1,720,967 research outputs found
The maize microbiome warns for unintended effects of nanosilver application in agriculture
No full textAgriculture is constantly in development, driven by the ever increasing world
population and the need for green energy. This stimulates the development of
new techniques and substances which could be of use for agricultural growth. One
such substance is nanosilver, an offspring of the marriage between silver’s welldocumented antimicrobial properties and nanotechnology which increases the
applicability and efficiency of these properties. Nanosilver is applied purposely on
agricultural fields to prevent and counteract phytopathogen infections. It is
sprayed on plant shoots, leading to voluntary aboveground exposure of the plants
but also unavoidable unvoluntary build up in soil and therefore belowground
exposure. Accumulation in soil is increased by urban run-off and biosolid
application due to the myriad of urban nanosilver applications. Next to the desired
effect of counteracting phytopathogens, this exposure of crops to nanosilver is
likely to also produce side effects. The toxicity toolkit of nanosilver is strong
because of its variety: nanosilver binds to nucleophilic amino acids, and therefore
interferes with various proteins and compounds, leading to ROS production, DNA
damage and other harmful processes. Hydroponics studies showed that nanosilver
can be toxic to plants, as well as to beneficial and maleficent (phytopathogenic)
microorganisms which are naturally associated with plants. Predicting nanosilver’s
impact in the field from these in vitro studies is impossible, because of the highly
complex and interactive nature of the biological system. Nanosilver interacts with
soil particles, leading to an unknown concentration of mobile and active
nanosilver. Additionally, all effects aboveground and belowground on the plant
and its microbiome take place simultaneously. The interaction between these
organisms and the individual effect of nanosilver on each of them decide how
crops react. Hence, in order to understand the full impact of nanosilver in
agricultural fields, these processes should be individually dissected and the
gathered information consequently assembled into a complete image. Therefore,
in this PhD study we investigate the impact of nanosilver exposure on maize, the
third leading crop worldwide, and its associated microbiome in soil-based studies.
By focusing in detail on the multiple processes taking place, we aim to develop a
multi-level understanding of nanosilver’s agriculture as well as to gather more
information on the complex interactions between plants and their microbiome
The maize microbiome warns for unintended effects of nanosilver application in agriculture
No full textAgriculture is constantly in development, driven by the ever increasing world
population and the need for green energy. This stimulates the development of
new techniques and substances which could be of use for agricultural growth. One
such substance is nanosilver, an offspring of the marriage between silver’s welldocumented antimicrobial properties and nanotechnology which increases the
applicability and efficiency of these properties. Nanosilver is applied purposely on
agricultural fields to prevent and counteract phytopathogen infections. It is
sprayed on plant shoots, leading to voluntary aboveground exposure of the plants
but also unavoidable unvoluntary build up in soil and therefore belowground
exposure. Accumulation in soil is increased by urban run-off and biosolid
application due to the myriad of urban nanosilver applications. Next to the desired
effect of counteracting phytopathogens, this exposure of crops to nanosilver is
likely to also produce side effects. The toxicity toolkit of nanosilver is strong
because of its variety: nanosilver binds to nucleophilic amino acids, and therefore
interferes with various proteins and compounds, leading to ROS production, DNA
damage and other harmful processes. Hydroponics studies showed that nanosilver
can be toxic to plants, as well as to beneficial and maleficent (phytopathogenic)
microorganisms which are naturally associated with plants. Predicting nanosilver’s
impact in the field from these in vitro studies is impossible, because of the highly
complex and interactive nature of the biological system. Nanosilver interacts with
soil particles, leading to an unknown concentration of mobile and active
nanosilver. Additionally, all effects aboveground and belowground on the plant
and its microbiome take place simultaneously. The interaction between these
organisms and the individual effect of nanosilver on each of them decide how
crops react. Hence, in order to understand the full impact of nanosilver in
agricultural fields, these processes should be individually dissected and the
gathered information consequently assembled into a complete image. Therefore,
in this PhD study we investigate the impact of nanosilver exposure on maize, the
third leading crop worldwide, and its associated microbiome in soil-based studies.
By focusing in detail on the multiple processes taking place, we aim to develop a
multi-level understanding of nanosilver’s agriculture as well as to gather more
information on the complex interactions between plants and their microbiome
Nanoparticle treatment of maize analyzed through the metatranscriptome: compromised nitrogen cycling, possible phytopathogen selection, and plant hormesis
No full textBackground The beneficial use of nanoparticle silver or nanosilver may be confounded when its potent antimicrobial properties impact non-target members of natural microbiomes such as those present in soil or the plant rhizosphere. Agricultural soils are a likely sink for nanosilver due to its presence in agrochemicals and land-applied biosolids, but a complete assessment of nanosilver's effects on this environment is lacking because the impact on the natural soil microbiome is not known. In a study assessing the use of nanosilver for phytopathogen control with maize, we analyzed the metatranscriptome of the maize rhizosphere and observed multiple unintended effects of exposure to 100 mg kg(-1)nanosilver in soil during a growth period of 117 days. Results We found several unintended effects of nanosilver which could interfere with agricultural systems in the long term. Firstly, the archaea community was negatively impacted with a more than 30% decrease in relative abundance, and as such, their involvement in nitrogen cycling and specifically, nitrification, was compromised. Secondly, certain potentially phytopathogenic fungal groups showed significantly increased abundances, possibly due to the negative effects of nanosilver on bacteria exerting natural biocontrol against these fungi as indicated by negative interactions in a network analysis. Up to 5-fold increases in relative abundance have been observed for certain possibly phytopathogenic fungal genera. Lastly, nanosilver exposure also caused a direct physiological impact on maize as illustrated by increased transcript abundance of aquaporin and phytohormone genes, overall resulting in a stress level with the potential to yield hormetically stimulated plant root growth. Conclusions This study indicates the occurrence of significant unintended effects of nanosilver use on corn, which could turn out to be negative to crop productivity and ecosystem health in the long term. We therefore highlight the need to include the microbiome when assessing the risk associated with nano-enabled agriculture.This work was supported by Hasselt University Bijzonder Onderzoeksfonds Methusalem Project 08M03VGRJ. JCW acknowledges USDA AFRI 2016-6702124985 and USDA Hatch CONH00147. W.S., S.T. and N.W. were research fellows and a postdoctoral fellow, respectively, of the Research Foundation-Flanders (FWO).Sillen, WMA (corresponding author), Hasselt Univ, Ctr Environm Sci, Agoralaan,Bldg D, B-3590 Diepenbeek, Belgium.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Bacteria associated with Zn‑hyperaccumulators Arabidopsis halleri and Arabidopsis arenosa from Zn–Pb–Cd waste heaps in Poland as promising tools for bioremediation
No full textTo identify metal adapted bacteria equipped with traits positively influencing the growth of two hyperaccumulator plant species Arabidopsis arenosa and Arabidopsis halleri, we isolated bacteria inhabiting rhizosphere and vegetative tissues (roots, basal and stem leaves) of plants growing on two old Zn-Pb-Cd waste heaps in Bolesław and Bukowno (S. Poland), and characterized their potential plant growth promoting (PGP) traits as well as determined metal concentrations in rhizosphere and plant tissues. To determine taxonomic position of 144 bacterial isolates, 16S rDNA Sanger sequencing was used. A metabolic characterization of isolated strains was performed in vitro using PGP tests. A. arenosa and A. halleri accumulate high amounts of Zn in their tissues, especially in stem leaves. Among in total 22 identified bacterial taxa, the highest level of the taxonomical diversity (H' = 2.01) was revealed in A. halleri basal leaf endophytes originating from Bukowno waste heap area. The 96, 98, 99, and 98% of investigated strains showed tolerant to Cd, Zn, Pb and Cu, respectively. Generally, higher percentages of bacteria could synthesize auxins, siderophores, and acetoin as well as could solubilize phosphate. Nine of waste heap origin bacterial strains were tolerant to toxic metals, showed in vitro PGP traits and are potential candidates for bioremediation.Authors would like to express the gratitude to Carine Put, Ann Wijgaerts, Edyta Żuk-Kempa for laboratory assistance, and to Krzysztof Oleński for support in collecting the material used in present study. Te research was funded by a BOF Special Research Fund grant from Hasselt University to E.O. and the UHasselt Methusalem project 08M03VGRJ to J.V. Support was also provided by the Ministry of Education and Science Republic of Poland bailout for University of Bialystok (E.O.). Te Article Processing Charge was funded by Hasselt University
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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