JoVE General
FRET Microscopy for Real-time Monitoring of Signaling Events in Live Cells Using Unimolecular Biosensors
Förster resonance energy transfer (FRET) microscopy is a powerful technique for real-time monitoring of signaling events in live cells using various biosensors as reporters. Here we describe how to build a customized epifluorescence FRET imaging system from commercially available components and how to use it for FRET experiments.
JoVE Bioengineering
Quantitative FRET (Förster Resonance Energy Transfer) Analysis for SENP1 Protease Kinetics Determination
Department of Bioengineering, Bourns College of Engineering, University of California, Riverside
A novel method involving quantitative analysis of FRET (Förster Resonance Energy Transfer) signals is described for studying enzyme kinetics. KM and kcat were obtained for the hydrolysis of the catalytic domain of SENP1 (SUMO/Sentrin specific protease 1) to pre-SUMO1 (Small Ubiquitin-like MOdifier). The general principles of this quantitative-FRET-based protease kinetic study can be applied to other proteases.
JoVE General
Monitoring Kinase and Phosphatase Activities Through the Cell Cycle by Ratiometric FRET
Department of Cell and Molecular Biology, Karolinska Institutet
FRET-based reporters are increasingly used to monitor kinase and phosphatase activities in live cells. Here we describe a method on how to use FRET-based reporters to assess cell cycle-dependent changes in target phosphorylation.
JoVE General
Imaging Protein-protein Interactions in vivo
Biochemistry and Molecular Biology, Virginia Commonwealth University
This protocol describes how to image protein-protein interactions using a FRET-based proximity assay.
JoVE General
Real-time Monitoring of Ligand-receptor Interactions with Fluorescence Resonance Energy Transfer
Department of Chemistry and Biochemistry, Southern Illinois University
We demonstrate FRET between conjugated polymer polydiacetylene (PDA) and fluorophore attached to the surface of PDA liposomes for the sensing of biomolecules. PDA liposomes also contained receptor molecules on their surfaces for biomolecules to be used as probes. Ligand-receptor interactions lead to changes in the FRET efficiency between the fluorophore and PDA which is the basis of the sensing mechanism.
JoVE General
Combining QD-FRET and Microfluidics to Monitor DNA Nanocomplex Self-Assembly in Real-Time
1Mechanical Engineering, Johns Hopkins University, 2Biomedical Engineering, Duke University, 3Biomedical Engineering, Johns Hopkins University
We present a novel and powerful integration of nanophotonics (QD-FRET) and microfluidics to investigate the formation of polyelectrolyte polyplexes, which is expected to provide better control and synthesis of uniform and customizable polyplexes for future nucleic acid-based therapeutics.
JoVE General
Measuring Peptide Translocation into Large Unilamellar Vesicles
1Department of Chemistry, Wellesley College,
This protocol details a method for the quantitative measure of peptide translocation into large unilamellar lipid vesicles. This method also provides information about the rate of membrane translocation and can be used to identify peptides that efficiently and spontaneously cross lipid bilayers.
JoVE General
In vivo Quantification of G Protein Coupled Receptor Interactions using Spectrally Resolved Two-photon Microscopy
1Department of Physics, University of Wisconsin - Milwaukee, 2Department of Biological Sciences, University of Wisconsin - Milwaukee
By employing a spectrally resolved two-photon microscopy imaging system, pixel-level maps of Förster Resonance Energy Transfer (FRET) efficiencies are obtained for cells expressing membrane receptors hypothesized to form homo-oligomeric complexes. From the FRET efficiency maps, we are able to estimate stoichiometric information about the oligomer complex under study.
JoVE General
Real-time Analyses of Retinol Transport by the Membrane Receptor of Plasma Retinol Binding Protein
Here we describe an optimized technique to produce high-quality vitamin A/RBP complex and two real-time monitoring techniques to study vitamin A transport by STRA6, the RBP receptor.
JoVE General
Automated System for Single Molecule Fluorescence Measurements of Surface-immobilized Biomolecules
1Physics Department, Boston University, 2Department of Biomedical Engineering, Boston University
In this article we describe how we obtain FRET traces from individual DNA molecules immobilized to a surface using an automated scanning confocal microscope.
JoVE Bioengineering
Time-lapse Fluorescence Imaging of Arabidopsis Root Growth with Rapid Manipulation of The Root Environment Using The RootChip
1Department of Plant Biology, Carnegie Institution for Science, 2Howard Hughes Medical Institute, 3Departments of Applied Physics and Bioengineering, Stanford University, 4Department of Microsystems Engineering (IMTEK) and Center for Biological Signaling Studies (BIOSS), University of Freiburg
This article provides a protocol for cultivation of Arabidopsis seedlings in the RootChip, a microfluidic imaging platform that combines automated control of growth conditions with microscopic root monitoring and FRET-based measurement of intracellular metabolite levels.
JoVE General
Bimolecular Fluorescence Complementation
Department of Pharmacology, University of Illinois at Chicago
The subcellular localization of proteins is important in determining the spatio-temporal regulation of cell signaling. Here, we describe bimolecular fluorescence complementation (BiFC) as a straightforward method for monitoring the spatial interactions of proteins in the cell.
JoVE Bioengineering
Microfluidic Mixers for Studying Protein Folding
1Department of Physics and Astronomy, Michigan State University, 2Department of Mechanical Engineering, Hong Kong University of Science and Technology, 3Center for Biophotonics, University of California, Davis
In this work we explain the fabrication and use of a microfluidic mixer capable of mixing two solutions in ~8 μs. We also demonstrate the use of these mixers with spectroscopic detection using UV fluorescence and fluorescence resonance energy transfer (FRET).
JoVE General
Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Here, we describe detailed live cell imaging methods for investigating chemotaxis. We present fluorescence microscopic methods to monitor spatiotemporal dynamics of signaling events in migrating cells. Measurement of signaling events permits us to further understand how a GPCR-signaling network achieves gradient sensing of chemoattractants and controls directional migration of eukaryotic cells.
JoVE Neuroscience
In vivo Neuronal Calcium Imaging in C. elegans
1Department of Physiology and Biophysics, Boston University School of Medicine, 2Boston University Photonics Center
With its small transparent body, well-documented neuroanatomy and a host of amenable genetic techniques and reagents, C. elegans makes an ideal model organism for in vivo neuronal imaging using relatively simple, low-cost techniques. Here we describe single neuron imaging within intact adult animals using genetically encoded fluorescent calcium indicators.
JoVE General
DNA Transfection of Mammalian Skeletal Muscles using In Vivo Electroporation
Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles
We describe detailed procedures for the efficient transfection of plasmid DNA into the fibers of foot muscles of live mice using electroporation and the subsequent visualization of protein expression using fluorescence microscopy.
JoVE Immunology and Infection
Real-time Imaging of Leukotriene B4 Mediated Cell Migration and BLT1 Interactions with β-arrestin
Microbiology and Immunology, James Graham Brown Cancer Center, University of Louisville
This paper describes the methodology to determine the chemotactic response of leukocytes to specific ligands and identify interactions between the cell surface receptors and cytosolic proteins using live cell imaging techniques.
JoVE General
Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation (BiFC) System
1Department of Biology, University of Western Ontario, 2Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada
We have developed a technique to test protein-protein interactions in plant. A yellow fluorescent protein (YFP) is split into two non-overlapping fragments. Each fragment is cloned in-frame to a gene of interest via Gateway system, enabling expression of fusion proteins. Reconstitution of YFP signal only occurs when the inquest proteins interact.
JoVE Editorial
The 2009 Lindau Nobel Laureate Meeting: Roger Y. Tsien, Chemistry 2008
American biochemist Roger Tsien shared the 2008 Nobel Prize in Chemistry with Martin Chalfie and Osamu Shimomura for their discovery and development of the Green Fluorescent Protein (GFP). Tsien dramatically improved the wild-type GFP resulting in increased fluorescence, increased photostability, and a shift in the major excitation peak to 488 nm (matching FITC).
JoVE General
Detection of Signaling Effector-Complexes Downstream of BMP4 Using in situ PLA, a Proximity Ligation Assay
Medical Research Council, Clinical Sciences Centre, Imperial College, Hammersmith Hospital
Here we show how to use Proximity Ligation Assay (PLA), with a combination of antibodies to visualize Bone Morphogenetic Protein (BMP) signaling in fixed cells. This technique allowed us to follow the nuclear accumulation of endogenous BMP activated effector-complexes and quantify their levels over time under BMP4 stimulation.
JoVE Neuroscience
Spectral Confocal Imaging of Fluorescently tagged Nicotinic Receptors in Knock-in Mice with Chronic Nicotine Administration
Department of Biology, University of Victoria
We have developed a novel technique of quantifying nicotinic acetylcholine receptor changes within subcellular regions of specific subtypes of CNS neurons to better understand the mechanisms of nicotine addiction by using a combination of approaches including fluorescent protein tagging of the receptor using the knock-in approach and spectral confocal imaging.
JoVE General
Fluorescent Labeling of COS-7 Expressing SNAP-tag Fusion Proteins for Live Cell Imaging
Division of Chemical Biology, New England Biolabs
SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest in live cells. Once cloned and expressed, the tagged protein can be used with a variety of substrates for numerous downstream applications without having to clone again.
JoVE Bioengineering
Fluorescence detection methods for microfluidic droplet platforms
1Department of Chemistry, Imperial College London, 2Department of Biochemistry, Protein Chip Research Center, Chungbuk National University, 3Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich
Droplet-based microfluidic platforms are promising candidates for high throughput experimentation since they are able to generate picoliter, self-compartmentalized vessels inexpensively at kHz rates. Through integration with fast, sensitive and high resolution fluorescence spectroscopic methods, the large amounts of information generated within these systems can be efficiently extracted, harnessed and utilized.
JoVE Bioengineering
In vitro Assembly of Semi-artificial Molecular Machine and its Use for Detection of DNA Damage
1Neurosurgery, Baylor College of Medicine, 2Michael E. DeBakey Veterans Affairs Medical Center, 3Molecular & Cellular Biology, Baylor College of Medicine
We demonstrate the assembly and application of a molecular-scale device powered by a topoisomerase protein. The construct is a bio-molecular sensor which labels two major types of DNA breaks in tissue sections by attaching two different fluorophores to their ends.
JoVE General
Heterokaryon Technique for Analysis of Cell Type-specific Localization
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute- WPI
A flexible and efficient method for the characterization of cell type-specific protein localization and nucleocytoplasmic shuttling is described. This heterokaryon approach uses fluorescently-labeled fusion proteins to image protein localizations after cell fusion. The protocol is amenable to steady-state localizations or more dynamic determinations based on live cell imaging.
JoVE Bioengineering
Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
1Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University, 2Graduate School of Pharmaceutical Sciences, University of Tokyo, 3Biomedical Engineering, Johns Hopkins University
A method for spatio-temporal control of small GTPase activity by light is described. This method is based on rapamycin-induced FKBP-FRB heterodimerization and photo-caging systems. Optimization of light-irradiation enables the spatio-temporally controlled activation of small GTPases at the subcellular level.
JoVE Bioengineering
Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry
1Biomedical Engineering Department, Johns Hopkins University School of Medicine, 2Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, 3Wilmer Eye Institute, Johns Hopkins University School of Medicine, 4Institute for Nanobiotechnology, Johns Hopkins University School of Medicine
A protocol for nanoparticle tracking analysis (NTA) and high-throughput flow cytometry to evaluate polymeric gene delivery nanoparticles is described. NTA is utilized to characterize the nanoparticle particle size distribution and the plasmid per particle distribution. High-throughput flow cytometry enables quantitative transfection efficacy evaluation for a library of gene delivery biomaterials.
JoVE Neuroscience
Analyzing Murine Schwann Cell Development Along Growing Axons
1Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg, 2Department of Neuroanatomy, University of Heidelberg, 3FRIAS, University of Freiburg
Here we describe a Schwann cell (SC) migration assay in which SCs are able to develop along extending axons.
JoVE General
Synthesis and Calibration of Phosphorescent Nanoprobes for Oxygen Imaging in Biological Systems
Department of Biochemistry and Biophysics, University of Pennsylvania
We present principles of oxygen measurements by phosphorescence quenching and review design of porphyrin-based dendritic nanosensors for oxygen imaging in biological systems.
JoVE General
Quantitative, Real-time Analysis of Base Excision Repair Activity in Cell Lysates Utilizing Lesion-specific Molecular Beacons
1Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, 2Hillman Cancer Center, University of Pittsburgh Cancer Institute, 3Department of Experimental Therapy, The Netherlands Cancer Institute, 4Department of Human Genetics, University of Pittsburgh School of Public Health
We describe a method for the quantitative, real-time measurement of DNA glycosylase and AP endonuclease activities in cell nuclear lysates. The assay yields rates of DNA Repair activity amenable to kinetic analysis and is adaptable for quantification of DNA Repair activity in tissue and tumor lysates or with purified proteins.
JoVE General
Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
1Department of Radiation Oncology, Virginia Commonwealth University, 2Department of Biochemistry & Molecular Biology, Virginia Commonwealth University, 3Department of Anatomy & Neurobiology, Virginia Commonwealth University, 4Massey Cancer Center, Virginia Commonwealth University
This protocol describes a method for visualizing a DNA double-strand break signaling protein activated in response to DNA damage as well as its localization during mitosis.
JoVE Immunology and Infection
Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs
1Department of Biomedical Engineering, Vanderbilt University, 2Vanderbilt Institute for Nanoscale Science & Engineering, Vanderbilt University, 3Interdisciplinary Materials Science Program, Vanderbilt University, 4Monroe Carell Jr. Children's Hospital, Vanderbilt University Medical Center, 5Department of Chemical & Biomolecular Engineering, Vanderbilt University, 6Department of Cancer Biology, Vanderbilt University
A hemolysis assay can be used as a rapid, high-throughput screen of drug delivery systems' cytocompatibility and endosomolytic activity for intracellular cargo delivery. The assay measures the disruption of erythrocyte membranes as a function of environmental pH.
JoVE General
Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute
We will describe a method which measures the kinetics of ion transport of membrane proteins alongside site-specific analysis of conformational changes using fluorescence on single cells. This technique is adaptable to ion channels, transporters and ion pumps and can be utilized to determine distance constraints between protein subunits.
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