1,720,976 research outputs found
Investigations of immunogenic, allergenic and adjuvant properties of Cry1Ab protein after intragastric exposure in a food allergy model in mice
Full text linkBackground
In genetically modified (GM) crops there is a risk that the inserted genes may introduce new allergens and/or adjuvants into the food and feed chain. The MON810 maize, expressing the insecticidal Cry1Ab toxin, is grown in many countries worldwide. In animal models, intranasal and intraperitoneal immunisations with the purified Cry1Ab proteins have induced immune responses, and feeding trials with Cry1Ab-containing feed have revealed some altered immune responses. Previous investigations have primarily measured antibody responses to the protein, while investigations of clinical food allergy symptoms, or allergy promotion (adjuvant effect) associated with the Cry1Ab protein are largely missing. We aimed to investigate immunogenic, allergenic and adjuvant properties of purified Cry1Ab toxin (trypCry1Ab, i.e., trypsin activated Cry1Ab) in a mouse model of food allergy.
Method
Female C3H/HeJ mice were immunized by intragastric gavage of 10 μg purified, trypsin activated Cry1Ab toxin (trypCry1Ab) alone or together with the food allergen lupin. Cholera toxin was added as a positive control for adjuvant effect to break oral tolerance. Clinical symptoms (anaphylaxis) as well as humoral and cellular responses were assessed.
Results
In contrast to results from previous airway investigations, we observed no indication of immunogenic properties of trypCry1Ab protein after repeated intragastric exposures to one dose, with or without CT as adjuvant. Moreover, the results indicated that trypCry1Ab given by the intragastric route was not able to promote allergic responses or anaphylactic reactions against the co-administered allergen lupin at the given dose.
Conclusion
The study suggests no immunogenic, allergenic or adjuvant capacity of the given dose of trypCry1Ab protein after intragastric exposure of prime aged mic
Levels of DNA methylation and transcript accumulation in leaves of transgenic maize varieties
Full text linkAdditional file 4. Position and distribution of methylated and unmethylated cytosines for the cry1A.105 gene sequence in all analysed hybrids. Each line corresponds to one sequenced bacteria colony (clone). Clones from the same hybrid contain the same nomenclature, ranging from 1â24. Class I: CG residue; Class II: CHG residue; Class III: CHH residue. Filled icons: methylated cytosine; Empty icons: non-methylated cytosines
Revisiting Risk Governance of GM Plants: The Need to Consider New and Emerging Gene-Editing Techniques
Full text linkNew and emerging gene-editing techniques make it possible to target specific genes in species with greater speed and specificity than previously possible. Of major relevance for plant breeding, regulators and scientists are discussing how to regulate products developed using these gene-editing techniques. Such discussions include whether to adopt or adapt the current framework for GMO risk governance in evaluating the impacts of gene-edited plants, and derived products, on the environment, human and animal health and society. Product classification or definition is one of several aspects of the current framework being criticized. Further, knowledge gaps related to risk assessments of gene-edited organisms—for example of target and off-target effects of intervention in plant genomes—are also of concern. Resolving these and related aspects of the current framework will involve addressing many subjective, value-laden positions, for example how to specify protection goals through ecosystem service approaches. A process informed by responsible research and innovation practices, involving a broader community of people, organizations, experts, and interest groups, could help scientists, regulators, and other stakeholders address these complex, value-laden concerns related to gene-editing of plants with and for society
Molecular responses of genetically modified maize to abiotic stresses as determined through proteomic and metabolomic analyses.
Full text linkSome genetically modified (GM) plants have transgenes that confer tolerance to abiotic stressors. Meanwhile, other transgenes may interact with abiotic stressors, causing pleiotropic effects that will affect the plant physiology. Thus, physiological alteration might have an impact on the product safety. However, routine risk assessment (RA) analyses do not evaluate the response of GM plants exposed to different environmental conditions. Therefore, we here present a proteome profile of herbicide-tolerant maize, including the levels of phytohormones and related compounds, compared to its near-isogenic non-GM variety under drought and herbicide stresses. Twenty differentially abundant proteins were detected between GM and non-GM hybrids under different water deficiency conditions and herbicide sprays. Pathway enrichment analysis showed that most of these proteins are assigned to energetic/carbohydrate metabolic processes. Among phytohormones and related compounds, different levels of ABA, CA, JA, MeJA and SA were detected in the maize varieties and stress conditions analysed. In pathway and proteome analyses, environment was found to be the major source of variation followed by the genetic transformation factor. Nonetheless, differences were detected in the levels of JA, MeJA and CA and in the abundance of 11 proteins when comparing the GM plant and its non-GM near-isogenic variety under the same environmental conditions. Thus, these findings do support molecular studies in GM plants Risk Assessment analyses
Acquisition of foreign DNA by natural transformation in Acinetobacter baylyi: quantitative estimates and molecular characterization of the introgression process
Full text linkVery little is known about introgression in bacteria. Introgression is the process where the genes of one species infiltrate the gene pool of another organism by subsequent backcross transformations of a hybrid with one of its parents. After the initial acquisition of foreign DNA, DNA from the newly made transformants is used as donor DNA in backcross transformations with the recipient. DNA is released to the environment after decomposing of dead cells, disrupting of cells or through excretion from living organisms. The extracellular DNA can be degraded after release, thus fragmented DNA can be taken up by bacteria.
One previous unpublished study investigated the effect of introgression of foreign unselected DNA. The donor DNA in this study was of high molecular weight (20 to 30 kilo bases (Kb)) and it was suggested that introgression in backcross transformation could be a mechanism by which unselected DNA was eliminated from the genome.
I wanted to study the effect of introgression when the foreign donor DNA was of low molecular weight (1000 to 4000 base pairs (bp)). We wanted to determine how fragmentation affects the speed at which unselected DNA from Acinetobacter sp. strain 16.4 was eliminated from the genome of Acinetobacter baylyi strain BD413 during the introgression process.
I have developed a method for optimal fragmentation of DNA to the desired size for this study. The DNA was fragmented by sonication, which gave an effective, gradual reduction in the fragment size of DNA. The size of the sonicated DNA was checked on an agarose gel and I found out that a gel fraction between 1000 to 4000 bp was the desired size for fragmented DNA. The DNA was extracted from the gel piece and used as low molecular weight donor DNA.
This method can be used to determine the effect of introgression when the foreign donor DNA is of low molecular weight (1000 to 4000 base pairs bp) and to get a better understanding for natural fragmentation of extracellular DNA in the environment
Antibiotic resistance profiles and polystyrene biofilm formation capabilities of bacteria isolated from wastewater in Tromsø
Full text linkPollution of plastic in itself has become a growing focus in the last 15 years. In addition, the impact of plastic as a reservoir for pathogenic bacteria and transfer of antibiotic resistance genes has become a global concern, for individuals, organizations, policymakers and health organizations. It is important to document the relationship of microbiota associated to different types of plastic material. This project is part of a larger project (MICROPLASTRESIST) and aims to document the connection between antibiotic resistance patterns in bacteria, identify potential pathogens in wastewater, and further document biofilm formation capabilities on polystyrene (PS) plastic.
Antibiotic resistant bacteria were isolated from two wastewater treatment plants in Tromsø, Norway, using ampicillin agar. The identities of the pure isolated strains of bacteria were confirmed using mass spectrometric analysis (MALDI-TOF) that is mainly based on species specific ribosomal proteins. The result showed an abundance of bacteria from genus Pseudomonas, followed
by Aeromonas, Klebsiella, Raoultella and Acinetobacter, which are all Gram-negative bacteria. Some of the species were closely related to known pathogens like A. salmonicida. Others were characterized within the same genus, but being non-pathogens, like A. media. This implies that the bacteria are able to exchange genetic material, both resistance and pathogenicity from pathogens to non-pathogenic bacteria. Biofilms in particular are believed to create opportunities for this exchange of genetic material and thus form resistance reservoirs.
Antibiotic resistance patterns were mapped out using 8 of the most prescribed antibiotics used at the University Hospital of North Norway (UNN). In total, 13/55 of the identified bacterial species contained antibiotic resistant genes to ≥ 5 of these 8 antibiotics. Most of the identified strains were able to form biofilm on polystyrene microtiter plates at 30°C and 35°C. Most biofilm mass was formed using TSB and BHI broth for the raw wastewater, whereas bacteria in wastewater without any added nutrients form biofilm after 24 h at 30°C.
This pilot study confirms existence of multi-resistant bacteria, both human and fish pathogens, at both wastewater stations in Tromsø. Most of them are also biofilm forming on polystyrene at 30°C and 35°C
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
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