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| 5. |
- Sattar, Muhammad Naeem, et al.
(författare)
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Cotton leaf curl disease - an emerging threat to cotton production worldwide
- 2013
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Ingår i: Journal of General Virology. - : Microbiology Society. - 0022-1317 .- 1465-2099. ; 94, s. 695-710
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Forskningsöversikt (refereegranskat)abstract
- Cotton leaf curl disease (CLCuD) is a serious disease of cotton which has characteristic symptoms, the most unusual of which is the formation of leaf-like enations on the undersides of leaves. The disease is caused by whitefly-transmitted geminiviruses (family Geminiviridae, genus Begomovirus) in association with specific, symptom-modulating satellites (betasatellites) and an evolutionarily distinct group of satellite-like molecules known as alphasatellites. CLCuD occurs across Africa as well as in Pakistan and north-western India. Over the past 25 years, Pakistan and India have experienced two epidemics of the disease, the most recent of which involved a virus and satellite that are resistance breaking. Loss of this conventional host-plant resistance, which saved the cotton growers from ruin in the late 1990s, leaves farmers with only relatively poor host plant tolerance to counter the extensive losses the disease causes. There has always been the fear that CLCuD could spread from the relatively limited geographical range it encompasses at present to other cotton-growing areas of the world where, although the disease is not present, the environmental conditions are suitable for its establishment and the whitefly vector occurs. Unfortunately recent events have shown this fear to be well founded, with CLCuD making its first appearance in China. Here, we outline recent advances made in understanding the molecular biology of the components of the disease complex, their interactions with host plants, as well as efforts being made to control CLCuD.
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| 6. |
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| 7. |
- Moore, Jason W., 1971-
(författare)
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The end of the road? : agricultural revolutions in the capitalist World-ecology, 1450-2010
- 2010
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Ingår i: Journal of Agrarian Change. - : Wiley - Blackwell. - 1471-0358 .- 1471-0366. ; 10:3, s. 389-413
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Tidskriftsartikel (refereegranskat)abstract
- Does the present socio-ecological impasse – captured in popular discussions of the ‘end’ of cheap food and cheap oil – represent the latest in a long history of limits and crises that have been transcended by capital, or have we arrived at an epochal turning point in the relation of capital, capitalism and agricultural revolution? For the better part of six centuries, the relation between world capitalism and agriculture has been a remarkable one. Every great wave of capitalist development has been paved with ‘cheap’ food. Beginning in the long sixteenth century, capitalist agencies pioneered successive agricultural revolutions, yielding a series of extraordinary expansions of the food surplus. This paper engages the crisis of neoliberalism today, and asks: Is another agricultural revolution, comparable to those we have known in the history of capitalism, possible? Does the present conjuncture represent a developmental crisis of capitalism that can be resolved by establishing new agro-ecological conditions for another long wave of accumulation, or are we now witnessing an epochal crisis of capitalism? These divergent possibilities are explored from a perspective that views capitalism as ‘world-ecology’, joining together the accumulation of capital and the production of nature in dialectical unity.
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| 8. |
- Öhman, David
(författare)
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Function of MAP20 and MYB103 in cellulose and lignin formation of xylem secondary cell walls
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lignocellulose from trees and other crops will have tremendous impact on the next generation of sustainable biofuels and biomaterials. To take advantage of modern breeding tools, it is therefore important to understand the genetic and molecular regulation underlying secondary cell wall formation. Here, functional analysis was performed on two genes specifically involved in secondary cell wall formation, using Arabidopsis and Populus as model species. PttMAP20 was earlier identified as a wood-specific microtubule-associated protein in hybrid aspen, but not functionally assessed [Rajangam et al. (2008). Plant Physiology, pp. 1283–1294]. In this thesis, AtMAP20 was found to be generally expressed in secondary wall forming cell types in Arabidopsis, including xylem cells, and its binding to microtubules was confirmed. A domain-mapping study showed that its central TPX2 domain, together with the N- and/or C-terminal domain, is required for complete microtubule binding. Overexpression of AtMAP20 induced shorter roots and right-handed twisting, mimicking treatment with the microtubule-stabilizing drug taxol. Loss-of-function map20 mutants had longer etiolated hypocotyls and altered cell wall chemistry. This phenotype was interpreted as resulting from mechanical weakening in the secondary walls of their spiral protoxylem vessels. In line with this, overexpression of PttMAP20 in hybrid aspen affected cellulose microfibril angle. Taken together, MAP20 is a novel microtubule-stabilizing protein, specifically active during secondary cell wall formation and important for the patterning of cellulose microfibrils. MYB103 is a xylem-specific transcription factor, previously demonstrated to be directly activated by the secondary wall NAC master switches SND1/NST1 and VND6/VND7 [Zhong et al. (2008). Plant Cell, pp. 2763–2782]. This thesis demonstrates that loss-of-function Arabidopsis myb103 mutants have reduced levels of syringyl lignin in their basal stems. This was compensated for by an increase in guaiacyl lignin, resulting in a modified syringyl to guaiacyl ratio. The altered lignin composition, characterized by Py/GC-MS, FT-IR microspectroscopy and 2D NMR, was caused by a suppression of F5H, a key gene in syringyl lignin biosynthesis. Thus, it is concluded that MYB103 is required for F5H expression. Taken together, this thesis presents novel knowledge on function of genes important for secondary cell wall formation and, hence, wood formation. These findings have the potential to improve wood characteristics to benefit forest growers and industries.
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| 9. |
- Axelsson, Petter, et al.
(författare)
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Can leaf litter from genetically modified trees affect aquatic ecosystems?
- 2010
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 13:7, s. 1049-1059
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Tidskriftsartikel (refereegranskat)abstract
- In addition to potential benefits, biotechnology in silviculture may also be associated with environmental considerations, including effects on organisms associated with the living tree and on ecosystems and processes dependent on tree residue. We examined whether genetic modification of lignin characteristics (CAD and COMT) in Populus sp. affected leaf litter quality, the decomposition of leaf litter, and the assemblages of aquatic insects colonizing the litter in three natural streams. The decomposition of leaf litter from one of the genetically modified (GM) lines (CAD) was affected in ways that were comparable over streams and harvest dates. After 84 days in streams, CAD-litter had lost approximately 6.1% less mass than the non-GM litter. Genetic modification also affected the concentration of phenolics and carbon in the litter but this only partially explained the decomposition differences, suggesting that other factors were also involved. Insect community analyses comparing GM and non-GM litter showed no significant differences, and the two GM litters showed differences only in the 84-day litterbags. The total abundance and species richness of insects were also similar on GM and non-GM litter. The results presented here suggest that genetic modifications in trees can influence litter quality and thus have a potential to generate effects that can cross ecosystem boundaries and influence ecosystem processes not directly associated with the tree. Overall, the realized ecological effects of the GM tree varieties used here were nevertheless shown to be relatively small.
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| 10. |
- Ramesh, Vetukuri, et al.
(författare)
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Evidence for Small RNAs Homologous to Effector-Encoding Genes and Transposable Elements in the Oomycete Phytophthora infestans
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:12, s. e51399-
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans is the oomycete pathogen responsible for the devastating late blight disease on potato and tomato. There is presently an intense research focus on the role(s) of effectors in promoting late blight disease development. However, little is known about how they are regulated, or how diversity in their expression may be generated among different isolates. Here we present data from investigation of RNA silencing processes, characterized by non-coding small RNA molecules (sRNA) of 19-40 nt. From deep sequencing of sRNAs we have identified sRNAs matching numerous RxLR and Crinkler (CRN) effector protein genes in two isolates differing in pathogenicity. Effector gene-derived sRNAs were present in both isolates, but exhibited marked differences in abundance, especially for CRN effectors. Small RNAs in P. infestans grouped into three clear size classes of 21, 25/26 and 32 nt. Small RNAs from all size classes mapped to RxLR effector genes, but notably 21 nt sRNAs were the predominant size class mapping to CRN effector genes. Some effector genes, such as PiAvr3a, to which sRNAs were found, also exhibited differences in transcript accumulation between the two isolates. The P. infestans genome is rich in transposable elements, and the majority of sRNAs of all size classes mapped to these sequences, predominantly to long terminal repeat (LTR) retrotransposons. RNA silencing of Dicer and Argonaute genes provided evidence that generation of 21 nt sRNAs is Dicer-dependent, while accumulation of longer sRNAs was impacted by silencing of Argonaute genes. Additionally, we identified six microRNA (miRNA) candidates from our sequencing data, their precursor sequences from the genome sequence, and target mRNAs. These miRNA candidates have features characteristic of both plant and metazoan miRNAs.
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| 11. |
- Källman, Thomas, et al.
(författare)
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A significant fraction of 21-nucleotide small RNA originates from phased degradation of resistance genes in several perennial species
- 2013
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 162:2, s. 741-754
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Tidskriftsartikel (refereegranskat)abstract
- Small RNAs (sRNAs), including microRNA (miRNA) and short-interfering RNA (siRNA), are important in the regulation of diverse biological processes. Comparative studies of sRNAs from plants have mainly focused on miRNA, even though they constitute a mere fraction of the total sRNA diversity. In this study, we report results from an in-depth analysis of the sRNA population from the conifer spruce (Picea abies) and compared the results with those of a range of plant species. The vast majority of sRNA sequences in spruce can be assigned to 21-nucleotide-long siRNA sequences, of which a large fraction originate from the degradation of transcribed sequences related to nucleotide-binding site-leucine-rich repeat-type resistance genes. Over 90% of all genes predicted to contain either a Toll/interleukin-1 receptor or nucleotide-binding site domain showed evidence of siRNA degradation. The data further suggest that this phased degradation of resistance-related genes is initiated from miRNA-guided cleavage, often by an abundant 22-nucleotide miRNA. Comparative analysis over a range of plant species revealed a huge variation in the abundance of this phenomenon. The process seemed to be virtually absent in several species, including Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), and nonvascular plants, while particularly high frequencies were observed in spruce, grape (Vitis vinifera), and poplar (Populus trichocarpa). This divergent pattern might reflect a mechanism to limit runaway transcription of these genes in species with rapidly expanding nucleotide-binding site-leucine-rich repeat gene families. Alternatively, it might reflect variation in a counter-counter defense mechanism between plant species.
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| 12. |
- Niazi, Adnan, et al.
(författare)
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Genome Analysis of Bacillus amyloliquefaciens Subsp. plantarum UCMB5113: A Rhizobacterium That Improves Plant Growth and Stress Management
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The Bacillus amyloliquefaciens subsp. plantarum strain UCMB5113 is a Gram-positive rhizobacterium that can colonize plant roots and stimulate plant growth and defense based on unknown mechanisms. This reinforcement of plants may provide protection to various forms of biotic and abiotic stress. To determine the genetic traits involved in the mechanism of plantbacteria association, the genome sequence of UCMB5113 was obtained by assembling paired-end Illumina reads. The assembled chromosome of 3,889,532 bp was predicted to encode 3,656 proteins. Genes that potentially contribute to plant growth promotion such as indole-3-acetic acid (IAA) biosynthesis, acetoin synthesis and siderophore production were identified. Moreover, annotation identified putative genes responsible for non-ribosomal synthesis of secondary metabolites and genes supporting environment fitness of UCMB5113 including drug and metal resistance. A large number of genes encoding a diverse set of secretory proteins, enzymes of primary and secondary metabolism and carbohydrate active enzymes were found which reflect a high capacity to degrade various rhizosphere macromolecules. Additionally, many predicted membrane transporters provides the bacterium with efficient uptake capabilities of several nutrients. Although, UCMB5113 has the possibility to produce antibiotics and biosurfactants, the protective effect of plants to pathogens seems to be indirect and due to priming of plant induced systemic resistance. The availability of the genome enables identification of genes and their function underpinning beneficial interactions of UCMB5113 with plants.
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| 13. |
- Englund, Oskar, 1982, et al.
(författare)
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Meeting Sustainability Requirements for SRC Bioenergy: Usefulness of Existing Tools, Responsibilities of Involved Stakeholders, and Recommendations for Further Developments
- 2012
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Ingår i: Bioenergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 5:3, s. 606-620
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Tidskriftsartikel (refereegranskat)abstract
- Short rotation coppice (SRC) is considered an important biomass supply option for meeting the European renewable energy targets. This paper presents an overview of existing and prospective sustainability requirements, Member State reporting obligations and parts of the methodology for calculating GHG emissions savings within the EU Renewable Energy Directive (RED), and shows how these RED-associated sustainability criteria may affect different stakeholders along SRC bioenergy supply chains. Existing and prospective tools are assessed on their usefulness in ensuring that SRC bioenergy is produced with sufficient consideration given to the RED-associated criteria. A sustainability framework is outlined that aims at (1) facilitating the development of SRC production systems that are attractive from the perspectives of all stakeholders, and (2) ensuring that the SRC production is RED eligible. Producer manuals, EIAs, and voluntary certification schemes can all be useful for ensuring RED eligibility. However, they are currently not sufficiently comprehensive, neither individually nor combined, and suggestions for how they can be more complementary are given. Geographical information systems offer opportunities for administrative authorities to provide stakeholders with maps or databases over areas/fields suitable for RED-eligible SRC cultivation. However, proper consideration of all relevant aspects requires that all stakeholders in the SRC supply chain become engaged in the development of SRC production systems and that a landscape perspective is used.
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| 14. |
- Meijer, Johan, et al.
(författare)
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Control of Drought Stress in Wheat Using Plant-Growth-Promoting Bacteria
- 2013
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Ingår i: Journal of Plant Growth Regulation. - : Springer Science and Business Media LLC. - 0721-7595 .- 1435-8107. ; 32, s. 122-130
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Tidskriftsartikel (refereegranskat)abstract
- Abiotic stress conditions are the main limiting factors for crop cultivation around the world. In the present study we aimed to improve wheat growth under drought stress conditions through priming with beneficial bacteria considered as plant-growth promoting bacteria (PGPB). Two bacterial strains, Bacillus amyloliquefaciens 5113 and Azospirillum brasilense NO40, were used to prime the wheat cv. Sids1. To generate drought stress for 12-day-old seedlings, water was withheld for 4, 5, or 7 days while growth and survival were recorded. Furthermore, several stress markers were examined by molecular and biochemical assays to study the role of priming on different stress tolerance mechanisms. Priming significantly alleviated the deleterious effect of drought stress on wheat. Drought resulted in the upregulation of some stress-related genes (APX1, SAMS1, and HSP17.8) in the leaves and increased activity of enzymes involved in the plant ascorbate-glutathione redox cycle. Bacteria-treated plants showed attenuated transcript levels suggesting improved homeostatic mechanisms due to priming. The present study reports on the ability of certain PGPB to attenuate several stress consequences in plants which strongly supports the potential of such an approach to control drought stress in wheat.
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| 15. |
- Hansson, Sven Ove, et al.
(författare)
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Crop Biotechnology for the Environment?
- 2013
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Ingår i: Journal of Agricultural and Environmental Ethics. - : Springer Science and Business Media LLC. - 1187-7863 .- 1573-322X. ; 26:4, s. 759-770
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Forskningsöversikt (refereegranskat)abstract
- In public debates, agricultural biotechnology is almost invariably discussed as a potential threat to the environment and to human health. Without downplaying the risks associated with this technology we emphasize that if properly regulated, it can be a forceful tool to solve environmental problems and promote human health. Agricultural biotechnology can reduce environmental problems in at least three ways: it can diminish the need for environmentally damaging agricultural practices such as pesticides, fertilizers, tillage, and irrigation. It can reduce the land area needed for agriculture, thus reducing the CO2 effect of agriculture and improving biodiversity. It can produce energy in a CO2-neutral way (especially if new technologies involving the cultivation of microalgae become successful). Furthermore, agricultural biotechnology can have positive effects on human health by decreasing occupational and dietary exposure to pesticides, improving the nutritional value of food, and producing pharmaceuticals more efficiently. We argue that those who wish to give high priority to environmental goals cannot afford any longer to be mere onlookers while others decide the future directions of agricultural biotechnology.
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| 16. |
- Chawade, Aakash, et al.
(författare)
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Global expression profiling of low temperature induced genes in the chilling tolerant japonica rice jumli marshi
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:12, s. e81729-
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Tidskriftsartikel (refereegranskat)abstract
- Low temperature is a key factor that limits growth and productivity of many important agronomical crops worldwide. Rice (Oryza sativa L.) is negatively affected already at temperatures below +10°C and is therefore denoted as chilling sensitive. However, chilling tolerant rice cultivars exist and can be commercially cultivated at altitudes up to 3,050 meters with temperatures reaching as low as +4°C. In this work, the global transcriptional response to cold stress (+4°C) was studied in the Nepalese highland variety Jumli Marshi (spp. japonica) and 4,636 genes were identified as significantly differentially expressed within 24 hours of cold stress. Comparison with previously published microarray data from one chilling tolerant and two sensitive rice cultivars identified 182 genes differentially expressed (DE) upon cold stress in all four rice cultivars and 511 genes DE only in the chilling tolerant rice. Promoter analysis of the 182 genes suggests a complex cross-talk between ABRE and CBF regulons. Promoter analysis of the 511 genes identified over-represented ABRE motifs but not DRE motifs, suggesting a role for ABA signaling in cold tolerance. Moreover, 2,101 genes were DE in Jumli Marshi alone. By chromosomal localization analysis, 473 of these cold responsive genes were located within 13 different QTLs previously identified as cold associated.
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| 17. |
- Shu, Huan, et al.
(författare)
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Arabidopsis replacement histone variant H3.3 occupies promoters of regulated genes
- 2014
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X .- 1474-7596. ; 15:4, s. R62-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Histone variants establish structural and functional diversity of chromatin by affecting nucleosome stability and histone-protein interactions. H3.3 is an H3 histone variant that is incorporated into chromatin outside of S-phase in various eukaryotes. In animals, H3.3 is associated with active transcription and possibly maintenance of transcriptional memory. Plant H3 variants, which evolved independently of their animal counterparts, are much less well understood.RESULTS: We profile the H3.3 distribution in Arabidopsis at mono-nucleosomal resolution using native chromatin immunoprecipitation. This results in the precise mapping of H3.3-containing nucleosomes, which are not only enriched in gene bodies as previously reported, but also at a subset of promoter regions and downstream of the 3[prime] ends of active genes. While H3.3 presence within transcribed regions is strongly associated with transcriptional activity, H3.3 at promoters is often independent of transcription. In particular, promoters with GA motifs carry H3.3 regardless of the gene expression levels. H3.3 on promoters of inactive genes is associated with H3K27me3 at gene bodies. In addition, H3.3-enriched plant promoters often contain RNA Pol II considerably upstream of the transcriptional start site. H3.3 and RNA Pol II are found on active as well as on inactive promoters and are enriched at strongly regulated genes.CONCLUSIONS: In animals and plants, H3.3 organizes chromatin in transcribed regions and in promoters. The results suggest a function of H3.3 in transcriptional regulation and support a model that a single ancestral H3 evolved into H3 variants with similar sub-functionalization patterns in plants and animals.
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| 18. |
- Palsdottir, Vilborg, 1979, et al.
(författare)
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Postnatal deficiency of essential fatty acids in mice results in resistance to diet-induced obesity and low plasma insulin during adulthood
- 2011
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Ingår i: Prostaglandins, Leukotrienes and Essential Fatty Acids. - : Elsevier BV. - 1532-2823 .- 0952-3278. ; 84:3-4, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- Our objective was to investigate the long-term metabolic effects of postnatal essential fatty acid deficiency (EFAD). Mouse dams were fed an EFAD diet or an isoenergetic control diet 4 days before delivery and throughout lactation. The pups were weaned to standard diet (STD) and were later subdivided into two groups: receiving high fat diet (HFD) or STD. Body composition, energy expenditure, food intake and leptin levels were analyzed in adult offspring. Blood glucose and plasma insulin concentrations were measured before and during a glucose tolerance test. EFAD offspring fed STD were leaner with lower plasma leptin and insulin concentrations compared to controls. EFAD offspring fed HFD were resistant to diet-induced obesity, had higher energy expenditure and lower levels of plasma leptin and insulin compared to controls. These results indicate that the fatty acid composition during lactation is important for body composition and glucose tolerance in the adult offspring.
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| 19. |
- Roos, Jonas
(författare)
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Verticillium longisporum and plant immunity responses in Arabidopsis
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Verticillium spp. are soil-borne ascomycete fungi belonging to a subgroup of Sordariomycetes, and the three major plant pathogens Verticillium longisporum, V. dahliae and V. albo-atrum cause disease on numerous plant species worldwide. In Sweden, V. longisporum poses a threat to Brassica oilseed crops, and is thus emphasized in this thesis. Here the early immune responses to V. longisporum in the model plant Arabidopsis and recent data on the V. longisporum genome are presented. Three genes of importance in the Arabidopsis–V. longisporum interaction were studied. The genes were identified via transcriptome and single nucleotide polymorphism (SNP) analysis. RabGAP22, a RabGTPase-regulating protein, was found to contribute to V. longisporum resistance. Pull-down assays revealed SERINE:GLYOXYLATE AMINOTRANSFERASE (AGT1) as an interacting partner during V. longisporum infection and the two proteins were shown to co-localize in the peroxisomes. Unexpectedly, a role for RabGAP22 was also found in stomatal immunity. The monoterpene synthase TPS23/27 was on the other hand found to contribute to fungal invasion, by triggering germination of V. longisporum conidia. The third gene codes for a nitrate/peptide transporter, NPF5.12. Pull-down experiments and fluorescent imaging revealed interaction between NPF5.12 and a major latex protein family member, NPFBP1. Implications in plant immunity processes of these three genes are further discussed. The genomes of two Swedish V. longisporum isolates were sequenced and found to have a size of approximately 70 Mb and harbor ~21,000 protein-coding genes. Initial analyses revealed that 86% of the V. longisporum genomes are shared with V. dahliae and V. albo-atrum, with a high extent of gene duplications. Large numbers of proteins were predicted to contain secretion motifs, and this group of proteins is presumed to play major roles in the interactions with V. longisporum host plants. In conclusion, this thesis work has revealed new fungal and plant host genes and thereby laid the basis for new plant breeding and disease protection strategies.
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| 20. |
- Cifuentes, Carolina, et al.
(författare)
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Biosynthesis of Callose and Cellulose by Detergent Extracts of Tobacco Cell Membranes and Quantification of the Polymers Synthesized in vitro
- 2010
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Ingår i: J INTEGR PLANT BIOL. - : Wiley. - 1672-9072. ; 52:2, s. 221-233
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Tidskriftsartikel (refereegranskat)abstract
- The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of membranes from 11-day-old tobacco BY-2 cells in the presence of 1 mM UDP-glucose, 8 mM Ca2+ and 8 mM Mg2+. Under these conditions, up to nearly 40% of the polysaccharides synthesized in vitro corresponded to cellulose, the other polymer synthesized being callose. Transmission electron microscopy analysis revealed the occurrence of two types of structures in the synthetic reactions. The first type consisted of small aggregates with a diameter between 3 and 5 nm that associated to form fibrillar strings of a maximum length of 400 nm. These structures were sensitive to the acetic/nitric acid treatment of Updegraff and corresponded to callose. The second type of structures was resistant to the Updegraff reagent and corresponded to straight cellulose microfibrils of 2-3 nm in diameter and 200 nm to up to 5 mu m in length. In vitro reactions performed on electron microscopy grids indicated that the minimal rate of microfibril elongation in vitro is 120 nm/min. Measurements of retardance by liquid crystal polarization microscopy as a function of time showed that small groups of microfibrils increased in retardance by up to 0.047 nm/min per pixel, confirming the formation of organized structures.
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| 21. |
- Nahar, Noor, et al.
(författare)
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In silico and in vivo studies of an Arabidopsis thaliana gene, ACR2, putatively involved in arsenic accumulation in plants
- 2012
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Ingår i: Journal of Molecular Modeling. - : Springer. - 1610-2940 .- 0948-5023. ; 18:9, s. 4249-4262
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Tidskriftsartikel (refereegranskat)abstract
- Previously, our in silico analyses identified four candidate genes that might be involved in uptake and/or accumulation of arsenics in plants: arsenate reductase 2 (ACR2), phytochelatin synthase 1 (PCS1) and two multi-drug resistant proteins (MRP1 and MRP2) [Lund et al. (2010) J Biol Syst 18:223–224]. We also postulated that one of these four genes, ACR2, seems to play a central role in this process. To investigate further, we have constructed a 3D structure of the Arabidopsis thaliana ACR2 protein using the iterative implementation of the threading assembly refinement (I-TASSER) server. These analyses revealed that, for catalytic metabolism of arsenate, the arsenate binding-loop (AB-loop) and residues Phe-53, Phe-54, Cys-134, Cys-136, Cys-141, Cys-145, and Lys-135 are essential for reducing arsenate to arsenic intermediates (arsenylated enzyme-substrate intermediates) and arsenite in plants. Thus, functional predictions suggest that the ACR2 protein is involved in the conversion of arsenate to arsenite in plant cells. To validate the in silico results, we exposed a transfer-DNA (T-DNA)-tagged mutant of A. thaliana (mutation in the ACR2 gene) to various amounts of arsenic. Reverse transcriptase PCR revealed that the mutant exhibits significantly reduced expression of the ACR2 gene. Spectrophotometric analyses revealed that the amount of accumulated arsenic compounds in this mutant was approximately six times higher than that observed in control plants. The results obtained from in silico analyses are in complete agreement with those obtained in laboratory experiments.
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| 22. |
- Bejai, Sarosh, et al.
(författare)
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ML3: a novel regulator of herbivory-induced responses in Arabidopsis thaliana
- 2013
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Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 64, s. 935-948
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Tidskriftsartikel (refereegranskat)abstract
- ML (MD2-related lipid recognition) proteins are known to enhance innate immune responses in mammals. This study reports the analysis of the putative ML gene family in Arabidopsis thaliana and suggests a role for the ML3 gene in herbivory-associated responses in plants. Feeding by larvae of the Lepidopteran generalist herbivore Spodoptera littoralis and larvae of the specialist herbivore Plutella xylostella activated ML3 transcription in leaf tissues. ML3 loss-of-function Arabidopsis plants were compromised in the upregulation of herbivory-induced genes and displayed a semi-dwarf phenotype. Herbivory bioassays showed that larvae of S. littoralis fed on ml3 mutant plants gained more weight compared to larvae fed on wild-type plants while larvae of P. xylostella did not show any significant difference. Virus-induced gene silencing of ML3 expression in plants compromised in jasmonic acid (JA) and salicylic acid (SA) signalling revealed a complex role of ML3 in JA/defence signalling affecting both JA- and SA-dependent responses. The data suggest that ML3 is involved in herbivory-mediated responses in Arabidopsis and that it has a potential role in herbivory-associated molecular pattern recognition.
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| 23. |
- Zubair, Muhammad
(författare)
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Genetic variation, biochemical contents and wound healing activity of Plantago major
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plantago major L. (greater plantain, common plantain) has been used as a wound healing remedy in different parts of the world for centuries. Different bioactive compounds have been proposed to contribute to the wound healing properties of this plant. The present study was undertaken to investigate the impact of some genetic and environmental factors on the wound healing activity of common plantain. Seeds of P. major were collected from five populations in different parts of Sweden, and were germinated and grown in a greenhouse. As expected for an inbreeding species, RAPD analyses demonstrated considerable between-population variation but very sparse within-population and within-subpopulation variation. Six major phenolic compounds were encountered in samples of P. major, four of which were identified for the first time in this thesis; PLMA 1–PLMA 4. Between-population and sub-population differences in the contents of these chemical compounds showed no correlation with RAPD-based estimates of genetic relatedness. The contents of these compounds differed greatly between different plant organs of P. major. The highest concentration of plantamajoside and PLMA 2 was found in leaves whereas the highest concentration of verbascoside was found in flower stalks and seeds. Contents were significantly higher in freeze-dried leaf samples compared to samples dried at higher temperatures. Both water and ethanol-based extracts of P. major leaves stimulated the cell proliferation and migration in an in vitro scratch assay, and also showed anti-inflammatory activity in an in vitro NF-kB assay with oral epithelial cell cultures. Similarly, these extracts stimulated wound healing activities in ex vivo tests using detached pig ears. Further breeding efforts aimed at developing P. major as a crop plant, and medicinal research aimed at elucidating and optimizing extracts with wound healing properties, are thus warranted.
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| 24. |
- Dimitriou, Ioannis, et al.
(författare)
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Slow expansion and low yields of willow short rotation coppice in Sweden; implications for future strategies
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 35:11, s. 4613-4618
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Tidskriftsartikel (refereegranskat)abstract
- About 16 000 ha of commercial willow Short Rotation Coppice (SRC) fields for production of biomass for energy were planted in the early 1990s in Sweden. The cultivated with SRC area has remained almost stable and was slightly decreased during the last years despite the incentives and predictions for drastic increases. Similar incentives and predictions in other countries have been lately launched. The bioenergy produced in the planted SRC areas in Sweden has been lower than anticipated, partly due to the lower than expected biomass yields and the termination of some willow SRC plantations. Explanations for the low yields are depicted based on analyzing the results of a survey where 175 willow SRC growers participated. Lower biomass yields are attributed to: (i) the low input in management activities; (ii) the choice of land for the willow SRC plantation; (iii) and the level of personal involvement of the farmer. Understanding the reasons to earlier years' performance of willow SRC is important for development of better performing systems in the future, in Sweden as well as in other countries. © 2011 Elsevier Ltd.
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| 25. |
- Prade, Thomas, et al.
(författare)
-
Introduction of grass-clover crops as biogas feedstock in cereal dominated crop rotations. Part I: Effects on soil organic carbon and food production
- 2014
-
Ingår i: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector. - 9780988214576 ; , s. 1032-1040
-
Konferensbidrag (refereegranskat)abstract
- Changes of soil organic carbon (SOC) ontent can have a substantial effect on greenhouse gas emissions, but are rarely included in cropproduction LCAs. SOC content strongly influences soil fertility and therefore crop yields, but is declining in many European soils. The present study investigated if integration of 1-2 years of grass-clover crops in a cereal-dominated crop rotation can increase the SOC pool and how this would impact food production. Results show that when grass-clover crops are integrated, the potential SOC content at steady state will be 41 to 52% higher than in the conventional cereal-dominated crop rotation. The net increase of wheat yields based on SOC improvements indicate that for a crop rotation with one year of grass-clover crops, the initial loss of food production can be counterbalanced due to the impact on fertility of the SOC increase.
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| 26. |
- Johansson, Mikael, 1981-
(författare)
-
The circadian clock in annuals and perennials : coordination of Growth with Environmental Rhythms
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since the first signs of life on planet earth, organisms have had to adapt to the daily changes between light and dark, and high and low temperatures. This has led to the evolution of an endogenous time keeper, known as the circadian clock. This biological timing system helps the organism to synchronize developmental and metabolic events to the most favorable time of the day. Such a mechanism is of considerable value to plants, since they in contrast to animals cannot change location when the environment becomes unfavorable. Thus is the ability to predict coming events of central importance in a plants life. This thesis is a study of the molecular machinery behind the clockwork in the small weed plant Arabidopsis thaliana as well as its close relative perennial; the woody species Populus. We have characterized a novel component of the circadian clock, EARLY BIRD (EBI). EBI is involved in transcriptional and translational regulation, via interaction with the known post-translational clock regulator ZEITLUPE (ZTL). In Populus, we describe the role of the circadian clock and its components with respect to entry and exit of dormancy and show that gene expression of the Populus LATE ELONATED HYPOCOTYL (LHY) genes are crucial importance for freezing tolerance and thereby survival at high latitudes. Furthermore, the input to the Populus clock is mediated via the phytochrome A (phyA) photoreceptor.
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| 27. |
- Mayers, Joshua, 1988, et al.
(författare)
-
Influence of the N: P supply ratio on biomass productivity and time-resolved changes in elemental and bulk biochemical composition of Nannochloropsis sp.
- 2014
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 169, s. 588-595
-
Tidskriftsartikel (refereegranskat)abstract
- This work reports for the first time the detailed impacts of dual nitrogen (N) and phosphorus (P) stress on growth dynamics and biochemical composition in the Eustigmatophyte Nannochloropsis sp. P-stress concurrent with N-stress had subtle effects on culture bulk biochemical composition, but negatively influenced biomass productivity. However, the N:P supply ratio can be raised to at least 32:1 without compromising productivity (yielding a maximum lipid content of 52% of dry weight and volumetric lipid concentration of 233mgL-1). The maximum biomass and lipid yields per unit of cell-P were 1.2kgDW (gP)-1 and 0.54kglipid (gP)-1. The P concentration of many common media is thus in surplus for optimal Nannochloropsis sp. biomass and lipid production, offering potential for significant savings in P usage and improving the sustainability of algal cultivation. © 2014 Elsevier Ltd.
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| 28. |
- Önneby, Karin
(författare)
-
Bioaugmentation for reduction of diffuse pesticide contamination : a bioprophylactic concept
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pesticides and their residues frequently contaminate surface waters and groundwater so consequently there is a great need to identify methods and practices that reduce such contamination. This thesis examined the potential of a 'bioprophylactic' concept based on the hypothesis that diffuse contamination after application in the field can be significantly reduced if pesticides are degraded as rapidly as possible after the intended effect has been achieved. This involves adding pesticide degraders together with the pesticide at the time of application. Such enhanced degradation is particularly important for pesticides used on non-agricultural soils with low degradation and high leaching potential (e.g. roadsides, railway embankments, paths, farmyards, urban land). The herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) was used as a model herbicide in this thesis, together with its degrader Sphingobium sp. T51. Soil inoculation with Sphingobium sp. T51 in microcosms significantly enhanced the degradation of MCPA compared with an uninoculated soil, without losing the herbicidal effect. In sand, 105 cells g-1 dry weight of soil reduced the MCPA concentration by 79-86% within one day, while only 0-31% reduction was observed in the uninoculated control after three days. However, Sphingobium sp. T51 needs to be formulated to retain its viability and degradation activity during prolonged storage and also for protection from the harsh environmental stresses associated with its application and functioning in the field. Both freeze drying and fluidised bed drying of Sphingobium sp. T51 resulted in high initial cell survival rates, of 67-85%. The storage stability of formulated Sphingobium sp. T51 was dependent on the formulation excipient/carrier used, storage temperature and atmospheric conditions. Sphingobium sp. T51 demonstrated approximately 50% survival in a freeze-dried sucrose formulation after six months of storage under partial vacuum at 25 °C. A fluidised bed-dried formulation with cottonseed flour as carrier resulted in the highest MCPA degradation in microcosms, but the storage stability was insufficient. Formulated and long-term stored Sphingobium sp. T51 reduced pesticide leaching by 85-94% of the total amount added in sand columns. Future research needs regarding practical implementation of the concept are discussed.
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| 29. |
- Biswal, Ajaya K., et al.
(författare)
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Aspen pectate lyase PtxtPL1-27 mobilizes matrix polysaccharides from woody tissues and improves saccharification yield
- 2014
-
Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 7, s. 11-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Wood cell walls are rich in cellulose, hemicellulose and lignin. Hence, they are important sources of renewable biomass for producing energy and green chemicals. However, extracting desired constituents from wood efficiently poses significant challenges because these polymers are highly cross-linked in cell walls and are not easily accessible to enzymes and chemicals. Results: We show that aspen pectate lyase PL1-27, which degrades homogalacturonan and is expressed at the onset of secondary wall formation, can increase the solubility of wood matrix polysaccharides. Overexpression of this enzyme in aspen increased solubility of not only pectins but also xylans and other hemicelluloses, indicating that homogalacturonan limits the solubility of major wood cell wall components. Enzymatic saccharification of wood obtained from PL1-27-overexpressing trees gave higher yields of pentoses and hexoses than similar treatment of wood from wild-type trees, even after acid pretreatment. Conclusions: Thus, the modification of pectins may constitute an important biotechnological target for improved wood processing despite their low abundance in woody biomass.
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| 30. |
- Shaikhali, Jehad, et al.
(författare)
-
The CRYPTOCHROME1-Dependent Response to Excess Light Is Mediated through the Transcriptional Activators ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 and ZML2 in Arabidopsis
- 2012
-
Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 24:7, s. 3009-3025
-
Tidskriftsartikel (refereegranskat)abstract
- Exposure of plants to light intensities that exceed the electron utilization capacity of the chloroplast has a dramatic impact on nuclear gene expression. The photoreceptor Cryptochrome 1 (cry1) is essential to the induction of genes encoding photoprotective components in Arabidopsis thaliana. Bioinformatic analysis of the cry1 regulon revealed the putative ciselement CryR1 (GnTCKAG), and here we demonstrate an interaction between CryR1 and the zinc finger GATA-type transcription factors ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 (ZML1) and ZML2. The ZML proteins specifically bind to the CryR1 cis-element as demonstrated in vitro and in vivo, and TCTAG was shown to constitute the core sequence required for ZML2 binding. In addition, ZML2 activated transcription of the yellow fluorescent protein reporter gene driven by the CryR1 cis-element in Arabidopsis leaf protoplasts. T-DNA insertion lines for ZML2 and its homolog ZML1 demonstrated misregulation of several cry1-dependent genes in response to excess light. Furthermore, the zml1 and zml2 T-DNA insertion lines displayed a high irradiance-sensitive phenotype with significant photoinactivation of photosystem II (PSII), indicated by reduced maximum quantum efficiency of PSII, and severe photobleaching. Thus, we identified the ZML2 and ZML1 GATA transcription factors as two essential components of the cry1-mediated photoprotective response.
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| 31. |
- Ulfstedt, Mikael
(författare)
-
Functional studies of plant hexokinases and development of genetic methods in the moss Physcomitrella patens
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the field of biology, model systems are frequently used for practical reasons. Model organisms possess several features that make them easy to work with in a laboratory setting. In addition they usually have a host of established genetic tools that have been developed by the research community. This thesis explores the potential of adapting methods and tools used in the yeast Saccharomyces cerevisiae to the plant model system Physcomitrella patens. We have studied the fate and integrity of plasmids transformed into Physcomitrella with the purpose of developing a working shuttle plasmids system in moss. Other methods from yeast genetics such as the use of auxotrophic strains would also be useful if adapted to the Physcomitrella model system. Experiments using Physcomitrella patens showed that a histidine auxotrophic moss strain can be complemented with the wild type gene on a plasmid and that the plasmid can be rescued back into E. coli. This indicates that shuttle plasmids, auxotrophic marker genes such as PpHIS3, cloning by complementation and perhaps even dosage suppressor screens could be used in Physcomitrella patens. Furthermore this thesis investigates the hexose phosphorylating enzyme hexokinase in Physcomitrella patens as well as in the charophyte alga Klebsormidium nitens. The characterization and localization studies performed on the eleven Physcomitrella hexokinases led to the discovery of two new types of plant hexokinases, the type C and type D hexokinases. In addition to these two new types, Physcomitrella contained several of the previously described type A and type B hexokinases. In addition to its enzymatic function, hexokinases in both plants and fungi have been implicated in glucose sensing and signaling. This thesis examines if hexokinase 1 of the microalga Klebsormidium nitens may play a similar role in glucose sensing as observed in higher plants. With this purpose in mind transgenic lines of the Arabidopsis thaliana glucose insensitive mutant gin2-1 expressing the Klebsormidium nitens hexokinase 1 were created. It was found that the K. nitens hexokinase can complement the glucose signaling defect in the gin2-1 mutant.
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| 32. |
- Ståhlberg, Jerry
(författare)
-
Product Binding Varies Dramatically between Processive and Nonprocessive Cellulase Enzymes
- 2012
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287, s. 24807-24813
-
Tidskriftsartikel (refereegranskat)abstract
- Cellulases hydrolyze beta-1,4 glycosidic linkages in cellulose, which are among the most prevalent and stable bonds in Nature. Cellulases comprise many glycoside hydrolase families and exist as processive or nonprocessive enzymes. Product inhibition negatively impacts cellulase action, but experimental measurements of product-binding constants vary significantly, and there is little consensus on the importance of this phenomenon. To provide molecular level insights into cellulase product inhibition, we examine the impact of product binding on processive and nonprocessive cellulases by calculating the binding free energy of cellobiose to the product sites of catalytic domains of processive and nonprocessive enzymes from glycoside hydrolase families 6 and 7. The results suggest that cellobiose binds to processive cellulases much more strongly than nonprocessive cellulases. We also predict that the presence of a cellodextrin bound in the reactant site of the catalytic domain, which is present during enzymatic catalysis, has no effect on product binding in nonprocessive cellulases, whereas it significantly increases product binding to processive cellulases. This difference in product binding correlates with hydrogen bonding between the substrate-side ligand and the cellobiose product in processive cellulase tunnels and the additional stabilization from the longer tunnel-forming loops. The hydrogen bonds between the substrate-and product-side ligands are disrupted by water in nonprocessive cellulase clefts, and the lack of long tunnel-forming loops results in lower affinity of the product ligand. These findings provide new insights into the large discrepancies reported for binding constants for cellulases and suggest that product inhibition will vary significantly based on the amount of productive binding for processive cellulases on cellulose.
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| 33. |
- Minina, Alyona, et al.
(författare)
-
Autophagy and metacaspase determine the mode of cell death in plants
- 2013
-
Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 203, s. 917-927
-
Tidskriftsartikel (refereegranskat)abstract
- Although animals eliminate apoptotic cells using macrophages, plants use cell corpses throughout development and disassemble cells in a cell-autonomous manner by vacuolar cell death. During vacuolar cell death, lytic vacuoles gradually engulf and digest the cytoplasmic content. On the other hand, acute stress triggers an alternative cell death, necrosis, which is characterized by mitochondrial dysfunction, early rupture of the plasma membrane, and disordered cell disassembly. How both types of cell death are regulated remains obscure. In this paper, we show that vacuolar death in the embryo suspensor of Norway spruce requires autophagy. In turn, activation of autophagy lies downstream of metacaspase mcII-Pa, a key protease essential for suspensor cell death. Genetic suppression of the metacaspase-autophagy pathway induced a switch from vacuolar to necrotic death, resulting in failure of suspensor differentiation and embryonic arrest. Our results establish metacaspase-dependent autophagy as a bona fide mechanism that is responsible for cell disassembly during vacuolar cell death and for inhibition of necrosis.
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| 34. |
- Hjältén, Joakim, et al.
(författare)
-
Innate and Introduced Resistance Traits in Genetically Modified Aspen Trees and Their Effect on Leaf Beetle Feeding
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:9, s. e73819-
-
Tidskriftsartikel (refereegranskat)abstract
- Genetic modifications of trees may provide many benefits, e. g. increase production, and mitigate climate change and herbivore impacts on forests. However, genetic modifications sometimes result in unintended effects on innate traits involved in plant-herbivore interactions. The importance of intentional changes in plant defence relative to unintentional changes and the natural variation among clones used in forestry has not been evaluated. By a combination of biochemical measurements and bioassays we investigated if insect feeding on GM aspens is more affected by intentional (induction Bt toxins) than of unintentional, non-target changes or clonal differences in innate plant defence. We used two hybrid wildtype clones (Populus tremula x P. tremuloides and Populus tremula x P. alba) of aspen that have been genetically modified for 1) insect resistance (two Bt lines) or 2) reduced lignin properties (two lines COMT and CAD), respectively. Our measurements of biochemical properties suggest that unintended changes by GM modifications (occurring due to events in the transformation process) in innate plant defence (phenolic compounds) were generally smaller but fundamentally different than differences seen among different wildtype clones (e. g. quantitative and qualitative, respectively). However, neither clonal differences between the two wildtype clones nor unintended changes in phytochemistry influenced consumption by the leaf beetle (Phratora vitellinae). By contrast, Bt induction had a strong direct intended effect as well as a post experiment effect on leaf beetle consumption. The latter suggested lasting reduction of beetle fitness following Bt exposure that is likely due to intestinal damage suffered by the initial Bt exposure. We conclude that Bt induction clearly have intended effects on a target species. Furthermore, the effect of unintended changes in innate plant defence traits, when they occur, are context dependent and have in comparison to Bt induction probably less pronounced effect on targeted herbivores.
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| 35. |
- Wright, Sandra, A. I., 1962, et al.
(författare)
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Barley lesion mimics, supersusceptible or highly resistant to leaf rust and net blotch
- 2013
-
Ingår i: Plant Pathology. - : Wiley. - 0032-0862 .- 1365-3059. ; 62:5, s. 982-992
-
Tidskriftsartikel (refereegranskat)abstract
- Lesion mimic mutants of plants have the feature of spontaneously displaying necrotic spots or bands on their leaves. Lesion mimics have often displayed enhanced resistance to biotrophic pathogens whilst showing increased susceptibility to necrotrophs. This paper identifies three novel, non-allelic mutants of barley (Hordeum vulgare), which spontaneously form necrotic leaf lesions: Necrotic leaf spot 9.3091 (nec9.3091), Mottled leaf 8.1661 (mtt8.1661) and Mottled leaf 9.2721 (mtt9.2721). The Necrotic leaf spot 8.3550 mutant (nec8.3550), formerly known as bst1, was included in the study because it is a lesion mimic mutant belonging to the same original pool. The reactions of the mutants to the biotroph Puccinia hordei and the necrotroph Pyrenophora teres f. sp. teres were investigated. Mutants nec8.3550 and mtt8.1661 were more resistant than the parental Bowman near-isogenic line with the Rph3.c gene (Bowman Rph3.c, NGB 22452) to leaf rust, caused by P.hordei. Mutants nec8.3550, mtt8.1661 and mtt9.2721 were more susceptible than Bowman Rph3.c to net blotch, caused by P.teres f. sp. teres. Autofluorescence was detected in leaf tissues of all mutants. Based on the high expression of the PR1 and Hv-HIR genes, combined with the low susceptibility to P.hordei, nec8.3550 appears to have entered a state of systemic acquired resistance, which is quite distinct from the resistance expressed in mtt8.1661. The latter mutant has low or no expression of PR1 and Hv-HIR genes, yet it is highly resistant to rust. It is also extremely susceptible to net blotch. These mutants can serve as genetic sources of novel disease resistance for barley improvement.
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| 36. |
- Ding, Bao-Jian, et al.
(författare)
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A plant factory for moth pheromone production
- 2014
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 1-3353
-
Tidskriftsartikel (refereegranskat)abstract
- Moths depend on pheromone communication for mate finding and synthetic pheromones are used for monitoring or disruption of pheromone communication in pest insects. Here we produce moth sex pheromone, using Nicotiana benthamiana as a plant factory, by transient expression of up to four genes coding for consecutive biosynthetic steps. We specifically produce multicomponent sex pheromones for two species. The fatty alcohol fractions from the genetically modified plants are acetylated to mimic the respective sex pheromones of the small ermine moths Yponomeuta evonymella and Y. padella. These mixtures are very efficient and specific for trapping of male moths, matching the activity of conventionally produced pheromones. Our long-term vision is to design tailor-made production of any moth pheromone component in genetically modified plants. Such semisynthetic preparation of sex pheromones is a novel and cost-effective way of producing moderate to large quantities of pheromones with high purity and a minimum of hazardous waste.
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| 37. |
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| 38. |
- Kradolfer, David, et al.
(författare)
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An Imprinted Gene Underlies Postzygotic Reproductive Isolation in Arabidopsis thaliana
- 2013
-
Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 26, s. 525-535
-
Tidskriftsartikel (refereegranskat)abstract
- Postzygotic reproductive isolation in response to interploidy hybridizations is a well-known phenomenon in plants that forms a major path for sympatric speciation. A main determinant for the failure of interploidy hybridizations is the endosperm, a nutritious tissue supporting embryo growth, similar to the functional role of the placenta in mammals. Although it has been suggested that deregulated imprinted genes underpin dosage sensitivity of the endosperm, the molecular basis for this phenomenon remained unknown. In a genetic screen for suppressors of trip-bid seed abortion, we have identified the paternally expressed imprinted gene ADMETOS (ADM). Here, we present evidence that increased dosage of ADM causes triploid seed arrest. A large body of theoretical work predicted that deregulated imprinted genes establish the barrier to interploidy hybridization. Our study thus provides evidence strongly supporting this hypothesis and generates the molecular basis for our understanding of postzygotic hybridization barriers in plants.
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| 39. |
- Ernfors, Maria, 1973, et al.
(författare)
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Effects of wood ash fertilization on forest floor greenhouse gas emissions and tree growth in nutrient poor drained peatland forests
- 2010
-
Ingår i: SCIENCE OF THE TOTAL ENVIRONMENT. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 408:20, s. 4580-4590
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Tidskriftsartikel (refereegranskat)abstract
- Wood ash (3.1, 3.3 or 6.6 tonnes dry weight ha(-1)) was used to fertilize two drained and forested peatland sites in southern Sweden. The sites were chosen to represent the Swedish peatlands that are most suitable for ash fertilization, with respect to stand growth response. The fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the forest floor, measured using opaque static chambers, were monitored at both sites during 2004 and 2005 and at one of the sites during the period 1 October 2007-1 October 2008. No significant (p>0.05) changes in forest floor greenhouse gas exchange were detected. The annual emissions of CO2 from the sites varied between 6.4 and 15.4 tonnes ha(-1), while the CH4 fluxes varied between 1.9 and 12.5 kg ha(-1). The emissions of N2O were negligible. Ash fertilization increased soil pH at a depth of 0-0.05 m by up to 0.9 units (p<0.01) at one site, 5 years after application, and by 0.4 units (p<0.05) at the other site, 4 years after application. Over the first 5 years after fertilization, the mean annual tree stand basal area increment was significantly larger (p<0.05) at the highest ash dose plots compared with control plots (0.64 m(2) ha(-1) year(-1) and 0.52 m(2) ha(-1) year(-1), respectively). The stand biomass, which was calculated using tree biomass functions, was not significantly affected by the ash treatment. The groundwater levels during the 2008 growing season were lower in the high ash dose plots than in the corresponding control plots (p<0.05), indicating increased evapotranspiration as a result of increased tree growth. The larger basal area increment and the lowered groundwater levels in the high ash dose plots suggest that fertilization promoted tree growth, while not affecting greenhouse gas emissions.
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| 40. |
- Ek, Weronica, et al.
(författare)
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Mapping QTL affecting a systemic sclerosis-like disorder in a cross between UCD-200 and red jungle fowl chickens.
- 2012
-
Ingår i: Developmental and comparative immunology. - : Elsevier BV. - 1879-0089 .- 0145-305X. ; 38:2, s. 352-9
-
Tidskriftsartikel (refereegranskat)abstract
- Systemic sclerosis (SSc) or scleroderma is a rare, autoimmune, multi-factorial disease characterized by early microvascular alterations, inflammation, and fibrosis. Chickens from the UCD-200 line develop a hereditary SSc-like disease, showing all the hallmarks of the human disorder, which makes this line a promising model to study genetic factors underlying the disease. A backcross was generated between UCD-200 chickens and its wild ancestor - the red jungle fowl and a genome-scan was performed to identify loci affecting early (21 days of age) and late (175 days of age) ischemic lesions of the comb. A significant difference in frequency of disease was observed between sexes in the BC population, where the homogametic males were more affected than females, and there was evidence for a protective W chromosome effect. Three suggestive disease predisposing loci were mapped to chromosomes 2, 12 and 14. Three orthologues of genes implicated in human SSc are located in the QTL region on chromosome 2, TGFRB1, EXOC2-IRF4 and COL1A2, as well as CCR8, which is more generally related to immune function. IGFBP3 is also located within the QTL on chromosome 2 and earlier studies have showed increased IGFBP3 serum levels in SSc patients. To our knowledge, this study is the first to reveal a potential genetic association between IGFBP3 and SSc. Another gene with an immunological function, SOCS1, is located in the QTL region on chromosome 14. These results illustrate the usefulness of the UCD-200 chicken as a model of human SSc and motivate further in-depth functional studies of the implicated candidate genes.
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| 41. |
- Gustafsson, Kerstin, et al.
(författare)
-
Direct and indirect effects of the fungicide azoxystrobin in outdoor brackish water microcosms
- 2010
-
Ingår i: Ecotoxicology. - : Springer Science and Business Media LLC. - 0963-9292 .- 1573-3017. ; 19:2, s. 431-444
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Tidskriftsartikel (refereegranskat)abstract
- The effects of the strobilurin fungicide azoxystrobin were studied in brackish water microcosms, with natural plankton communities and sediment. Two experiments were conducted: Experiment 1 (nominal conc. 0, 15 and 60 mu g/L, 24-L outdoor microcosms for 21 days) and a second, follow-up, Experiment 2 (nominal conc. 0, 3, 7.5, 15 mu g/L, 4-L indoor microcosms for 12 days). The microcosms represent a simplified brackish water community found in shallow semi-enclosed coastal areas in agricultural districts in the Baltic Sea region. Measured water concentrations of the fungicide (Experiment 1) were, on average, 83 and 62% of nominal concentrations directly after application, and 25 and 30% after 21 days, for the low and high dose treatments, respectively, corresponding to mean DT50-values of 15.1 and 25.8 days, for low and high dose treatments, respectively. In Experiment 1, direct toxic effects on calanoid copepods at both test concentrations were observed. Similarly, in Experiment 2, the copepod abundance was significantly reduced at all tested concentrations. There were also significant secondary effects on zooplankton and phytoplankton community structure, standing stocks and primary production. Very few ecotoxicological studies have investigated effects of plant protection products on Baltic organisms in general and effects on community structure and function specifically. Our results show that azoxystrobin is toxic to brackish water copepods at considerably lower concentrations than previously reported from single species tests on freshwater crustaceans, and that direct toxic effects on this ecologically important group may lead to cascade effects altering lower food webs and ecosystem functioning.
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| 42. |
- Derkacheva, Maria, et al.
(författare)
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Arabidopsis MSI1 connects LHP1 to PRC2 complexes
- 2013
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 32, s. 2073-2085
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Tidskriftsartikel (refereegranskat)abstract
- Polycomb group (PcG) proteins form essential epigenetic memory systems for controlling gene expression during development in plants and animals. However, the mechanism of plant PcG protein functions remains poorly understood. Here, we probed the composition and function of plant Polycomb repressive complex 2 (PRC2). This work established the fact that all known plant PRC2 complexes contain MSI1, a homologue of Drosophila p55. While p55 is not essential for the in vitro enzymatic activity of PRC2, plant MSI1 was required for the functions of the EMBRYONIC FLOWER and the VERNALIZATION PRC2 complexes including trimethylation of histone H3 Lys27 (H3K27) at the target chromatin, as well as gene repression and establishment of competence to flower. We found that MSI1 serves to link PRC2 to LIKE HETEROCHROMATIN PROTEIN 1 (LHP1), a protein that binds H3K27me3 in vitro and in vivo and is required for a functional plant PcG system. The LHP1-MSI1 interaction forms a positive feedback loop to recruit PRC2 to chromatin that carries H3K27me3. Consequently, this can provide a mechanism for the faithful inheritance of local epigenetic information through replication.
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| 43. |
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Karlgren, Anna, et al.
(författare)
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Conserved function of core clock proteins in the gymnosperm Norway spruce (Picea abies L. Karst)
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:3, s. e60110-
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Tidskriftsartikel (refereegranskat)abstract
- From studies of the circadian clock in the plant model species Arabidopsis (Arabidopsis thaliana), a number of important properties and components have emerged. These include the genes CIRCADIAN CLOCK ASSOCIATED 1 (CCA1), GIGANTEA (GI), ZEITLUPE (ZTL) and TIMING OF CAB EXPRESSION 1 (TOC1 also known as PSEUDO-RESPONSE REGULATOR 1 (PRR1)) that via gene expression feedback loops participate in the circadian clock. Here, we present results from ectopic expression of four Norway spruce (Picea abies) putative homologs (PaCCA1, PaGI, PaZTL and PaPRR1) in Arabidopsis, their flowering time, circadian period length, red light response phenotypes and their effect on endogenous clock genes were assessed. For PaCCA1-ox and PaZTL-ox the results were consistent with Arabidopsis lines overexpressing the corresponding Arabidopsis genes. For PaGI consistent results were obtained when expressed in the gi2 mutant, while PaGI and PaPRR1 expressed in wild type did not display the expected phenotypes. These results suggest that protein function of PaCCA1, PaGI and PaZTL are at least partlyconserved compared to Arabidopsis homologs, however further studies are needed to reveal the protein function of PaPRR1. Our data suggest that components of thethree-loop network typical of the circadian clock in angiosperms were present beforethe split of gymnosperms and angiosperms.
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| 48. |
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| 49. |
- Cavka, Adnan, et al.
(författare)
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Effect of sulfur oxyanions on lignocellulose-derived fermentation inhibitors
- 2011
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 108:11, s. 2592-2599
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Tidskriftsartikel (refereegranskat)abstract
- Recent results show that treatments with reducing agents, including the sulfur oxyanions dithionite and hydrogen sulfite, efficiently improve the fermentability of inhibitory lignocellulose hydrolysates, and that the treatments are effective when the reducing agents are added in situ into the fermentation vessel at low temperature. In the present investigation, dithionite was added to medium with model inhibitors (coniferyl aldehyde, furfural, 5-hydroxymethylfurfural, or acetic acid) and the effects on the fermentability with yeast were studied. Addition of 10 mM dithionite to medium containing 2.5 mM coniferyl aldehyde resulted in a nine-fold increase in the glucose consumption rate and a three-fold increase in the ethanol yield. To investigate the mechanism behind the positive effects of adding sulfur oxyanions, mixtures containing 2.5 mM of a model inhibitor (an aromatic compound, a furan aldehyde, or an aliphatic acid) and 15 mM dithionite or hydrogen sulfite were analyzed using mass spectrometry (MS). The results of the analyses, which were performed by using UHPLC-ESI-TOF-MS and UHPLC-LTQ/Orbitrap-MS/MS, indicate that the positive effects of sulfur oxyanions are primarily due to their capability to react with and sulfonate inhibitory aromatic compounds and furan aldehydes at low temperature and slightly acidic pH (such as 25°C and pH 5.5).
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| 50. |
- Munthe, Christian, 1962
(författare)
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Precautionary Principle
- 2013
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Ingår i: International Encyclopedia of Ethics. - Chichester : Blackwell. - 9781444367072 ; , s. 4031-4039
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Bokkapitel (refereegranskat)abstract
- Following the statement in the United Nations' Rio Declaration of 1992 that countries should apply a “precautionary approach” in policymaking on environmental and technological issues, the notion of a precautionary principle (PP) has gained ground in worldwide policymaking and regulation, thus catching the interest of ethics scholars. Although seldom explained in much detail, and resulting in quite different policy results in different countries and areas (O'Riordan et al. 2001; Sandin 1999; Trouwborst 2002; Zander 2010), PP is generally understood as a norm urging or permitting policymakers to take preventive action in the face of unknown, uncertain, or probable dangers, motivated by the experience of how seemingly valuable and promising practices may lead to seriously adverse consequences in spite of lack of solid evidence to this effect (Sandin 1999). In ethics debate, this idea has been applied not only to matters regarding the large-scale introduction and use of technology (e.g., regarding energy production, transport and communication, nano- or biotechnology, and so on) (see Biotechnology; Nanotechnology, Ethics of) with possible ensuing impact on the natural environment connecting to the notion of sustainability (see Sustainability), but also, for example, to abortion (see Abortion), medical genetics, embryo experimentation (see Embryo Research), the treatment of animals (see Animal Experimentation), terrorism (see Terrorism), and general research ethics (see Research Ethics) (Munthe 2011). Many of these applications advocate strong conclusions in spite of the fact that PP or its normative justification have not been made very clear. At the same time, PP has been the subject of criticism, much of which boils down to three points: lack of clarity, lack of practicality, and/or ethical implausibility. Curiously, these critical points have often been made in conjunction, in spite of the fact that a clear sense of what PP means seems necessary for backing up the other two objections.
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