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Effect of environmental stresses on plant grow promoting characteristics of the arsenite oxidizer Pseudomonas sp. strain N2
No full textHeavy metals resistant bacteria with plant growth-promoting (PGP) characteristics can be used to facilitate the proliferation of plants under environmentally stressful conditions, such as drought, salinity and heavy metals contamination. Moreover, arsenic-transforming PGP bacteria, influencing arsenic mobilization in soil, can enhance arsenic uptake by plant.
The aims of this study were: (i) to characterize an arsenic-resistant Pseudomonas sp. strain N2 for resistance to osmotic stresses, production of stress-related phytohormones, PGP traits and arsenic transformation, and (ii) to evaluate the effect of arsenic on these characteristics.The capability to respond to osmotic stresses (-1.5 MPa) was evaluated by measuring the bacterial growth in LB medium separately added of: 175 mmol/L of Na3AsO4, 400 mmol/L of NaCl, or 26% (w/v) PEG6000 (Sosa et al., 2005). Production of stress-related phytohormones (indole acetic acid IAA, and jasmonic acid, JA) was determined in yeast mannitol medium (YEM) in the absence and in the presence of arsenate (50 mmol/L), arsenite (3 mmol/L), and PEG6000 (13.7% w/v), as stress agents. Tested PGP characteristics were: the ability to grow on 1-aminocyclopropane-1-carboxylic acid (ACC) as sole nitrogen source, the production of siderophores and proteolitic, chitinase and phosphate solubilising activities. Phosphate solubilisation activity was evaluated in YEM with Ca3(PO4)2 (5 g/L) in the absence or in the presence of arsenite or arsenate. Arsenic transforming capabilities were evaluated during 72 h growth in Tris Mineral Medium (Mergey et al., 1985) supplemented with 0.6% (w/v) gluconate (TMMG) spiked with 3 mmol/L of arsenite or arsenate.
Strain N2 was able to tolerate -1.5 MPa: osmotic stress generated by the presence of arsenic was tolerated better than those generated by NaCl and PEG6000. The strain was able to produce 68 pmol/ml of IAA and 0.18 pmol/ml of JA and to solubilise 100 mg/L phosphate. While the production of IAA was enhanced by the presence of arsenic forms it was not affected by osmotic stress. On the contrary, phosphate solubilization was impaired by arsenic. Strain N2 possessed all the tested PGP characteristics and it completely oxidized arsenite to arsenate, while it did not reduce arsenate.
Our results suggest that strain N2 possesses PGP characteristics not affected by the presence of arsenic and of osmotic stresses. Moreover, the ability to solubilize phosphate may contribute to improve plants’ phosphorous nutrition. Pseudomonas sp. strain N2 might be a candidate inoculum useful to amplify plant resistance in stress conditions.
Acknowledgments
Funding for this work was provided by: Fondazione CARIPLO (project 2010-2221) and PRIN (project 2010JBNLJ7_004)
Functional biomarkers for monitoring propylene glycol degrading bacteria in contaminated sites
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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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Caratterizzazione della comunità microbica di un suolo contaminato da scarti di lavorazione della pirite
No full textkoamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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