1,721,121 research outputs found
Some new grand questions in soil biology and biochemistry
No full texthttp://dx.doi.org/10.13039/501100004434 Università degli Studi di Firenzehttp://dx.doi.org/10.13039/501100018647 RUDN Universit
Nannipieri, P., Ascher, J., Ceccherini, M.T., Landi, L., Pietramellara, G. & Renella, G. 2003. Microbial diversity and soil functions. European Journal of Soil Science, 54, 655-670.: Reflections by P. Nannipieri, J. Ascher-Jenull, M. T. Ceccherini, L. Giagnoni, G. Pietramellara & G. Renella
No full textLandmark papers. Our review discussed the meaning of both microbial diversity and microbial activity at the dawn of the ‘soil omics’ era. It focused on problems with the methods to determine them and on the main ways that soil functions depend on microbial processes. Between 2003 and 2016, the molecular techniques applied in the study of soil microbial diversity have improved markedly. Sequencing techniques today provide accurate estimates of microbial diversity in soil, whereas determining the expression of microbial genes as synthesized proteins is still problematic (Renella et al., 2014a). The assumption was and still is that with a fuller understanding of microbial diversity we might be able to control some soil function
Enzyme activity and microbial community structure in the rhizosphere of two maize lines differing in N use efficiency
No full textAims: Study of the changes in soil microbial biomass, enzyme activity and the microbial community structure in the rhizosphere of two contrasting maize lines differing in the nitrogen use efficiency (NUE).
Methods: The Lo5 and T250 inbred maize characterized by high and low NUE, respectively, were grown in rhizoboxes allowing precise sampling of rhizosphere and bulk soil and solution. We also determined microbial biomass, enzyme activities involved in the C, N, P and S cycles, and the microbial community structure using a phylogenetic group specific PCR-DGGE approach in the rhizosphere and bulk soil of both Lo5 and T250 maize lines.
Results: High NUE Lo5 maize induced faster inorganic N depletion in the rhizosphere and larger changes in microbial biomass and enzyme activities than the low NUE T250 maize line. The two maize lines induced differences in the studied microbial groups in the rhizosphere, with the larger modifications induced by the high NUE Lo5 maize line.
Conclusions: The Lo5 maize line with higher NUE induced larger changes in soil chemical properties and in the enzyme activity, soil microbial biomass and community structure than the low NUE T250 maize line, probably due to differences in the root exudates of the two maize lines
GENES CODIFYING ENZYMES AND ENZYME ACTIVITIES IN SOIL
No full textThe discussion of links between genes codifying enzymes and enzyme activities of soil involves two
different philosophical approaches since the classical soil enzymology is based on the holistic approach
whereas the molecular approach is based on a detailed knowledge of enzymes involved in the measured
enzyme activity. The latter approach requires the classification of the target enzyme. Soil enzymologists
are dealing with enzyme activities which are the result of different enzymes catalyzing the same reaction
and this is not always taken into consideration. Another drawback about the present soil enzymology is the
fact that the extensive bibliography before the arrival of electronic searches is frequently ignored with the
risk “to reinvent the wheel”.
Increases in chitinase activity of soil by sludge or sludge and lime treatment were associated with a lower
diversity in chitinase enzymes whereas casein-hydrolysing activity was mainly associated with sub genes
encoding subtilisin, mainly present in soil bacteria. Laccase-encoding genes of basidiomycetes paralleled
laccase activity of the soil extract, are assumed to represent the respective soil enzyme activity.
Future research should involve to set up reliable soil assays for determining the activity of important
enzymes such as nuclease, phytase, laccase, lignin peroxidase, etc. Since most of the microbial species
inhabiting soil are unknown also some of the enzymes contributing to the measured enzyme activities are
unknown. The degenerated primers may help if they cover a sufficiently long target region without
loosing their specificity as it has been recently shown in the amplification of dioxygenase encoding genes
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
Desorbimento di ferro da chelati con sostanze umiche da parte di acidi organici e un acido idrossiamminico
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