 - 1070.
middle-income countries - female sex workers - plasmodium-falciparum malaria - active antiretroviral therapy - millennium development goals - severe febrile illness - prospective cohort - verbal autopsy - projection package - cost-effectiveness
Background The Millennium Declaration in 2000 brought special global attention to HIV, tuberculosis, and malaria through the formulation of Millennium Development Goal (MDG) 6. The Global Burden of Disease 2013 study provides a consistent and comprehensive approach to disease estimation for between 1990 and 2013, and an opportunity to assess whether accelerated progress has occured since the Millennium Declaration. Methods To estimate incidence and mortality for HIV, we used the UNAIDS Spectrum model appropriately modified based on a systematic review of available studies of mortality with and without antiretroviral therapy (ART). For concentrated epidemics, we calibrated Spectrum models to fit vital registration data corrected for misclassification of HIV deaths. In generalised epidemics, we minimised a loss function to select epidemic curves most consistent with prevalence data and demographic data for all-cause mortality. We analysed counterfactual scenarios for HIV to assess years of life saved through prevention of mother-to-child transmission (PMTCT) and ART. For tuberculosis, we analysed vital registration and verbal autopsy data to estimate mortality using cause of death ensemble modelling. We analysed data for corrected case-notifications, expert opinions on the case-detection rate, prevalence surveys, and estimated cause-specific mortality using Bayesian meta-regression to generate consistent trends in all parameters. We analysed malaria mortality and incidence using an updated cause of death database, a systematic analysis of verbal autopsy validation studies for malaria, and recent studies (2010–13) of incidence, drug resistance, and coverage of insecticide-treated bednets. Findings Globally in 2013, there were 1·8 million new HIV infections (95% uncertainty interval 1·7 million to 2·1 million), 29·2 million prevalent HIV cases (28·1 to 31·7), and 1·3 million HIV deaths (1·3 to 1·5). At the peak of the epidemic in 2005, HIV caused 1·7 million deaths (1·6 million to 1·9 million). Concentrated epidemics in Latin America and eastern Europe are substantially smaller than previously estimated. Through interventions including PMTCT and ART, 19·1 million life-years (16·6 million to 21·5 million) have been saved, 70·3% (65·4 to 76·1) in developing countries. From 2000 to 2011, the ratio of development assistance for health for HIV to years of life saved through intervention was US$4498 in developing countries. Including in HIV-positive individuals, all-form tuberculosis incidence was 7·5 million (7·4 million to 7·7 million), prevalence was 11·9 million (11·6 million to 12·2 million), and number of deaths was 1·4 million (1·3 million to 1·5 million) in 2013. In the same year and in only individuals who were HIV-negative, all-form tuberculosis incidence was 7·1 million (6·9 million to 7·3 million), prevalence was 11·2 million (10·8 million to 11·6 million), and number of deaths was 1·3 million (1·2 million to 1·4 million). Annualised rates of change (ARC) for incidence, prevalence, and death became negative after 2000. Tuberculosis in HIV-negative individuals disproportionately occurs in men and boys (versus women and girls); 64·0% of cases (63·6 to 64·3) and 64·7% of deaths (60·8 to 70·3). Globally, malaria cases and deaths grew rapidly from 1990 reaching a peak of 232 million cases (143 million to 387 million) in 2003 and 1·2 million deaths (1·1 million to 1·4 million) in 2004. Since 2004, child deaths from malaria in sub-Saharan Africa have decreased by 31·5% (15·7 to 44·1). Outside of Africa, malaria mortality has been steadily decreasing since 1990. Interpretation Our estimates of the number of people living with HIV are 18·7% smaller than UNAIDS's estimates in 2012. The number of people living with malaria is larger than estimated by WHO. Incidence rates for HIV, tuberculosis, and malaria have all decreased since 2000. At the global level, upward trends for malaria and HIV deaths have been reversed and declines in tuberculosis deaths have accelerated. 101 countries (74 of which are developing) still have increasing HIV incidence. Substantial progress since the Millennium Declaration is an encouraging sign of the effect of global action.
Counting whales in a challenging, changing environment
Williams, R. ; Kelly, N. ; Boebel, O. ; Friedlaender, A. ; Herr, H. ; Kock, K.H. ; Lehnert, L.S. ; Maksym, T. ; Roberts, J. ; Scheidat, M. ; Siebert, U. ; Brierley, A. - \ 2014
Scientific Reports 4 (2014). - ISSN 2045-2322 - 6 p.
antarctic sea-ice - abundance - extent - ocean - krill - ecosystem - shelf - edge
Estimating abundance of Antarctic minke whales is central to the International Whaling Commission's conservation and management work and understanding impacts of climate change on polar marine ecosystems. Detecting abundance trends is problematic, in part because minke whales are frequently sighted within Antarctic sea ice where navigational safety concerns prevent ships from surveying. Using icebreaker-supported helicopters, we conducted aerial surveys across a gradient of ice conditions to estimate minke whale density in the Weddell Sea. The surveys revealed substantial numbers of whales inside the sea ice. The Antarctic summer sea ice is undergoing rapid regional change in annual extent, distribution, and length of ice-covered season. These trends, along with substantial interannual variability in ice conditions, affect the proportion of whales available to be counted by traditional shipboard surveys. The strong association between whales and the dynamic, changing sea ice requires reexamination of the power to detect trends in whale abundance or predict ecosystem responses to climate change.
Mathematical models for the trimethylamine (TMA) formation on packed cod fish fillets at different temperatures
Heising, J.K. ; Boekel, M.A.J.S. van; Dekker, M. - \ 2014
Food Research International 56 (2014). - ISSN 0963-9969 - p. 272 - 278.
spoilage bacteria - growth - freshness - food
The microbial formation of trimethylamine (TMA) can be used as a quality indicator compound to predict the freshness of fish during its shelf life. In a supply chain with fluctuating temperatures, mathematical models will be valuable tools to simulate this formation as a function of temperature and time. Thesemodels are essential to link sensor data on the formation of TMA to the actual freshness of fish. Existing models for the formation of TMA in fish needed improvements and secondary models for the effect of temperature on the formation of TMA are lacking in the literature. Three different approaches were evaluated on their ability to simulate the experimental observed TMA formation at 4 different temperatures (0, 5, 10 and 15 °C). In the first approach the existing models were improved and the temperature effect was modelled by an empirical model using four parameters. This model is able to simulate the TMA formation at static temperatures. Since TMA is produced on fresh cod fillets by the micro-organisms Shewanella putrefaciens and Photobacterium phosphoreum the microbial Baranyi–Roberts model was initially used for modelling the TMA formation, but this model was found to be too complex (too many correlated parameters that could not be estimated). In the third approach it was seen that a simplified Baranyi–Roberts model with only three parameters could be used to predict the TMA formation with equal accuracy. The influence of the temperature on the parameter µmax was modelled using the extended square rootmodel of Ratkowsky and the differences inTMA formation profiles of different batches could be described by the batch specific parameter N0 representing the initial quality. The presented dynamic model is valuable in predicting the formation of TMA in a fresh fish supply chain with dynamic temperatures. This model has the potential to be used to link sensor data of TMA in the headspace to the actual freshness status of the fish.
In vitro pituitary and thyroid cell proliferation assays and their relevance as alternatives to animal testing
Jomaa, B. ; Aarts, M.M.J.G. ; Haan, L.H.J. de; Peijnenburg, A.A.C.M. ; Bovee, T.F.H. ; Murk, A.J. ; Rietjens, I.M.C.M. - \ 2013
In: Book of Abstracts of the 49th Congress of the European Societies of Toxicology (EUROTOX). - - p. S151 - S151.
This study investigates the in vitro effect of eleven thyroid-active compounds, known to affect pituitary and/or thyroid weights in vivo, using the proliferation of GH3 rat pituitary cells in the so-called “T-screen,” and of FRTL-5 rat thyroid cells in a newly developed test denoted “TSH-screen” to gain insight into the relative value of these in vitro proliferation tests for an integrated testing strategy (ITS) for thyroid activity. Pituitary cell proliferation in the T-screen was stimulated by three out of eleven tested compounds, namely thyrotropin releasing hormone (TRH), triiodothyronine (T3) and thyroxine (T4). Of these three compounds, only T4 causes an increase in relative pituitary weight, and thus T4 was the only compound for which the effect in the in vitro assay correlated with a reported in vivo effect. As to the newly developed TSH-screen, two compounds had an effect, namely, thyroid-stimulating hormone (TSH) induced and T4 antagonized FRTL-5 cell proliferation. These effects correlated with in vivo changes induced by these compounds on thyroid weight. Altogether, the results indicate that most of the selected compounds affect pituitary and thyroid weights by modes of action different from a direct thyroid hormone receptor (THR) or TSH receptor (TSHR)-mediated effect, and point at the need for additional in vitro tests for an ITS. Additional analysis of the T-screen revealed a positive correlation between the THR-mediated effects of the tested compounds in vitro, and their effects on relative heart weight in vivo, suggesting that the T-screen may directly predict this THR-mediated in vivo adverse effect.
The role of the potato (Solanum tuberosum) CCD8 gene in stolon and tuber development
Pasare, S.A. ; Ducreux, L.J.M. ; Morris, W.L. ; Campbell, R. ; Sharma, S.K. ; Roumeliotis, E. ; Kohlen, W. ; Krol, A.R. van der; Bramley, P.M. ; Roberts, A.G. ; Fraser, P.D. ; Taylor, M.A. - \ 2013
New Phytologist 198 (2013)4. - ISSN 0028-646X - p. 1108 - 1120.
striga-lutea lour - apical-dominance - strigolactone biosynthesis - pisum-sativum - germination stimulants - plant architecture - acts downstream - auxin transport - bud outgrowth - beta-carotene
Strigolactones (SLs) are a class of phytohormones controlling shoot branching. In potato (Solanum tuberosum), tubers develop from underground stolons, diageotropic stems which originate from basal stem nodes. As the degree of stolon branching influences the number and size distribution of tubers, it was considered timely to investigate the effects of SL production on potato development and tuber life cycle. Transgenic potato plants were generated in which the CAROTENOID CLEAVAGE DIOXYGENASE8 (CCD8) gene, key in the SL biosynthetic pathway, was silenced by RNA interference (RNAi). The resulting CCD8-RNAi potato plants showed significantly more lateral and main branches than control plants, reduced stolon formation, together with a dwarfing phenotype and a lack of flowering in the most severely affected lines. New tubers were formed from sessile buds of the mother tubers. The apical buds of newly formed transgenic tubers grew out as shoots when exposed to light. In addition, we found that CCD8 transcript levels were rapidly downregulated in tuber buds by the application of sprout-inducing treatments. These results suggest that SLs could have an effect, solely or in combination with other phytohormones, in the morphology of potato plants and also in controlling stolon development and maintaining tuber dormancy.
Species richness declines and biotic homogenisation have slowed down for NW-European pollinators and plants.
Carvalheiro, L.G. ; Kunin, W.E. ; Keil, P. ; Aguirre-Gutiérrez, J. ; Ellis, W.N. ; Fox, R. ; Groom, Q. ; Hennekens, S. ; Landuyt, W. Van; Maes, D. ; Meutter, F. Van de; Michez, D. ; Rasmont, P. ; Ode, B. ; Potts, S.G. ; Reemer, M. ; Roberts, S.P.M. ; Schaminée, J. ; Wallis de Vries, M.F. ; Biesmeijer, J.C. - \ 2013
Ecology Letters 16 (2013)7. - ISSN 1461-023X - p. 870 - 878.
agri-environment schemes - global biodiversity - british butterflies - diversity - abundance - britain - scale - netherlands - indicators - similarity
Concern about biodiversity loss has led to increased public investment in conservation. Whereas there is a widespread perception that such initiatives have been unsuccessful, there are few quantitative tests of this perception. Here, we evaluate whether rates of biodiversity change have altered in recent decades in three European countries (Great Britain, Netherlands and Belgium) for plants and flower visiting insects. We compared four 20-year periods, comparing periods of rapid land-use intensification and natural habitat loss (1930–1990) with a period of increased conservation investment (post-1990). We found that extensive species richness loss and biotic homogenisation occurred before 1990, whereas these negative trends became substantially less accentuated during recent decades, being partially reversed for certain taxa (e.g. bees in Great Britain and Netherlands). These results highlight the potential to maintain or even restore current species assemblages (which despite past extinctions are still of great conservation value), at least in regions where large-scale land-use intensification and natural habitat loss has ceased.
Atmospheric blocking in a high resolution climate model: influences of mean state, orography and eddy forcing
Berckmans, J.N.J. ; Woollings, T. ; Demory, M. ; Vidale, P. ; Roberts, M. - \ 2013
Atmospheric Science Letters 14 (2013)1. - ISSN 1530-261X - p. 34 - 40.
eddies - flow - propagation - simulations - patterns - project
An underestimate of atmospheric blocking occurrence is a well-known limitation of many climate models. This article presents an analysis of Northern Hemisphere winter blocking in an atmospheric model with increased horizontal resolution. European blocking frequency increases with model resolution, and this results from an improvement in the atmospheric patterns of variability as well as a simple improvement in the mean state. There is some evidence that the transient eddy momentum forcing of European blocks is increased at high resolution, which could account for this. However, it is also shown that the increase in resolution of the orography is needed to realise the improvement in blocking, consistent with the increase in height of the Rocky Mountains acting to increase the tilt of the Atlantic jet stream and giving higher mean geopotential heights over northern Europe. Blocking frequencies in the Pacific sector are also increased with atmospheric resolution, but in this case the improvement in orography actually leads to a decrease in blocking
Testosterone treatment can increase circulating carotenoids but does not affect yellow carotenoid-based plumage colour in blue tits
Peters, A. ; Roberts, M.L. ; Kurvers, R.H.J.M. ; Delhey, K. - \ 2012
Journal of Avian Biology 43 (2012)4. - ISSN 0908-8857 - p. 362 - 368.
superb fairy-wrens - sexual attractiveness - trade-offs - interspecific variation - plasma testosterone - structural plumage - sturnus-vulgaris - malurus-cyaneus - zebra finches - molt
A number of mechanisms are responsible for producing the variation in natural colours, and these need not act in isolation. A recent hypothesis states that carotenoid-based coloration, in addition to carotenoid availability, is also enhanced by elevated levels of circulating testosterone (T). This has only been tested for carotenoid-coloured bare parts in birds. We performed an experimental manipulation of T levels and examined the effects on the yellow carotenoid-based breast plumage in captive yearling blue tits Cyanistes caeruleus, of which half received a diet supplemented with carotenoids. T treatment resulted in elevated plasma T compared to controls and carotenoid supplementation strongly increased plasma carotenoid levels. T treatment resulted in an additional increase in plasma carotenoid levels but only in the carotenoid-supplemented males. Carotenoid supplementation resulted in more intense breast colour (carotenoid chroma), as expected. However, there was no effect of testosterone on plumage coloration at either dietary carotenoid level. Our results suggest that T can cause an increase in plasma carotenoid concentration, but that this does not necessarily lead to improved carotenoid-based plumage coloration
Practice-based evidence for weight management: alliance between primary care and public health
Truswell, A.S. ; Hiddink, G.J. ; Green, L.W. ; Roberts, R. ; Weel, C. van - \ 2012
Family Practice 29 (2012)Suppl 1. - ISSN 0263-2136 - p. i6 - i9.
family doctors
Acquired antibiotic resistance genes: an overview
Hoek, A.H. van; Mevius, D.J. ; Guerra, B. ; Mullany, P. ; Roberts, A.P. ; Aarts, H.J. - \ 2011
Frontiers in Microbiology 2 (2011). - ISSN 1664-302X - 27 p.
In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance, attention is also paid to mobile genetic elements such as plasmids, transposons, and integrons, which are associated with AR genes, and involved in the dispersal of antimicrobial determinants between different bacteria.
The respiratory allergen glutaraldehyde in the local lymph node assay: Sensitization by skin exposure, but not by inhalation
Triel, J.J. ; Bree, B.W.J. ; Roberts, D.W. ; Muijser, H. ; Duistermaat, E. ; Woutersen, R.A. ; Kuper, C.F. - \ 2011
Toxicology 279 (2011)1-3. - ISSN 0300-483X - p. 115 - 122.
trimellitic anhydride - occupational asthma - contact allergens - guinea-pigs - hypersensitivity - identification - induction - chemicals - hazard - mice
Previously, a selection of low molecular weight contact and respiratory allergens had tested positive in both a skin and a respiratory local lymph node assay (LLNA), but formaldehyde was negative for sensitization by inhalation. To investigate whether this was due to intrinsic properties of aldehyde sensitizers, the structurally related allergen glutaraldehyde (GA) was tested. BALB/c mice were exposed by inhalation to 6 or 18 ppm GA (respiratory LLNA), both generated as a vapor and as an aerosol. Other groups received 0.25% or 2.5% GA on the skin of the ears (skin LLNA). Lymphocyte proliferation and cytokine production were measured in the draining lymph nodes. GA was positive in the skin LLNA and its cytokine profile (IL-4/IFN-gamma) skewed towards a Th2-type immune response with increasing dose. Inhalation exposure did not result in increased lymphocyte proliferation or increased cytokine levels, despite comparable tissue damage (irritation) in the skin and respiratory tract. We hypothesize that the highly reactive and hydrophilic GA oligomerizes in the protein-rich mucous layer of the respiratory tract, which impedes sensitization but still facilitates local irritation. Within the context of risk assessment in respiratory allergy, our results stress the importance of prevention of skin - besides inhalation - exposure to aldehydes like GA.
Plant Microbial Fuel Cells; a new marine energy source
Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Helder, M. ; Timmers, R.A. ; Steinbusch, K.J.J. ; Buisman, C.J.N. - \ 2011
Worldwide there is need for more clean, renewable, sustainable energy. Plant microbial fuel cells (Plant- MFCs) generate in-situ green electricity(Strik, Hamelers et al. 2008). How does this work? By photosynthesis the plant is capturing solar energy which is transformed into chemical energy as organic matter. Easily 20 to 40% of this organic matter is released via the plant roots into the bioanode of the microbial fuel cell. At the anode electrochemically active oxidise the organic matter while using the carbon anode electrode as final electron acceptor. The released electrons flow via energy harvester to the cathode were typically oxygen is reduced. Under Western European weather conditions a power output of 3.2 W/m2 is expected which is up to 10 times higher than conventional biomass electricity systems (Strik, Timmers et al. 2011). At this moment the Plant-MFCs long term power output is 50 mW/m2 which is attractive for powering sensors or LEDs (Timmers, Strik et al. 2010). To achieve more plantpower larger areas are needed. Plants in Plant-MFCs grown under waterlogged conditions to support the preferred conditions in the anode. Therefore it's interesting to integrate Plant-MFCs into salt marsh wetlands as these are widely present. In Western Europe salt marshes, common cord-grass (Spartina anglica) is one of the dominant species (Roberts and Pullin 2008). Spartina anglica is used as one of the model plants in the Plant-MFC. The objective of the presentation is to give an overview of recent results of Spartina anglica Plant-MFCs and show the identified challenges to improve system performance. Lab scale experiments and model work was performed. Discussed will be the value of the technology and challenges to introduce a Plant-MFC into marine ecosystems
No evidence for general condition-dependence of structural plumage colour in blue tits: an experiment
Peters, A. ; Kurvers, R.H.J.M. ; Roberts, M.L. ; Delhey, K. - \ 2011
Journal of Evolutionary Biology 24 (2011)5. - ISSN 1010-061X - p. 976 - 987.
white-crowned sparrows - melanin-based coloration - bluebirds sialia-sialis - male uv attractiveness - parus-caeruleus - sexual selection - cyanistes-caeruleus - feather growth - satin bowerbirds - postnuptial molt
Condition-dependence is a central but contentious tenet of evolutionary theories on the maintenance of ornamental traits, and this is particularly true for structural plumage colour. By providing diets of different nutritional quality to moulting male and female blue tits, we experimentally manipulated general condition within the natural range, avoiding deprivation or stressful treatments. We measured reflectance of the structural-coloured UV/blue crown, a sexually selected trait in males, and the white cheek, a nonpigmented structural colour, directly after moult and again during the following spring mating season. We employed a variety of colour indices, based on spectral shape and avian visual models but, despite significant variation in condition and coloration, found no evidence for condition-dependence of UV/blue or white plumage colour during either season. These and previously published results suggest that structural colour might be sensitive to stress, rather than reduced body condition, during moult.
Developing European conservation and mitigation tools for pollination services: approaches of the STEP (Status and Trends of European Pollinators) project
Potts, S.G. ; Biesmeijer, J.C. ; Bommarco, R. ; Felicioli, A. ; Fischer, M. ; Jokinen, P. ; Kleijn, D. ; Klein, A.M. ; Kunin, W.E. ; Neumann, P. ; Penev, L.D. ; Petanidou, T. ; Rasmont, P. ; Roberts, S.P.M. ; Smith, H.G. ; Sorensen, P.B. ; Steffan-Dewenter, I. ; Vaissiere, B.E. ; Vila, M. ; Vujic, A. ; Woyciechowski, M. ; Zobel, M. ; Settele, J. ; Schweiger, O. - \ 2011
Journal of Apicultural Research 50 (2011)2. - ISSN 0021-8839 - p. 152 - 164.
life-history traits - agri-environment schemes - different spatial scales - bee population-dynamics - agricultural landscapes - pollen limitation - land-use - fragmented habitats - plant reproduction - species responses
Pollinating insects form a key component of European biodiversity, and provide a vital ecosystem service to crops and wild plants. There is growing evidence of declines in both wild and domesticated pollinators, and parallel declines in plants relying upon them. The STEP project (Status and Trends of European Pollinators, 2010-2015, www.stepproject.net) is documenting critical elements in the nature and extent of these declines, examining key functional traits associated with pollination deficits, and developing a Red List for some European pollinator groups. Together these activities are laying the groundwork for future pollinator monitoring programmes. STEP is also assessing the relative importance of potential drivers of pollinator declines, including climate change, habitat loss and fragmentation, agrochemicals, pathogens, alien species, light pollution, and their interactions. We are measuring the ecological and economic impacts of declining pollinator services and floral resources, including effects on wild plant populations, crop production and human nutrition. STEP is reviewing existing and potential mitigation options, and providing novel tests of their effectiveness across Europe. Our work is building upon existing and newly developed datasets and models, complemented by spatially-replicated campaigns of field research to fill gaps in current knowledge. Findings are being integrated into a policy-relevant framework to create evidence-based decision support tools. STEP is establishing communication links to a wide range of stakeholders across Europe and beyond, including policy makers, beekeepers, farmers, academics and the general public. Taken together, the STEP research programme aims to improve our understanding of the nature, causes, consequences and potential mitigation of declines in pollination services at local, national, continental and global scales.
Cetacean surveys in the Southern Ocean using icebreaker-supported helicopters
Scheidat, M. ; Friedlaender, A. ; Kock, K.H. ; Lehnert, L. ; Boebel, O. ; Roberts, J. ; Williams, R. - \ 2011
Polar Biology 34 (2011)10. - ISSN 0722-4060 - p. 1513 - 1522.
western antarctic peninsula - abundance - whales
Cetaceans in the Southern Ocean are potentially impacted by anthropogenic activities, such as direct hunting or through indirect effects of a reduced sea ice due to climate change. Knowledge on the distribution of cetacean species in this area is important for conservation, but the remoteness of the study area and the presence of sea ice make it difficult to conduct shipboard surveys to obtain this information. In this study, aerial surveys were conducted from ship-based helicopters. In the 2006/07 (ANT XXIII/8) and 2008/09 (ANT XXV/2) polar summers, the icebreaker RV ‘Polarstern’ conducted research cruises in the Weddell Sea, which offered the opportunity to use the helicopters to conduct dedicated cetacean surveys. Combining the results from both cruises, over 26,000 km were covered on survey effort, 13 different cetacean species were identified, and a total of 221 cetacean sightings consisting of a total of 650 animals were made. Using digital photography, it was possible to identify four different beaked whale species and to conduct individual photo-identification of humpback and southern right whales. Helicopter surveys allow the collection of additional information on sightings, (e.g. group size, species), as well as the coverage of areas with high ice coverage. The flexibility and manoeuvrability of helicopters make them a powerful scientific tool to investigate cetaceans in the Southern Ocean, especially in combination with an icebreaker
Antarctic minke whale density in relation to sea ices: helicopter surveys in the Weddell Sea
Williams, R. ; Friedlaender, A. ; Kock, K.H. ; Lehnert, L.S. ; Roberts, J. ; Scheidat, M. - \ 2010
Agadir : International Whaling Commission
The spectral dimension in urban remote sensing
Herold, M. ; Roberts, D.A. - \ 2010
In: Remote Sensing of Urban and Suburban Areas / Rashed, T., Juergens, C., Dordrecht : Springer - ISBN 9781402043710 - p. 47 - 65.
Urban environments are characterized by different types of materials and land cover surfaces than found in natural landscapes. The analysis of remote sensing data has to consider these unique spectral characteristics. This chapter describes the spectral properties of urban areas, how different urban land cover types are spectrally discriminated, and which sensor configurations are most useful to map urban areas. We also show how new remote sensing technologies improve our capabilities to map urban areas in high spatial and thematic detail.
Development of a Coronary Heart Disease Risk Prediction Model for Type 1 Diabetes: The Pittsburgh CHD in Type 1 Diabetes Risk Mode
Zgibor, J.C. ; Ruppert, K. ; Orchard, T.J. ; Soedamah-Muthu, S.S. ; Fuller, J.H. ; Chaturvedi, N. ; Roberts, M.S. - \ 2010
Diabetes Research and Clinical Practice 88 (2010)3. - ISSN 0168-8227 - p. 314 - 321.
cardiovascular-disease - artery-disease - insulin-resistance - iddm - complications - hypertension - mellitus - europe - time
Aim - To create a coronary heart disease (CHD) risk prediction model specific to type 1 diabetes. Methods - Development of the model used data from the Pittsburgh Epidemiology of Diabetes Complications Study (EDC). EDC subjects had type 1 diabetes diagnosed between 1950 and 1980, received their first study exam between 1986 and 1988, and have been followed biennially since. The final cohort for model development consisted of 603 subjects and 46 incident events. Hard CHD was defined as CHD death, fatal/non-fatal MI or Q-waves. Baseline CHD risk factors were tested bivariately and introduced into a Weibull model. The prediction model was externally validated in the EURODIAB Prospective Complications Study. Results - In males, predictors were higher white blood cell count, micro- or macroalbuminuira, lower HDLc and longer diabetes duration. In females, larger waist/hip ratio, higher non-HDLc, higher systolic blood pressure, use of blood pressure medication, and longer diabetes duration were included. Models were robust to internal and external validation procedures. Conclusions - CHD risk prediction models for hard CHD in those with type 1 diabetes should include risk factors not considered by existing models. Using models specifically developed for predicting CHD in type 1 diabetes may allow for more targeted prevention strategies
Identification of markers associated with bacterial blight resistance loci in cowpea (Vigna unguiculata (L.) Walp.)
Agbicodo, A.C.M.E. ; Fatokun, C.A. ; Bandyopadhyay, R. ; Wydra, K. ; Diop, N.N. ; Muchero, W. ; Ehlers, J.D. ; Roberts, P.A. ; Close, T.J. ; Visser, R.G.F. ; Linden, C.G. van der - \ 2010
Euphytica 175 (2010)2. - ISSN 0014-2336 - p. 215 - 226.
quantitative trait loci - yield-related traits - seed-filling period - grain-yield - growth-rate - developmental behavior - genotypic variation - genetic dissection - agronomic traits - tiller number
Cowpea bacterial blight (CoBB), caused by Xanthomonas axonopodis pv. vignicola (Xav), is a worldwide major disease of cowpea [Vigna unguiculata (L.) Walp.]. Among different strategies to control the disease including cultural practices, intercropping, application of chemicals, and sowing pathogen-free seeds, planting of cowpea genotypes with resistance to the pathogen would be the most attractive option to the resource poor cowpea farmers in sub-Saharan Africa. Breeding resistance cultivars would be facilitated by marker-assisted selection (MAS). In order to identify loci with effects on resistance to this pathogen and map QTLs controlling resistance to CoBB, eleven cowpea genotypes were screened for resistance to bacterial blight using 2 virulent Xav18 and Xav19 strains isolated from Kano (Nigeria). Two cowpea genotypes Danila and Tvu7778 were identified to contrast in their responses to foliar disease expression following leaf infection with pathogen. A set of recombinant inbred lines (RILs) comprising 113 individuals derived from Danila (resistant parent) and Tvu7778 (susceptible parent) were infected with CoBB using leaf inoculation method. The experiments were conducted under greenhouse conditions (2007 and 2008) and disease severity was visually assessed using a scale where 0 = no disease and 4 = maximum susceptibility with leaf drop. A single nucleotide polymorphism (SNP) genetic map with 282 SNP markers constructed from the same RIL population was used to perform QTL analysis. Using Kruskall-Wallis and Multiple-QTL model of MapQTL 5, three QTLs, CoBB-1, CoBB-2 and CoBB-3 were identified on linkage group LG3, LG5 and LG9 respectively showing that potential resistance candidate genes cosegregated with CoBB resistance phenotypes. Two of the QTLs CoBB-1, CoBB-2 were consistently confirmed in the two experiments accounting for up to 22.1 and to 17.4% respectively for the first and second experiments. Whereas CoBB-3 was only discovered for the first experiment (2007) with less phenotypic variation explained of about 10%. Our results represent a resource for molecular marker development that can be used for marker assisted selection of bacterial blight resistance in cowpea
No consistent female preference for higher crown UV reflectance in Blue Tits Cyanistes caeruleus: a mate choice experiment
Kurvers, R.H.J.M. ; Delhey, K. ; Roberts, M.L. ; Peters, A. - \ 2010
Ibis 152 (2010)2. - ISSN 0019-1019 - p. 393 - 396.
plumage coloration - sex-ratio - ornamentation - grosbeaks - traits
Although male UV structural plumage coloration can indicate male quality (e.g. Keyser & Hill 2000) and female reproductive investment strategies (e.g. Sheldon et al. 1999, Griffith et al. 2003), unambiguous evidence that such plumage is a direct target of female choice is still lacking. A straightforward way of testing this is by conducting controlled mate choice experiments that exclude confounding factors such as male–male competition or territory quality. The first experiments on the role of structural colours in mate choice used UV-blocking windows (e.g. Bennett et al. 1996, Hunt et al. 1999), thereby completely removing male UV reflectance. A better approach is to vary UV reflectance within the natural range under natural light conditions. Only two such mate choice experiments have been undertaken to date (Ballentine & Hill 2003, Liu et al. 2007). In neither study did females show a preference for more UV-ornamented males. In the present study, we manipulated crown reflectance of first-year male Blue Tits Cyanistes caeruleus to test the hypothesis that females prefer males with a higher crown UV reflectance, as predicted by patterns of sex allocation, paternity and female parental investment in this species (Johnsen et al. 2005, Delhey et al. 2007a,b). In a mate choice experiment, females were offered a choice of two males (matched for yellow breast colour), one with a UV-reduced crown reflectance and one control-manipulated male. The results indicated that female preference was inconsistent and may be context-dependent
Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds
Koch, E. ; Schmitt, A. ; Stephan, D. ; Kromphardt, C. ; Jahn, M. ; Krauthausen, H.J. ; Forsberg, G. ; Werner, S. ; Amein, T. ; Wright, S.A.I. ; Tinivella, F. ; Gullino, M.L. ; Roberts, S.J. ; Wolf, J.M. van der; Groot, S.P.C. - \ 2010
European Journal of Plant Pathology 127 (2010)1. - ISSN 0929-1873 - p. 99 - 112.
physical sanitation treatments - biological-control - vegetable seed - leaf-blight - black rot - germination - hot - sensitivity - infection - diseases
The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems.
Role of Horizontal Gene Transfer in the Evolution of Plant Parasitism Among Nematodes
Mitreva, M. ; Smant, G. ; Helder, J. - \ 2009
In: Horizon Gene Transfer: Genomes in Flux / Gogarten, M.B, Gogarten, J.P., Olendzenski, L.C., Humana Press (Methods in Molecular Biology 532) - ISBN 9781603278522 - p. 517 - 535.
Horizontal gene transfer (HGT) implies the non-sexual exchange of genetic material between species ¿ in some cases even across kingdoms. Although common among Bacteria and Archaea, HGTs from pro- to eukaryotes and between eukaryotes were thought to be extremely rare. Recent studies on intracellular bacteria and their hosts seriously question this view. Recipient organisms could benefit from HGT as new gene packages could allow them to broaden or change their diet, colonize new habitats, or survive conditions that previously would have been lethal. About a decade ago, plant parasitic nematodes were shown to produce and secrete cellulases. Prior to this, animals were thought to fully depend on microbial symbionts for the breakdown of plant cell walls. This discovery prompted Keen and Roberts (1) to hypothesize that the ability of nematodes to parasitize plants was acquired by HGT from soil bacteria to (ancestral) bacterivorous nematodes. Since the identification of the first nematode cellulases, many more plant cell wall¿degrading enzymes (CWDE) have been identified in a range of plant parasitic nematode species. Here we discuss a number of criteria that can be used to underpin an HGT claim. HGT requires close physical contact between donor and recipient, and this could be achieved in, for example, a symbiont¿host, or a trophic relationship. The former type of relationship was indeed shown to potentially result in the transfer of genetic material (e.g., Brugia malayi and Wolbachia). However, currently known endosymbionts of nematodes may not be the source of CWDEs. Remarkably, all cellulases discovered so far within the order Tylenchida belong to a single glycoside hydrolase family (GHF5). A range of soil bacteria harbours GHF5 cellulases, but of course nothing can be said about the gene content of soil bacteria at the time HGT took place (if at all). We suggest that characterisation of cellulases (and other CWDEs) and their genomic organisation in more basal (facultative) plant parasitic Tylenchida is needed to find out if CWDEs were indeed acquired via HGT from bacteria. A more complete picture about the evolution of CWDEs among plant parasitic Tylenchida will require a detailed characterisation of two ¿ so far ¿ fully unexplored basal suborders, Tylenchina and Criconematina. Finally, we performed a computational high-throughput identification of potential HGT candidates (including ones unrelated to CWDEs) in plant parasitic nematodes using a genomics approach
Validating a coronary heart disease prediction model for type 1 diabetes
Zgibor, J. ; Ruppert, K. ; Orchard, T.J. ; Soedamah-Muthu, S.S. ; Fuller, J.H. ; Chaturvedi, N. ; Roberts, M.S. - \ 2008
Diabetologia 51 (2008)Suppl. 1. - ISSN 0012-186X - p. S50 - S55.
Scientific report of EFSA prepared by Working group on Eel welfare on Animal Welfare Aspects of Husbandry Systems for farmed European Eel
Roberts, R. ; Peeler, E. ; Sures, B. ; Vis, J.W. van de - \ 2008
[S.l.] : European Food Safety Authority (EFSA Journal 809 annex) - 50
palingteelt - european eels - visteelt - transport - europese unie - agrarische productiesystemen - eel culture - european eels - fish culture - transport - european union - agricultural production systems
This report covers the welfare aspects of the capture operations and transport of the glass eels to the farm, as well as the different culture systems to which the various life stages of eels are then exposed. These systems are analysed in some detail and the various areas within eel husbandry where specific welfare risks exist have been defined and analysed in relation to the different life stages and production systems. The objective of the report is to define the systems used for culture of the European eel, and to highlight any areas where such systems may increase the likelihood of negative effects on the welfare of the fish
STOVE: Seed treatments for organic vegetable production
Schmitt, A. ; Jahn, M. ; Kromphardt, C. ; Krauthausen, H.J. ; Roberts, S.J. ; Wright, S.A.I. ; Amein, T. ; Forsberg, G. ; Tinivella, F. ; Gullino, M.L. ; Wikström, M. ; Wolf, J.M. van der; Groot, S.P.C. ; Werner, S. ; Koch, E. - \ 2008
biologische landbouw - zaadproductie - onderzoeksprojecten - groenteteelt - organic farming - seed production - research projects - vegetable growing
The aim of the EU-financed research project „STOVE“ (Seed Treatments for Organic Vegetable Production) is to evaluate different methods potentially suited for seed treatment of vegetables in organic farming regarding their efficacy, to optimise these methods, and where feasible to combine them with each other. Scientists from seven European research institutions and a producer of organic vegetable seeds carry out the project.
Gene expression profiling during asexual development of the late blight pathogen Phytophthora infestans reveals a highly dynamic transcriptome
Judelson, H.S. ; Ah-Fong, A.M.V. ; Aux, G. ; Avrova, A.O. ; Bruce, C. ; Cakir, C. ; Cunha, L. da; Grenville-Briggs, L. ; Latijnhouwers, M. ; Ligterink, W. ; Meijer, H.J.G. ; Roberts, S. ; Thurber, C.S. ; Whisson, S.C. ; Birch, P.R.J. ; Govers, F. ; Kamoun, S. ; West, P. van; Windass, J. - \ 2008
Molecular Plant-Microbe Interactions 21 (2008)4. - ISSN 0894-0282 - p. 433 - 447.
host-plant cells - zoospore motility - parallel analysis - cyst germination - potato infection - protein-kinase - rt-pcr - rna - sporulation - family
Much of the pathogenic success of Phytophthora infestans, the potato and tomato late blight agent, relies on its ability to generate from mycelia large amounts of sporangia, which release zoospores that encyst and form infection structures. To better understand these stages, Affymetrix GeneChips based on 15,650 unigenes were designed and used to profile the life cycle. Approximately half of P. infestans genes were found to exhibit significant differential expression between developmental transitions, with approximately (1)/(10) being stage-specific and most changes occurring during zoosporogenesis. Quantitative reverse-transcription polymerase chain reaction assays confirmed the robustness of the array results and showed that similar patterns of differential expression were obtained regardless of whether hyphae were from laboratory media or infected tomato. Differentially expressed genes encode potential cellular regulators, especially protein kinases; metabolic enzymes such as those involved in glycolysis, gluconeogenesis, or the biosynthesis of amino acids or lipids; regulators of DNA synthesis; structural proteins, including predicted flagellar proteins; and pathogenicity factors, including cell-wall-degrading enzymes, RXLR effector proteins, and enzymes protecting against plant defense responses. Curiously, some stage-specific transcripts do not appear to encode functional proteins. These findings reveal many new aspects of oomycete biology, as well as potential targets for crop protection chemicals.
Scientific opinion of BIOHAZ Panel on the request from the Commission for review of the opinion on microbiological risks in infant formulae and follow-on formulae with regard to Enterobacteriaceae as indicators
Cerf, O. ; Colin, P. ; Collins, D. ; Forsythe, S. ; Noerrung, B. ; Roberts, T. ; Zwietering, M.H. - \ 2007
EFSA Journal 444 (2007). - p. 1 - 14.
The European Commission requested EFSA to review the former EFSA/BIOHAZ opinion on microbiological risks in infant formulae and follow-on formulae. Particularly it was requested to provide a scientific opinion on the possible correlation between Enterobacteriaceae and Enterobacter sakazakii and Enterobacteriaceae and Salmonella in infant formulae as well as on the correlation between Enterobacteriaceae and Salmonella in follow-on formulae, in the light of new scientific data. The usefulness of Enterobacteriaceae as indicators for E. sakazakiiand Salmonella in powdered infant formulae and follow-on formulae was also requested if available scientific data do not indicate a clear correlation. The products of concern are powdered infant formulae and powdered follow-on formulae. Consideration of microbiological criteria is outside of the remit of this opinion. Enterobacter sakazakii and Salmonella, both in the family Enterobacteriaceae, are hazards that are occasionally present in powdered infant formulae and powdered follow-on formulae. Given that Salmonella and E. sakazakii are both members of the family Enterobacteriaceae, there is some relationship between the presence of E. sakazakii and Salmonella and the presence of Enterobacteriaceae. If E. sakazakii or Salmonella are present, Enterobacteriaceae should be found provided that the methods are equally sensitive. In some instances levels are so low that if E. sakazakii or Salmonella is detected, Enterobacteriaceae are not detected, just due to “chance”. However, the reverse is not inevitably true since the presence of Enterobacteriaceae does not necessarily mean the presence of Salmonella or E. sakazakii. Industry data from different companies showed that E. sakazakii / Enterobacteriaceae ratios range from 9 to 30%. A correlation between the prevalences of Enterobacteriaceae and that of E. sakazakii was observed in one plant but sufficient specific information was not available for the other plants. A correlation might be apparent according to the ecology of industrial units, with each unit having a characteristic ratio. The BIOHAZ Panel concluded that there is a relationship between the presence of Enterobacteriaceae and E. sakazakii in powdered infant formulae. No universal correlation can be established. There are indications that correlations could be established at individual plant level. It is not possible to establish a correlation between Enterobacteriaceae and Salmonella in infant formulae and in follow-on formulae and, because Salmonella is so rarely present, suitable data are not available. Industrial experience indicates that monitoring Enterobacteriaceae in the processing environment and in the product can be used to confirm the application of GMP/GHP and HACCP and would be expected to reduce the prevalence of E. sakazakii. The BIOHAZ Panel recommended that documented data ideally using standardized methods be accumulated (by industry, regulators, academia) testing for Enterobacteriaceae, Salmonella, and E. sakazakii in the same samples (ingredients, end-product and environmental) across the industry to explore correlations and their relevance in setting control measures
The components of plant tissue culture media II. Organic additions, osmotic and pH effects, and support systems
Thorpe, T. ; Stasolla, C. ; Yeung, E.C. ; Klerk, G.J.M. de; Roberts, A. ; George, E.F. - \ 2007
In: Plant Propagation by Tissue Culture Vol. 1: The Background / George, E.F., Hall, M.A., de Klerk, G.J.M., Springer - ISBN 9781402050046 - p. 115 - 173.
The need for a supply of high quality organic vegetable seeds
Schmitt, A. ; Jahn, M. ; Kromphardt, C. ; Krauthausen, H.J. ; Roberts, S.J. ; Wright, S.A.J. ; Amein, T. ; Forsberg, G. ; Tinivella, F. ; Guliino, M.L. ; Wikstrom, M. ; Wolf, J.M. van der; Groot, S.P.C. ; Werner, S. ; Koch, E. - \ 2006
In: The first Joint European Organic Congress, Odense, Denmark, 30 - 31 May, 2006. - Odense, Denmark : - p. 414 - 415.
Is regional air quality model diversity representative of uncertainty for ozone simulation?
Vautard, R. ; Loon, M. van; Schaap, M. ; Bergstrom, R. ; Bessagnet, B. ; Brandt, J. ; Builtjes, P.J.H. ; Christensen, J.H. ; Cuvelier, C. ; Graff, A. ; Jonson, J.E. ; Krol, M.C. ; Langner, J. ; Roberts, P. ; Rouil, L. ; Stern, R. ; Tarrason, L. ; Thunis, P. ; Vignati, E. ; White, L. ; Wind, P. - \ 2006
Geophysical Research Letters 33 (2006). - ISSN 0094-8276 - 5 p.
pollution model - western-europe - ensemble
We examine whether seven state-of-the-art European regional air quality models provide daily ensembles of predicted ozone maxima that encompass observations. Using tools borrowed from the evaluation of ensemble weather forecasting, we analyze statistics of simulated ensembles of ozone daily maxima over an entire summer season. Although the model ensemble overestimates ozone, the distribution of simulated concentrations is representative of the uncertainty. The spread of simulations is due to random fluctuations resulting from differences in model formulations and input data, but also to the spread between individual model systematic biases. The ensemble average skill increases as the spread decreases. The skill of the ensemble in giving probabilistic predictions of threshold exceedances is also demonstrated. These results allow for optimism about the ability of this ensemble to simulate the uncertainty of the impact of emission control scenarios.
The future of imaging spectroscopy - Prospective technologies and applications
Schaepman, M.E. ; Green, R.O. ; Ungar, S. ; Boardman, J. ; Plaza, A.J. ; Gao, B.C. ; Ustin, S. ; Miller, J. ; Jacquemoud, S. ; Ben-Dor, E. ; Clark, R. ; Davis, C. ; Dozier, J. ; Goodenough, D. ; Roberts, D. ; Goetz, A.F.H. - \ 2006
In: Proceedings 2006 IEEE International Geoscience and Remote Sensing Symposium. - Denver : IEEE - p. 2005 - 2008.
Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain and the Netherlands
Biesmeijer, J.S. ; Roberts, S.P.M. ; Reemer, M. ; Ohlemüller, R. ; Edwards, M. ; Peeters, T. ; Schaffers, A.P. ; Potts, S.G. ; Kleukers, R. ; Thomas, C.D. ; Settele, J. ; Kunin, W.E. - \ 2006
Science 313 (2006)5785. - ISSN 0036-8075 - p. 351 - 354.
british butterflies - climate-change - biodiversity - crisis
Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species
Stabilized baculovirus vector expressing a heterologous gene and GP64 from a single bicistronic transcript
Pijlman, G.P. ; Roode, E.C. ; Fan, X.X. ; Roberts, L.O. ; Belsham, G.J. ; Vlak, J.M. ; Oers, M.M. van - \ 2006
Journal of Biotechnology 123 (2006)1. - ISSN 0168-1656 - p. 13 - 21.
nuclear polyhedrosis-virus - ribosome entry site - non-hr origin - autographa-californica - insect cells - spodoptera-frugiperda - dna-replication - recombinant baculovirus - trichoplusia-ni - foreign genes
The efficient scale-up of recombinant protein production in insect-cell bioreactors using baculovirus expression vectors is hampered by reductions in yield with increasing viral passage, the so-called passage effect. This phenomenon is characterized by the generation and subsequent accumulation of defective interfering baculoviruses (DIs), which interfere with the replication of genomically intact virus. A novel baculovirus expression vector is presented equipped with a bicistronic expression cassette that allows the simultaneous expression of the recombinant gene (GFP, first cistron) and an essential baculovirus gene (GP64, second cistron) from a single messenger RNA (mRNA). The translation of GP64 is mediated by an internal ribosome entry site (IRES) element from Rhopalosiphum padi virus (RhPV) while the native GP64 gene is deleted. In this way, a dominant selection pressure is placed on the entire bicistronic mRNA and hence on the maintenance of the foreign gene. The bicistronic expression vector was superior to the control baculovirus vector in that GFP expression remained at much higher levels upon continued virus passage. The versatility of this stabilized vector was demonstrated by its ability to propagate in a number of cell lines including Sf21, Sf9 and High Five cells. This novel baculovirus vector is especially valuable for large-scale recombinant protein production in insect-cell bioreactors where the number of viral passages is high.
A proposal for defining the geographical boundaries of Amazonia; synthesis of the results from an expert consultation workshop organized by the European Commission in collaboration with the Amazon Cooperation Treaty Organization - JRC Ispra, 7-8 June 2005
Eva, H.D. ; Huber, O. ; Achard, F. ; Balslev, H. ; Beck, S. ; Behling, H. ; Belward, A.S. ; Beuchle, R. ; Cleef, A.M. ; Colchester, M. ; Duivenvoorden, J. ; Hoogmoed, M. ; Junk, W. ; Kabat, P. ; Kruijt, B. ; Malhi, Y. ; Müller, J.M. ; Pereira, J.M. ; Peres, C. ; Prance, G.T. ; Roberts, J. ; Salo, J. - \ 2005
Luxembourg : EC (EUR 21808-EN) - ISBN 9279000128 - 40 p.
Understanding the coordinated effects of PPARs on lipid metabolism using microarrays
Kersten, A.H. ; Escher, P. ; Tafuri, S. ; Wahli, W. - \ 2005
In: Unraveling lipid metabolism with microarrays / Berger, A., Roberts, M.A., New York : Marcel Dekker - ISBN 0824758110 - p. 249 - 263.
Large-scale gene discovery in the oomycete Phytophthora infestans reveals likely components of phytopathogenicity shared with true fungi
Randall, T.A. ; Dwyer, R.A. ; Huitema, E. ; Beyer, K. ; Cvitanich, C. ; Kelkar, H. ; Ah Fong, A.M.V. ; Gates, K. ; Roberts, S. ; Yatzkan, E. ; Gaffney, T. ; Law, M. ; Testa, A. ; Torto-Alalibo, T. ; Zhang Meng, ; Zheng Li, ; Mueller, E. ; Windass, J. ; Binder, A. ; Birch, P.R.J. ; Gisi, U. ; Govers, F. ; Gow, N.A. ; Mauch, F. ; West, P. van; Waugh, M.E. ; Yu Jun, ; Boller, T. ; Kamoun, S. ; Lam, S.T. ; Judelson, H.S. - \ 2005
Molecular Plant-Microbe Interactions 18 (2005)3. - ISSN 0894-0282 - p. 229 - 243.
artificial chromosome library - expressed sequences - codon usage - fusarium-graminearum - cluster-analysis - chitin synthesis - late blight - pathogen - family - evolution
o overview the gene content of the important pathogen Phytophthora infestans, large-scale cDNA and genomic sequencing was performed. A set of 75,757 high-quality expressed sequence tags (ESTs) from P. infestans was obtained from 20 cDNA libraries representing a broad range of growth conditions, stress responses, and developmental stages. These included libraries from P. infestans¿potato and ¿tomato interactions, from which 963 pathogen ESTs were identified. To complement the ESTs, onefold coverage of the P. infestans genome was obtained and regions of coding potential identified. A unigene set of 18,256 sequences was derived from the EST and genomic data and characterized for potential functions, stage-specific patterns of expression, and codon bias. Cluster analysis of ESTs revealed major differences between the expressed gene content of mycelial and spore-related stages, and affinities between some growth conditions. Comparisons with databases of fungal pathogenicity genes revealed conserved elements of pathogenicity, such as class III pectate lyases, despite the considerable evolutionary distance between oomycetes and fungi. Thirty-seven genes encoding components of flagella also were identified. Several genes not anticipated to occur in oomycetes were detected, including chitin synthases, phosphagen kinases, and a bacterial-type FtsZ cell-division protein. The sequence data described are available in a searchable public database.
Interaction between the blood fluke, Sanguinicola inermis and humoral components of the immune response of carp, Cyprinus carpio
Roberts, M.L. ; Lewis, J.W. ; Wiegertjes, G.F. ; Hoole, D. - \ 2005
Parasitology 131 (2005)2. - ISSN 0031-1820 - p. 261 - 271.
salmo-gairdneri richardson - ligula-intestinalis cestoda - diplostomum-spathaceum digenea - rainbow-trout - schistosoma-mansoni - cryptobia-salmositica - alternative pathway - oncorhynchus-mykiss - ichthyophthirius-multifiliis - antibody-response
The effect of Sanguinicola inermis on serum antibody and complement activity in Cyprinus carpio was assessed using an ELISA and haemolytic assays. Possible immune evasion strategies were assessed using immunodetection of host proteins on the surface of the parasite. Carp acclimatized to 20 or 25 °C were infected by exposure to 500 cercariae or injected intraperitoneally with 150 cercariae, and serum monitored over a 63-day period. In cercariae-injected carp, irrespective of time and temperature, a significant increase occurred in complement activity being greatest at 25 °C. In addition, fish exposed to the cercariae of S. inermis and maintained at 20 °C the level of complement activity was significantly higher after 5 weeks compared to controls. At 20 °C intraperitoneal injections of parasites increased serum antibody levels which peaked after 7 days. In contrast, at 25 °C, antibody levels were maintained over 63 days. Exposure offish to infection did not appear to stimulate antibody production. Immunofluorescence studies revealed 'host-like' molecules on the surface of the cercarial body exposed to carp serum and adult flukes obtained directly from the fish or cultured for 24 h in L15 medium. The possible role of 'host-like' molecules in immune evasion is discussed and the response at different temperatures is related to infection dynamics
Assessing potential environmental impacts of soil phosphorus by soil testing
Maguire, R.O. ; Chardon, W.J. ; Simard, R.R. - \ 2005
In: Phosphorus: agriculture and the environment / Sims, J.T., Sharpley, A.N., Pierzynski, G.M., Westermann, D.T., Cabrera, M.L., Powell, J.M., Daniel, T.C., Withers, P.J.A., Al-Amoodi, L.K., Barbarick, K.A., Roberts, C.A., Dick, W.A., Madison WI : ASA/CSSA/SSSA (Agronomy Monograph 46) - ISBN 0891181571 - p. 145 - 180.
The Role of Oral Processing Inflavour Perception
Prinz, J.F. ; Wijk, R.A. de - \ 2004
In: Flavor perception / Taylor, A.J., Roberts, D.D., London : Blackwell - ISBN 1405116277 - p. 39 - 56.
G.D. Schmidt, L.S. Roberts' Foundations of Parasitology
Borgsteede, F.H.M. - \ 2004
Veterinary Parasitology 125 (2004). - ISSN 0304-4017 - p. 421 - 422.
Comparative analyses of a small molecule/enzyme interaction by multiple users of Biacore technology
Cannon, M.J. ; Papalia, G.A. ; Navratilova, I. ; Fisher, R.J. ; Roberts, L.R. ; Worthy, K.M. ; Stephen, A.G. ; Marchesini, G.R. ; Collins, E.J. ; Casper, D. ; Qiu, H. ; Satpaev, D. ; Liparoto, S.F. ; Rice, D.A. ; Gorshkova, I. ; Darling, R.J. ; Bennett, D.B. ; Sekar, M. ; Hommema, E. ; Liang, A.M. ; Day, E.S. ; Inman, J. ; Karlicek, S.H. ; Ullrich, S.J. ; Hodges, D. ; Chu, T. ; Sullivan, E. ; Simpson, J. ; Rafique, A. ; Luginbühl, B. ; Nyholm Westin, S. ; Bynum, M. ; Cachia, P. ; Li, Y.J. ; Kao, D. ; Neurauter, A. ; Wong, M. - \ 2004
Analytical Biochemistry 330 (2004)1. - ISSN 0003-2697 - p. 98 - 113.
plasmon resonance biosensors - kinetic-analysis - mass-transport - rate constants - carbonic-anhydrase - surface - binding
To gauge the experimental variability associated with Biacore analysis, 36 different investigators analyzed a small molecule/enzyme interaction under similar conditions. Acetazolamide (222 g/mol) binding to carbonic anhydrase II (CAII; 30,000 Da) was chosen as a model system. Both reagents were stable and their interaction posed a challenge to measure because of the low molecular weight of the analyte and the fast association rate constant. Each investigator created three different density surfaces of CAII and analyzed an identical dilution series of acetazolamide (ranging from 4.1 to 1000 nM). The greatest variability in the results was observed during the enzyme immobilization step since each investigator provided their own surface activating reagents. Variability in the quality of the acetazolamide binding responses was likely a product of how well the investigators' instruments had been maintained. To determine the reaction kinetics, the responses from the different density surfaces were fit globally to a 1:1 interaction model that included a term for mass transport. The averaged association and dissociation rate constants were 3.1 ± 1.6 × 106 M-1 s-1 and 6.7 ± 2.5 × 10-2 s-1, respectively, which corresponded to an average equilibrium dissociation constant (KD) of 2.6 ± 1.4 × 10-8 M. The results provide a benchmark of variability in interpreting binding constants from the biosensor and highlight keys areas that should be considered when analyzing small molecule interactions.
Encyclopedia of Rose Science
Roberts, A. ; Debener, T. ; Gudin, S. ; Byrne, D.B. ; Cairns, T. ; Vries, D.P. de; Dubois, L.A.M. ; Forkmann, G. ; Fruchter, M. ; Helsper, J.P.F.G. ; Horst, R.K. ; Jay, M. ; Kwakkenbosch, T.A.M. ; Pemberton, B. ; Put, H.M.C. ; Rajapakse, S. ; Reid, M. ; Schum, A. ; Shorthouse, J.D. ; Ueda, Y. ; Vainstein, A. ; Pol, P.A. van de; Zieslin, N. - \ 2003
Amsterdan : Elsevier/Academic Press - ISBN 0122276205
rosa - rozen - encyclopedieën - rosa - roses - encyclopedias
The Encyclopedia of Rose Science brings together a wealth of information on the rose, long treasured for its captivating perfumes and splendid colors. Now, more than ever, science plays a central place in the production of this flower at the center of one of the world's biggest floricultural industries. A team of internationally renowned experts has contributed scores of articles, from the history of rose cultivation to discoveries in rose genetics. For researchers and students, as well as commercial rose growers and breeders, the Encyclopedia of Rose Science is an invaluable reference. tp://books.elsevier.com/contentimages/bnr_mrws_sd.gif" alt="Reference Works on ScienceDirect" width="378" height="50" border="0"> The Encyclopedia of Rose Science is available online on ScienceDirect . The print edition price for this reference work does not include online access. For more information on pricing for access to the online edition, please review our Licensing Options . The richness and authority of Elsevier reference works is now lent valuable functionality and accessibility through the online launch of Elsevier Reference Works on ScienceDirect . Features: Extensive browsing and searching across subject, thematic, alphabetical, author and cited author indexes - as applicable to the work Basic and advanced search functionality within volumes, parts of volumes, or across the whole work Ability to build, save and re-run searches as well as combine saved searches Internal cross-referencing between articles in the work, plus dynamic linking to journal articles and abstract databases, making navigation flexible and easy All articles are available as full-text HTML files, and as PDF files that can be viewed, downloaded or printed out in their original print format A dedicated Reference Works navigation tab and homepage on ScienceDirect to enable easy linking from your OPAC or library website For more information about the Elsevier Reference Works on ScienceDirect Program, please visit: http://www.info.sciencedirect.com/reference_works .
Own-Rooted Cuttings
Costa, J.M. ; Pol, P.A. van de - \ 2003
In: Encyclopedia of Rose Science / Roberts, A., Debener, T., Gudin, S., Elsevier Academic Press - ISBN 0122276205
History of the Perfume Industry
Pol, P.A. van de - \ 2003
In: Encyclopedia of Rose Science / Roberts, A., Debener, T., Gudin, S., Elsevier - ISBN 0122276205 - p. 410 - 414.
parfumerie - geschiedenis - etherische oliehoudende planten - rosa - rozen - perfumery - history - essential oil plants - roses
Postharvest Physiology: Effects of supplemental carbohydrates
Garcia Victoria, N. ; Marissen, N. ; Meeteren, U. van - \ 2003
In: Encyclopedia of Rose Science / Roberts, E., Ebener, T, Gudin, S., Elsevier - ISBN 0122276205 - p. 549 - 554.
Microorganisms in Foods 7 : Microbial Testing in Safety Management
Tompkin, R.B. ; Roberts, T.A. ; Schothorst, M. van; Cole, M.B. ; Gram, L. ; Buchanan, R.L. - \ 2002
New York : Aspen Publishers - ISBN 9780306472626 - 362
voedselmicrobiologie - voedselveiligheid - testen - bemonsteren - risicoschatting - voedselhygiëne - voedselinspectie - micro-organismen - haccp - food microbiology - food safety - testing - sampling - risk assessment - food hygiene - food inspection - microorganisms
An idiosyncratic introduction to deterministic epidemic models
Heesterbeek, J.A.P. ; Roberts, M.G. - \ 2000
In: Encyclopedia of Epidemiologic Methods / Gail, M.H., Benichou, J., Chichester : John Wiley and Sons
Release of volatile oxidation products from sunflower oil and its oil-in-water emulsion in a model mouth system
Ruth, S.M. ; Roozen, J.P. - \ 2000
In: ACS Symposium Series 763, Flavor Release : ACS Symposium Series 763, Flavor Release / Roberts, D.D., Taylor, A.J., Washington, DC : American Chemical Society - ISBN 9780841236929 - p. 309 - 320.
Biological glasses : nature's way to preserve life
Buitink, J. - \ 2000
Agricultural University. Promotor(en): L.H.W. van der Plas; F.A. Hoekstra; M.A. Hemminga. - S.l. : s.n. - ISBN 9789058082398 - 202
zaden - stuifmeel - germplasm - anhydrobiose - glazig worden - verouderen - gebruiksduur - paramagnetische elektronenresonantiespectroscopie - seeds - pollen - germplasm - anhydrobiosis - vitrification - aging - longevity - electron paramagnetic resonance spectroscopy - cum laude

As a result of drying, the cytoplasm of desiccation-tolerant organisms, such as seed and pollen, enters into a highly viscous, solid-like, semi-equilibrium state: the glassy state. The work in this dissertation is focussed on the function and characteristics of intracellular glasses in these organisms.

It was established that intracellular glasses are formed in both desiccation-tolerant and -intolerant pollen (chapter 1). However, desiccation-intolerant pollen loses its viability during drying before intracellular glasses are formed. This indicates that desiccation tolerance is not related with the formation of glasses during drying. Storage of cattail ( Typha latifolia ) pollen under different water contents and temperatures revealed the existence of an optimum water content for survival at a constant relative humidity (11-15%) (chapter 2). The water content corresponding to this relative humidity shifted to higher values with lower storage temperatures, and was found to be associated with the Brunauer, Emmet, and Teller monolayer value. Drying of the pollen below these water contents had detrimental effects on longevity. The water content-temperature combinations of optimal storage were found to be below the glass transition curve, indicating that optimum storage conditions are achieved when intracellular glasses are present. There was a change in ageing kinetics of cattail pollen associated with the melting of the intracellular glass. Above the glass transition temperature (T g ) the activation energy of the ageing rates increased two to three times. This suggests that the presence of glasses in the dry state improves storage stability by decreasing viscosity and, thus, ageing rate. It was concluded that T g curves might be useful for predictions of storage longevity above optimum water contents. However, they cannot be used solely to predict the precise conditions of optimum storage. Subsequently, we sought for a more direct measurement to assess the viscosity of the cytoplasm of tissues.

For this purpose, we used electron paramagnetic resonance (EPR) spectroscopy to study the molecular mobility of the hydrophilic nitroxide spin probe 3-carboxy-proxyl (CP) that was incorporated into embryonic axes of pea seeds and cattail pollen. Using the distance between the outer extrema of the EPR spectrum (2 A zz ) as a measure of molecular mobility, a sharp increase in mobility was observed at a definite temperature during heating (chapter 3). This temperature increased with decreasing water content of the samples, and was found to be associated with the melting of the glassy state as measured by differential scanning calorimetry (DSC). Molecular mobility was found to be inversely correlated with storage stability: the higher the molecular mobility, the shorter the longevity: with decreasing water content, the molecular mobility reached a minimum, in concert with ageing rates. At very low water contents, both molecular mobility and ageing rates increased again. Minimum mobility and maximum storage stability occurred at similar water contents, suggesting that storage stability might be partially controlled by molecular mobility. To understand the nature of the changes in 2 A zz in spectra of CP in the tissues, echo detected (ED) EPR spectroscopy was employed (chapter 4). The shape of the ED EPR spectrum revealed the presence of librational motion of the spin probe, a motion typically present in glassy materials. The change in 2 A zz appeared to be the result of librational motion of the spin probe.

With the use of saturation transfer (ST) EPR spectroscopy, a more quantitative measure of molecular mobility was acquired: the rotational correlation time (τ R ), which corresponds to the time it takes for the spin probe to rotate a radian around its axis (chapter 5). At room temperature,τ R of CP in pea embryonic axes increased during drying from 10 -11 s in de hydrated state to 10 -4 s in the dry state. At T gR was constant ataproximately10 -4 s for all water contents studied. The temperature dependence ofτ R at all water contents studied followed Arrhenius behaviour with a break at T g . The temperature effect onτ R above T g was much smaller in pea axes as found previously for sugar and polymer glasses. Thus, the melting of the intracellular glass by raising the temperature caused only a moderate increase in molecular mobility in the cytoplasm as compared to a huge increase in amorphous sugars.

The application of saturation transfer EPR spectroscopy to biological tissues enabled a quantitative comparison between storage stability and molecular mobility in different tissues (section III). The temperature and moisture dependence of ageing rates of seeds and pollen was found to correlate with the rotational motion of CP in the cytoplasm (chapter 6-8). An increase in the temperature resulted in a faster rotational motion in the cytoplasm of cattail pollen, analogous to faster ageing rates (chapter 6). Decreasing the water content of the pollen resulted in a decrease in rotational motion until a minimum was reached, after which rotational motion slightly increased again. The water content at which this minimal rotational motion was observed increased with decreasing temperature, comparable to the pattern of ageing rate. A significant linear relationship was found between ageing rates and rotational motion in the cytoplasm of the pollen.

We also investigated the relationship between the longevity of lettuce seeds and the molecular mobility in the cytoplasm of their radicles (chapter 7). Longevity of lettuce seeds was predicted using the viability equation of Ellis and Roberts. Increasing the temperature resulted in faster rotational motion and shorter longevity. There was a linear relationship between the logarithms of rotational motion and estimated longevity for temperatures above 5°C, which is the same temperature range for which experimental data were used to obtain the viability constants of the viability equation. Below 5°C, there was a deviation from linearity, which might stem from inaccurate predictions by the viability equation at low temperatures.

Chapter 8 further demonstrates that there is a linear relationship between the logarithms of rotational motion in the cytoplasm of seed and pollen of several plant species and their ageing rates or longevities. This linearity suggests that cytoplasmic mobility might be an important controlling factor of ageing rates. The linear relationship between the two parameters could be used to predict lifespan of germplasm at low temperatures (at which experimental determination of longevity is practically impossible) by simply measuring theτ R values at these low temperatures (chapter 7 and 8). Based on the predictions using the linear regression between ageing rate and rotational motion of CP in pea embryonic axes, an optimum water content of storage was found. This optimum water content shifted to higher values with lowering the storage temperature, as was found previously for cattail pollen based on experimental data (chapter 2). It was predicted that the longevity of seeds at high (0.12 to 0.16 g/g) water content is much higher than previously suggested on the basis of the viability equation. The predictions show that drying germplasm too far leads to decreased longevity compared to storage of germplasm at higher water contents, suggesting that current storage protocols might have to be re-examined.

Desiccation-tolerant organisms contain large amounts of soluble sugars. This, and the fact that sugars are excellent glass-formers has led to the suggestion that sugars play an important role in intracellular glass formation. The presence and amounts of oligosaccharides have been found to correlate with longevity. Furthermore, oligosaccharide glasses are known to increase the T g and viscosity of model sucrose glasses. This suggests that oligosaccharides might enhance the stability of intracellular glasses (chapter 9 and 10). Osmo-priming, i.e. pre-imbibition of seeds in an osmotic solution, can result in a decrease in oligosaccharide content and longevity. Priming pea seeds decreased the total oligosaccharide content in the embryonic axes (chapter 9). Despite the change in oligosaccharide:sucrose ratio, no differences in T g values were detected in the dry axes before and after priming as determined by DSC. Also no difference was found between the rotational mobility of CP in dry untreated axes and that of dry primed axes. Chapter 10 demonstrates that osmo-priming of impatiens and bell pepper seeds resulted in considerable decreases in longevity and oligosaccharide contents, while sucrose contents increased. Again, no differences in the T g curves were found between control and primed impatiens seeds. Similarly, there was no difference in rotational motion of CP in the cytoplasm between control and primed impatiens seeds and between control and primed bell pepper embryonic axes. It was concluded that oligosaccharides in seeds do not appear to affect the stability of the intracellular glassy state, and that the reduced longevity after priming is not the result of increased molecular mobility in the cytoplasm.

To understand the nature and composition of biological glasses we investigated the molecular mobility around T g in sugars, poly-L-lysine and dry desiccation-tolerant biological systems, using ST-EPR, 1 H-NMR and FTIR spectroscopy. Two distinct changes in the temperature dependence of molecular mobility were detected in sugars and poly-L-lysine. With heating, the first change was associated with the melting of the glassy state (T g ). The second change, at which the molecular mobility abruptly increased over several orders of magnitude, was found to correspond with a critical temperature (T c ) where the dynamics of the system changed from solid-like to liquid-like. The temperature interval between T g and T c increased with increasing molecular weight of the sugars. The interval between T g and T c in biological tissues was over 50°C, implying that the stability remained high even at temperatures far above T g . A comparably high T c -T g interval was found for the molecular mobility of poly-L-lysine, suggesting that proteins rather than sugars play an important role in the intracellular glass formation. The exceptionally high T c of intracellular glasses is expected to provide excellent long-term stability to dry organisms, maintaining a slow molecular motion in the cytoplasm even at temperatures far above T g .

Report of the IDECG Working Group on energy and macronutrient metabolism and requirements of the elderly
BeaufrOre, B. ; Castaneda, C. ; Groot, C.P.G.M. de; Kurpad, A. ; Roberts, S. ; Tessari, P. - \ 2000
In: European Journal of Clinical Nutrition 54 suppl.3 (2000) - p. S162 - S163.
Microbial reference materials in seed health test standardization
Bulk, R.W. van den; Langerak, C.J. ; Roberts, S.J. ; Lyons, N.F. - \ 1999
In: Proceedings 3rd ISTA-PDC Seed Health Symposium, International Seed Testing Association, Zurich, Switzerland - p. 133 - 135.
Mapping a novel heat-stable resistance to Meloidogyne in Lycopersicon peruvianum
Veremis, J.C. ; Heusden, A.W. van; Roberts, P.A. - \ 1999
Theoretical and Applied Genetics 98 (1999). - ISSN 0040-5752 - p. 274 - 280.
Predictive modelling : Models, predictions, product validation, use
Zwietering, M.H. - \ 1999
In: Cost 914 Predictive modelling of microbial growth and survival in foods / Ed. T.A. Roberts. - [S.l.] : EUR 19103 en Directorate-General Science, Research and Developmant, 1999. - [ISBN 92-828-6493-6] - p. 85 - 89.
Characteristic numbers to support HACCP-decisions on a quantitative basis
Zwietering, M.H. - \ 1999
In: Cost 914 predictive modelling of microbial growth and survival in foods / ed. T.A. Roberts. - [S.l.] : EUR 19103 en Directorate-General Science, Research and Development, 1999. - [ISBN 92-828-6493-6] - p. 39 - 44.
Release of volatile oxidation products from sunflower oil and its oil-in-water emulsion in a model mouth system
Ruth, S.M. van; Roozen, J.P. - \ 1999
In: Flavor release: linking experiments, theory and reality : proceedings American Chemical Society/Royal Society of Chemistry symposium, New Orleans, USA, 22-27 August 1999 / D. Roberts (Nestlé, Zwitserland), A. Taylor (University of Nottingham, UK - p. 32 - 32.
Risk analysis studies of bacillus cereus presents in pasteurised milk
Notermans, S. ; Dufrenne, J. ; Zwietering, M. - \ 1999
In: Cost 914 predictive modelling of microbial growth and survival in foods / Roberts, T.A., - p. 135 - 139.
Colony growth and mass transfer
Martens, D.E. ; Malakar, P.K. ; Breukelen, W. ; Zwietering, M.H. - \ 1999
In: Cost 914 Predictive modelling of microbial growth and survival in foods / Ed. T.A. Roberts. - [S.l.] : EUR 19103 en Directorate-General Science, Research and Development, 1999. - [ISBN 92-828-6493-6] - p. 213 - 215.
Mixed cultures and shelf-life predictions
Malakar, P.K. ; Martens, D.E. ; Zwietering, M.H. ; Riet, K. van 't - \ 1999
In: Cost 914 predictive modelling of microbial growth and survival in foods / Roberts, T.A., - p. 211 - 212.
Brand Equity, Consumer Learning, and Choice
Erdem, T. ; Swait, J. ; Broniarczyk, S. ; Chakravarti, D. ; Kapferer, J.N. ; Keane, M. ; Roberts, J. ; Steenkamp, J.E.B.M. ; Zettelmeyer, F. - \ 1999
Marketing Letters 10 (1999)3. - ISSN 0923-0645 - p. 301 - 318.
ABC transporters and their impact on pathogenesis and drug sensitivity
Andrade, A.C. ; Zwiers, L.H. ; Waard, M.A. de - \ 1999
In: Pesticide Chemistry and BioScience / Brooks, G.T., Roberts, T.R., - p. 221 - 235.
Common genes are involved in the formation of endomycorrhiza and legume root nodules
Albrecht, C. ; Geurts, R. ; Bisseling, T. - \ 1999
In: The Samuel Roberts Noble Foundation, Plant Biology Division, 1988-1998, 10th Anniversary Symposium Proceedings : October 7th - 10th, 1998, Ardmore, Oklahoma / ed. by R.A. Dixon, M.J. Harrison and M.J. Roossinck. - Ardmore : The Samual Roberts Noble Foundation, 1999 - p. 114 - 121.
Unravelling the genome by genome sequencing & gene function analysis
Stiekema, W.J. ; Pereira, A. - \ 1998
In: Annual Plant Reviews Vol. 1: Arabidopsis. Sheffield Academic Press, Sheffield, UK / Anderson, M., Roberts, J.A., - p. 31 - 62.
A simple parasite model with complicated dynamics
Roberts, M.G. ; Heesterbeek, J.A.P. - \ 1998
Journal of Mathematical Biology 37 (1998). - ISSN 0303-6812 - p. 272 - 290.
Las structuras agrarias de America Latino, 1930-1990.
Long, N. ; Roberts, B. - \ 1998
In: Historia de America Latino: II Economia y Sociedad Desde 1930 / Bethell, L., - p. 373 - 383.
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