2,901 research outputs found

    Co-production of bio-oil and propylene through the hydrothermal liquefaction of polyhydroxybutyrate producing cyanobacteria

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    A polyhydroxybutyrate (PHB) producing cyanobacteria was converted through hydrothermal liquefaction (HTL) into propylene and a bio-oil suitable for advanced biofuel production. HTL of model compounds demonstrated that in contrast to proteins and carbohydrates, no synergistic effects were detected when converting PHB in the presence of algae. Subsequently, Synechocystis cf. salina, which had accumulated 7.5wt% PHB was converted via HTL (15% dry weight loading, 340°C). The reaction gave an overall propylene yield of 2.6%, higher than that obtained from the model compounds, in addition to a bio-oil with a low nitrogen content of 4.6%. No propylene was recovered from the alternative non-PHB producing cyanobacterial strains screened, suggesting that PHB is the source of propylene. PHB producing microorganisms could therefore be used as a feedstock for a biorefinery to produce polypropylene and advanced biofuels, with the level of propylene being proportional to the accumulated amount of PHB

    OmniMapFree: A unified tool to visualise and explore sequenced genomes

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    <p>Abstract</p> <p>‱ Background</p> <p>Acquiring and exploring whole genome sequence information for a species under investigation is now a routine experimental approach. On most genome browsers, typically, only the DNA sequence, EST support, motif search results, and GO annotations are displayed. However, for many species, a growing volume of additional experimental information is available but this is rarely searchable within the landscape of the entire genome.</p> <p>‱ Results</p> <p>We have developed a generic software which permits users to view a single genome in entirety either within its chromosome or supercontig context within a single window. This software permits the genome to be displayed at any scales and with any features. Different data types and data sets are displayed onto the genome, which have been acquired from other types of studies including classical genetics, forward and reverse genetics, transcriptomics, proteomics and improved annotation from alternative sources. In each display, different types of information can be overlapped, then retrieved in the desired combinations and scales and used in follow up analyses. The displays generated are of publication quality.</p> <p>‱ Conclusions</p> <p>OmniMapFree provides a unified, versatile and easy-to-use software tool for studying a single genome in association with all the other datasets and data types available for the organism.</p

    Identification and functional characterisation of a locus for target site integration in Fusarium graminearum

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    Background Fusarium Head Blight (FHB) is a destructive floral disease of different cereal crops. The Ascomycete fungus Fusarium graminearum (Fg) is one of the main causal agents of FHB in wheat and barley. The role(s) in virulence of Fg genes include genetic studies that involve the transformation of the fungus with different expression cassettes. We have observed in several studies where Fg genes functions were characterised that integration of expression cassettes occurred randomly. Random insertion of a cassette may disrupt gene expression and/or protein functions and hence the overall conclusion of the study. Target site integration (TSI) is an approach that consists of identifying a chromosomal region where the cassette can be inserted. The identification of a suitable locus for TSI in Fg would avert the potential risks of ectopic integration. Results Here, we identified a highly conserved intergenic region on chromosome 1 suitable for TSI. We named this intergenic region TSI locus 1. We developed an efficient cloning vector system based on the Golden Gate method to clone different expression cassettes for use in combination with TSI locus 1. We present evidence that integrations in the TSI locus 1 affects neither fungal virulence nor fungal growth under different stress conditions. Integrations at the TSI locus 1 resulted in the expression of different gene fusions. In addition, the activities of Fg native promoters were not altered by integration into the TSI locus 1. We have developed a bespoke bioinformatic pipeline to analyse the existence of ectopic integrations, cassette truncations and tandem insertions of the cassette that may occurred during the transformation process. Finally, we established a protocol to study protein secretion in wheat coleoptiles using confocal microscopy and the TSI locus 1. Conclusion The TSI locus 1 can be used in Fg and potentially other cereal infecting Fusarium species for diverse studies including promoter activity analysis, protein secretion, protein localisation studies and gene complementation. The bespoke bioinformatic pipeline developed in this work together with PCR amplification of the insert could be an alternative to Southern blotting, the gold standard technique used to identify ectopic integrations, cassette truncations and tandem insertions in fungal transformation

    PHI-base update: additions to the pathogen–host interaction database

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    The pathogen–host interaction database (PHI-base) is a web-accessible database that catalogues experimentally verified pathogenicity, virulence and effector genes from bacterial, fungal and Oomycete pathogens, which infect human, animal, plant, insect, fish and fungal hosts. Plant endophytes are also included. PHI-base is therefore an invaluable resource for the discovery of genes in medically and agronomically important pathogens, which may be potential targets for chemical intervention. The database is freely accessible to both academic and non-academic users. This publication describes recent additions to the database and both current and future applications. The number of fields that characterize PHI-base entries has almost doubled. Important additional fields deal with new experimental methods, strain information, pathogenicity islands and external references that link the database to external resources, for example, gene ontology terms and Locus IDs. Another important addition is the inclusion of anti-infectives and their target genes that makes it possible to predict the compounds, that may interact with newly identified virulence factors. In parallel, the curation process has been improved and now involves several external experts. On the technical side, several new search tools have been provided and the database is also now distributed in XML format. PHI-base is available at: http://www.phi-base.org/

    Evaluation and application of microsatellites for population identification of Fraser River chinook salmon (Oncorhynchus tshawytscha)

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    Variation at 13 microsatellite loci was previously surveyed in approximately 7400 chinook salmon (Oncorhynchus tshawytscha) sampled from 50 localities in the Fraser River drainage in southern British Columbia. Evaluation of the utility of the microsatellite variation for population-specific stock identification applications indicated that the accuracy of the stock composition estimates generally improved with an increasing number of loci used in the estimation procedure, but an increase in accuracy was generally marginal after eight loci were used. With 10–14 populations in a simulated fishery sample, the mean error in population-specific estimated stock composition with a 50-popula-tion baseline was <1.4%. Identification of individuals to specific populations was highest for lower Fraser River and lower and North Thompson River populations; an average of 70% of the individual fish were correctly assigned to specific populations. The average error of the estimated percentage for the seven populations present in a coded-wire tag sample was 2% per population. Estimation of stock composition in the lower river commercial net fishery prior to June is of key local fishery management interest. Chinook salmon from the Chilcotin River and Nicola River drainages were important contributors to the early commercial fishery in the lower river because they comprised approximately 50% of the samples from the net fishery prior to mid April

    The geographic basis for population structure in Fraser River chinook salmon (Oncorhynchus tshawytscha)

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    We surveyed variation at 13 microsatellite loci in approximately 7400 chinook salmon sampled from 52 spawning sites in the Fraser River drainage during 1988–98 to examine the spatial and temporal basis of population structure in the watershed. Genetically discrete chinook salmon populations were associated with almost all spawning sites, although gene flow within some tributaries prevented or limited differentiation among spawning groups. The mean FST value over 52 samples and 13 loci surveyed was 0.039. Geographic structuring of populations was apparent: distinct groups were identified in the upper, middle, and lower Fraser River regions, and the north, south, and lower Thompson River regions. The geographically and temporally isolated Birkenhead River population of the lower Fraser region was sufficiently genetically distinctive to be treated as a separate region in a hierarchial analysis of gene diversity. Approximately 95% of genetic variation was contained within populations, and the remainder was accounted for by differentiation among regions (3.1%), among populations within regions (1.3%), and among years within populations (0.5%).Analysis of allelic diversity and private alleles did not support the suggestion that genetically distinctive populations of chinook salmon in the south Thompson were the result of postglacial hybridization of ocean-type and stream-type chinook in the Fraser River drainage. However, the relatively small amount of differentiation among Fraser River chinook salmon populations supports the suggestion that gene flow among genetically distinct groups of postglacial colonizing groups of chinook salmon has occurred, possibly prior to colonization of the Fraser River drainage

    Search for a new gauge boson in the Aâ€ČA' Experiment (APEX)

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    We present a search at Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling αâ€Č\alpha' to electrons. Such a particle Aâ€ČA' can be produced in electron-nucleus fixed-target scattering and then decay to an e+e−e^+e^- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175--250 MeV, found no evidence for an Aâ€Č→e+e−A'\to e^+e^- reaction, and set an upper limit of αâ€Č/α≃10−6\alpha'/\alpha \simeq 10^{-6}. Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.Comment: 5 pages, 5 figures, references adde

    Evolution of age and length at maturation of Alaskan salmon under size-selective harvest

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    Spatial and temporal trends and variation in life-history traits, including age and length at maturation, can be influenced by environmental and anthropogenic processes, including size-selective exploitation. Spawning adults in many wild Alaskan sockeye salmon populations have become shorter at a given age over the past half-century, but their age composition has not changed. These fish have been exploited by a gillnet fishery since the late 1800s that has tended to remove the larger fish. Using a rare, long-term dataset, we estimated probabilistic maturation reaction norms (PMRNs) for males and females in nine populations in two basins and correlated these changes with fishery size selection and intensity to determine whether such selection contributed to microevolutionary changes in maturation length. PMRN midpoints decreased in six of nine populations for both sexes, consistent with the harvest. These results support the hypothesis that environmental changes in the ocean (likely from competition) combined with adaptive microevolution (decreased PMRNs) have produced the observed life-history patterns. PMRNs did not decrease in all populations, and we documented differences in magnitude and consistency of size selection and exploitation rates among populations. Incorporating evolutionary considerations and tracking further changes in life-history traits can support continued sustainable exploitation and productivity in these and other exploited natural resources

    Physics beyond colliders at CERN:Beyond the Standard Model Working Group Report

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    The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics. This document presents the status of the proposals presented in the framework of the Beyond Standard Model physics working group, and explore their physics reach and the impact that CERN could have in the next 10-20 years on the international landscape.</p
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