1,720,986 research outputs found
VvPMEI1 GENE ENCODES A NOVEL FUNCTIONAL CELL WALL PECTIN METHYL ESTERASE INHIBITOR INVOLVED IN GRAPE BERRY DEVELOPMENT
No full textPectin is secreted in a highly methyl esterified form and partially de-methyl esterified in cell wall by pectin methyl esterases (PMEs). PME activity is expressed during plant growth, development and biotic stresses. At post-transcriptional level, PME activity is controlled by proteins named PME inhibitors (PMEIs). We have identified, expressed and characterized VvPMEI1, a new functional PME inhibitor of Vitis vinifera. VvPMEI1 typically affects the activity of plant PMEs and is inactive against microbial PMEs. The kinetics of PMEI-PME interaction, studied by surface plasmon resonance, indicate that the inhibitor strongly interacts with immobilized PME at apoplastic pH while the stability of the complex is reduced by increasing the pH. The analysis of VvPMEI1 expression in different grapevine tissues and during grape fruit development suggests that this inhibitor controls PME activity manly during the earlier phase of berry development. A proteomic analysis performed at this stage identifies a PME isoform as possible target of VvPMEI1
Radical cation scavenging activity of berberine bridge enzyme-like oligosaccharide oxidases acting on short cell wall fragments
No full text: Oligogalacturonide-oxidases (OGOXs) and cellodextrin-oxidase (CELLOX) are plant berberine bridge enzyme-like oligosaccharide-oxidases (OSOXs) that oxidize, respectively, oligogalacturonides (OGs) and cellodextrins (CDs), thereby inactivating their elicitor nature and concomitantly releasing H2O2. Little is known about the physiological role of OSOX activity. By using an ABTS·+-reduction assay, we identified a novel reaction mechanism through which the activity of OSOXs on cell wall oligosaccharides scavenged the radical cation ABTS·+ with an efficiency dependent on the type and length of the oxidized oligosaccharide. In contrast to the oxidation of longer oligomers such as OGs (degree of polymerization from 10 to 15), the activity of OSOXs on short galacturonan- and cellulose-oligomers (degree of polymerization ≤ 4) successfully counteracted the radical cation-generating activity of a fungal laccase, suggesting that OSOXs can generate radical cation scavenging activity in the apoplast with a power proportional to the extent of degradation of the plant cell wall, with possible implications for redox homeostasis and defense against oxidative stress
Berberine Bridge Enzyme-like Oligosaccharide Oxidases Act as Enzymatic Transducers Between Microbial Glycoside Hydrolases and Plant Peroxidases
Full text linkOligogalacturonide (OG)-oxidase 1 (OGOX1) and cellodextrin (CD)-oxidase (CELLOX) are plant berberine bridge enzyme-like oligosaccharide oxidases that oxidize OGs and CDs, cell-wall fragments with the nature of damage-associated molecular patterns. The oxidation of OGs and CDs attenuates their elicitor activity and concomitantly releases H2O2. By using a multiple enzyme-based assay, we demonstrate that the H2O2 generated downstream of the combined action between a fungal polygalacturonase and OGOX1 or an endoglucanase and CELLOX can be directed by plant peroxidases (PODs) either towards a reaction possibly involved in plant defense, such as the oxidation of monolignol or a reaction possibly involved in a developmental event, such as the oxidation of auxin (indole-3-acetic acid), pointing to OGOX1 and CELLOX as enzymatic transducers between microbial glycoside hydrolases and plant PODs. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license
Analysis of the interaction of trichodiene synthase 5 (TRI5) with natural and natural-like inhibitors of trichothecene biosynthesis
No full textThe fungal pathogen Fusarium culmorum causes Fusarium head blight (FHB) on cereals, resulting in yield loss and contamination of grain with type B trichothecene mycotoxins. A key step in the synthesis of trichothecenes is catalyzed by the trichodiene synthase 5 (TRI5) that converts farnesyl pyrophosphate to trichodiene. Ferulic acid proved an efficient inhibitor of type B trichothecene biosynthesis and TRI5 gene expression in Fusarium liquid cultures. In this work several natural and natural-like compounds belonging to phenol and hydroxylated biphenyl structural classes were tested in vitro to determine their inhibitory activity towards TRI5. The recombinant TRI5 was expressed in E. coli, and the interaction with different inhibitors was analyzed by Surface Plasmon Resonance (SPR). The screening of inhibitors was performed in both direct and competitive binding format to determine which inhibitors could compete with the binding of farnesyl pyrophosphate to the enzyme active site. A combination of inhibition kinetics and computational modeling of interacting-structures may facilitate the testing of novel potential TRI5 inhibitors and the prediction of their inhibitory mechanism
Cell wall traits that influence plant development, immunity, and bioconversion
No full textThe architecture of the plant cell wall is highly dynamic, being substantially re-modeled during growth and development. Cell walls determine the size and shape of cells and contribute to the functional specialization of tissues and organs. Beyond the physiological dynamics, the wall structure undergoes changes upon biotic or abiotic stresses. In this review several cell wall traits, mainly related to pectin, one of the major matrix components, will be discussed in relation to plant development, immunity and industrial bioconversion of biomass, especially for energy production. Plant cell walls are a source of oligosaccharide fragments with a signaling function for both development and immunity. Sensing cell wall damage, sometimes through the perception of released damage-associated molecular patterns (DAMPs), is crucial for some developmental and immunity responses. Methodological advances that are expected to deepen our knowledge of cell wall (CW) biology will also be presented
The reducing end of cell wall oligosaccharides is critical for DAMP activity in Arabidopsis thaliana and can be exploited by oligosaccharide oxidases in the reduction of oxidized phenolics
Full text linkThe enzymatic hydrolysis of cell wall polysaccharides results in the production of oligosaccharides with nature of damage-associated molecular patterns (DAMPs) that are perceived by plants as danger signals. The in vitro oxidation of oligogalacturonides and cellodextrins by plant FAD-dependent oligosaccharide-oxidases (OSOXs) suppresses their elicitor activity in vivo, suggesting a protective role of OSOXs against a prolonged activation of defense responses potentially deleterious for plant health. However, OSOXs are also produced by phytopathogens and saprotrophs, complicating the understanding of their role in plant-microbe interactions. Here, we demonstrate the oxidation catalyzed by specific fungal OSOXs also converts the elicitor-active cello-tetraose and xylo-tetraose into elicitor-inactive forms, indicating that the oxidation state of cell wall oligosaccharides is crucial for their DAMP function, irrespective of whether the OSOX originates from fungi or plants. In addition, we also found that certain OSOXs can transfer the electrons from the reducing end of these oligosaccharides to oxidized phenolics (bi-phenoquinones) instead of molecular O2, highlighting an unexpected sub-functionalization of these enzymes. The activity of OSOXs may be crucial for a thorough understanding of cell wall metabolism since these enzymes can redirect the reducing power from sugars to phenolic components of the plant cell wall, an insight with relevant implications for plant physiology and biotechnology
Treating head and neck venous malformations with cold helium plasma electrosurgical device: A 17 patients case series
Full text linkVenous malformations (VMs) are some of the most common vascular malformations. Their treatment varies from laser to sclerotherapy and surgery. For many years, radiofrequency and argon plasma devices have been used on soft tissues VMs. However, their use has been limited because of high thermal impact of nearby structures. The here described cold-helium plasma electrosurgical device carries intrinsic bio-technical advantages, as the helium plasma beam manages to move towards tissues with less impedance, such as VM vessels. The primary objective of this study was to assess if J-Plasma® could be effective on treating the superficial portion of VMs, in a single or multimodal approach. From January 2022 to January 2024, 17 patients affected by head and neck VM involving mucosa or skin were treated using J-Plasma®, in addition to sclerotherapy. More than 1 session was needed in all but 1 patient. All patients showed a progressive shrinkage of the venous chambers and thickening of the surface, while no major intraoperative and perioperative complications, such as necrosis or severe bleeding were observed. Minor complications like oedema or exfoliation were mild. All 17 patients had a complete healing of the mucosal surface one week after treatment. The grade of effectiveness and the stability of the results correlated with the complexity of the VMs. This research may serve as groundwork for future studies that may aim to explore the use of this device on other vascular malformations. Level of evidence: Case series: level 4
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
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