Showing papers by "University of Fribourg published in 2008"
TL;DR: A more integrated overview of the key role of these signalling lipids in inflammation, cancer and metabolic disease is attempted, and emerging strategies for therapeutic intervention are discussed.
Abstract: Signalling lipids such as eicosanoids, phosphoinositides, sphingolipids and fatty acids control important cellular processes, including cell proliferation, apoptosis, metabolism and migration. Extracellular signals from cytokines, growth factors and nutrients control the activity of a key set of lipid-modifying enzymes: phospholipases, prostaglandin synthase, 5-lipoxygenase, phosphoinositide 3-kinase, sphingosine kinase and sphingomyelinase. These enzymes and their downstream targets constitute a complex lipid signalling network with multiple nodes of interaction and cross-regulation. Imbalances in this network contribute to the pathogenesis of human disease. Although the function of a particular signalling lipid is traditionally studied in isolation, this review attempts a more integrated overview of the key role of these signalling lipids in inflammation, cancer and metabolic disease, and discusses emerging strategies for therapeutic intervention.
1,134 citations
TL;DR: In this paper, a review of the use of tree rings in natural hazards research is presented, starting with a description of the different types of disturbances by geomorphic processes and the resulting growth reactions, and a summary of different methods commonly used for the analysis and interpretation of reactions in affected trees.
Abstract: . The understanding of geomorphic processes and knowledge of past events are important tasks for the assessment of natural hazards. Tree rings have on varied occasions proved to be a reliable tool for the acquisition of data on past events. In this review paper, we provide an overview on the use of tree rings in natural hazards research, starting with a description of the different types of disturbances by geomorphic processes and the resulting growth reactions. Thereafter, a summary is presented on the different methods commonly used for the analysis and interpretation of reactions in affected trees. We illustrate selected results from dendrogeomorphological investigations of geomorphic processes with an emphasis on fluvial (e.g., flooding, debris flows) and mass-movement processes (e.g., landslides, snow avalanche), where lots of data have been generated over the past few decades. We also present results from rockfall and permafrost studies, where data are much scarcer, albeit data from tree-ring studies have proved to be of great value in these fields as well. Most studies using tree rings have focused on alpine environments in Europe and North America, whereas other parts of the world have been widely neglected by dendrogeomorphologists so far. We therefore challenge researchers to focus on other regions with distinct climates as well, to look on less frequently studied processes as well and to broaden and improve approaches and methods commonly used in tree-ring research so as to allow a better understanding of geomorphic processes, natural hazards and risk.
391 citations
TL;DR: The artificially synthesized perovskite SrIrO3 showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state, and a Mott insulator-metal transition with a change of bandwidth as the authors increased n.
Abstract: We investigated the electronic structures of the 5d Ruddlesden-Popper series Sr n+1Ir nO3n+1 (n=1, 2, and infinity) using optical spectroscopy and first-principles calculations. As 5d orbitals are spatially more extended than 3d or 4d orbitals, it has been widely accepted that correlation effects are minimal in 5d compounds. However, we observed a Mott insulator-metal transition with a change of bandwidth as we increased n. In addition, the artificially synthesized perovskite SrIrO3 showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state.
389 citations
TL;DR: The spontaneous onset of a one-dimensional, incommensurate modulation of the spin system in the high-transition-temperature superconductor YBa2Cu3O6 suggests that soft spin fluctuations are a microscopic route toward electronic liquid crystals and that nematic order can coexist with high-tem temperature superconductivity in underdoped cuprates.
Abstract: Electronic phases with symmetry properties matching those of conventional liquid crystals have recently been discovered in transport experiments on semiconductor heterostructures and metal oxides at millikelvin temperatures. We report the spontaneous onset of a one-dimensional, incommensurate modulation of the spin system in the high-transition-temperature superconductor YBa2Cu3O6.45 upon cooling below ∼150 kelvin, whereas static magnetic order is absent above 2 kelvin. The evolution of this modulation with temperature and doping parallels that of the in-plane anisotropy of the resistivity, indicating an electronic nematic phase that is stable over a wide temperature range. The results suggest that soft spin fluctuations are a microscopic route toward electronic liquid crystals and that nematic order can coexist with high-temperature superconductivity in underdoped cuprates.
382 citations
TL;DR: It is shown that mammal species with larger brains tend to be more successful than species with smaller brains at establishing themselves when introduced to novel environments, when both taxonomic and regional autocorrelations are accounted for.
Abstract: Large brains, relative to body size, can confer advantages to individuals in the form of behavioral flexibility Such enhanced behavioral flexibility is predicted to carry fitness benefits to individuals facing novel or altered environmental conditions, a theory known as the brain size-environmental change hypothesis Here, we provide the first empirical link between brain size and survival in novel environments in mammals, the largest-brained animals on Earth Using a global database documenting the outcome of more than 400 introduction events, we show that mammal species with larger brains, relative to their body mass, tend to be more successful than species with smaller brains at establishing themselves when introduced to novel environments, when both taxonomic and regional autocorrelations are accounted for This finding is robust to the effect of other factors known to influence establishment success, including introduction effort and habitat generalism Our results replicate similar findings in birds, increasing the generality of evidence for the idea that enlarged brains can provide a survival advantage in novel environments
376 citations
TL;DR: A role of circadian-clock components in dopamine metabolism highlighting a role of the clock in regulating mood-related behaviors is suggested.
371 citations
TL;DR: The [3 + 2] cycloaddition of azides and acetylenes followed by nitrogen quaternization was applied for the generation of novel and highly modular triazolium salts and the donor properties were found to be slightly stronger than those the most basic normal carbenes.
Abstract: The [3 + 2] cycloaddition of azides and acetylenes followed by nitrogen quaternization was applied for the generation of novel and highly modular triazolium salts. The selective substitution of the 1,3,4-substitution pattern presets such salts as precursors for a new class of abnormal carbene ligands, thus expanding the family of these high-impact ligands. Metalation of the triazolium salts is highly versatile and is illustrated by direct C−H bond activation as well as by applying a transmetalation protocol, thus providing access to Pd(II), Ru(II), Rh(I), and Ir(I) abnormal carbene complexes. The donor properties of these carbenes were analyzed by using Tolman electronic parameters and were found to be slightly stronger than those the most basic normal carbenes.
361 citations
TL;DR: A new surgical case scheduling approach is proposed which uses a novel extension of the Job Shop scheduling problem called multi-mode blocking job shop (MMBJS) as a mixed integer linear programming (MILP) problem and the use of the MMBJS model for scheduling elective and add-on cases is discussed.
338 citations
TL;DR: Investigation of SA in the double ics1 ics2 double mutant that is completely devoid of phylloquinone provides genetic evidence of the existence of an ICS-independent SA biosynthetic pathway in Arabidopsis.
Abstract: Salicylic acid (SA) is an important mediator of plant defense response. In Arabidopsis (Arabidopsis thaliana), this compound was proposed to derive mainly from isochorismate, itself produced from chorismate through the activity of ISOCHORISMATE SYNTHASE1 (ICS1). Null ics1 mutants still accumulate some SA, suggesting the existence of an enzymatic activity redundant with ICS1 or of an alternative ICS-independent SA biosynthetic route. Here, we studied the role of ICS2, a second ICS gene of the Arabidopsis genome, in the production of SA. We have shown that ICS2 encodes a functional ICS enzyme and that, similar to ICS1, ICS2 is targeted to the plastids. Comparison of SA accumulation in the ics1, ics2, and ics1 ics2 mutants indicates that ICS2 participates in the synthesis of SA, but in limited amounts that become clearly detectable only when ICS1 is lacking. This unequal redundancy relationship was also observed for phylloquinone, another isochorismate-derived end product. Furthermore, detection of SA in the double ics1 ics2 double mutant that is completely devoid of phylloquinone provides genetic evidence of the existence of an ICS-independent SA biosynthetic pathway in Arabidopsis.
321 citations
TL;DR: In this paper, a review of the recent results in the field of metal-organic frameworks (MOFs) is presented, bringing together the systematic approaches with results obtained by serendipity to give an overview on current and future possibilities.
319 citations
TL;DR: In this paper, the location of Gondwana-derived terranes should not only be guided by the models, but should also consider the possible detrital input from some Asian blocks (hunia), which accreted in the Silurian to the North-Chinese block.
TL;DR: The use of an ordinary white-light microscope for the study of the q-dependent dynamics of colloidal dispersions is demonstrated and the results are found to be in good agreement with the theoretically expected values for Brownian motion in a viscous medium.
Abstract: We demonstrate the use of an ordinary white-light microscope for the study of the q-dependent dynamics of colloidal dispersions. Time series of digital video images are acquired in bright field with a fast camera, and image differences are Fourier analyzed as a function of the time delay between them. This allows for the characterization of the particle dynamics independent of whether or not they can be resolved individually. The characteristic times are measured in a wide range of wave vectors and the results are found to be in good agreement with the theoretically expected values for Brownian motion in a viscous medium.
TL;DR: The formation of complexes between SDS and the various protein aggregates at pH 3.0 was shown to occur by two main mechanisms: at low concentration of SDS, the complex formation occurs essentially by ionic binding between the positive residues of the protein and the negative sulfate heads of the surfactant.
TL;DR: The findings highlight the importance of phytochrome photoperception during systemic rather than local resistance induction, and seem to accommodate the supply of light energy to the energetically costly increase in whole plant resistance.
Abstract: We have examined molecular and physiological principles underlying the light dependency of defense activation in Arabidopsis ( Arabidopsis thaliana ) plants challenged with the bacterial pathogen Pseudomonas syringae . Within a fixed light/dark cycle, plant defense responses and disease resistance significantly depend on the time of day when pathogen contact takes place. Morning and midday inoculations result in higher salicylic acid accumulation, faster expression of pathogenesis-related genes, and a more pronounced hypersensitive response than inoculations in the evening or at night. Rather than to the plants9 circadian rhythm, this increased plant defense capability upon day inoculations is attributable to the availability of a prolonged light period during the early plant-pathogen interaction. Moreover, pathogen responses of Arabidopsis double mutants affected in light perception, i.e. cryptochrome1cryptochrome2 ( cry1cry2 ), phototropin1phototropin2 ( phot1phot2 ), and phytochromeAphytochromeB ( phyAphyB ) were assessed. Induction of defense responses by either avirulent or virulent P. syringae at inoculation sites is relatively robust in leaves of photoreceptor mutants, indicating little cross talk between local defense and light signaling. In addition, the blue-light receptor mutants cry1cry2 and phot1phot2 are both capable of establishing a full systemic acquired resistance (SAR) response. Induction of SAR and salicylic-acid-dependent systemic defense reactions, however, are compromised in phyAphyB mutants. Phytochrome regulation of SAR involves the essential SAR component FLAVIN-DEPENDENT MONOOXYGENASE1. Our findings highlight the importance of phytochrome photoperception during systemic rather than local resistance induction. The phytochrome system seems to accommodate the supply of light energy to the energetically costly increase in whole plant resistance.
TL;DR: It is shown that Ca2+ channel subunit immunoreactivity is highly concentrated in the active zone of GABAergic presynaptic terminals of putative parvalbumin-containing basket cells in the hippocampus, and tight coupling contributes to fast feedforward and feedback inhibition in the hippocampal network.
TL;DR: The promising results accomplished in this relatively short period of time demonstrate the potential of C4-bound imidazolylidenes as unique carbene ligands for inducing catalytic activity and for mediating unprecedented transformations.
TL;DR: Results show that ingestion of glucose and fructose drinks is characterized by specific hemodynamic responses, and fructose ingestion elicits an increase in blood pressure that is probably mediated by a increase in cardiac output without compensatory peripheral vasodilatation.
Abstract: Overconsumption of fructose, particularly in the form of soft drinks, is increasingly recognized as a public health concern. The acute cardiovascular responses to ingesting fructose have not, however, been well-studied in humans. In this randomized crossover study, we compared cardiovascular autonomic regulation after ingesting water and drinks containing either glucose or fructose in 15 healthy volunteers (aged 21-33 yr). The total volume of each drink was 500 ml, and the sugar content 60 g. For 30 min before and 2 h after each drink, we recorded beat-to-beat heart rate, arterial blood pressure, and cardiac output. Energy expenditure was determined on a minute-by-minute basis. Ingesting the fructose drink significantly increased blood pressure, heart rate, and cardiac output but not total peripheral resistance. Glucose ingestion resulted in a significantly greater increase in cardiac output than fructose but no change in blood pressure and a concomitant decrease in total peripheral resistance. Ingesting glucose and fructose, but not water, significantly increased blood pressure variability and decreased cardiovagal baroreflex sensitivity. Energy expenditure increased by a similar amount after glucose and fructose ingestion, but fructose elicited a significantly greater increase in respiratory quotient. These results show that ingestion of glucose and fructose drinks is characterized by specific hemodynamic responses. In particular, fructose ingestion elicits an increase in blood pressure that is probably mediated by an increase in cardiac output without compensatory peripheral vasodilatation.
TL;DR: The importance of isochorismate for SA biosynthesis in Nicotiana benthamiana is determined using virus‐induced gene silencing of the isoch orismate synthase (ICS) gene.
TL;DR: The continuous emergence in the weakly ordered state of a low-lying but massive excitation corresponding to longitudinal fluctuations of the magnetic moment is demonstrated by neutron spectroscopy.
Abstract: We follow the evolution of the elementary excitations of the quantum antiferromagnet TlCuCl3 through the pressure-induced quantum critical point, which separates a dimer-based quantum disordered phase from a phase of long-ranged magnetic order. We demonstrate by neutron spectroscopy the continuous emergence in the weakly ordered state of a low-lying but massive excitation corresponding to longitudinal fluctuations of the magnetic moment. This mode is not present in a classical description of ordered magnets, but is a direct consequence of the quantum critical point.
TL;DR: The results are in line with previous studies on the effect of intimacy on cortisol stress responses in the laboratory as well as with epidemiologic data on health beneficial effects of happy marital relationships.
Abstract: Objective:To determine whether intimacy might be associated with reduced daily salivary cortisol levels in couples, thereby adding to the epidemiologic literature on reduced health burden in happy couples.Methods:A total of 51 dual-earner couples reported time spent on intimacy, stated their current
TL;DR: Wang et al. as discussed by the authors proposed a recommendation algorithm based on a weighted object network, which is sensitive to the configuration of initial resource distribution, and demonstrated that a degree-dependent initial configuration can outperform the uniform case for both accuracy and personalization strength.
Abstract: In this paper, based on a weighted object network, we propose a recommendation algorithm, which is sensitive to the configuration of initial resource distribution. Even under the simplest case with binary resource, the current algorithm has remarkably higher accuracy than the widely applied global ranking method and collaborative filtering. Furthermore, we introduce a free parameter β to regulate the initial configuration of resource. The numerical results indicate that decreasing the initial resource located on popular objects can further improve the algorithmic accuracy. More significantly, we argue that a better algorithm should simultaneously have higher accuracy and be more personal. According to a newly proposed measure about the degree of personalization, we demonstrate that a degree-dependent initial configuration can outperform the uniform case for both accuracy and personalization strength.
TL;DR: Treatment of yeast cells with the specificTORC1 inhibitor rapamycin or caffeine releases Rim15 from TORC1‐Sch9‐mediated inhibition and consequently increases lifespan, suggesting that caffeine may extend lifespan in other eukaryotes, including man.
Abstract: Dietary nutrient limitation (dietary restriction) is known to increase lifespan in a variety of organisms. Although the molecular events that couple dietary restriction to increased lifespan are not clear, studies of the model eukaryote Saccharomyces cerevisiae have implicated several nutrient-sensitive kinases, including the target of rapamycin complex 1 (TORC1), Sch9, protein kinase A (PKA) and Rim15. We have recently demonstrated that TORC1 activates Sch9 by direct phosphorylation. We now show that Sch9 inhibits Rim15 also by direct phosphorylation. Treatment of yeast cells with the specific TORC1 inhibitor rapamycin or caffeine releases Rim15 from TORC1-Sch9-mediated inhibition and consequently increases lifespan. This kinase cascade appears to have been evolutionarily conserved, suggesting that caffeine may extend lifespan in other eukaryotes, including man.
TL;DR: Lower GSH levels of pad2-1 were correlated with reduced accumulation of the two major indole and aliphatic GSs of Arabidopsis, indolyl-3-methyl-GS and 4-methylsulfinylbutyl-GS, in response to insect feeding, which suggests a crucial role for GSH in GS biosynthesis and insect resistance.
Abstract: Summary Plants often respond to pathogen or insect attack by inducing the synthesis of toxic compounds such as phytoalexins and glucosinolates (GS). The Arabidopsis mutant pad2-1 has reduced levels of the phytoalexin camalexin and is known for its increased susceptibility to fungal and bacterial pathogens. We found that pad2-1 is also more susceptible to the generalist insect Spodoptera littoralis but not to the specialist Pieris brassicae. The PAD2 gene encodes a gamma-glutamylcysteine synthetase that is involved in glutathione (GSH) synthesis, and consequently the pad2-1 mutant contains about 20% of the GSH found in wild-type plants. Lower GSH levels of pad2-1 were correlated with reduced accumulation of the two major indole and aliphatic GSs of Arabidopsis, indolyl-3-methyl-GS and 4-methylsulfinylbutyl-GS, in response to insect feeding. This effect was specific to GSH, was not complemented by treatment of pad2-1 with the strong reducing agent dithiothreitol, and was not observed with the ascorbate-deficient mutant vtc1-1. In contrast to the jasmonate-insensitive mutant coi1-1, expression of insect-regulated and GS biosynthesis genes was not affected in pad2-1. Our data suggest a crucial role for GSH in GS biosynthesis and insect resistance.
TL;DR: The structure and functionality of foods are described from the perspective of recent advances in soft condensed matter physics and recent developments in the understanding of the physics of gels, micelles, liquid crystals, biopolymer complexes and amorphous carbohydrates are presented.
Abstract: The structure and functionality of foods are described from the perspective of recent advances in soft condensed matter physics. An overview is given of the structure and properties of food materials in terms of the physically relevant length scales. Recent developments in the understanding of the physics of gels, micelles, liquid crystals, biopolymer complexes and amorphous carbohydrates are presented.
TL;DR: Results revealed that Triple P was effective with Swiss families, and the question whether this program that was developed in Australia is culturally accepted by Swiss parents was answered.
TL;DR: The results indicate that the choice of an appropriate provenance and a sufficient genotypic diversity are important issues in ecological restoration, with a large provenance differentiation in fitness-related traits, particularly in seedling emergence.
Abstract: The increased translocation of plant species for biodiversity restoration and habitat creation has provoked a debate on provenance and genotypic diversity of the used plant material. Nonlocal provenances are often not adapted to the local environmental conditions, and low population genotypic diversity may result in genetic bottlenecks hampering successful establishment. We tested provenance differentiation of four plant species used in agri-environment schemes to increase biodiversity of agricultural landscapes (wildflower strips). Provenances were collected close to the experimental field and at four further sites of different distances ranging from 120 to 900 km. In two of these provenances, different levels of genotypic diversity were simulated by sowing seed from a high and low number of mother plants. We found a large provenance differentiation in fitness-related traits, particularly in seedling emergence. There was no evidence for a general superiority of the local population. The productivity was greater in populations of high genotypic diversity than in those of low diversity, but the effect was only significant in one species. Productivity was also more constant among populations of high diversity, reducing the risk of establishment failure. Our results indicate that the choice of an appropriate provenance and a sufficient genotypic diversity are important issues in ecological restoration. The use of local provenances does not always guarantee the best performance, but a spread of superior alien genotypes can be avoided. A sufficient genotypic diversity of the sown plants might be a biological insurance against fluctuations in ecosystem processes increasing the reliability of restoration measures.
TL;DR: This review summarizes the state of the art concerning commonalities of the different models and indicates a roadmap for the successful implementation of 3D models in routine screening.
Abstract: Integrated approaches using different in vitro methods in combination with bioinformatics can (i) increase the success rate and speed of drug development; (ii) improve the accuracy of toxicological risk assessment; and (iii) increase our understanding of disease. Three-dimensional (3D) cell culture models are important building blocks of this strategy which has emerged during the last years. The majority of these models are organotypic, i.e., they aim to reproduce major functions of an organ or organ system. This implies in many cases that more than one cell type forms the 3D structure, and often matrix elements play an important role. This review summarizes the state of the art concerning commonalities of the different models. For instance, the theory of mass transport/metabolite exchange in 3D systems and the special analytical requirements for test endpoints in organotypic cultures are discussed in detail. In the next part, 3D model systems for selected organs – liver, lung, skin, brain – are presented and characterized in dedicated chapters. Also, 3D approaches to the modeling of tumors are presented and discussed. All chapters give a historical background, illustrate the large variety of approaches, and highlight up- and downsides as well as specific requirements. Moreover, they refer to the application in disease modeling, drug discovery and safety assessment. Finally, consensus recommendations indicate a roadmap for the successful implementation of 3D models in routine screening. It is expected that the use of such models will accelerate progress by reducing error rates and wrong predictions from compound testing.
TL;DR: The aim in this review is to provide a snapshot of previous and ongoing research, existing methods and challenges, the nature of questions that can be investigated and prospects for the future of admixture mapping.
Abstract: Genetic mapping in natural populations is increasing rapidly in feasibility and accessibility. As with many areas in genetics, advances in molecular techniques and statistics are drastically altering how we can investigate inheritance in wild organisms. For ecology and evolution, this is particularly significant and promising, because many of the organisms of interest are not amenable to conventional genetic approaches. Admixture mapping falls within a family of statistical approaches that use natural recombination and linkage disequilibrium between genetic markers and phenotypes as the basis for mapping. Our aim in this review is to provide a snapshot of previous and ongoing research, existing methods and challenges, the nature of questions that can be investigated and prospects for the future of admixture mapping.
TL;DR: A systematic empirical exploration of the time between two consecutive ratings of movies (the interevent time) is presented, finding a monotonous relation between the activity of individuals and the power law exponent of the intereven time distribution.
Abstract: The human society is a very complex system; still, there are several non-trivial, general features. One type of them is the presence of power-law-distributed quantities in temporal statistics. In this letter, we focus on the origin of power laws in rating of movies. We present a systematic empirical exploration of the time between two consecutive ratings of movies (the interevent time). At an aggregate level, we find a monotonous relation between the activity of individuals and the power law exponent of the interevent time distribution. At an individual level, we observe a heavy-tailed distribution for each user, as well as a negative correlation between the activity and the width of the distribution. We support these findings by a similar data set from mobile phone text-message communication. Our results demonstrate a significant role of the activity of individuals on the society-level patterns of human behavior. We believe this is a common character in the interest-driven human dynamics, corresponding to (but different from) the universality classes of task-driven dynamics.
TL;DR: In this paper, the authors demonstrate that the scale is applicable for retail brands in Germany, that it serves well to clearly differentiate between retailers and that the dimensions of the brand personality directly influence the store loyalty of consumers.
Abstract: In recent years, marketing research has paid considerable attention to the symbolic meaning consumers attribute to brands. One important symbolic brand association is brand personality. While the brand personality scale that Aaker has proposed in her well-known article has been applied to different products and product groups in different countries, an application to retailing is rare. Based on the data of an empirical study in Germany (n = 1337), we demonstrate that the scale is applicable for retail brands in Germany, that it serves well to clearly differentiate between retailers and that the dimensions of the brand personality directly influence the store loyalty of consumers.