996 resultados para Seedling field emergence


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The complete sequence of the 7.07 Mb genome of the biological control agent Pseudomonas fluorescens Pf-5 is now available, providing a new opportunity to advance knowledge of biological control through genomics. P. fluorescens Pf-5 is a rhizosphere bacterium that suppresses seedling emergence diseases and produces a spectrum of antibiotics toxic to plant-pathogenic fungi and oomycetes. In addition to six known secondary metabolites produced by Pf-5, three novel secondary metabolite biosynthesis gene clusters identified in the genome could also contribute to biological control. The genomic sequence provides numerous clues as to mechanisms used by the bacterium to survive in the spermosphere and rhizosphere. These features include broad catabolic and transport capabilities for utilizing seed and root exudates, an expanded collection of efflux systems for defense against environmental stress and microbial competition, and the presence of 45 outer membrane receptors that should allow for the uptake of iron from a wide array of siderophores produced by soil microorganisms. As expected for a bacterium with a large genome that lives in a rapidly changing environment, Pf-5 has an extensive collection of regulatory genes, only some of which have been characterized for their roles in regulation of secondary metabolite production or biological control. Consistent with its commensal lifestyle, Pf-5 appears to lack a number of virulence and pathogenicity factors found in plant pathogen.

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Daptomycin is bactericidal against meticillin-resistant Staphylococcus aureus (MRSA), glycopeptide-intermediate-resistant S. aureus (GISA) and vancomycin-susceptible and -resistant enterococci. However, selection for daptomycin-resistant derivatives has occasionally been reported during therapy in humans. Here we evaluate whether selection for daptomycin-resistant S. aureus or enterococci could be prevented in vitro by combining daptomycin with amoxicillin/clavulanic acid, ampicillin, gentamicin or rifampicin. Six strains of S. aureus (four MRSA and two GISA) and four strains of enterococci (two Enterococcus faecalis and two Enterococcus faecium) were serially exposed in broth to two-fold stepwise increasing concentrations of daptomycin alone or in combination with a fixed concentration [0.25x minimum inhibitory concentration (MIC)] of either of the second agents. The daptomycin MIC was examined after each cycle. Exposure to daptomycin alone gradually selected for S. aureus and enterococci with an increased MIC. Gentamicin did not prevent the emergence of daptomycin-resistant bacteria. Rifampicin was also unable to prevent daptomycin resistance, although resistance was slightly delayed. In contrast, amoxicillin/clavulanic acid or ampicillin prevented or greatly delayed the selection of daptomycin-resistant mutants in S. aureus and enterococci, respectively. Addition of amoxicillin/clavulanic acid or ampicillin to daptomycin prevents, or greatly delays, daptomycin resistance in vitro. Future studies in animal models are needed to predict the utility of these combinations in humans.

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Portugal’s historical past strongly influences the composition of the country’s immigrant population. The main third-country foreign nationals in Portugal originate traditionally from Portuguese-speaking African countries (namely Cape Verde, Angola, Guinea Bissau, and S. Tomé e Príncipe) and Brazil. In 2001, a newly created immigrant status entitled “permanence” authorization uncovered a quantitative and a qualitative change in the structure of immigrant population in Portugal. First, there was a quantitative jump from 223.602 foreigners in 2001 to 364.203 regularized foreigners in 2003. Secondly, there was a substantial qualitative shift in the composition of immigrants. The majority of the new immigrants began coming from Eastern European countries, such as Ukraine, Moldavia, Romania, and the Russian Federation. Thus, European countries outside the E.U. zone now rank second (after African countries) in their contribution of individuals to the stocks of immigrant population in Portugal. The differences between the new and traditional immigration flows are visible in the geographical distribution of immigrants and in their insertion into the labour market. While the traditional flows would congregate around the metropolitan area of Lisbon and in the Algarve, the new migratory flows tend to be more geographically dispersed and present in less urbanized areas of Portugal. In terms of insertion in the labour market, although the construction sector is still the most important industry for immigrant labour, Eastern European workers may also be found in the agriculture and manufacturing sectors. The institutional conditions that encourage immigrants’ civic participation are divided at three different levels: the state, the local, and the civil society levels. At the state level, the High Commissioner for Migrations and Ethnic Minorities is the main organizational structure along with a set of interrelated initiatives operating under specific regulatory frameworks, which act as mediators between state officials and the Portuguese civil society, and more specifically, immigrant communities. At the local level, some municipalities created consultative councils and municipal departments aiming at encouraging the participation and representation of interests from immigrant groups and association in local policies. In the civil society sphere, the main actors in Portugal spurring immigrants civic participation are immigrant associations, mainstream associations directed toward immigration topics, and unions. The legal conditions framing immigrants’ access to social housing, education, health, and social security in Portugal are also considered to be positive. Conditions restricting immigrants’ civic participation are mainly normative and include the Portuguese nationality law, the regulations shaping the political participation of immigrants, namely in what concerns their right to vote, and employment regulations restricting immigrants’ access to public administration positions. Part II of the report focuses on the active civic participation of third country immigrants. First, reasons for the lack of research on this issue in Portugal are explained. On the one hand, the recent immigration history and the more urgent needs regarding school and economic integration kept this issue out of the research spotlight. On the other hand, it was just in the beginning of the 1990s that immigrants took the very first steps toward collective mobilisation. Secondly, the literature review of Portuguese bibliography covers research on third country immigrants’ associative movement, research on local authorities’ policies and discussion about ethnic politics and political mobilisation of immigrants in Portugal. As political mobilisation of these groups has been made mainly through ethnic and/or migrant organisations, a brief history of immigrants' associative movement is given. Immigrant associations develop multiple roles, covering the social, the cultural, the economic and the political domains. Political claiming for the regularisation of illegal immigrants has been a permanent and important field of intervention since the mid-1990s. Research results reveal the com5 plex relations between ethnic mobilisation and the set of legal and institutional frameworks developed by local and national governmental authorities targeted to the incorporation of minority groups. Case studies on the Oeiras district and on the Amadora district are then presented. Conclusions underline that the most active immigrant groups are those from Cape Verde and Guinea Bissau, since these groups have constituted a higher number of ethnic associations, give priority to political claiming and present a more politicised discourse. Reflecting on the future of research on civic participation of third country immigrants in Portugal, the authors state that it would be interesting and relevant to compare the Portuguese situation with those of other European countries, with an older immigration history, and analyse how the Portuguese immigrants’ associative movement will be affected by a changing legal framework and the emergence of new opportunities within the set of structures regarding the political participation of minority groups.

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The position of the anthropologist in the field is discussed, in this article, as a position of “estranged intimacy”, that is to say, the anthropologist occupies an ambiguous position of becoming intimately involved whilst concurrently standing back. This definition derives from reflections upon fieldwork, conducted in the north of Portugal, with Cape Verdean migrant young women and their experiences as mothers. The article discusses two aspects related to the fieldwork. Firstly, the way in which diverse strategies of establishing relations in the field placed me in a position of “estranged intimacy” which reconfigured the meanings I had initially attributed to the term “Cape Verdean women”. Secondly, how becoming unexpectedly involved in a situation of intense conjugal conflict led me to reconsider my understanding of Cape Verdean gender relations. Both cases demonstrate how the endeavour to produce analytical and ethnographical knowledge was shot through with an unstable mix of detachment and involvement and how coming up against the unexpected may contribute towards the reconfiguration of ethnographic knowledge, in this specific case, with regard to the dynamics of gender relations.

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The detection of Parkinson's disease (PD) in its preclinical stages prior to outright neurodegeneration is essential to the development of neuroprotective therapies and could reduce the number of misdiagnosed patients. However, early diagnosis is currently hampered by lack of reliable biomarkers. (1) H magnetic resonance spectroscopy (MRS) offers a noninvasive measure of brain metabolite levels that allows the identification of such potential biomarkers. This study aimed at using MRS on an ultrahigh field 14.1 T magnet to explore the striatal metabolic changes occurring in two different rat models of the disease. Rats lesioned by the injection of 6-hydroxydopamine (6-OHDA) in the medial-forebrain bundle were used to model a complete nigrostriatal lesion while a genetic model based on the nigral injection of an adeno-associated viral (AAV) vector coding for the human α-synuclein was used to model a progressive neurodegeneration and dopaminergic neuron dysfunction, thereby replicating conditions closer to early pathological stages of PD. MRS measurements in the striatum of the 6-OHDA rats revealed significant decreases in glutamate and N-acetyl-aspartate levels and a significant increase in GABA level in the ipsilateral hemisphere compared with the contralateral one, while the αSyn overexpressing rats showed a significant increase in the GABA striatal level only. Therefore, we conclude that MRS measurements of striatal GABA levels could allow for the detection of early nigrostriatal defects prior to outright neurodegeneration and, as such, offers great potential as a sensitive biomarker of presymptomatic PD.

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In the field, immature individuals of Ascia monuste orseis (Godart), the kale caterpillars, migrate in great proportion to other regions of the host in order to complete their development; there, they find leaves of different ages and are exposed to the nutritional variation of these leaves. The objective of this study was to find out how the change to leaves of different ages affects the A. monuste orseis performance. The experiments were carried out providing one kind of leaf during the three first instars, and afterwards providing leaves of different ages during the fourth and fifth instars, since it is in these two instars that the changing movement prevails in that species. The parameters to measure performance were time of development (both to complete the three first instars and the fourth and fifth instars), ingestion of food, incorporated biomass, digestive indices that evaluated efficiency in food utilization, relative growth and intake rates, percentage of emergence, weight and size of the adults. In general, the caterpillars which were first fed on new leaves presented a better performance, but this study concluded that the A. monuste orseis caterpillars have shown skills to compensate food with lower nutritional value or less abundant in nature.

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We study how to promote compliance with rules in everyday situations. Having access to unique data on the universe of users of all public libraries inBarcelona, we test the effect of sending email messages with dierent contents.We find that users return their items earlier if asked to do so in a simple email.Emails reminding users of the penalties associated with late returns are more effective than emails with only a generic reminder. We find differential treatmenteffects by user types. The characteristics we analyze are previous compliance,gender, age, and nationality.

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It was studied the parasitism capacity of Trichogramma acacioi on Anagasta kuehniella and Sitotroga cerealella eggs at different temperatures (15, 20, 25, 30 and 35 ± 1°C). The parasitism of T. acacioi varied with temperature and host. The highest parasitism (³80%) were observed during the first days after emergence in both hosts, at all tested temperatures. The accumulated parasitism varied with both host and temperature, being higher on A. kuehniella at 20°C, what shows good parasitoid species adaptation to this temperature. Thus, we conclude that the best host and best temperature to be used at mass-rearing of T. acacioi is A. kuehniella and 20ºC, respectively. Moreover, this Trichogramma species has great potential to be used in field releases at regions where average temperature is around 20ºC.

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We investigate whether the gender composition of teams affect theireconomic performance. We study a large business game, played in groups ofthree, where each group takes the role of a general manager. There are twoparallel competitions, one involving undergraduates and the other involvingMBAs. Our analysis shows that teams formed by three women aresignificantly outperformed by any other gender combination, both at theundergraduate and MBA levels. Looking across the performancedistribution, we find that for undergraduates, three women teams areoutperformed throughout, but by as much as 10pp at the bottom and by only1pp at the top. For MBAs, at the top, the best performing group is two menand one woman. The differences in performance are explained bydifferences in decision-making. We observe that three women teams are lessaggressive in their pricing strategies, invest less in R&D, and invest more insocial sustainability initiatives, than any other gender combination teams.Finally, we find support for the hypothesis that it is poor work dynamicsamong the three women teams that drives the results.

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This study aimed at evaluating the biological characteristics and the capacity of parasitism of a Trichogramma pretiosum Riley, 1869 (Hymenoptera, Trichogrammatidae) strain (T. pretiosum RV) collected in Rio Verde County, State of Goiás, Brazil. The study was carried out on eggs of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera, Noctuidae) and conducted under controlled environmental conditions at different constant temperatures. The biological parameters determined were: developmental time (egg-adult; days); emergence (%); sex ratio; number of progeny/egg; number of generation/year; thermal constant (K); temperature threshold (Tb); daily number of parasitized eggs; cumulative parasitism (%); total number of eggs parasitized by T. pretiosum; and female longevity. To study the T. pretiosum parasitism capacity, 20 S. frugiperda eggs (< 24 h old) were placed into 8.0 cm x 2.0 cm glass vials containing one female (< 24 h old) each. Trials were carried out in a completely randomized experimental design, with 20 replications at each temperature. The environmental chambers (BOD type) were set at 18ºC, 20ºC, 22ºC, 25ºC, 28ºC and 32ºC ± 1ºC, 70 ±10% relative humidity, and 14/10 h (L:D) photoperiod. The eggs of S. frugiperda were replaced daily until parasitoid death. Results have shown an inverse correlation between developmental time and temperature, with statistically significant differences among means, except at 25ºC and 28ºC (10 days). Parasitoid emergence (%) was also influenced by temperature. The lowest percent emergence was observed at 32ºC, and the highest ones at 18ºC and 20ºC temperatures. The temperature did not affect T. pretiosum sex ratio and number of parasitoids per egg, thus allowing changes in the temperature to control insect mass production in the laboratory to meet the needs for field releases.

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The drug discovery process has been deeply transformed recently by the use of computational ligand-based or structure-based methods, helping the lead compounds identification and optimization, and finally the delivery of new drug candidates more quickly and at lower cost. Structure-based computational methods for drug discovery mainly involve ligand-protein docking and rapid binding free energy estimation, both of which require force field parameterization for many drug candidates. Here, we present a fast force field generation tool, called SwissParam, able to generate, for arbitrary small organic molecule, topologies, and parameters based on the Merck molecular force field, but in a functional form that is compatible with the CHARMM force field. Output files can be used with CHARMM or GROMACS. The topologies and parameters generated by SwissParam are used by the docking software EADock2 and EADock DSS to describe the small molecules to be docked, whereas the protein is described by the CHARMM force field, and allow them to reach success rates ranging from 56 to 78%. We have also developed a rapid binding free energy estimation approach, using SwissParam for ligands and CHARMM22/27 for proteins, which requires only a short minimization to reproduce the experimental binding free energy of 214 ligand-protein complexes involving 62 different proteins, with a standard error of 2.0 kcal mol(-1), and a correlation coefficient of 0.74. Together, these results demonstrate the relevance of using SwissParam topologies and parameters to describe small organic molecules in computer-aided drug design applications, together with a CHARMM22/27 description of the target protein. SwissParam is available free of charge for academic users at www.swissparam.ch.

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Colony cycle of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae). This study describes some aspects of the colony cycle of the Neotropical social wasp Mischocyttarus consimilis, from data obtained under field conditions. Our results showed that the colony cycle in M. consimilis is annual and asynchronous in relation to the months of the year. The colonies remained active for approximately eight months. Most of the abandonments were associated with natural causes, and were most frequent in the pre-emergence stage. The nests were constructed preferentially in man-made structures, especially in sites protected from direct sunlight and rain. Colony foundation was either by haplometrosis or pleometrosis, being the first form predominant.

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Game theory is a branch of applied mathematics used to analyze situation where two or more agents are interacting. Originally it was developed as a model for conflicts and collaborations between rational and intelligent individuals. Now it finds applications in social sciences, eco- nomics, biology (particularly evolutionary biology and ecology), engineering, political science, international relations, computer science, and philosophy. Networks are an abstract representation of interactions, dependencies or relationships. Net- works are extensively used in all the fields mentioned above and in many more. Many useful informations about a system can be discovered by analyzing the current state of a network representation of such system. In this work we will apply some of the methods of game theory to populations of agents that are interconnected. A population is in fact represented by a network of players where one can only interact with another if there is a connection between them. In the first part of this work we will show that the structure of the underlying network has a strong influence on the strategies that the players will decide to adopt to maximize their utility. We will then introduce a supplementary degree of freedom by allowing the structure of the population to be modified along the simulations. This modification allows the players to modify the structure of their environment to optimize the utility that they can obtain.

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In recent years, elevated arsenic concentrations have been found in waters and soils of many, countries, often resulting in a health threat for the local population. Switzerland is not an exception and this paper deals with the release and subsequent fate of arsenic in a 200-km(2) mountainous watershed, characterized by crystalline silicate rocks (gneisses, schists, amphibolites) that contain abundant As-bearing sulfide ore deposits, some of which have been mined for iron and gold in the past. Using analytical methods common for mineralogical, ground water and soil studies (XRD, XRF, XAS-XANES and -EXAFS, electron microprobe, extraction, ICP, AAS with hydride generator, ion chromatography), seven different field situations and related dispersion processes of natural arsenic have been studied: (1) release by rock weathering, (2) transport and deposition by water and ice; (3) release of As to the ground and surface water due to increasing pH; (4) accumulation in humic soil horizons; (5) remobilization by reduction in water-saturated soils and stagnant ground waters; (6) remobilization by using P-rich fertilizers or dung and (7) oxidation, precipitation and dilution in surface waters. Comparison of the results with experimental adsorption studies and speciation diagrams from the literature allows us to reconstruct and identify the typical behavior of arsenic in a natural environment under temperate climatic conditions. The main parameters identified are: (a) once liberated from the primary minerals, sorption processes on Fe-oxy-hydroxides dominate over Al-phases, such as Al-hydroxides or clay minerals and limit the As concentrations in the spring and well waters between 20 and 300 mug/l. (b) Precipitation as secondary minerals is limited to the weathering domain, where the As concentrations are still high and not yet too diluted by rain and soils waters. (c) Although neutral and alkaline pH conditions clearly increase the mobility of As, the main factor to mobilize As is a low redox potential (Eh close or below 0 mV), which favors the dissolution of the Fe-oxy-hydroxides on which the As is sorbed. (d) X-ray absorption spectroscopy (XAS) of As in water-logged humic forest soils indicates that the reduction to As III only occurs at the solid-water interface and that the solid contains As as As V (e) A and Bh horizons of humic cambisols can effectively capture As when As-rich waters flow through them. Complex spatial and temporal variation of the various parameters in a watershed results in repeated mobilization and immobilization of As, which continuously transports As from the upper to the lower part of a watershed and ultimately to the ocean. (C) 2004 Elsevier B.V. All rights reserved.

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PURPOSE: Recent work practices in the conservation and restoration involve the use of cyclododecane (CDD, CAS 294-62-2) to protect fragile artifacts during their handling or transportation. Little is known about its toxicity, and no previous exposure has been reported. A short field investigation was conducted to characterize the exposure conditions to both CDD vapors and aerosols.METHODS: Measurements were conducted in the laboratory of conservation and restoration of the archeological service in Bern (Switzerland). Three indoor and four outdoor typical work situations, either during brush or spray gun applications, were investigated. Measurements were performed on charcoal adsorbent tube and analyzed by a gas chromatograph equipped with a flame ionization detector.RESULTS: Measurements have been conducted during both brush and spray gun applications. Indoor exposures were of 0.75-15.5 mg/m(3), while outdoors exposures were 19.5-53.9 mg/m(3). Exposures appear to be extremely localized due to both physicochemical properties and application methods of the CDD. Vapor exposure increases dramatically with the confinement of the workplace.CONCLUSION: Preventive measures should be undertaken to limit as much as possible these exposures. Field work in confined areas (ditches, underground) is of particular concern. CDD-coated artifacts or materials should be stored in ventilated areas to avoid delayed exposures. [Authors]