619 research outputs found

    Does a Carbonatite Deposit Influence Its Surrounding Ecosystem?

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    Carbonatites are unusual alkaline rocks with diverse compositions. Although previous work has characterized the effects these rocks have on soils and plants, little is known about their impacts on local ecosystems. Using a deposit within the Great Lakes–St. Lawrence forest in northern Ontario, Canada, we investigated the effect of a carbonatite on soil chemistry and on the structure of plant and soil microbial communities. This was done using a vegetation survey conducted above and around the deposit, with corresponding soil samples collected for determining soil nutrient composition and for assessing microbial community structure using 16S/ITS Illumina Mi-Seq sequencing. In some soils above the deposit a soil chemical signature of the carbonatite was found, with the most important effect being an increase in soil pH compared with the non-deposit soils. Both plants and microorganisms responded to the altered soil chemistry: the plant communities present in carbonatite-impacted soils were dominated by ruderal species, and although differences in microbial communities across the surveyed areas were not obvious, the abundances of specific bacteria and fungi were reduced in response to the carbonatite. Overall, the deposit seems to have created microenvironments of relatively basic soil in an otherwise acidic forest soil. This study demonstrates for the first time how carbonatites can alter ecosystems in situ

    MTR and the EU Commission Proposal for the WTO: - An analysis of their effect on the EU and Irish agricultural sector

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    Further information may be found at http://www.tnet.teagasc.ie/fapri/pubandrep2003.htmIn the short history of the FAPRI-Ireland Partnership there has been no shortage of policy proposals to analyse. As part of the Agenda 2000 process the CAP is undergoing significant reform following the agreement made at the European Council in Berlin in 1999. This agreement had widespread implications for agriculture in Ireland, particularly for the beef sector. The changes that were agreed at that time have not even been fully implemented and there is already another reform document on the table, containing even more radical proposals for reform

    Identification and characterization of the intracellular poly-3-hydroxybutyrate depolymerase enzyme PhaZ of Sinorhizobium meliloti

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    <p>Abstract</p> <p>Background</p> <p><it>S. meliloti </it>forms indeterminate nodules on the roots of its host plant alfalfa (<it>Medicago sativa</it>). Bacteroids of indeterminate nodules are terminally differentiated and, unlike their non-terminally differentiated counterparts in determinate nodules, do not accumulate large quantities of Poly-3-hydroxybutyrate (PHB) during symbiosis. PhaZ is in intracellular PHB depolymerase; it represents the first enzyme in the degradative arm of the PHB cycle in <it>S. meliloti </it>and is the only enzyme in this half of the PHB cycle that remains uncharacterized.</p> <p>Results</p> <p>The <it>S. meliloti phaZ </it>gene was identified by <it>in silico </it>analysis, the ORF was cloned, and a <it>S. meliloti phaZ </it>mutant was constructed. This mutant exhibited increased PHB accumulation during free-living growth, even when grown under non-PHB-inducing conditions. The <it>phaZ </it>mutant demonstrated no reduction in symbiotic capacity; interestingly, analysis of the bacteroids showed that this mutant also accumulated PHB during symbiosis. This mutant also exhibited a decreased capacity to tolerate long-term carbon starvation, comparable to that of other PHB cycle mutants. In contrast to other PHB cycle mutants, the <it>S. meliloti phaZ </it>mutant did not exhibit any decrease in rhizosphere competitiveness; however, this mutant did exhibit a significant increase in succinoglycan biosynthesis.</p> <p>Conclusions</p> <p><it>S. meliloti </it>bacteroids retain the capacity to synthesize PHB during symbiosis; interestingly, accumulation does not occur at the expense of symbiotic performance. <it>phaZ </it>mutants are not compromised in their capacity to compete for nodulation in the rhizosphere, perhaps due to increased succinoglycan production resulting from upregulation of the succinoglycan biosynthetic pathway. The reduced survival capacity of free-living cells unable to access their accumulated stores of PHB suggests that PHB is a crucial metabolite under adverse conditions.</p

    FAPRI-Ireland 2003 EU Baseline Briefing Book

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    For six years the FAPRI-Ireland Partnership has been producing analysis of agricultural policy for the EU, with a focus on the impacts for Ireland. The process that generates this analysis involves first developing a baseline, a set of figures produced under the assumption that current policies remain in place. In the case of Europe, this means that agricultural policy in the EU is that which prevailed in January 2003. The baseline does include the reforms that were agreed under Agenda 2000 that have yet to be implemented for the dairy sector, where intervention prices were scheduled to fall between 2005 and 2007, and provisions from the Uruguay round

    Genome-Wide Screen for Salmonella Genes Required for Long-Term Systemic Infection of the Mouse

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    A microarray-based negative selection screen was performed to identify Salmonella enterica serovar Typhimurium (serovar Typhimurium) genes that contribute to long-term systemic infection in 129X1/SvJ (Nramp1(r)) mice. A high-complexity transposon-mutagenized library was used to infect mice intraperitoneally, and the selective disappearance of mutants was monitored after 7, 14, 21, and 28 d postinfection. One hundred and eighteen genes were identified to contribute to serovar Typhimurium infection of the spleens of mice by 28 d postinfection. The negatively selected mutants represent many known aspects of Salmonella physiology and pathogenesis, although the majority of the identified genes are of putative or unknown function. Approximately 30% of the negatively selected genes correspond to horizontally acquired regions such as those within Salmonella pathogenicity islands (SPI 1–5), prophages (Gifsy-1 and −2 and remnant), and the pSLT virulence plasmid. In addition, mutations in genes responsible for outer membrane structure and remodeling, such as LPS- and PhoP-regulated and fimbrial genes, were also selected against. Competitive index experiments demonstrated that the secreted SPI2 effectors SseK2 and SseJ as well as the SPI4 locus are attenuated relative to wild-type bacteria during systemic infection. Interestingly, several SPI1-encoded type III secretion system effectors/translocases are required by serovar Typhimurium to establish and, unexpectedly, to persist systemically, challenging the present description of Salmonella pathogenesis. Moreover, we observed a progressive selection against serovar Typhimurium mutants based upon the duration of the infection, suggesting that different classes of genes may be required at distinct stages of infection. Overall, these data indicate that Salmonella long-term systemic infection in the mouse requires a diverse repertoire of virulence factors. This diversity of genes presumably reflects the fact that bacteria sequentially encounter a variety of host environments and that Salmonella has evolved to respond to these selective forces in a way that permits both the bacteria and the host to survive

    CAP Reform and the WTO: Potential Impacts on EU Agriculture

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    Selected Paper prepared for presentation at the American Agricultural Economics Association Annual Meeting, Denver, Colorado.In 2003 an agreement was finalized to instigate arguably the most significant reform of the European Union's (EU) Common Agricultural Policy (CAP) since its inception. In the Luxembourg Agreement many of the direct payments that have been linked to production are decoupled and instead provided in the form of a land-based payment. The reforms did not include any significant changes to either EU border support or the ability of the EU to utilize export subsidies that have been widely criticized by other nations. Even though the reforms do not directly address trade in agricultural products it is argued that World Trade Organization (WTO) concerns played a significant role in the designs of the reforms. In this paper an analysis of the Luxembourg reforms and the European proposal for agriculture under the WTO is presented. The results are used as the basis for a discussion of the interaction of the WTO and CAP reform and the implications for the agricultural sector in the EU

    FAPRI-Ireland 2001 EU Baseline Briefing Book

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    In April 2001, members of the FAPRI-Ireland partnership prepared baseline projections for European Union cereal, oilseed, meat, and dairy markets. These projections represent our best estimate of what EU markets would look like under a very specific set of assumptions

    FAPRI - Ireland 2002 EU Baseline Briefing Book

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    Each year the FAPRI-Ireland Partnership produces a baseline series of projections for the major European agricultural markets. Projections are produced for the EU as a whole as well as Ireland, France, Germany, Italy and the United Kingdom

    Viral factors in influenza pandemic risk assessment

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    The threat of an influenza A virus pandemic stems from continual virus spillovers from reservoir species, a tiny fraction of which spark sustained transmission in humans. To date, no pandemic emergence of a new influenza strain has been preceded by detection of a closely related precursor in an animal or human. Nonetheless, influenza surveillance efforts are expanding, prompting a need for tools to assess the pandemic risk posed by a detected virus. The goal would be to use genetic sequence and/or biological assays of viral traits to identify those non-human influenza viruses with the greatest risk of evolving into pandemic threats, and/or to understand drivers of such evolution, to prioritize pandemic prevention or response measures. We describe such efforts, identify progress and ongoing challenges, and discuss three specific traits of influenza viruses (hemagglutinin receptor binding specificity, hemagglutinin pH of activation, and polymerase complex efficiency) that contribute to pandemic risk
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