搜索结果：Journal of visualized experiments : JoVE

ARTICLES DISCUSSED: Ahmad, M. U. D. et al. Nano-differential scanning fluorimetry for screening in fragment-based lead discovery. Journal of Visualized Experiments: JoVE. (171), e62469 (2021). Barbieri, L., Luchinat, E. Monitoring protein-ligand interactions in human cells by real-time quantitative in-cell NMR using a high cell density bioreactor. Journal of Visualized Experiments: JoVE. (169), e62323 (2021). Berg, H. et al. NMR-based fragment screening in a minimum sample but maximum automation mode. Journal of Visualized Experiments: JoVE. (172), e62262 (2021). Beriashvili, D., Schellevis, R. D., Napoli, F., Weingarth, M., Baldus, M. High-resolution studies of proteins in natural membranes by solid-state NMR. Journal of Visualized Experiments: JoVE. (169), e62197 (2021). Cornaciu, I. et al. The automated crystallography pipelines at the EMBL HTX facility in grenoble. Journal of Visualized Experiments: JoVE. (172), e62200 (2021). Crawshaw, A. et al. A sample preparation pipeline for microcrystals at the VMXm beamline. Journal of Visualized Experiments: JoVE. (172), e62306 (2021). Douangamath, A. et al. Achieving efficient fragment screening at XChem facility at diamond light source. Journal of Visualized Experiments: JoVE. (171), e62414 (2021). Groen, J. et al. A 3D cartographic description of the cell by Cryo Soft X-ray tomography. Journal of Visualized Experiments: JoVE. (169), e62190 (2021). Horrell, S. et al. Fixed target serial data collection at diamond light source. Journal of Visualized Experiments: JoVE. (168), e62491 (2021). Jiménez-Moreno, A. et al. Cryo-EM and single-particle analysis with scipion. Journal of Visualized Experiments: JoVE. (171), e62261 (2021). Moravcová, J., Pinkas, M., Holbová, R., Nováček, J. Preparation and CryoFIB micromachining of Saccharomyces cerevisiae for CryoElectron tomography. Journal of Visualized Experiments: JoVE. e62351 (2021). Vyas, N. et al. Cryo-structured illumination microscopic data collection from cryogenically preserved cells. Journal of Visualized Experiments: JoVE. (171), e62274 (2021). Weis, F., Hagen, W. J. H., Schorb, M., Mattei, S. Strategies for optimization of cryogenic electron tomography data acquisition. Journal of Visualized Experiments: JoVE. (169), e62383 (2021). White, J. B. R. et al. Single particle cryo-electron microscopy: From sample to structure. Journal of Visualized Experiments: JoVE. (171), e62415 (2021). Wollenhaupt, J. et al. Workflow and tools for crystallographic fragment screening at the helmholtz-zentrum Berlin. Journal of Visualized Experiments: JoVE. (169), e62208 (2021).

Traditional microscopy requires lens objectives to magnify specimens, and can involve numerous optical components like additional objectives, filters, and mirrors to refract and direct light to optical sensors. The August 2012 issue of JoVE (Journal of Visualized Experiments) is marked by the third publication from the Ozcan Lab (University of California, Los Angeles) on their lens free lens-free "on-chip" microscopy platform, which they have pioneered. Back in 2009, the Ozcan lab published their first article, which demonstrated the use of a lens-free imaging platform that could image cells within whole blood. This imaging technique involves placing a sample directly on an optoelectric sensor array, like the CCD or CMOS chips found in the standard camcorder. Then, LED illumination from above the sample casts shadows on the chip, which are recorded as digital holograms that can be subjected to image processing. Not only does this lensless imaging system allow for an extremely large field of view (FOV of 0.6-8 cm2), the lack of bulky optical components makes it excellent for microfluidic applications. The Ozcan group demonstrates this in their follow-up 2011 JoVE article, in which fluorescently labeled white blood cells are imaged within a microfluidic chip. This August in JoVE, the Ozcan group demonstrates further advancements to their lens-free microscopy platform by applying it to tomographic imaging of the nematode, C. elegans. By changing the angle of illumination, using a motorized rotation stage, the Ozcan group shows how multiple holographic slices may be generated for a sample-which, following processing, can be combined into tomograms. The Ozcan group confirms that their 3D reconstruction of the worm is successful by citing that the pharyngeal tube, a 5-micron-thick structure, is only visible in a single slice and in a 3D reconstructed cross section. The compact and inexpensive nature of the lens-free imaging systems - designed and assembled by the Ozcan group - make them well suited for point-of-care diagnostic applications, or even cell phone based microscopy that can be performed in the field. At the Ernest Gallo Clinic and Research Center at University of California, San Francisco JoVE learns how to visualize morphological changes in single cells using three-dimensional fluorescence microscopy and computer analysis. In this procedure, cells are given agonist, antagonist plus agonist, or no treatment, and prepared for immunofluorescence microscopy. Three-dimensional images are acquired with the help of a two-photon laser system, and the fluorescence data are processed on the computer using Imaris and Matlab. To demonstrate the power of this technique, our authors quantify single-cell phenotypic changes in transfected HEK293 cells. Three-dimensional morphometric analysis shows dramatic changes in cells treated with agonist. These changes are not always apparent when using conventional 2D analysis. This technique allows morphological changes in single cells to be quantified and characterized in response to pharmacologic stimuli, offering a powerful new assessment tool to the arsenal of drug discovery research. This month, in JoVE Applied Physics, we travel to South Carolina to visit the School of Materials Science and Engineering at Clemson University. Here, researchers show us how to construct lithium batteries for laboratory research. The basic components of a lithium coin cell are the working electrode, the lithium electrolyte, and a lithium foil counter electrode. The different components of the coin cell are carefully assembled and sealed with a crimping machine. The finished coin cell can then be characterized in a battery tester. Using their homemade coin cells, our researchers can experiment with using different materials to make the cathodes of lithium coin cells. This month in JoVE Immunology and Infection, we head to Basel, Switzerland to witness two techniques for diagnosing helminth infections. We also see how investigators perform the shuttle run test in children, in order to assess the effects of these infections on physical fitness. Helminths are parasitic worms that can live inside humans and animals. Many species infect the intestinal tract, and may be transmitted through soil. Our authors demonstrate the Kato-Katz technique, which is used for diagnosing several common soil-transmitted helminths. They also demonstrate the Baermann technique, which uses light to stimulate the migration of certain types of phototactic helminths out of sample preparations. The various types of helminth species can subsequently be determined based on morphology. Our authors then demonstrate how to set up and perform a 20-meter shuttle run test for children, and to measure the impact of helminth infections on physical fitness. This method can help determine the true burden of soil-transmitted helminth infections on overall health. This brief summary highlights but a few notable video-articles that will be released in August. We'll also feature articles that demonstrate how to express genes in the midbrain of the chick embryo, study neutrophil transmigration in parallel flow chambers lined with endothelial cells, and precisely measure proteolytic degradation of the extracellular matrix.

ARTICLES DISCUSSED: 1. Pongerard, A., Mallo, L., Gachet, C., Lanza, F., Strassel, C. Leukodepletion filters-derived CD34+ cells as a cell source to study megakaryocyte differentiation and platelet formation. Journal of Visualized Experiments: JoVE. (171), e62499 (2021). 2. Kimmerlin, Q., Tavian, M., Gachet, C., Lanza, F., Brouard, N. Isolation of mouse megakaryocyte progenitors. Journal of Visualized Experiments: JoVE. (171), e62498 (2021). 3. Boscher, J., Gachet, C., Lanza, F., Léon, C. Megakaryocyte culture in 3D methylcellulose-based hydrogel to improve cell maturation and study the impact of stiffness and confinement. Journal of Visualized Experiments: JoVE. (171), e62511 (2021). 4. Scandola, C., Lanza, F., Gachet, C., Eckly, A. In situ exploration of murine megakaryopoiesis using transmission electron microscopy. Journal of Visualized Experiments: JoVE. (171) e62494 (2021). 5. Guinard, I., Gachet, C., Lanza, F., Léon, C., Eckly, A. Proplatelet formation dynamics of mouse fresh bone marrow explants. Journal of Visualized Experiments: JoVE. (171), e62501 (2021). 6. Bornert, A., Pertuy, F., Gachet, C., Lanza, F., Léon, C. In vivo two-photon imaging of megakaryocytes and proplatelets in the mouse skull bone marrow. Journal of Visualized Experiments: JoVE. (171), e62515 (2021)

The use of visual representations (i.e., photographs, diagrams, models) has been part of science, and their use makes it possible for scientists to interact with and represent complex phenomena, not observable in other ways. Despite a wealth of research in science education on visual representations, the emphasis of such research has mainly been on the conceptual understanding when using visual representations and less on visual representations as epistemic objects. In this paper, we argue that by positioning visual representations as epistemic objects of scientific practices, science education can bring a renewed focus on how visualization contributes to knowledge formation in science from the learners’ perspective. This is a theoretical paper, and in order to argue about the role of visualization, we first present a case study, that of the discovery of the structure of DNA that highlights the epistemic components of visual information in science. The second case study focuses on Faraday’s use of the lines of magnetic force. Faraday is known of his exploratory, creative, and yet systemic way of experimenting, and the visual reasoning leading to theoretical development was an inherent part of the experimentation. Third, we trace a contemporary account from science focusing on the experimental practices and how reproducibility of experimental procedures can be reinforced through video data. Our conclusions suggest that in teaching science, the emphasis in visualization should shift from cognitive understanding—using the products of science to understand the content—to engaging in the processes of visualization. Furthermore, we suggest that is it essential to design curriculum materials and learning environments that create a social and epistemic context and invite students to engage in the practice of visualization as evidence, reasoning, experimental procedure, or a means of communication and reflect on these practices. Implications for teacher education include the need for teacher professional development programs to problematize the use of visual representations as epistemic objects that are part of scientific practices.

Madhu has given a detailed account of a video journal and highlighted the need for developing a similar medium in India. When the Journal of Visualized Experiments (JoVE) was launched about a decade ago, there was some skepticism about it. Today, the video journal is not only an accepted format, but many longstanding as well as new journals include videos as supplementary content to the articles. However, the video journal is only one of the many formats of scholarly journals that have emerged since the turn of the 21st century.

Delivery of exogenous mRNA using lipid nanoparticles (LNPs) is a promising strategy for therapeutics. However, a bottleneck remains in the poor understanding of the parameters that correlate with endosomal escape versus cytotoxicity. To address this problem, we compared the endosomal distribution of six LNP-mRNA formulations of diverse chemical composition and efficacy, similar to those used in mRNA-based vaccines, in primary human adipocytes, fibroblasts, and HeLa cells. Surprisingly, we found that total uptake is not a sufficient predictor of delivery, and different LNPs vary considerably in endosomal distributions. Prolonged uptake impaired endosomal acidification, a sign of cytotoxicity, and caused mRNA to accumulate in compartments defective in cargo transport and unproductive for delivery. In contrast, early endocytic/recycling compartments have the highest probability for mRNA escape. By using super-resolution microscopy, we could resolve a single LNP-mRNA within subendosomal compartments and capture events of mRNA escape from endosomal recycling tubules. Our results change the view of the mechanisms of endosomal escape and define quantitative parameters to guide the development of mRNA formulations toward higher efficacy and lower cytotoxicity.

近年の分子生物学などの飛躍的な発展の一因として，複雑な実験手技についての明確なプロトコルが確立されていることが挙げられる。しかし，テキスト形式のプロトコルでは伝達できる情報量が限られており，実験系の確立に手間や時間がかかることが多い。そこで注目を集めているのがオンラインビデオジャーナルのJoVE（Journal of Visualized Experiments）である。実験プロトコルや実験の結果についてのより多くの情報を，動画を用いて科学コミュニティー全体で共有するというJoVEの取り組みや今後の展開を紹介する。

Visual impairment due to glaucoma currently impacts 70 million people worldwide. While disease progression can be slowed or stopped with effective lowering of intraocular pressure, current medical treatments are often inadequate. Fortunately, three new classes of therapeutics that target the diseased conventional outflow tissue responsible for ocular hypertension are in the final stages of human testing. The rho kinase inhibitors have proven particularly efficacious and additive to current therapies. Unfortunately, non-contact technology that monitors the health of outflow tissue and its response to conventional outflow therapy is not available clinically. Using optical coherence tomographic (OCT) imaging and novel segmentation software, we present the first demonstration of drug effects on conventional outflow tissues in living eyes. Topical netarsudil (formerly AR-13324), a rho kinase/ norepinephrine transporter inhibitor, affected both proximal (trabecular meshwork and Schlemm's Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract. Hence, increased perfusion of outflow tissues was reliably resolved by OCT as widening of the trabecular meshwork and significant increases in cross-sectional area of Schlemm's canal following netarsudil treatment. These changes occurred in conjunction with increased outflow facility, increased speckle variance intensity of outflow vessels, increased tracer deposition in conventional outflow tissues and decreased intraocular pressure. This is the first report using live imaging to show real-time drug effects on conventional outflow tissues and specifically the mechanism of action of netarsudil in mouse eyes. Advancements here pave the way for development of a clinic-friendly OCT platform for monitoring glaucoma therapy.

Digital media have the potential to foster genre innovation and change in\nscholarly communication, by 1) opening up new, diversified audiences to\nacademics, and 2) facilitating the use of a range of multimodal semiotic\nresources, that combine word and image, in academic writing. However,\nrelatively little applied linguistic research has investigated innovation in research\ngenres, especially high stakes genres like the research article. In addition, some of\nthe existing literature on the topic has concluded that the addition of digital\nelements to research articles (for example, embedded video) fails to add\nsignificant meaning to the genre, perhaps indicating a poor match between the\naffordances of digital media and the communicative purposes of the academic\nwriters. This exploratory study provides a multi-dimensional genre analysis of a\nnew research genre in the field of science: the video methods article (VMA),\npublished online by the Journal of Visualized Experiments (JoVE). In order to\nunderstand the intertextual communicative context of this genre, community\ndocuments were reviewed and two specialist informants were interviewed. A\nsample of eleven VMAs from JoVE, one per year of publication from 2006-\n2016, was examined. The multimodal analysis shows how the VMA genre draws\non the affordances of digital video in order to meet genuine needs of academic\nwriters. The findings also show some innovation and development in the genre\nover time, which moves through an initial period of experimentation before\nsettling on a stable generic structure