731 research outputs found

    Root-TRAPR: a modular plant growth device to visualize root development and monitor growth parameters, as applied to an elicitor response of Cannabis sativa

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    Background Plant growth devices, for example, rhizoponics, rhizoboxes, and ecosystem fabrication (EcoFAB), have been developed to facilitate studies of plant root morphology and plant-microbe interactions in controlled laboratory settings. However, several of these designs are suitable only for studying small model plants such as Arabidopsis thaliana and Brachypodium distachyon and therefore require modification to be extended to larger plant species like crop plants. In addition, specific tools and technical skills needed for fabricating these devices may not be available to researchers. Hence, this study aimed to establish an alternative protocol to generate a larger, modular and reusable plant growth device based on different available resources. Results Root-TRAPR (Root-Transparent, Reusable, Affordable three-dimensional Printed Rhizo-hydroponic) system was successfully developed. It consists of two main parts, an internal root growth chamber and an external structural frame. The internal root growth chamber comprises a polydimethylsiloxane (PDMS) gasket, microscope slide and acrylic sheet, while the external frame is printed from a three-dimensional (3D) printer and secured with nylon screws. To test the efficiency and applicability of the system, industrial hemp (Cannabis sativa) was grown with or without exposure to chitosan, a well-known plant elicitor used for stimulating plant defense. Plant root morphology was detected in the system, and plant tissues were easily collected and processed to examine plant biological responses. Upon chitosan treatment, chitinase and peroxidase activities increased in root tissues (1.7- and 2.3-fold, respectively) and exudates (7.2- and 21.6-fold, respectively). In addition, root to shoot ratio of phytohormone contents were increased in response to chitosan. Within 2 weeks of observation, hemp plants exhibited dwarf growth in the Root-TRAPR system, easing plant handling and allowing increased replication under limited growing space. Conclusion The Root-TRAPR system facilitates the exploration of root morphology and root exudate of C. sativa under controlled conditions and at a smaller scale. The device is easy to fabricate and applicable for investigating plant responses toward elicitor challenge. In addition, this fabrication protocol is adaptable to study other plants and can be applied to investigate plant physiology in different biological contexts, such as plant responses against biotic and abiotic stresses

    Global Governance Behind Closed Doors : The IMF Boardroom, the Enhanced Structural Adjustment Facility, and the Intersection of Material Power and Norm Change in Global Politics

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    Up on the 12th floor of its 19th Street Headquarters, the IMF Board sits in active session for an average of 7 hours per week. Although key matters of policy are decided on in the venue, the rules governing Boardroom interactions remain opaque, resting on an uneasy combination of consensual decision-making and weighted voting. Through a detailed analysis of IMF Board discussions surrounding the Enhanced Structural Adjustment Facility (ESAF), this article sheds light on the mechanics of power in this often overlooked venue of global economic governance. By exploring the key issues of default liability and loan conditionality, I demonstrate that whilst the Boardroom is a more active site of contestation than has hitherto been recognized, material power is a prime determinant of both Executive Directors’ preferences and outcomes reached from discussions. And as the decisions reached form the backbone of the ‘instruction sheet’ used by Fund staff to guide their everyday operational decisions, these outcomes—and the processes through which they were reached—were factors of primary importance in stabilizing the operational norms at the heart of a controversial phase in the contemporary history of IMF concessional lending

    Climate vulnerability assessment for Pacific salmon and steelhead in the California Current Large Marine Ecosystem.

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    Major ecological realignments are already occurring in response to climate change. To be successful, conservation strategies now need to account for geographical patterns in traits sensitive to climate change, as well as climate threats to species-level diversity. As part of an effort to provide such information, we conducted a climate vulnerability assessment that included all anadromous Pacific salmon and steelhead (Oncorhynchus spp.) population units listed under the U.S. Endangered Species Act. Using an expert-based scoring system, we ranked 20 attributes for the 28 listed units and 5 additional units. Attributes captured biological sensitivity, or the strength of linkages between each listing unit and the present climate; climate exposure, or the magnitude of projected change in local environmental conditions; and adaptive capacity, or the ability to modify phenotypes to cope with new climatic conditions. Each listing unit was then assigned one of four vulnerability categories. Units ranked most vulnerable overall were Chinook (O. tshawytscha) in the California Central Valley, coho (O. kisutch) in California and southern Oregon, sockeye (O. nerka) in the Snake River Basin, and spring-run Chinook in the interior Columbia and Willamette River Basins. We identified units with similar vulnerability profiles using a hierarchical cluster analysis. Life history characteristics, especially freshwater and estuary residence times, interplayed with gradations in exposure from south to north and from coastal to interior regions to generate landscape-level patterns within each species. Nearly all listing units faced high exposures to projected increases in stream temperature, sea surface temperature, and ocean acidification, but other aspects of exposure peaked in particular regions. Anthropogenic factors, especially migration barriers, habitat degradation, and hatchery influence, have reduced the adaptive capacity of most steelhead and salmon populations. Enhancing adaptive capacity is essential to mitigate for the increasing threat of climate change. Collectively, these results provide a framework to support recovery planning that considers climate impacts on the majority of West Coast anadromous salmonids

    Aflatoxin contamination of groundnuts in Mozambique

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    The incidence of fungal infection and levels of aflatoxin contamination (produced by Aspergillus flavus) were studied in groundnuts collected from farmers at lifting and after drying/curing, and from traders in Nampula, Mozambique, during 1997-98. Of 34 samples collected at lifting, 13 were contaminated with aflatoxins and 8 had aflatoxin levels >30 µg/kg. Of 30 samples collected after drying, 10 had aflatoxins and 4 had >30 µg/kg. Of 10 samples collected from traders, only 2 had aflatoxin contamination. Aflatoxin G1 was predominant in samples collected at lifting and aflatoxin B1 in samples collected from traders

    Direct and indirect transmission of four Salmonella enterica serotypes in pigs

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    <p>Abstract</p> <p>Background</p> <p>Feed-borne spread of <it>Salmonella </it>spp. to pigs has been documented several times in recent years in Sweden. Experiences from the field suggest that feed-associated serotypes might be less transmittable and subsequently easier to eradicate from pig herds than other serotypes more commonly associated to pigs. Four <it>Salmonella </it>serotypes were selected for experimental studies in pigs in order to study transmissibility and compare possible differences between feed-assoociated (<it>S </it>Cubana and <it>S </it>Yoruba) and pig-associated serotypes (<it>S </it>Derby and <it>S </it>Typhimurium).</p> <p>Methods</p> <p>Direct contact transmission was studied in four groups of pigs formed by six 10-week-old salmonella negative pigs commingled with two fatteners excreting one of the four salmonella serotypes. Indirect transmission was studied by putting six 10-week-old salmonella negative pigs in each of four salmonella contaminated rooms. Each room had previously housed a group of pigs, excreting one of the four selected serotypes.</p> <p>All pigs were monitored for two weeks with respect to the faecal excretion of salmonella and the presence of serum antibodies. At the end of the trial, eight samples from inner tissues and organs were collected from each pig at necropsy.</p> <p>Results</p> <p>In the four direct transmission groups, one pig shed <it>Salmonella </it>(Cubana) at one occasion. At necropsy, <it>S </it>Typhimurium was isolated from one pig.</p> <p>In the indirect transmission groups, two pigs in the Yoruba room and one pig in each of the other rooms were excreting detectable levels of <it>Salmonella </it>once during the study period of two weeks. At necropsy, <it>S </it>Derby was isolated from one of six pigs in the Derby room and <it>S </it>Typhimurium was isolated from four of the six pigs in the Typhimurium room.</p> <p>No significant serological response could be detected in any of the 48 pigs.</p> <p>Conclusions</p> <p>These results show that all four selected serotypes were able to be transmitted in at least one of these field-like trials, but the transmission rate was low in all groups and no obvious differences between feed-associated and pig-associated serotypes in the transmission to naïve pigs and their subsequent faecal shedding were revealed. However, the post mortem results indicated a higher detection of <it>S </it>Typhimurium in the ileocecal lymph nodes of pigs introduced into a contaminated environment in comparison with the other three serotypes.</p

    International Coercion, Emulation and Policy Diffusion: Market-Oriented Infrastructure Reforms, 1977-1999

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    Why do some countries adopt market-oriented reforms such as deregulation, privatization and liberalization of competition in their infrastructure industries while others do not? Why did the pace of adoption accelerate in the 1990s? Building on neo-institutional theory in sociology, we argue that the domestic adoption of market-oriented reforms is strongly influenced by international pressures of coercion and emulation. We find robust support for these arguments with an event-history analysis of the determinants of reform in the telecommunications and electricity sectors of as many as 205 countries and territories between 1977 and 1999. Our results also suggest that the coercive effect of multilateral lending from the IMF, the World Bank or Regional Development Banks is increasing over time, a finding that is consistent with anecdotal evidence that multilateral organizations have broadened the scope of the “conditionality” terms specifying market-oriented reforms imposed on borrowing countries. We discuss the possibility that, by pressuring countries into policy reform, cross-national coercion and emulation may not produce ideal outcomes.http://deepblue.lib.umich.edu/bitstream/2027.42/40099/3/wp713.pd

    Can urban coffee consumption help predict US inflation?

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    Motivated by the importance of coffee to Americans and the significance of the coffee subsector to the US economy, we pursue three notable innovations. First, we augment the traditional Phillips curve model with the coffee price as a predictor, and show that the resulting model outperforms the traditional variant in both in-sample and out-of-sample predictability of US inflation. Second, we demonstrate the need to account for the inherent statistical features of predictors such as persistence, endogeneity, and conditional heteroskedasticity effects when dealing with US inflation. Consequently, we offer robust illustrations to show that the choice of estimator matters for improved US inflation forecasts. Third, the proposed augmented Phillips curve also outperforms time series models such as autoregressive integrated moving average and the fractionally integrated version for both in-sample and out-of-sample forecasts. Our results show that augmenting the traditional Phillips curve with the urban coffee price will produce better forecast results for US inflation only when the statistical effects are captured in the estimation process. Our results are robust to alternative measures of inflation, different data frequencies, higher order moments, multiple data samples and multiple forecast horizons

    TRY plant trait database - enhanced coverage and open access

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    Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    Prevalence of extended-spectrum beta-lactamases in the local farm environment and livestock: challenges to mitigate antimicrobial resistance

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    The effectiveness of antibiotics has been challenged by the increasing frequency of antimicrobial resistance (AR), which has emerged as a major threat to global health. Despite the negative impact of AR on health, there are few effective strategies for reducing AR in food-producing animals. Of the antimicrobial resistant microorganisms (ARMs), extended-spectrum beta-lactamases (ESBLs)-producing Enterobacteriaceae are an emerging global threat due to their increasing prevalence in livestock, even in animals raised without antibiotics. Many reviews are available for the positive selection of AR associated with antibiotic use in livestock, but less attention has been given to how other factors including soil, water, manure, wildlife, and farm workers, are associated with the emergence of ESBL-producing bacteria. Understanding of antibiotic resistance genes and bacteria transfer at the interfaces of livestock and other potential reservoirs will provide insights for the development of mitigation strategies for AR

    The rate of telomere loss is related to maximum lifespan in birds

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    Telomeres are highly conserved regions of DNA that protect the ends of linear chromosomes. The loss of telomeres can signal an irreversible change to a cell's state, including cellular senescence. Senescent cells no longer divide and can damage nearby healthy cells, thus potentially placing them at the crossroads of cancer and ageing. While the epidemiology, cellular and molecular biology of telomeres are well studied, a newer field exploring telomere biology in the context of ecology and evolution is just emerging. With work to date focusing on how telomere shortening relates to individual mortality, less is known about how telomeres relate to ageing rates across species. Here, we investigated telomere length in cross-sectional samples from 19 bird species to determine how rates of telomere loss relate to interspecific variation in maximum lifespan. We found that bird species with longer lifespans lose fewer telomeric repeats each year compared with species with shorter lifespans. In addition, phylogenetic analysis revealed that the rate of telomere loss is evolutionarily conserved within bird families. This suggests that the physiological causes of telomere shortening, or the ability to maintain telomeres, are features that may be responsible for, or co-evolved with, different lifespans observed across species.This article is part of the theme issue 'Understanding diversity in telomere dynamics'
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