1,720,992 research outputs found
Quantitative optical lock-in detection for quantitative imaging of switchable and non-switchable components
No full textReversible photoswitching has been proposed as a way to identify molecules that are present in small numbers over a large, non-switching, background. This approach, called optical-lock-indetection (OLID) requires the deterministic control of the fluorescence of a photochromic emitter through optical modulation between a bright (on) and a dark state (off). OLID yields a high-contrast map where the switching molecules are pinpointed, but the fractional intensities of the emitters are not returned. The present work presents a modified OLID approach (quantitative OLID or qOLID) that yields quantitative information of the switching (f(SW)) and non-switching (f(NS)) components. After the validation of the method with a sample dataset and image sequence, we apply qOLID to measurements in cells that transiently express the photochromic protein EYQ1. We show that qOLID is efficient in separating the modulated from the non-modulated signal, the latter deriving from background/autofluorescence or fluorophores emitting in the same spectral region. Finally, we apply qOLID to Forster (Fluorescence) Resonance Energy Transfer (FRET) imaging. We here demonstrate that qOLID is able to highlight the distribution of FRET intensity in a sample by using a photochromic donor and a non-photochromic acceptor
Correction: Automatic generation of high-fidelity representative volume elements and computational homogenization for the determination of thermal conductivity in foamed concretes (Materials and Structures, (2023), 56, 10, (179), 10.1617/s11527-023-02253-2)
No full textThe article 'Automatic generation of high-fidelity representative volume elements and computational homogenization for the determination of thermal conductivity in foamed concretes', written by Víctor D. Fachinotti, Ignacio Peralta, Sebastián Toro, Bruno A. Storti and Antonio Caggiano, was originally published in volume 56, issue 10, Article 179 without open access. With the society's decision to grant Open Choice the copyright of the article changed in April 2024 to © The Author(s) 2023 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0. Open access funding enabled and organized by RILEM
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
Intact Microtubules Preserve Transient Receptor Potential Vanilloid 1 (TRPV1) Functionality through Receptor Binding
No full textThe transient receptor potential cation channel subfamily V member 1 (TRPV1) is a protein currently under scrutiny as a pharmacological target for pain management therapies. Recently, the role of TRPV1-microtubule interaction in transducing nociception stimuli to cells by cytoskeletal rearrangement was proposed. In this work, we investigate TRPV1-microtubule interaction in living cells under the resting or activated state of TRPV1, as well as in presence of structurally intact or depolymerized cytoskeletal microtubules. We combined a tool-box of high resolution/high sensitivity fluorescence imaging techniques (such as FRET, correlation spectroscopy, and fluorescence anisotropy) to monitor TRPV1 aggregation status, membrane mobility, and interaction with microtubules. We found that TRPV1 is a dimeric membrane protein characterized by two populations with different diffusion properties in basal condition. After stimulation with resiniferatoxin, TRPV1 dimers tetramerize. The tetramers and the slower population of TRPV1 dimers bind dynamically to intact microtubules but not to tubulin dimers. Upon microtubule disassembly, the interaction with TRPV1 is lost thereby inducing receptor self-aggregation with partial loss of functionality. Intact microtubules play an essential role in maintaining TRPV1 functionality toward activation stimuli. This previously undisclosed property mirrors the recently reported role of TRPV1 in modulating microtubule assembly/disassembly and suggests the participation of these two players in a feedback cycle linking nociception and cytoskeletal remodeling. RI Bizzarri, Ranieri/H-1779-201
Main photophysical properties of oxyblepharismin
No full textOxyblepharismin is the photo-oxidized form of blepharismin, the chromophore responsible for the photophobic response of heterotrich ciliate Blepharisma joponicum, and represents a nice model for the study of phototransduction. In this work, we focused on the photophysical characterization of OxyBP, in view of highlighting the main features related to excitation and emission. By a combined experimental and computational approach we identified the main features of absorption and fluorescence emission of the molecule in solvents of different properties, identifying the nature of transitions as well as the possible heterogeneity at ground/excited state. The thorough photophysical characterization of OxyBP is meant to provide the starting point for the elucidation of the photo-transduction pathway in vivo
Polarity-Sensitive Coumarins Tailored to Live Cell Imaging
No full textPolarity-dependent fluorescent probes are recently attracting interest for high-resolution cell imaging. Following a stepwise rational approach, we prepared and tested a toolbox of new coumarin derivatives tailored to in vivo imaging applications. Our compounds are characterized by a donor-(coumarin core)-acceptor molecular structure, where the electron donor is represented by alkylether or naphthyl groups, and the electron acceptor is represented by benzothiazene and cyano groups. Prior to synthesis, the substitution patterns were screened by computational methods to provide functional fluorescent derivatives easy to synthesize, and with excitation in the visible region of spectrum. We set up a robust synthetic procedure tunable on the substitution patterns to achieve. These coumarins possess excellent fluorescence quantum yields (up to 0.95), high molar extinction coefficients (up to 46,000 M(-1) cm(-1)), and large Stokes shifts. Furthermore, they display strong solvatochromism, being almost non-emissive in water and very fluorescent in less polar media (up to 780-fold enhancement in brightness). The solvatochromism of these compounds can be accounted for by a photophysical method encompassing two communicating excited states. When tested on cultured cells, the results showed that the developed coumarins were not harmful and their photophysical properties were unchanged compared to free solution. According to the determined solvatochromic properties, the coumarin fluorescence was detected only in the most lipophilic environments of the cell. The prepared compounds represent remarkable tools to investigate subtle biochemical processes in the cell environment after appropriate conjugation to biomolecules, and at the same time constitute the basis for further engineering of a new generation of biosensors
Fluorescence lifetime microscopy reveals the biologically-related photophysical heterogeneity of oxyblepharismin in light-adapted (blue) Blepharisma japonicum cells
No full textThe step-up photophobic response of the heterotrich ciliate Blepharisma japonicum is mediated by a hypericinic pigment, blepharismin, which is not present in any of the known six families of photoreceptors, namely rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins, and BLUF proteins. Upon irradiation, native cells become light-adapted (blue) by converting blepharismin into the photochemically stable oxyblepharismin (OxyBP). So far, OxyBP has been investigated mainly from a photophysical point of view in vitro, either alone or complexed with proteins. In this work, we exploit the vivid fluorescence of OxyBP to characterize its lifetime emission in blue B. Japonicum cells, on account of the recognized role of the fluorescence lifetime to provide physicochemical insights into the fluorophore environment at the nanoscale. In a biological context, OxyBP modifies its emission lifetime as compared to isotropic media. The phasor approach to fluorescence lifetime microscopy in confocal mode highlights that fluorescence originates from two excited states, whose relative balance changes throughout the cell body. Additionally, Cilia and kinetids, i.e., the organelles involved in photomovement, display lifetime asymmetry between the anterior and posterior part of the cell. From these data, some hypotheses on the phototransduction mechanism are proposed
Development and In Vivo Application of a Novel Family of Dendrimer-Based Fluorescent Biosensors
No full textVariations 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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