311 research outputs found

    Advanced bearing study. Part 2: Bearing tests

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    Tests of ball bearings of various material combinations in liquid hydroge

    Soil–plant interactions in a pasture of the Italian Alps

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    A detailed assessment of a pasture\u2019s functioning based on soil properties characterization, floristic composition, and \u2018functional summary\u2019 by evaluating competitor\u2013stress tolerator\u2013ruderal (CSR) strategies is provided for a doline in Central Italian Alps. A floristic survey was carried out at 35 sampling points, representative of the main topographic features, soil and vegetation types; the functional profile at the community level was evaluated by assessing for each species its Grime\u2019s CSR strategy; each point was characterized through soil profiles and topsoil (0\u201310 cm) sampling; pH, soil organic carbon and total nitrogen, available P, soil humus fraction, root density, bulk density, water content, and available water capacity were determined. Our study showed i) a strong relationship between vegetation, soil properties, topography, and grazing; ii) a prevalence of stress-tolerant strategies; iii) the ability of plant strategy variation to reflect the ecological parameters; and iv) the vegetation potentiality to be an indicator of environmental spatial variability

    Bioethanol from poplar clone Imola: an environmentally viable alternative to fossil fuel?

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    BACKGROUND: Environmental issues, e.g. climate change, fossil resource depletion have triggered ambitious national/regional policies to develop biofuel and bioenergy roles within the overall energy portfolio to achieve decarbonising the global economy and increase energy security. With the 10 % binding target for the transport sector, the Renewable Energy Directive confirms the EU’s commitment to renewable transport fuels especially advanced biofuels. Imola is an elite poplar clone crossed from Populus deltoides Bartr. and Populus nigra L. by Research Units for Intensive Wood Production, Agriculture Research Council in Italy. This study examines its suitability for plantation cultivation under short or very short rotation coppice regimes as a potential lignocellulosic feedstock for the production of ethanol as a transport biofuel. A life cycle assessment (LCA) approach was used to model the cradle-to-gate environmental profile of Imola-derived biofuel benchmarked against conventional fossil gasoline. Specific attention was given to analysing the agroecosystem fluxes of carbon and nitrogen occurring in the cultivation of the Imola biomass in the biofuel life cycle using a process-oriented biogeochemistry model (DeNitrification-DeComposition) specifically modified for application to 2G perennial bioenergy crops and carbon and nitrogen cycling. RESULTS: Our results demonstrate that carbon and nitrogen cycling in perennial crop–soil ecosystems such as this example can be expected to have significant effects on the overall environmental profiles of 2G biofuels. In particular, soil carbon accumulation in perennial biomass plantations is likely to be a significant component in the overall greenhouse gas balance of future biofuel and other biorefinery products and warrants ongoing research and data collection for LCA models. We conclude that bioethanol produced from Imola represents a promising alternative transport fuel offering some savings ranging from 35 to 100 % over petrol in global warming potential, ozone depletion and photochemical oxidation impact categories. CONCLUSIONS: Via comparative analyses for Imola-derived bioethanol across potential supply chains, we highlight priority issues for potential improvement in 2G biofuel profiling. Advanced clones of poplar such as Imola for 2G biofuel production in Italy as modelled here show potential to deliver an environmentally sustainable lignocellulosic biorefinery industry and accelerate advanced biofuel penetration in the transport sector. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-015-0318-8) contains supplementary material, which is available to authorized users

    Membrane vesicles as a novel strategy for shedding encrusted cell surfaces

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    Surface encrustation by minerals, which impedes cellular metabolism, is a potential hazard for microbes. The reduction of U(VI) to U(IV) by Shewanella oneidensis strain MR-1 leads to the precipitation of the mineral uraninite, as well as a non-crystalline U(IV) product. The wild-type (WT) strain can produce extracellular polymeric substances (EPS), prompting precipitation of U some distance from the cells and precluding encrustation. Using cryo-transmission electron microscopy and scanning transmission X-ray microscopy we show that, in the biofilm-deficient mutant Delta mxdA, as well as in the WT strain to a lesser extent, we observe the formation of membrane vesicles (MVs) as an additional means to lessen encrustation. Additionally, under conditions in which the WT does not produce EPS, formation of MVs was the only observed mechanism to mitigate cell encrustation. Viability studies comparing U-free controls to cells exposed to U showed a decrease in the number of viable cells in conditions where MVs alone are detected, yet no loss of viability when cells produce both EPS and MVs. We conclude that MV formation is a microbial strategy to shed encrusted cell surfaces but is less effective at maintaining cell viability than the precipitation of U on EPS

    Comparative genomics in acid mine drainage biofilm communities reveals metabolic and structural differentiation of co-occurring archaea

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    Background Metal sulfide mineral dissolution during bioleaching and acid mine drainage (AMD) formation creates an environment that is inhospitable to most life. Despite dominance by a small number of bacteria, AMD microbial biofilm communities contain a notable variety of coexisting and closely related Euryarchaea, most of which have defied cultivation efforts. For this reason, we used metagenomics to analyze variation in gene content that may contribute to niche differentiation among co-occurring AMD archaea. Our analyses targeted members of the Thermoplasmatales and related archaea. These results greatly expand genomic information available for this archaeal order. Results We reconstructed near-complete genomes for uncultivated, relatively low abundance organisms A-, E-, and Gplasma, members of Thermoplasmatales order, and for a novel organism, Iplasma. Genomic analyses of these organisms, as well as Ferroplasma type I and II, reveal that all are facultative aerobic heterotrophs with the ability to use many of the same carbon substrates, including methanol. Most of the genomes share genes for toxic metal resistance and surface-layer production. Only Aplasma and Eplasma have a full suite of flagellar genes whereas all but the Ferroplasma spp. have genes for pili production. Cryogenic-electron microscopy (cryo-EM) and tomography (cryo-ET) strengthen these metagenomics-based ultrastructural predictions. Notably, only Aplasma, Gplasma and the Ferroplasma spp. have predicted iron oxidation genes and Eplasma and Iplasma lack most genes for cobalamin, valine, (iso)leucine and histidine synthesis. Conclusion The Thermoplasmatales AMD archaea share a large number of metabolic capabilities. All of the uncultivated organisms studied here (A-, E-, G-, and Iplasma) are metabolically very similar to characterized Ferroplasma spp., differentiating themselves mainly in their genetic capabilities for biosynthesis, motility, and possibly iron oxidation. These results indicate that subtle, but important genomic differences, coupled with unknown differences in gene expression, distinguish these organisms enough to allow for co-existence. Overall this study reveals shared features of organisms from the Thermoplasmatales lineage and provides new insights into the functioning of AMD communities.United States. Dept. of Energy. Genomics:GTL (Grant DE-FG02-05ER64134)National Science Foundation (U.S.). Graduate Research Fellowshi

    Crowding Promotes the Switch from Hairpin to Pseudoknot Conformation in Human Telomerase RNA

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    Formation of a pseudoknot in the conserved RNA core domain in the ribonucleoprotein human telomerase is required for function. In vitro experiments show that the pseudoknot (PK) is in equilibrium with an extended hairpin (HP) structure. We use molecular simulations of a coarse-grained model, which reproduces most of the salient features of the experimental melting profiles of PK and HP, to show that crowding enhances the stability of PK relative to HP in the wild type and in a mutant associated with dyskeratosis congenita. In monodisperse suspensions, small crowding particles increase the stability of compact structures to a greater extent than larger crowders. If the sizes of crowders in a binary mixture are smaller than the unfolded RNA, the increase in melting temperature due to the two components is additive. In a ternary mixture of crowders that are larger than the unfolded RNA, which mimics the composition of ribosome, large enzyme complexes and proteins in E. coli, the marginal increase in stability is entirely determined by the smallest component. We predict that crowding can restore partially telomerase activity in mutants, which dramatically decrease the PK stability.Comment: File "JACS_MAIN_archive_PDF_from_DOC.pdf" (PDF created from DOC) contains the main text of the paper File JACS_SI_archive.tex + 7 figures are the supplementary inf

    Impaired bone marrow hematopoietic progenitor cell function in rheumatoid arthritis patients candidated to autologous hematopoietic stem cell transplantation

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    We have evaluated bone marrow morphology, percentage of bone marrow CD34(+) cells, proliferative activity of bone marrow precursors, clonogenic assay ( BFU- E and CFU- GM) in short- term bone marrow cultures, and bone marrow cell apoptosis, together with serum TNF-alpha and IL- 6, in 16 chronic, refractory RA patients, as well as in five healthy controls. Of 16 RA patients ( 68.7%), 11 showed a reduced bone marrow cellularity, while it was normal in all the controls. In RA patients, the median percentage of CD34(+) bone marrow cells, the median percentage of proliferating bone marrow myeloid precursors, and the median number of both BFU- E and CFU-GM colonies were significantly lower than observed in the controls. As far as TNF-alpha and IL- 6 titers is concerned, the latter did not significantly differ from controls' values, while TNF-alpha titers were significantly lower in healthy controls. Finally, the median apoptotic index of early bone marrow myeloid cells of RA patients was significantly higher compared with controls. These observations may identify the biological risk factors for impaired mobilization and/ or engraftment when RA patients are candidates for autologous hematopoietic stem cell grafting

    Mariprofundus ferrooxydans PV-1 the First Genome of a Marine Fe(II) Oxidizing Zetaproteobacterium

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    © The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e25386, doi:10.1371/journal.pone.0025386.Mariprofundus ferrooxydans PV-1 has provided the first genome of the recently discovered Zetaproteobacteria subdivision. Genome analysis reveals a complete TCA cycle, the ability to fix CO2, carbon-storage proteins and a sugar phosphotransferase system (PTS). The latter could facilitate the transport of carbohydrates across the cell membrane and possibly aid in stalk formation, a matrix composed of exopolymers and/or exopolysaccharides, which is used to store oxidized iron minerals outside the cell. Two-component signal transduction system genes, including histidine kinases, GGDEF domain genes, and response regulators containing CheY-like receivers, are abundant and widely distributed across the genome. Most of these are located in close proximity to genes required for cell division, phosphate uptake and transport, exopolymer and heavy metal secretion, flagellar biosynthesis and pilus assembly suggesting that these functions are highly regulated. Similar to many other motile, microaerophilic bacteria, genes encoding aerotaxis as well as antioxidant functionality (e.g., superoxide dismutases and peroxidases) are predicted to sense and respond to oxygen gradients, as would be required to maintain cellular redox balance in the specialized habitat where M. ferrooxydans resides. Comparative genomics with other Fe(II) oxidizing bacteria residing in freshwater and marine environments revealed similar content, synteny, and amino acid similarity of coding sequences potentially involved in Fe(II) oxidation, signal transduction and response regulation, oxygen sensation and detoxification, and heavy metal resistance. This study has provided novel insights into the molecular nature of Zetaproteobacteria.Funding has been provided by the NSF Microbial Observatories Program (KJE, DE), NSF’s Science and Technology Program, by the Gordon and Betty Moore Foundation (KJE), the College of Letters, Arts, and Sciences at the University of Southern California (KJE), and by the NASA Astrobiology Institute (KJE, DE). Advanced Light Source analyses at the Lawrence Berkeley National Lab are supported by the Office of Science, Basic Energy Sciences, Division of Materials Science of the United States Department of Energy (DE-AC02-05CH11231)
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