1,721,025 research outputs found
Erratum to: Candidates of trichocyst matrix proteins of the dinoflagellate Oxyrrhis marina
No full textSolvent stress response of the denitrifying bacterium "Aromatoleum aromaticum" strain EbN1
Get PDFThe denitrifying betaproteobacterium “Aromatoleum aromaticum” strain EbN1 degrades several aromatic compounds, including ethylbenzene, toluene, p-cresol, and phenol, under anoxic conditions. The hydrophobicity of these aromatic solvents determines their toxic properties. Here, we investigated the response of strain EbN1 to aromatic substrates at semi-inhibitory (about 50% growth inhibition) concentrations under two different conditions: first, during anaerobic growth with ethylbenzene (0.32 mM) or toluene (0.74 mM); and second, when anaerobic succinate-utilizing cultures were shocked with ethylbenzene (0.5 mM), toluene (1.2 mM), p-cresol (3.0 mM), and phenol (6.5 mM) as single stressors or as a mixture (total solvent concentration, 2.7 mM). Under all tested conditions impaired growth was paralleled by decelerated nitrate-nitrite consumption. Additionally, alkylbenzene-utilizing cultures accumulated poly(3-hydroxybutyrate) (PHB) up to 10% of the cell dry weight. These physiological responses were also reflected on the proteomic level (as determined by two-dimensional difference gel electrophoresis), e.g., up-regulation of PHB granule-associated phasins, cytochrome cd1 nitrite reductase of denitrification, and several proteins involved in oxidative (e.g., SodB) and general (e.g., ClpB) stress responses
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Regulation of anaerobic alkylbenzene utilization in the denitrifying strain EbN1
No full textThe anaerobic degradation pathways of toluene and ethylbenzene and the adaptation to toxicological effects of these alkylbenzenes are studied with the denitrifying strain EbN1 in a combined physiological and proteomic approach. How specific is the substrate-dependend regulation of the two degradation pathways? Which molecular-physiological effects become apparent at growth with sublethal concentrations? What reaction follows an alkylbenzene-shock in absence of operative degradation pathways
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Advancing shaken bioreactors for the characterization of anaerobic microorganisms
No full textAnaerobic microorganisms possess vast potential for the sustainable production of chemicals. Particular organic acids, such as succinate, can be utilized as basic components in the industry. However, since cultivations of anaerobic bacteria are challenging, there is a knowledge gap in understanding their metabolisms and cultivation performance. Advanced and complex cultivation modes such as fed-batch or continuous cultivation even increase the requirements for anaerobicity. As a result, the potential of anaerobic microorganisms for industrial bioprocesses often remains hidden. This study established shaken bioreactors with batch, fed-batch, and continuous operation modes for anaerobic cultivations. Constructive changes were made to the systems for this purpose, and a new gas sensor system was implemented to measure the CO2 and H2 transfer rates online. In axenic cultures of the gut bacterium Phocaeicola vulgatus in batch shake flask experiments, the minimum buffer concentration and an optimal initial pH were identified to mitigate the pH inhibition of P. vulgatus. The initial addition of different acids revealed an inhibitory effect of lactate on P. vulgatus, starting at a concentration of 1 g L 1. A comparison of a pH-buffered and a pH-controlled batch fermentation demonstrated a switch in acid production from lactate to succinate under pH control. Aerobic, membrane-based fed-batch shake flasks were rebuilt into anaerobic cultivation systems and successfully applied in anaerobic conditions. However, an inhibition of the fed-batch process due to high lactate production was observed, which must be considered in future process development. The aerobic continuous shaken cultivation system COSBIOS was also modified into an anaerobic cultivation system, and anaerobic continuous cultivations were performed. Nevertheless, various technical aspects, such as leakages due to tube abrasion, require additional optimization. For a comprehensive analysis, thermal conductivity sensors were implemented to monitor hydrogen production by anaerobes online in the cultivation systems mentioned. Since thermal conductivity sensors are not hydrogen-specific, their cross-sensitivity to CO2 concentration, temperature, and humidity was evaluated. The sensor measurement range was validated with two anaerobes: the highly H2-producing Clostridium pasteurianum and the low H2-producing P. vulgatus. The online monitoring of H2 production enabled the determination of hydrogen transfer rates. In combination with online CO2 transfer rates, molar gas balances of the cultivations were closed, and an anaerobic respiration quotient was introduced. The presented work paves the way for more efficient bioprocesses utilizing anaerobic microorganisms by addressing cultivation challenges and providing online monitoring solutions for gas transfer rates
Metabolic reconstruction and regulation in Desulfobacterium autotrophicum
No full text:i: Desulfobacterium autotrophicum :/i: is a marine sulfate-reducing bacterium, which is metabolically quite versatile. Here the it was tried to investigate metabolic regulation using a physiological, proteomic and RNA based methods. The investigations were focussed on cold-adaption, alcohol metabolism and the terminal oxidation of substrates
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