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Find video protocols related to scientific articles indexed in Pubmed.
Functional organization of a multimodular bacterial chemosensory apparatus.
PLoS Genet.
PUBLISHED: 03-01-2014
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Chemosensory systems (CSS) are complex regulatory pathways capable of perceiving external signals and translating them into different cellular behaviors such as motility and development. In the ?-proteobacterium Myxococcus xanthus, chemosensing allows groups of cells to orient themselves and aggregate into specialized multicellular biofilms termed fruiting bodies. M. xanthus contains eight predicted CSS and 21 chemoreceptors. In this work, we systematically deleted genes encoding components of each CSS and chemoreceptors and determined their effects on M. xanthus social behaviors. Then, to understand how the 21 chemoreceptors are distributed among the eight CSS, we examined their phylogenetic distribution, genomic organization and subcellular localization. We found that, in vivo, receptors belonging to the same phylogenetic group colocalize and interact with CSS components of the respective phylogenetic group. Finally, we identified a large chemosensory module formed by three interconnected CSS and multiple chemoreceptors and showed that complex behaviors such as cell group motility and biofilm formation require regulatory apparatus composed of multiple interconnected Che-like systems.
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Transcription termination controls prophage maintenance in Escherichia coli genomes.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 08-12-2013
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Prophages represent a large fraction of prokaryotic genomes and often provide new functions to their hosts, in particular virulence and fitness. How prokaryotic cells maintain such gene providers is central for understanding bacterial genome evolution by horizontal transfer. Prophage excision occurs through site-specific recombination mediated by a prophage-encoded integrase. In addition, a recombination directionality factor (or excisionase) directs the reaction toward excision and prevents the phage genome from being reintegrated. In this work, we describe the role of the transcription termination factor Rho in prophage maintenance through control of the synthesis of transcripts that mediate recombination directionality factor expression and, thus, excisive recombination. We show that Rho inhibition by bicyclomycin allows for the expression of prophage genes that lead to excisive recombination. Thus, besides its role in the silencing of horizontally acquired genes, Rho also maintains lysogeny of defective and functional prophages.
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Fe-S cluster biosynthesis controls uptake of aminoglycosides in a ROS-less death pathway.
Science
PUBLISHED: 07-02-2013
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All bactericidal antibiotics were recently proposed to kill by inducing reactive oxygen species (ROS) production, causing destabilization of iron-sulfur (Fe-S) clusters and generating Fenton chemistry. We find that the ROS response is dispensable upon treatment with bactericidal antibiotics. Furthermore, we demonstrate that Fe-S clusters are required for killing only by aminoglycosides. In contrast to cells, using the major Fe-S cluster biosynthesis machinery, ISC, cells using the alternative machinery, SUF, cannot efficiently mature respiratory complexes I and II, resulting in impendence of the proton motive force (PMF), which is required for bactericidal aminoglycoside uptake. Similarly, during iron limitation, cells become intrinsically resistant to aminoglycosides by switching from ISC to SUF and down-regulating both respiratory complexes. We conclude that Fe-S proteins promote aminoglycoside killing by enabling their uptake.
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M-CSF instructs myeloid lineage fate in single haematopoietic stem cells.
Nature
PUBLISHED: 02-20-2013
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Under stress conditions such as infection or inflammation the body rapidly needs to generate new blood cells that are adapted to the challenge. Haematopoietic cytokines are known to increase output of specific mature cells by affecting survival, expansion and differentiation of lineage-committed progenitors, but it has been debated whether long-term haematopoietic stem cells (HSCs) are susceptible to direct lineage-specifying effects of cytokines. Although genetic changes in transcription factor balance can sensitize HSCs to cytokine instruction, the initiation of HSC commitment is generally thought to be triggered by stochastic fluctuation in cell-intrinsic regulators such as lineage-specific transcription factors, leaving cytokines to ensure survival and proliferation of the progeny cells. Here we show that macrophage colony-stimulating factor (M-CSF, also called CSF1), a myeloid cytokine released during infection and inflammation, can directly induce the myeloid master regulator PU.1 and instruct myeloid cell-fate change in mouse HSCs, independently of selective survival or proliferation. Video imaging and single-cell gene expression analysis revealed that stimulation of highly purified HSCs with M-CSF in culture resulted in activation of the PU.1 promoter and an increased number of PU.1(+) cells with myeloid gene signature and differentiation potential. In vivo, high systemic levels of M-CSF directly stimulated M-CSF-receptor-dependent activation of endogenous PU.1 protein in single HSCs and induced a PU.1-dependent myeloid differentiation preference. Our data demonstrate that lineage-specific cytokines can act directly on HSCs in vitro and in vivo to instruct a change of cell identity. This fundamentally changes the current view of how HSCs respond to environmental challenge and implicates stress-induced cytokines as direct instructors of HSC fate.
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Changes in tau phosphorylation in hibernating rodents.
J. Neurosci. Res.
PUBLISHED: 01-17-2013
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Tau is a cytoskeletal protein present mainly in the neurons of vertebrates. By comparing the sequence of tau molecule among different vertebrates, it was found that the variability of the N-terminal sequence in tau protein is higher than that of the C-terminal region. The N-terminal region is involved mainly in the binding of tau to cellular membranes, whereas the C-terminal region of the tau molecule contains the microtubule-binding sites. We have compared the sequence of Syrian hamster tau with the sequences of other hibernating and nonhibernating rodents and investigated how differences in the N-terminal region of tau could affect the phosphorylation level and tau binding to cell membranes. We also describe a change, in tau phosphorylation, on a casein kinase 1 (ck1)-dependent site that is found only in hibernating rodents. This ck1 site seems to play an important role in the regulation of tau binding to membranes.
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Imaging type VI secretion-mediated bacterial killing.
Cell Rep
PUBLISHED: 01-03-2013
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In the environment, bacteria compete with each other for nutrient availability or to extend their ecological niche. The type VI secretion system contributes to bacterial competition by the translocation of antibacterial effectors from predators into prey cells. The T6SS assembles a dynamic structure-the sheath-wrapped around a tube constituted of the Hcp protein. It has been proposed that by cycling between extended and contracted conformations the sheath acts as a crossbow to propel the Hcp tube toward the target cell. While the sheath dynamics have been studied in monocultures, the activity of the T6SS has not been recorded in presence of the prey. Here, time-lapse fluorescence microscopy of cocultures demonstrates that prey cells are killed upon contact with predator cells. Additional experiments provide evidence that sheath contraction correlates with nearby cell fading and that prey lysis occurs within minutes after sheath contraction. The results support a model in which T6SS dynamics are responsible for T6SS effectors translocation into recipient cells.
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The YvcK protein is required for morphogenesis via localization of PBP1 under gluconeogenic growth conditions in Bacillus subtilis.
Mol. Microbiol.
PUBLISHED: 03-08-2011
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The YvcK protein was previously shown to be dispensable when B. subtilis cells are grown on glycolytic carbon sources but essential for growth and normal shape on gluconeogenic carbon sources. Here, we report that YvcK is localized as a helical-like pattern in the cell. This localization seems independent of the actin-like protein, MreB. A YvcK overproduction restores a normal morphology in an mreB mutant strain when bacteria are grown on PAB medium. Reciprocally, an additional copy of mreB restores a normal growth and morphology in a yvcK mutant strain when bacteria are grown on a gluconeogenic carbon source like gluconate. Furthermore, as already observed for the mreB mutant, the deletion of the gene encoding the penicillin-binding protein PBP1 restores growth and normal shape of a yvcK mutant on gluconeogenic carbon sources. The PBP1 is delocalized in an mreB mutant grown in the absence of magnesium and in a yvcK mutant grown on gluconate medium. Interestingly, its proper localization can be rescued by YvcK overproduction. Therefore, in gluconeogenic growth conditions, YvcK is required for the correct localization of PBP1 and hence for displaying a normal rod shape.
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3D reconstruction of granulomas from transmitted light images implemented for long-time microscope applications.
J. Immunol. Methods
PUBLISHED: 03-12-2010
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Image analysis tools are essential to describe and quantify dynamic biological phenomena, such as early stages of granuloma formation. Granulomas are constituted of a collection of immune cells that contain pathogens, leading to their elimination. We presented here a new method to obtain granuloma 3D reconstruction from transmitted light images. Granulomas were generated by incubating peripheral blood mononuclear cells with beads coated with sonicated Coxiella burnetii, a bacterial pathogen. Biological samples were observed under a confocal microscope, and recorded during several hours, providing a large set of data of several gigabytes. Our image processing, called Focus Detection Plugin (FDP), allowed to extract relevant images from large datasets and to perform a deblurring of image stacks. This FDP method, that was implemented as an ImageJ plugin, did not require powerful computer resources and was simple to use. To validate our FDP method, we compared our results with 3D reconstruction of fluorescent images. Both methods yielded comparable results. We concluded that our FDP method was able to generate processed images yielding robust 3D reconstruction of whole cell bodies, and presented major advantages for long-time recordings since no cell labeling was needed. This method was convenient to study the early stages of granuloma formation and may be applied to other complex biological systems.
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Efficacy of alpha lipoic acid in burning mouth syndrome: a randomized, placebo-treatment study.
J Oral Rehabil
PUBLISHED: 12-17-2009
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To study the efficacy of alpha lipoic acid (ALA) in a group of patients with burning mouth syndrome (BMS). Sixty BMS patients, 30 treated with ALA (Thioderm) 800 mg day(-1) for 8 weeks and 30 patients on the same protocol with a placebo. The symptomatology was measured on a Visual Analogue Scale (VAS). Sixty patients (54 females and 6 males, mean age 64.37 +/- 11.61 years) were included. Thirty-nine patients completed the treatment (23 with ALA and 16 with a placebo). Reviews were carried out at 0, 1 and 2 months. No statistically significant differences were found in the average pre- and post-treatment values for pain with the VAS scores, obtained in the placebo (6.6 +/- 2.5 - 2.8 +/- 25 = 3.8 +/- 3.7) versus ALA (6.3 +/- 2.8 - 4.0 +/- 2.7 = 2.2 +/- 2.6). Only one patient pertaining to the group treated with ALA abandoned because of adverse gastrointestinal side effects. The results showed no significant differences between the two groups.
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Giant Marseillevirus highlights the role of amoebae as a melting pot in emergence of chimeric microorganisms.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 12-09-2009
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Giant viruses such as Mimivirus isolated from amoeba found in aquatic habitats show biological sophistication comparable to that of simple cellular life forms and seem to evolve by similar mechanisms, including extensive gene duplication and horizontal gene transfer (HGT), possibly in part through a viral parasite, the virophage. We report here the isolation of "Marseille" virus, a previously uncharacterized giant virus of amoeba. The virions of Marseillevirus encompass a 368-kb genome, a minimum of 49 proteins, and some messenger RNAs. Phylogenetic analysis of core genes indicates that Marseillevirus is the prototype of a family of nucleocytoplasmic large DNA viruses (NCLDV) of eukaryotes. The genome repertoire of the virus is composed of typical NCLDV core genes and genes apparently obtained from eukaryotic hosts and their parasites or symbionts, both bacterial and viral. We propose that amoebae are "melting pots" of microbial evolution where diverse forms emerge, including giant viruses with complex gene repertoires of various origins.
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CD146 and its soluble form regulate monocyte transendothelial migration.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 02-19-2009
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During inflammation, cell adhesion molecules are modulated or redistributed for leukocyte transmigration. Among molecules at the interendothelial junction, CD146 is involved in cell-cell cohesion and permeability, but its role in monocyte transmigration is unknown.
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Value of in vivo T2 measurement for myocardial fibrosis assessment in diabetic mice at 11.75 T.
Invest Radiol
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The aim of the study was to assess the value of in vivo T2 measurements to noninvasively quantify myocardial fibrosis in diabetic mice at 11.75 T. Diabetic cardiomyopathy is characterized by extracellular matrix alteration and microcirculation impairment. These conditions might provide electrical heterogeneity, which is a substrate for arrhythmogenesis. T1 mapping has been proposed to quantify diffuse myocardial fibrosis in cardiac diseases but has several limitations. T2 measurement may represent an alternative for fibrosis quantification at high magnetic field.
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Defective monocyte dynamics in Q fever granuloma deficiency.
J. Infect. Dis.
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The outcome of Q fever, an infectious disease caused by Coxiella burnetii, is associated with granuloma formation. Granulomas are present in patients with resolutive Q fever but are lacking in patients with chronic Q fever.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.