130 research outputs found

    Regional métier definition: A comparative investigation of statistical methods using a workflow applied to the international otter trawl fisheries in the North Sea

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    The European Common Fisheries Policy recognizes the importance of accounting for heterogeneity in fishing practices, and metier-based sampling is now at the core of the EU Data Collection Framework. The implementation of such an approach would require Member States to agree on the standard regional metier definitions and on practical rules to categorize logbook records into metiers. Several alternative approaches have been used in the past to categorize landings profiles, but no consensus has yet emerged. A generic open-source workflow is developed to test and compare a selection of methods, including principal components analysis (PCA), hierarchical agglomerative clustering (HAC), K-means, and Clustering LARge Applications (CLARA), and to provide simple allocation rules. This workflow is applied to a unique regional dataset consisting of bottom-trawl logbooks of five North Sea countries. No method proved to be infallible, but combining PCA with either CLARA or HAC performed best. For 2008, a hierarchical classification with 14 species assemblages is proposed. Discriminant analysis proved more robust than simple ordination methods for allocating a new logbook record into an existing metier. The whole approach is directly operational and could contribute to defining more objective and consistent metiers across European fisheries

    Four PCR primers necessary for the detection of periplasmic nitrate reductase genes in all groups of Proteobacteria and in environmental DNA

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    Generic primers are available for detecting bacterial genes required for almost every reaction of the biological nitrogen cycle, the one notable exception being napA (gene for the molybdoprotein of the periplasmic nitrate reductase) encoding periplasmic nitrate reductases. Using an iterative approach, we report the first successful design of three forward oligonucleotide primers and one reverse primer that, in three separate PCRs, can amplify napA DNA from all five groups of Proteobacteria. All 140 napA sequences currently listed in the NCBI (National Center for Biotechnology Information) database are predicted to be amplified by one or more of these primer pairs. We demonstrate that two pairs of these primers also amplify PCR products of the predicted sizes from DNA isolated from human faeces, confirming their ability to direct the amplification of napA fragments from mixed populations. Analysis of the resulting amplicons by high-throughput sequencing will enable a good estimate to be made of both the range and relative abundance of nitrate-reducing bacteria in any community, subject only to any unavoidable bias inherent in a PCR approach to molecular characterization of a highly diverse target

    Substrate Specificity and Structural Characteristics of the Novel Rieske Nonheme Iron Aromatic Ring-Hydroxylating Oxygenases NidAB and NidA3B3 from Mycobacterium vanbaalenii PYR-1

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    The Rieske nonheme iron aromatic ring-hydroxylating oxygenases (RHOs) NidAB and NidA3B3 from Mycobacterium vanbaalenii PYR-1 have been implicated in the initial oxidation of high-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs), forming cis-dihydrodiols. To clarify how these two RHOs are functionally different with respect to the degradation of HMW PAHs, we investigated their substrate specificities to 13 representative aromatic substrates (toluene, m-xylene, phthalate, biphenyl, naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, carbazole, and dibenzothiophene) by enzyme reconstitution studies of Escherichia coli. Both Nid systems were identified to be compatible with type V electron transport chain (ETC) components, consisting of a [3Fe-4S]-type ferredoxin and a glutathione reductase (GR)-type reductase. Metabolite profiles indicated that the Nid systems oxidize a wide range of aromatic hydrocarbon compounds, producing various isomeric dihydrodiol and phenolic compounds. NidAB and NidA3B3 showed the highest conversion rates for pyrene and fluoranthene, respectively, with high product regiospecificity, whereas other aromatic substrates were converted at relatively low regiospecificity. Structural characteristics of the active sites of the Nid systems were investigated and compared to those of other RHOs. The NidAB and NidA3B3 systems showed the largest substrate-binding pockets in the active sites, which satisfies spatial requirements for accepting HMW PAHs. Spatially conserved aromatic amino acids, Phe-Phe-Phe, in the substrate-binding pockets of the Nid systems appeared to play an important role in keeping aromatic substrates within the reactive distance from the iron atom, which allows each oxygen to attack the neighboring carbons

    Report on the Workshop on Transversal Variables. (Linking economic and biological effort data (call) design). 19th -23rd January 2015

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    The Workshop on the Transversal Variables took place in Zagreb from the 19th to 23rd of January, 2015 mainly to tackle the issues related to the increasing need of having fisheries fleet economic data and fisheries biologic data on a level of disaggregation that would allow a proper interoperability between datasets to underpin bioeconomic modelling. For that, several analyses were carried out and conclusions taken. These analyses were : 1. comparison of economic and biological effort data calls both with respect to their level of resolution and the landings and effort values obtained from equivalent aggregations was performed. This was compared to what would be needed in order to undertake bioeconomic modelling for a chosen management plan. 2. The description of how MS are calculating effort variables and a proposal on the way forward to harmonize approaches, 3. Conclusions on how to harmonize levels of resolution, the variable definitions and the codification in use amongst data calls, in order to make them comparable and based on coherent standard codifications.JRC.G.3-Maritime affair

    Gene transfer from genetically modified plants to micro-organisms

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