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https://www.readbyqxmd.com/read/29473994/rapid-analysis-of-cell-nanoparticle-interaction-using-single-cell-raman-trapping-microscopy
#1
Maria Steinke, Florian Zunhammer, Elisavet Chatzopoulou, Henrik Teller, Karin Schütze, Heike Walles, Joachim Rädler, Cordula Grüttner
Iron oxide nanoparticles have been used in preclinical studies to label stem cells for non-invasive tracking and homing. There is continuous search for novel particle candidates that are suitable for clinical applications. Since standard analyses to investigate cell-particle interaction and safety are labor-intensive, an efficient procedure is required to guide future particle development and to exclude adverse health effects. Here, we report the application of combined Raman trapping microscopy with fluidic chips to analyze single cells that were labeled with different aminated iron oxide particle types...
February 23, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29463706/motab-like-machinery-drives-the-movement-of-mreb-filaments-during-bacterial-gliding-motility
#2
Guo Fu, Jigar N Bandaria, Anne Valérie Le Gall, Xue Fan, Ahmet Yildiz, Tâm Mignot, David R Zusman, Beiyan Nan
MreB is a bacterial actin that is important for cell shape and cell wall biosynthesis in many bacterial species. MreB also plays crucial roles in Myxococcus xanthus gliding motility, but the underlying mechanism remains unknown. Here we tracked the dynamics of single MreB particles in M. xanthus using single-particle tracking photoactivated localization microscopy. We found that a subpopulation of MreB particles moves rapidly along helical trajectories, similar to the movements of the MotAB-like gliding motors...
February 20, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29456262/mixed-analytical-stochastic-simulation-method-for-the-recovery-of-a-brownian-gradient-source-from-probability-fluxes-to-small-windows
#3
U Dobramysl, D Holcman
Is it possible to recover the position of a source from the steady-state fluxes of Brownian particles to small absorbing windows located on the boundary of a domain? To address this question, we develop a numerical procedure to avoid tracking Brownian trajectories in the entire infinite space. Instead, we generate particles near the absorbing windows, computed from the analytical expression of the exit probability. When the Brownian particles are generated by a steady-state gradient at a single point, we compute asymptotically the fluxes to small absorbing holes distributed on the boundary of half-space and on a disk in two dimensions, which agree with stochastic simulations...
February 15, 2018: Journal of Computational Physics
https://www.readbyqxmd.com/read/29451293/the-role-of-near-wall-drag-effects-in-the-dynamics-of-tethered-dna-under-shear-flow
#4
Guy Nir, Einat Chetrit, Anat Vivante, Yuval Garini, Ronen Berkovich
We utilized single-molecule tethered particle motion (TPM) tracking, optimized for studying the behavior of short (0.922 μm) dsDNA molecules under shear flow conditions, in the proximity of a wall (surface). These experiments track the individual trajectories through a gold nanobead (40 nm in radius), attached to the loose end of the DNA molecules. Under such circumstances, local interactions with the wall become more pronounced, manifested through hydrodynamic interactions. To elucidate the mechanical mechanism that affects the statistics of the molecular trajectories of the tethered molecules, we estimate the resting diffusion coefficient of our system...
February 16, 2018: Soft Matter
https://www.readbyqxmd.com/read/29447383/super-resolution-imaging-identifies-parp1-and-the-ku-complex-acting-as-dna-double-strand-break-sensors
#5
Guang Yang, Chao Liu, Shih-Hsun Chen, Muzaffer A Kassab, J Damon Hoff, Nils G Walter, Xiaochun Yu
DNA double-strand breaks (DSBs) are fatal DNA lesions and activate a rapid DNA damage response. However, the earliest stage of DSB sensing remains elusive. Here, we report that PARP1 and the Ku70/80 complex localize to DNA lesions considerably earlier than other DSB sensors. Using super-resolved fluorescent particle tracking, we further examine the relocation kinetics of PARP1 and the Ku70/80 complex to a single DSB, and find that PARP1 and the Ku70/80 complex are recruited to the DSB almost at the same time...
February 13, 2018: Nucleic Acids Research
https://www.readbyqxmd.com/read/29445035/comparative-dynamics-of-microglial-and-glioma-cell-motility-at-the-infiltrative-margin-of-brain-tumours
#6
Joseph Juliano, Orlando Gil, Andrea Hawkins-Daarud, Sonal Noticewala, Russell C Rockne, Jill Gallaher, Susan Christine Massey, Peter A Sims, Alexander R A Anderson, Kristin R Swanson, Peter Canoll
Microglia are a major cellular component of gliomas, and abundant in the centre of the tumour and at the infiltrative margins. While glioma is a notoriously infiltrative disease, the dynamics of microglia and glioma migratory patterns have not been well characterized. To investigate the migratory behaviour of microglia and glioma cells at the infiltrative edge, we performed two-colour time-lapse fluorescence microscopy of brain slices generated from a platelet-derived growth factor-B (PDGFB)-driven rat model of glioma, in which glioma cells and microglia were each labelled with one of two different fluorescent markers...
February 2018: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/29440510/educated-natural-killer-cells-show-dynamic-movement-of-the-activating-receptor-nkp46-and-confinement-of-the-inhibitory-receptor-ly49a
#7
Elina Staaf, Per Niklas Hedde, Sunitha Bagawath Singh, Joachim Piguet, Enrico Gratton, Sofia Johansson
Educated natural killer (NK) cells have inhibitory receptors specific for self major histocompatibility complex (MHC) class I molecules and kill cancer cells more efficiently than do NK cells that do not have such receptors (hyporesponsive NK cells). The mechanism behind this functional empowerment through education has so far not been fully described. In addition, distinctive phenotypic markers of educated NK cells at the single-cell level are lacking. We developed a refined version of the image mean square displacement (iMSD) method (called iMSD carpet analysis) and used it in combination with single-particle tracking to characterize the dynamics of the activating receptor NKp46 and the inhibitory receptor Ly49A on resting educated versus hyporesponsive murine NK cells...
February 13, 2018: Science Signaling
https://www.readbyqxmd.com/read/29433310/quantifying-the-average-number-of-nucleic-acid-therapeutics-per-nanocarrier-by-single-particle-tracking-microscopy
#8
Elisa Zagato, Lotte Vermeulen, Heleen Dewitte, Griet Van Imschoot, Roosmarijn E Vandenbroucke, Jo Demeester, Stefaan C De Schmedt, Kristiaan Neyts, Katrien Remaut, Kevin Braeckmans
Nucleic acid biopharmaceuticals are being investigated as potential therapeutics. They need to be incorporated into a bio-compatible carrier so as to overcome several biological barriers. Rational development of suitable nanocarriers requires high quality characterization techniques. While size, concentration and stability can be very well measured these days, even in complex biological fluids, a method to accurately quantify the number of nucleic acid therapeutics encapsulated in nanocarriers is still missing...
February 12, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29429094/bacterial-chemoreceptor-imaging-at-high-spatiotemporal-resolution-using-photoconvertible-fluorescent-proteins
#9
Jacopo Solari, Francois Anquez, Katharina M Scherer, Thomas S Shimizu
We describe two methods for high-resolution fluorescence imaging of the positioning and mobility of E. coli chemoreceptors fused to photoconvertible fluorescent proteins. Chemoreceptors such as Tar and Tsr are transmembrane proteins expressed at high levels (thousands of copies per cell). Together with their cognate cytosolic signaling proteins, they form clusters on the plasma membrane. Theoretical models imply that the size of these clusters is an important parameter for signaling, and recent PALM imaging has revealed a broad distribution of cluster sizes...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29394047/understanding-the-molecular-mechanisms-of-crispr-toolbox-using-single-molecule-approaches
#10
Digvijay Singh, Taekjip Ha
The adaptive immunity against foreign genetic elements conferred by CRISPR systems in microbial species has been repurposed as a revolutionary technology for wide-ranging biological applications, chiefly genome engineering. Biochemical, structural, genetic and genomics studies have revealed important insights into their function and mechanisms, but most ensemble studies cannot observe structural changes of these molecules during their function and are often blind to key reaction intermediates. Here we review the use of single molecule approaches such as fluorescence particle tracking, FRET, magnetic tweezers and atomic force microscopy image in improving our understanding of CRISPR toolbox...
February 2, 2018: ACS Chemical Biology
https://www.readbyqxmd.com/read/29392930/labeling-and-single-particle-tracking-based-entry-mechanism-study-of-vaccinia-virus-from-the-tiantan-strain
#11
Li-Li Huang, Li-Li Wu, Xue Li, Kejiang Liu, Dongxu Zhao, Hai-Yan Xie
Entry is the first and critical step of viral infection, while the entry mechanisms of many viruses are still unclear due to the lack of efficient technology. In this report, by taking advantage of the single-virion fluorescence tracking technique and simultaneous dual-labeling methods for viruses, we developed; the entry pathway of vaccinia virus from tiantan strain (VACV-TT) was studied in real-time. By combining with the technologies of virology and cell biology, we found that VACV-TT moved toward the Vero cell body along the filopodia induced by the virions interaction, and then, they were internalized through macropinocytosis, which was an actin-, ATP-dependent but clathrin-, caveolin-independent endocytosis...
February 2, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29389649/improved-super-resolution-ultrasound-microvessel-imaging-with-spatiotemporal-nonlocal-means-filtering-and-bipartite-graph-based-microbubble-tracking
#12
Pengfei Song, Joshua D Trzasko, Armando Manduca, Runqing Huang, Ramanathan Kadirvel, David F Kallmes, Shigao Chen
Super-resolution ultrasound microvessel imaging with contrast microbubbles has recently been proposed by multiple studies, demonstrating outstanding resolution with high potential for clinical applications. This paper aims at addressing the potential noise issue in in vivo human super-resolution imaging with ultrafast plane-wave imaging. The rich spatiotemporal information provided by ultrafast imaging presents features that allow microbubble signals to be separated from background noise. In addition, the high-frame-rate recording of microbubble data enables the implementation of robust tracking algorithms commonly used in particle tracking velocimetry...
February 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29388108/single-particle-tracking-of-cell-surface-proteins
#13
Laabiah Wasim, Bebhinn Treanor
Single-particle tracking has been used extensively to advance our understanding of the plasma membrane and the mechanisms controlling the movement of cell surface proteins. These studies provide fundamental insights into the regulation of membrane receptor activation and the assembly of signaling clusters. Here, we describe a method to label and track B cell receptor (BCR) and other cell surface proteins and how this method can be adapted to simultaneously track two molecular species or examine the movement of membrane proteins in relation to membrane microdomains...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29379879/activity-dependent-inhibitory-synapse-scaling-is-determined-by-gephyrin-phosphorylation-and-subsequent-regulation-of-gabaa-receptor-diffusion
#14
Sereina Battaglia, Marianne Renner, Marion Russeau, Etienne Côme, Shiva K Tyagarajan, Sabine Lévi
Synaptic plasticity relies on the rapid changes in neurotransmitter receptor number at postsynaptic sites. Using superresolution photoactivatable localization microscopy imaging and quantum dot-based single-particle tracking in rat hippocampal cultured neurons, we investigated whether the phosphorylation status of the main scaffolding protein gephyrin influenced the organization of the gephyrin scaffold and GABAA receptor (GABAAR) membrane dynamics. We found that gephyrin phosphorylation regulates gephyrin microdomain compaction...
January 2018: ENeuro
https://www.readbyqxmd.com/read/29369740/exploring-kinetic-energy-as-a-new-marker-of-cardiac-function-in-the-single-ventricle-circulation
#15
James Wong, Radomir Chabiniok, Shane M Tibby, Kuberan Pushparajah, Eva Sammut, David S Celermajer, Daniel Giese, Tarique Hussain, Gerald F Greil, Tobias Schaeffter, Reza Razavi
Ventricular volumetric ejection fraction (VV EF) is often normal in patients with single ventricle circulations despite them experiencing symptoms related to circulatory failure. We sought to determine if kinetic energy (KE) could be a better marker of ventricular performance. KE was prospectively quantified using 4D flow MRI in 41 patients with a single ventricle circulation (aged 0.5 - 28 years) and compared to 43 healthy volunteers (aged 1.5 - 62 years) and 14 patients with left ventricular (LV) dysfunction (aged 28 - 79 years)...
January 25, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29364246/a-protocol-for-real-time-3d-single-particle-tracking
#16
Shangguo Hou, Kevin Welsher
Real-time three-dimensional single particle tracking (RT-3D-SPT) has the potential to shed light on fast, 3D processes in cellular systems. Although various RT-3D-SPT methods have been put forward in recent years, tracking high speed 3D diffusing particles at low photon count rates remains a challenge. Moreover, RT-3D-SPT setups are generally complex and difficult to implement, limiting their widespread application to biological problems. This protocol presents a RT-3D-SPT system named 3D Dynamic Photon Localization Tracking (3D-DyPLoT), which can track particles with high diffusive speed (up to 20 µm2/s) at low photon count rates (down to 10 kHz)...
January 3, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29364242/in-vivo-single-molecule-tracking-at-the-drosophila-presynaptic-motor-nerve-terminal
#17
Adekunle T Bademosi, Elsa Lauwers, Rumelo Amor, Patrik Verstreken, Bruno van Swinderen, Frédéric A Meunier
An increasing number of super-resolution microscopy techniques are helping to uncover the mechanisms that govern the nanoscale cellular world. Single-molecule imaging is gaining momentum as it provides exceptional access to the visualization of individual molecules in living cells. Here, we describe a technique that we developed to perform single-particle tracking photo-activated localization microscopy (sptPALM) in Drosophila larvae. Synaptic communication relies on key presynaptic proteins that act by docking, priming, and promoting the fusion of neurotransmitter-containing vesicles with the plasma membrane...
January 14, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29347678/detection-of-transition-times-from-single-particle-tracking-trajectories
#18
Takuma Akimoto, Eiji Yamamoto
In heterogeneous environments, the diffusivity is not constant but changes with time. It is important to detect changes in the diffusivity from single-particle-tracking trajectories in experiments. Here, we devise a novel method for detecting the transition times of the diffusivity from trajectory data. A key idea of this method is the introduction of a characteristic time scale of the diffusive states, which is obtained by a fluctuation analysis of the time-averaged mean square displacements. We test our method in silico by using the Langevin equation with a fluctuating diffusivity...
November 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347613/test-of-the-diffusing-diffusivity-mechanism-using-near-wall-colloidal-dynamics
#19
Mpumelelo Matse, Mykyta V Chubynsky, John Bechhoefer
The mechanism of diffusing diffusivity predicts that, in environments where the diffusivity changes gradually, the displacement distribution becomes non-Gaussian, even though the mean-square displacement grows linearly with time. Here, we report single-particle tracking measurements of the diffusion of colloidal spheres near a planar substrate. Because the local effective diffusivity is known, we have been able to carry out a direct test of this mechanism for diffusion in inhomogeneous media.
October 2017: Physical Review. E
https://www.readbyqxmd.com/read/29347492/elucidating-fluctuating-diffusivity-in-center-of-mass-motion-of-polymer-models-with-time-averaged-mean-square-displacement-tensor
#20
Tomoshige Miyaguchi
There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here a method is developed to elucidate this fluctuating diffusivity from trajectory data. Time-averaged mean-square displacement (MSD), a common tool in single-particle-tracking (SPT) experiments, is generalized to a second-order tensor with which both magnitude and orientation fluctuations of the diffusivity can be clearly detected. This method is used to analyze the center-of-mass motion of four fundamental polymer models: the Rouse model, the Zimm model, a reptation model, and a rigid rodlike polymer...
October 2017: Physical Review. E
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