1,721,234 research outputs found
Soil Microbial and Enzymatic Diversity as Affected by the Presence of Xenobiotics
No full textSoil biodiversity and in particular soil microbial and enzymatic diversity are of paramount importance for assuring and maintaining a healthy soil. Any event that can impair them may alter, even irreversibly, the quality of soil and consequently the safety of environment and human life. Xenobiotic substances, i.e., foreign chemical substances of different chemical and structural complexities, not recognized by existing degradative enzymes, have been released into the environment by several industrial and/or agricultural activities. When reach soil, they may accumulate in it because several of these chemicals are recalcitrant and resist to any kind of degradative transformation. Negative effects on the life and functioning of microbial organisms may derive. Several investigations have been devoted to understanding the effect of xenobiotics on soil microorganisms and enzymes by using traditional and advanced methodologies. This chapter will briefly survey the mutual interactions establishing in soil among xenobiotic substances and microbial and enzymatic soil activities
Natural biomineralization in the contaminated sediment-water system at the Ingurtosu abandoned mine
No full textThe Ingurtosu Pb–Zn mine (S-W Sardinia) was exploited for about a century until 1968. Huge amounts of tailings were abandoned, resulting in long-term heavy metal dispersion processes in both soils and waters. Zn and Pb concentration in tailings and soils attains values up to thousands of mg per kilogram. The maximum Zn concentration in water attains several hundreds of mg per liter, whereas Cd and Pb concentrations are in the order of thousands of μg per liter. Heavy metal concentration in waters of Rio Naracauli, the main stream of the area, is abated by seasonal biomineralization processes. Precipitation of hydrozincite [Zn5(CO3)2(OH)6] and of a Zn-rich amorphous phase results in a decrease of Zn concentration down to a few mg per liter. Other metals such as Pb, Cd, Cu, and Ni are coprecipitated with the Zn phases. This chapter reports the state of our knowledge on the Naracauli biomineralization process
In vitro cultures open new prospects for basic research in arbuscular mycorrhizas
No full textIt is now 20 years since the publication of Bécard and Fortin’s article (1988) in which the modern basis for arbuscular mycorrhizal (AM) monoxenic cultures was established. Since then, many research projects have been carried out using in vitro systems, and new prospects have been opened up by utilizing the amazing research material provided by monoxenic plates. More and more researchers now acknowledge that in vitro AM production is the sole way of getting large amounts of clean, clonal, contamination-free AM fungal material. This has opened the doors for molecular biology and biochemical techniques to be applied to mycorrhizal research, and the direct consequence of this is an exponential increase in our knowledge in the basic biology of this mutualistic symbiosis over the last 10 years. However, monoxenic cultures have far more to offer than just being AM tissue factories; fields of AM research as different (yet interlinked) as colony architecture and dynamics, intra- and extraradical fungal morphology, mycorrhizal physiology, biotic and abiotic stress responses, microbial interactions and even the production of ultrapure, mycorrhiza-based biofertilizers have benefited from this ‘in vitro revolution’. This chapter aims to summarize the opportunities offered by using in vitro culture technology, and to encourage researchers to (1) utilize existing, yet little known monoxenic culture techniques, and (2) improve them and design new in vitro experimental systems. It should not be regarded as a compilation of methods, but rather as a brainstorming exercise designed to create new avenues of mycorrhizal research.Custodia Cano, Sandy Dickson, Manuel González-Guerrero and Alberto Bag
Frankia Nodulation, Mycorrhization and Interactions Between Frankia and Mycorrhizal Fungi in Casuarina Plants
No full textThe genus Casuarina, with approximately 18 species growing naturally in Australia and islands of the Pacific, belongs to the family Casuarinaceae. Casuarina has multi-purpose applications in agroforestry, silviculture, land reclamation and soil fertility improvement in the tropics and subtropics. Great progress in the past century has been made in ecology, physiology, cellular and molecular biology of Casuarina and its control by environmental factors. In Casuarina,N-fixation ranges 15 to 80% with the actinomycete Frankia, and mycorrhizal colonization ranges 10 to 70% with arbuscular mycorrhizal (AM) or 10 to 50% with ectomycorrhizal (EM) fungi for better soil nutrient and water acquisition. Casuarina could thus enhance the performance of other non-N-fixation trees in mixed populations. Plant height and wood production of Casuarina are greatly increased by Frankia inoculation, though nodulation is considerably affected by nutrient availability and other soil properties. Meanwhile, AM or EM could contribute to a successful Frankia symbiosis by enhancing Casuarina N-fixation and soil nutrient and water uptake, particularly in phosphorus-deficient or arid and semiarid environments. However, little is known about the mechanisms of interaction between Frankia and mycorrhizal fungi. In addition, antagonism does occur between AM and EM fungal species in Casuarina. The three organisms, Casuarina plants, mycorrhizal fungi, and actinomycete Frankia may impact each other for an apparent Casuarina performance. More research is warranted on a better understanding of the interaction among the host plants, mycorrhizal fungi and Frankia, and the sustainable application of Casuarina plants in agriculture, forestry and industry around the world
Conferencia: "Piriformospora indica the model symbiotic multifunctional fungus"
No full text"Piriformospora indica the model symbiotic multifunctional fungus". Conferencia a cargo de Ajit Varma, Director del Amity Institute of Microbial Sciences, Vice Chairman de la Amity Science, Technology & Innovation Foundation, Amity University Uttar Pradesh (India). Organiza: Vicerrectorado de Investigación. Sala de Grados de la Facultad de Veterinaria. Campus de Espinard
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
- …
