1Department of Pulmonary Diseases, Institute for Cardiovascular Research, VU University Medical Center, 2Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center
This protocol reviews Electric Cell-substrate Impedance Sensing, a method to record and analyze the impedance spectrum of adherent cells for the quantification of cell attachment, proliferation, motility, and cellular responses to pharmacological and toxic stimuli. Detection of endothelial permeability and assessment of cell-cell and cell-substrate contacts are emphasized.
Published March 28, 2014. Keywords: Bioengineering, ECIS, Impedance Spectroscopy, Resistance, TEER, Endothelial Barrier, Cell Adhesions, Focal Adhesions, Proliferation, Migration, Motility, Wound Healing
1Department of Biophysical Chemistry, Max Planck Institute of Biophysics, 2Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt
Here we present an electrophysiological method based on solid supported membranes with focus on its applications for the characterization of electrogenic membrane transporters.
Published May 11, 2013. Keywords: Biochemistry, Biophysics, Molecular Biology, Cellular Biology, Physiology, Proteins, Membrane Lipids, Membrane Transport Proteins, Kinetics, Electrophysiology, solid supported membrane, SSM, membrane transporter, lactose permease, lacY, capacitive coupling, solution exchange, model membrane, membrane protein, transporter, kinetics, transport mechanism
JoVE Applied Physics
1Experimental Molecular Biophysics, Freie Universität Berlin
Key steps of protein function, in particular backbone conformational changes and proton transfer reactions, often take place in the microsecond to millisecond time scale. These dynamical processes can be studied by time-resolved step-scan Fourier-transform infrared spectroscopy, in particular for proteins whose function is triggered by light.
Published June 27, 2014. Keywords: Biophysics, bacteriorhodopsin, channelrhodopsin, attenuated total reflection, proton transfer, protein dynamics, infrared spectroscopy, time-resolved spectroscopy, step-scan, membrane proteins, singular value decomposition
1Molecular and Cell Biology, University of Connecticut, 2University of Connecticut
The ECIS/Taxis system is an automated, real-time assay that measures cellular chemotaxis. In this assay, cells move beneath a layer of agarose to arrive at a target electrode. Cellular movement is measured by the onset of resistance to AC current 0.
Published April 1, 2012. Keywords: Cellular Biology, Electric Cell- substrate Impedance Sensing, ECIS, ECIS/Taxis, Chemotaxis
1Nanoscale Engineering Graduate Program, College of Nanoscale Science and Engineering, University at Albany, State University of New York, 2Nanoscale Science Undergraduate Program, College of Nanoscale Science and Engineering, University at Albany, State University of New York, 3Nanobioscience Constellation, College of Nanoscale Science and Engineering, University at Albany, State University of New York, 4The RNA Institute, University at Albany, State University of New York, 5Department of Biological Sciences, University at Albany, State University of New York
Optical tweezers have been used to study RNA folding by stretching individual molecules from their 5’ and 3’ ends. Here common procedures are described to synthesize RNA molecules for tweezing, calibration of the instrument, and methods to manipulate single molecules.
Published August 20, 2014. Keywords: Bioengineering, RNA folding, single-molecule, optical tweezers, nanomanipulation, RNA secondary structure, RNA tertiary structure
1Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology
Magnetic tweezers, a powerful single-molecule manipulation technique, can be adapted for the direct measurements of the twist (using a configuration called freely-orbiting magnetic tweezers) and torque (using a configuration termed magnetic torque tweezers) in biological macromolecules. Guidelines for performing such measurements are given, including applications to the study of DNA and associated nucleo-protein filaments.
Published May 19, 2014. Keywords: Bioengineering, magnetic tweezers, magnetic torque tweezers, freely-orbiting magnetic tweezers, twist, torque, DNA, single-molecule techniques
1LSA Biophysics, University of Michigan, 2LSA Biophysics, Department of Physics, University of Michigan
We illustrate the use of a constant force axial optical tweezers to explore the mechanical properties of short DNA molecules. By stretching DNA axially, we minimize steric hindrances and artifacts arising in conventional lateral manipulation, allowing us to study DNA molecules as short as ~100 nm.
Published October 13, 2011. Keywords: Bioengineering, Genetics, DNA stretching, DNA, Axial Optical Tweezers, Single-Molecule Biophysics, Biophysics
1Institute of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, 2Departments of Chemistry and Physics, McGill University
This paper provides a step by step guide to the fluctuation analysis technique k-Space Image Correlation Spectroscopy (kICS) for measuring diffusion coefficients of fluorescently labeled plasma membrane proteins in live mammalian cells.
Published May 10, 2014. Keywords: Biophysics, Amino Acids, Peptides and Proteins, Computer Programming and Software, Diffusion coefficient, Aquaporin-3, k-Space Image Correlation Spectroscopy, Analysis
1Institute of Chemistry, Technical University of Berlin, 2The Vollum Institute, Oregon Health & Science University
We describe a method to quantify the activity of K+-countertransporting P-type ATPases by heterologous expression of the enzymes in Xenopus oocytes and measuring Rb+ or Li+ uptake into individual cells by atomic absorption spectrophotometry. The method is a sensitive and safe alternative to radioisotope flux experiments facilitating complex kinetic studies.
Published February 19, 2013. Keywords: Biochemistry, Chemistry, Biophysics, Bioengineering, Physiology, Molecular Biology, electrochemical processes, physical chemistry, spectrophotometry (application), spectroscopic chemical analysis (application), life sciences, temperature effects (biological, animal and plant), Life Sciences (General), Na+, K+-ATPase, H+, K+-ATPase, Cation Uptake, P-type ATPases, Atomic Absorption Spectrophotometry (AAS), Two-Electrode Voltage-Clamp, Xenopus Oocytes, Rb+ Flux, Transversely Heated Graphite Atomizer (THGA) Furnace, electrophysiology, animal model
1Program in Biophysics, Harvard University, 2Division of Health Sciences and Technology, Harvard-MIT, 3Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School
The complete construction of a custom, real-time confocal scanning imaging system is described. This system, which can be readily used for video-rate microscopy and microendoscopy, allows for an array of imaging geometries and applications not accessible using standard commercial confocal systems, at a fraction of the cost.
Published October 20, 2011. Keywords: Bioengineering, Microscopy, confocal microscopy, microendoscopy, video-rate, fluorescence, scanning, in vivo imaging