principle Protocols

Category: Signalling Signal Transduction Protocols

Assay of cytokines in tissue culture supernatants describes a liquid suspension array for quantification of cytokines in tissue culture supernatants or serum. With this assay, it is possible to profile the level of multiple cytokines in a single well. The principle of this cytokine assay is similar to a capture sandwich immunoassay. Includes: Preparation for the Assay, Cytokine Assay, Reagents and Materials. - [Read Assay of Cytokines in Tissue Culture Supernatants]

Category: Microscopy Protocols: Optical Microscopy Protocols

The visibility of the faint star light is enormously enhanced against a dark background. This principle is applied in darkfield (also called darkground) microscopy, a simple and popular method for making unstained transparent specimens clearly visible. Such objects often have refractive indices very close in value to that of their surroundings and are difficult to image in conventional brightfield microscopy. - [Read Darkfield Illumination]

Category: DNA Protocols: EMSA DNA-Protein Protocols

Magnetic DNA affinity purification of yeast transcription factor tau--a new purification principle for the ultrarapid isolation of near homogeneous factor. Gabrielsen et al. 1989 - [Read DNA-Binding Protein Purification with Dynabeads.]

Category: Microscopy Protocols: Electron Microscopy Protocols

The scanning transmission electron microscope precision and reproducibility of mass measurements are comparable with those of the analytical ultracentrifuge, the possibility of determining the mass not only of entire supramolecular assemblies but also of their distinct components has opened exciting new avenues which have occasionally been entered but are not yet fully explored. Includes: Principle and application (The GroEL:GroES complex). - [Read Imaging and Measuring Biomolecules & Their Assemblies by Scanning Transmission Electron Microscopy]

Category: Microscopy Protocols

The atomic force microscope (AFM) is one of the most powerful tools for determining the surface topography of native biomolecules at subnanometer resolution. The AFM can also provide insight into the binding properties of biological systems. In order to determine the specific interaction between two kinds of molecules (e.g., avidin and biotin). Includes information on principle of AFM and application of AFM. - [Read Imaging, Measuring and Manipulating Native Biomolecular Systems with the Atomic Force Microscope]

Category: Cloning Protocols

Protocol can be used to optimize ligation conditions for difficult to clone (e.g. very large) fragments. The principle is to independently characterize the ligation kinetics of the vector and insert DNA fragments and then to combine them in optimal ratios. - [Read Ligation Optimization Protocol]

Category: Microscopy Protocols: Confocal Microscopy Protocols

Confocal laser scanning microscopy (CLSM) is a relatively new light microscopical imaging technique which has found wide applications in the biological sciences. The primary value of the CLSM to the biologist is its ability to produce optical sections through a 3-D specimen-e.g., an entire cell or a piece of tissue - that, to a good approximation, contain information from only one focal plane. Article includes principle and applications of confocal laser scanning microscope. - [Read Looking Inside Cells and Tissues by Optical Sectioning with a Confocal Laser Scanning Microscope]

Category: Microscopy Protocols: Fluorescence Microscopy Protocols

Multiphoton fluorescence microscopy is a powerful new technology that enables the acquisition of optical sections without the use of a pinhole aperture typically used for confocal microscopy. The technique is based upon the two-photon principle: A fluorescent molecule simultaneously absorbs two photons producing an electronic transition from the ground to excited state equal to two times the energy of each incident photon. - [Read Multiphoton Images from LSM 510 NLO System]

Category: Immunohistochemistry Protocols: Antibody Staining Protocols

Frozen tissue sections show good preservation of tissue structure and antigens. The principle disadvantages of using them in immunostaining are that the specimens must be stored frozen, and a special microtome, known as a cryostat, is required. Also, many clinical specimens are not available in this form, and most classic histological descriptions of tissue structure and pathology are based on the use of paraffin-embedded sections of formalin-fixed material. - [Read Preparing Frozen Tissue Sections for Immunostaining Protocol]

Category: Immunohistochemistry Protocols: Antigen Retrieval Protocols

Several methods have been developed to "retrieve" antigens that have been masked by fixation. The principle behind using the microwave oven method described here is to use extended periods of heat to break some of the subcellular structures that block antibody access. Be aware that any of the antigen retrieval methods should be avoided wherever possible, because they may introduce artifactual false-positive staining. - [Read Unmasking Hidden Epitopes Using the Microwave Oven Protocol]

Category: Immunohistochemistry Protocols: Antigen Retrieval Protocols

The principle behind the pressure cooker method described here is to use extended periods of heat to break some of the subcellular structures that block antibody access. This approach is appropriate for handling specimens on glass slides. The major advantages of the pressure cooker method are the ability to handle a large number of slides simultaneously, the convenience of using metal racks, and the avoidance of any hot spots that are found in the microwave. - [Read Unmasking Hidden Epitopes Using the Pressure Cooker Protocol]