18 research outputs found

    Selection for Nitrogen Use Efficiency in Perennial Ryegrass using Hydroponics

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    A selection method was tested for improving nitrogen use efficiency of perennial ryegrass (Lolium perenne L.) using a hydroponics system that controls the plant nitrogen concentration. Divergent selection for plant production, leaf area increase and dry matter distribution in six segregating populations under limiting nitrogen supply resulted in differences between offspring of upward and downward selections larger than 20 % in most characteristics. Moderately high realized heritabilities were found for some characteristics (up to 0.88). It is concluded that early selection for nitrogen use efficiency is feasible using this hydroponics system

    Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source

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    Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65–70 nm, which is considerably smaller than the previously reported ~600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single-particle imaging towards the single molecular imaging regime. The data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency

    The diversity and distribution of toxigenic \u3cem\u3eMicrocystis\u3c/em\u3e spp. In present day and archived pelagis and sediment samples from Lake Erie

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    The reoccurrence of significant cyanobacterial blooms in Lake Erie during the last 13 years has raised questions concerning the long-term persistence of microcystin-producing cyanobacteria and the presence of natural sediment reservoirs for potentially toxic cyanobacteria in this large lake system. To address these questions, we analyzed phytoplankton and sediment samples which were collected and preserved in the 1970s as well as samples collected in 2004 from locations within Lake Erie. The identification of microcystin-producing cyanobacteria in Lake Erie was examined via PCR amplification of the mcyA gene fragment. Based on the high % sequence similarity, the mcyA sequences from all 1970s phytoplankton and sediment samples were determined to belong to Microcystis spp., in spite of reports suggesting that Lake Erie was dominated by filamentous cyanobacteria in the 1970s. In sediment samples from 2004, signature genes for Microcystis were distributed and preserved not only in the surface sediments but also up to 10–12 cm in depth. Based on cell quantities determined by a quantitative polymerase chain reaction (qPCR) method, 0.18% of eubacteria in the sediments were Microcystis cells, of which 4.8% were potential microcystin producers. In combination with experiments showing that Microcystis cells can be cultured from Lake Erie surface sediments, this paper demonstrates the potential for these sediments to act as a reservoir for pelagic Microcystis populations and that the composition of the population of microcystin-producing cyanobacteria in Lake Erie has not changed remarkably since the 1970s

    The Bowland Shale Formation in the Blacon Basin: syngenetic processes, stacking patterns and heat productivity

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    We conducted a high-resolution multi-disciplinary analysis of two core sections in the borehole Ellesmere Port-1, Cheshire, UK. Biostratigraphic analysis indicates the core sections are Kinderscoutian and late Arnsbergian-Chokerian in age, respectively. Both cores are assigned to the Bowland Shale Formation (Holywell Shale). Coupled core scan and discrete geochemical analysis enables interpretation of syngenetic processes at a high stratigraphic resolution. Both cores exhibit the classic cyclicity of limestones, calcareous to non-calcareous mudstones and siltstones, interpreted to represent sediment deposition during fourth-order sea level fluctuation. Machine learning of the well log data coupled to the core scan data enabled prediction of the key lithofacies through the entire Bowland Shale interval in Ellesmere Port-1. The machine predictions show the Bowland Shale is interfingered with three turbiditic leaves of the Cefn-y-fedw Sandstone Formation and contains at least 12 complete fourth-order cycles. The Bowland Shale exhibits high radiogenic heat productivity (RHP) in comparison to other sedimentary rocks, due primarily to relative enrichment in U under intermittently euxinic conditions. Thermal modelling, however, shows Bowland Shale RHP contributes a negligible source of additional heat at the scale of 100s m
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