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fluorescence lifetime imaging microscopy

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https://www.readbyqxmd.com/read/28096507/de-novo-phosphorylation-and-conformational-opening-of-the-tyrosine-kinase-lck-act-in-concert-to-initiate-t-cell-receptor-signaling
#1
Lars Philipsen, Amarendra V Reddycherla, Roland Hartig, Janine Gumz, Matthias Kästle, Andreas Kritikos, Mateusz P Poltorak, Yury Prokazov, Evgeny Turbin, André Weber, Werner Zuschratter, Burkhart Schraven, Luca Simeoni, Andreas J Müller
The enzymatic activity of the Src family tyrosine kinase p56(Lck) (Lck) is tightly controlled by differential phosphorylation of two tyrosine residues, Tyr(394) and Tyr(505) Phosphorylation of Tyr(394) and the conformational opening of Lck are believed to activate the kinase, whereas Tyr(505) phosphorylation is thought to generate a closed, inactive conformation of Lck. We investigated whether the conformation of Lck and its phosphorylation state act in concert to regulate the initiation of T cell receptor (TCR) signaling...
January 17, 2017: Science Signaling
https://www.readbyqxmd.com/read/28073262/fluorescence-self-quenching-from-reporter-dyes-informs-on-the-structural-properties-of-amyloid-clusters-formed-in-vitro-and-in-cells
#2
WeiYue Chen, Laurence J Young, Meng Lu, Alessio Zaccone, Florian Ströhl, Na Yu, Gabriele S Kaminski Schierle, Clemens F Kaminski
The characterization of the aggregation kinetics of protein amyloids and the structural properties of the ensuing aggregates are vital in the study of the pathogenesis of many neurodegenerative diseases and the discovery of therapeutic targets. In this article, we show that the fluorescence lifetime of synthetic dyes covalently attached to amyloid proteins informs on the structural properties of amyloid clusters formed both in vitro and in cells. We demonstrate that the mechanism behind such a "lifetime sensor" of protein aggregation is based on fluorescence self-quenching and that it offers a good dynamic range to report on various stages of aggregation without significantly perturbing the process under investigation...
January 11, 2017: Nano Letters
https://www.readbyqxmd.com/read/28067047/solvatochromic-and-fluorogenic-dyes-as-environment-sensitive-probes-design-and-biological-applications
#3
Andrey S Klymchenko
Fluorescent environment-sensitive probes are specially designed dyes that change their fluorescence intensity (fluorogenic dyes) or color (e.g., solvatochromic dyes) in response to change in their microenvironment polarity, viscosity, and molecular order. The studies of the past decade, including those of our group, have shown that these molecules become universal tools in fluorescence sensing and imaging. In fact, any biomolecular interaction or change in biomolecular organization results in modification of the local microenvironment, which can be directly monitored by these types of probes...
January 9, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28063999/relationship-between-intracellular-ph-metabolic-co-factors-and-caspase-3-activation-in-cancer-cells-during-apoptosis
#4
Tatiana F Sergeeva, Marina V Shirmanova, Olga A Zlobovskaya, Alena I Gavrina, Varvara V Dudenkova, Maria M Lukina, Konstantin A Lukyanov, Elena V Zagaynova
A complex cascade of molecular events occurs in apoptotic cells but cell-to-cell variability significantly complicates determination of the order and interconnections between different processes. For better understanding of the mechanisms of programmed cell death, dynamic simultaneous registration of several parameters is required. In this paper we used multiparameter fluorescence microscopy to analyze energy metabolism, intracellular pH and caspase-3 activation in living cancer cells in vitro during staurosporine-induced apoptosis...
January 4, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28060890/developing-and-testing-a-bayesian-analysis-of-fluorescence-lifetime-measurements
#5
Bryan Kaye, Peter J Foster, Tae Yeon Yoo, Daniel J Needleman
FRET measurements can provide dynamic spatial information on length scales smaller than the diffraction limit of light. Several methods exist to measure FRET between fluorophores, including Fluorescence Lifetime Imaging Microscopy (FLIM), which relies on the reduction of fluorescence lifetime when a fluorophore is undergoing FRET. FLIM measurements take the form of histograms of photon arrival times, containing contributions from a mixed population of fluorophores both undergoing and not undergoing FRET, with the measured distribution being a mixture of exponentials of different lifetimes...
2017: PloS One
https://www.readbyqxmd.com/read/28059202/saturation-compensated-measurements-for-fluorescence-lifetime-imaging-microscopy
#6
Yide Zhang, Genevieve D Vigil, Lina Cao, Aamir A Khan, David Benirschke, Tahsin Ahmed, Patrick Fay, Scott S Howard
Fluorophore saturation is the key factor limiting the speed and excitation range of fluorescence lifetime imaging microscopy (FLIM). For example, fluorophore saturation causes incorrect lifetime measurements when using conventional frequency-domain FLIM at high excitation powers. In this Letter, we present an analytical theoretical description of this error and present a method for compensating for this error in order to extract correct lifetime measurements in the limit of fluorophore saturation. We perform a series of simulations and experiments to validate our methods...
January 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28042459/precision-targeted-ruthenium-ii-luminophores-highly-effective-probes-for-cell-imaging-by-stimulated-emission-depletion-sted-microscopy
#7
Aisling Byrne, Christopher S Burke, Tia E Keyes
Fluorescence microscopy has undergone a dramatic evolution over the past two decades with development of super-resolution far-field microscopy methods that break the light diffraction limited resolution of conventional microscopy, offering unprecedented opportunity to interrogate cellular processes at the nanoscale. However, these methods make special demands of the luminescent agents used for contrast and development of probes suited to super-resolution fluorescent methods is still relatively in its infancy...
October 19, 2016: Chemical Science
https://www.readbyqxmd.com/read/28029135/time-resolved-fluorescence-spectroscopy-and-fluorescence-lifetime-imaging-microscopy-for-characterization-of-dendritic-polymer-nanoparticles-and-applications-in-nanomedicine
#8
REVIEW
Alexander Boreham, Robert Brodwolf, Karolina Walker, Rainer Haag, Ulrike Alexiev
The emerging field of nanomedicine provides new approaches for the diagnosis and treatment of diseases, for symptom relief and for monitoring of disease progression. One route of realizing this approach is through carefully constructed nanoparticles. Due to the small size inherent to the nanoparticles a proper characterization is not trivial. This review highlights the application of time-resolved fluorescence spectroscopy and fluorescence lifetime imaging microscopy (FLIM) for the analysis of nanoparticles, covering aspects ranging from molecular properties to particle detection in tissue samples...
December 24, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28025889/detailed-study-of-bsa-adsorption-on-micro-and-nanocrystalline-diamond-%C3%AE-sic-composite-gradient-films-by-time-resolved-fluorescence-microscopy
#9
Stephan Handschuh-Wang, Tao Wang, Sergey I Druzhinin, Daniel Wesner, Xin Jiang, Holger Schönherr
The adsorption of bovine serum albumin (BSA) on micro- and nanocrystalline diamond/β-SiC composite films synthesized using the hot filament chemical vapor deposition (HFCVD) technique has been investigated by confocal fluorescence lifetime imaging microscopy. BSA labeled with fluorescein isothiocyanate (FITC) was employed as a probe. The BSA(FITC) conjugate was found to preferentially adsorb on both O-/OH-terminated microcrystalline and nanocrystalline diamond compared to the OH-terminated β-SiC, resulting in an increasing amount of BSA adsorbed to the gradient surfaces with an increasing diamond/β-SiC ratio...
January 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28018724/gpu-accelerated-real-time-confocal-fluorescence-lifetime-imaging-microscopy-flim-based-on-the-analog-mean-delay-amd-method
#10
Byungyeon Kim, Byungjun Park, Seungrag Lee, Youngjae Won
We demonstrated GPU accelerated real-time confocal fluorescence lifetime imaging microscopy (FLIM) based on the analog mean-delay (AMD) method. Our algorithm was verified for various fluorescence lifetimes and photon numbers. The GPU processing time was faster than the physical scanning time for images up to 800 × 800, and more than 149 times faster than a single core CPU. The frame rate of our system was demonstrated to be 13 fps for a 200 × 200 pixel image when observing maize vascular tissue. This system can be utilized for observing dynamic biological reactions, medical diagnosis, and real-time industrial inspection...
December 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/28004946/fluorescent-inhibitors-as-tools-to-characterize-enzymes-case-study-of-the-lipid-kinase-phosphatidylinositol-4-kinase-iii%C3%AE-pi4kb
#11
Jana Humpolickova, Ivana Mejdrová, Marika Matousova, Radim Nencka, Evzen Boura
The lipid kinase phosphatidylinositol 4-kinase IIIβ (PI4KB) is an essential host factor for many positive-sense single-stranded RNA (+RNA) viruses including human pathogens hepatitis C virus (HCV), Severe acute respiratory syndrome (SARS), coxsackie viruses, and rhinoviruses. Inhibitors of PI4KB are considered to be potential broad-spectrum virostatics, and it is therefore critical to develop a biochemical understanding of the kinase. Here, we present highly potent and selective fluorescent inhibitors that we show to be useful chemical biology tools especially in determination of dissociation constants...
December 22, 2016: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28004840/dual-observation-of-the-atp-evoked-small-gtpase-activation-and-ca-2-transient-in-astrocytes-using-a-dark-red-fluorescent-protein
#12
Yoshihisa Nakahata, Junichi Nabekura, Hideji Murakoshi
Intracellular signal transduction involves a number of biochemical reactions, which largely consist of protein-protein interactions and protein conformational changes. Monitoring Förster resonance energy transfer (FRET) by fluorescence lifetime imaging microscopy (FLIM), called FLIM-FRET, is one of the best ways to visualize such protein dynamics. Here, we attempted to apply dark red fluorescent proteins with significantly smaller quantum yields. Application of the dark mCherry mutants to single-molecule FRET sensors revealed that these dark mCherry mutants are a good acceptor in a pair with mRuby2...
December 22, 2016: Scientific Reports
https://www.readbyqxmd.com/read/28003430/conformational-changes-in-inhibitory-pas-domain-protein-associated-with-binding-of-hif-1%C3%AE-and-bcl-xl-in-living-cells
#13
Shuya Kasai, Shinji Kajimoto, Yuma Ito, Tomo Saito, Ken-Ichi Yasumoto, Makio Tokunaga, Kumiko Sakata-Sogawa, Hiroshi Fukumura, Kazuhiro Sogawa
Inhibitory PAS domain protein (IPAS) is a dual function protein acting as a transcriptional repressor and as a pro-apoptotic protein. Simultaneous dual-color single-molecule imaging of EGFP-IPAS coexpressed with Mit-TagRFP-T in living HeLa cells revealed that fraction of EGFP-IPAS was arrested in the nucleus and on mitochondria. Transiently expressed Cerulean-IPAS in HEK293T cells was present in nuclear speckles when coexpressed with Citrine-HIF-1α or Citrine-HLF. Fluorescence lifetime imaging microscopy (FLIM) analysis of Citrine-IPAS-Cerulean in living CHO-K1 cells clarified the presence of intramolecular FRET...
December 21, 2016: Journal of Biochemistry
https://www.readbyqxmd.com/read/27993567/cell-cycle-dependent-changes-in-the-plasma-membrane-organization-of-mammalian-cells
#14
Manuela Denz, Salvatore Chiantia, Andreas Herrmann, Peter Mueller, Thomas Korte, Roland Schwarzer
Lipid membranes are major structural elements of all eukaryotic and prokaryotic organisms. Although many aspects of their biology have been studied extensively, their dynamics and lateral heterogeneity are still not fully understood. Recently, we observed a cell-to-cell variability in the plasma membrane organization of CHO-K1 cells (Schwarzer et al., 2014). We surmised that cell cycle dependent changes of the individual cells from our unsynchronized cell population account for this phenomenon. In the present study, this hypothesis was tested...
December 18, 2016: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/27992081/non-invasive-metabolic-imaging-of-melanoma-progression
#15
Michael N Pastore, Hauke Studier, Claudine S Bonder, Michael S Roberts
Skin cancer is associated with abnormal cellular metabolism which if identified early introduces the possibility of intervention to prevent its progress to a deadly metastatic stage. This study combines multiphoton microscopy with fluorescence lifetime imaging (FLIM) using an syngeneic melanoma mouse model, to detect changes in metabolic state of single epidermal cells as a metabolic marker to monitor the progress of tumor growth. This method utilizes imaging of the ratio of the amounts of the free and protein-bound forms of the intracellular autofluorescent metabolic co-enzyme nicotinamide adenine dinucleotide (NADH)...
December 19, 2016: Experimental Dermatology
https://www.readbyqxmd.com/read/27991638/modulation-of-phase-separation-at-the-micron-scale-and-nanoscale-in-giant-polymer-lipid-hybrid-unilamellar-vesicles-ghuvs
#16
Thi Phuong Tuyen Dao, Fabio Fernandes, Emmanuel Ibarboure, Khalid Ferji, Manuel Prieto, Olivier Sandre, Jean-François Le Meins
Phase separation in giant polymer/lipid hybrid unilamellar vesicles (GHUVs) has been described over the last few years. However there is still a lack of understanding on the physical and molecular factors governing the phase separation in such systems. Among these parameters it has been suggested that in analogy to multicomponent lipid vesicles hydrophobic mismatches as well as lipid fluidity play a role. In this work, we aim to map a global picture of phase separation and domain formation in the membrane of GHUVs by using various copolymers based on poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) (PEO) with different architectures (grafted, triblock) and molar masses, combined with phospholipids in the fluid (POPC) or gel state (DPPC) at room temperature...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/27976589/a-key-role-of-xanthophylls-that-are-not-embedded-in-proteins-in-regulation-of-the-photosynthetic-antenna-function-in-plants-revealed-by-monomolecular-layer-studies
#17
Renata Welc, Rafal Luchowski, Wojciech Grudzinski, Michal Puzio, Karol Sowinski, Wieslaw I Gruszecki
The main physiological function of LHCII (light-harvesting pigment-protein complex of photosystem II), the largest photosynthetic antenna complex of plants, is absorption of light quanta and transfer of excitation energy toward the reaction centers, to drive photosynthesis. However, under strong illumination, the photosynthetic apparatus faces the danger of photodegradation and therefore excitations in LHCII have to be down-regulated, e.g., via thermal energy dissipation. One of the elements of the regulatory system, operating in the photosynthetic apparatus under light stress conditions, is a conversion of violaxanthin, the xanthophyll present under low light, to zeaxanthin, accumulated under strong light...
December 29, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27973570/use-of-fluorescence-lifetime-imaging-microscopy-flim-as-a-timer-of-cell-cycle-s-phase
#18
Irina A Okkelman, Ruslan I Dmitriev, Tara Foley, Dmitri B Papkovsky
Incorporation of thymidine analogues in replicating DNA, coupled with antibody and fluorophore staining, allows analysis of cell proliferation, but is currently limited to monolayer cultures, fixed cells and end-point assays. We describe a simple microscopy imaging method for live real-time analysis of cell proliferation, S phase progression over several division cycles, effects of anti-proliferative drugs and other applications. It is based on the prominent (~ 1.7-fold) quenching of fluorescence lifetime of a common cell-permeable nuclear stain, Hoechst 33342 upon the incorporation of 5-bromo-2'-deoxyuridine (BrdU) in genomic DNA and detection by fluorescence lifetime imaging microscopy (FLIM)...
2016: PloS One
https://www.readbyqxmd.com/read/27959558/sodium-chloride-triggered-the-fusion-of-vesicle-composed-of-fatty-acid-modified-protic-ionic-liquid-a-new-insight-into-the-membrane-fusion-monitored-through-fluorescence-lifetime-imaging-microscopy
#19
Niloy Kundu, Pavel Banerjee, Sangita Kundu, Rupam Dutta, Nilmoni Sarkar
The development of stable vesicular assemblies and the understanding of their interaction and dynamics in aqueous solution are long-standing topics in the research of chemistry and biology. Fatty acids are known to form vesicle structure in aqueous solution depending on the pH of the medium. Protic ionic liquid of fatty acid with ethyl amine (oleate ethyl amine, OEA) as a component spontaneously forms a vesicle in aqueous solution. The general comparison of dynamics and interaction of these two vesicles have been drawn using fluorescence correlation spectroscopy (FCS) and fluorescence lifetime imaging microscopy (FLIM) measurements...
December 28, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27951700/proton-transfer-pathways-of-2-2-bipyridine-3-3-diol-in-ph-responsive-fatty-acid-self-assemblies-multiwavelength-fluorescence-lifetime-imaging-in-a-single-vesicle
#20
Niloy Kundu, Pavel Banerjee, Rupam Dutta, Sangita Kundu, Rajesh Kumar Saini, Mintu Halder, Nilmoni Sarkar
Fatty acids are known to form different supramolecular aggregates in aqueous solutions depending on the pH of the medium. The dynamics of the transformation of oleate micelles into oleic acid/oleate vesicles has been investigated using a pH-sensitive intramolecular proton transfer fluorophore, 2,2'-bipyridine-3,3'-diol [BP(OH)2]. Different prototropic forms of BP(OH)2 exist in different pH values of the system, and thus, the ground state and the excited state dynamics of BP(OH)2 have been modulated in these confined media...
December 13, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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