contrast Protocols

Category: Microscopy Protocols: Optical Microscopy Protocols

When imaging specimens in the optical microscope, differences in intensity and/or color create image contrast, which allows individual features and details of the specimen to become visible. Contrast is defined as the difference in light intensity between the image and the adjacent background relative to the overall background intensity. In general, a minimum contrast value of 0.02 (2 percent) is needed by the human eye to distinguish differences between the image and its background. - [Read Contrast in Optical Microscopy]

Category: RNAi Technology Protocols: RNAi C. elegans Protocols

Cosuppression is a process in Caenorhabditis elegans that closely resembles RNAi.  In contrast to RNAi, however, the cosuppression effect in C. elegans does not spread throughout the animal.  Cosuppression in C. elegans can be triggered by highly repetitive transgenes that contain gene constructs. - [Read Cosuppression in C. elegans Protocol]

Category: Cytogenetics Protocols

CGH provides a comprehensive picture of all chromosomal gains and losses within a single experiment. In contrast to banding analysis, CGH requires no preparation of metaphase chromosomes from the cells to be analyzed (which in certain tumor types may be difficult or even impossible). - [Read Detection of Chromosomal Imbalances Using DOP-PCR and Comparative Genomic Hybridization (CGH)]

Category: Microscopy Protocols: Fluorescence Microscopy Protocols

Most biological specimens are relatively transparent, so details of internal and intracellular morphology are difficult to image in untreated living specimens using simple bright-field techniques. Fluorescence microscopy offers greater advantages and possibilities for increasing contrast and determining the specific localization of molecules in cells. Article outlines the three methods most commonly used to introduce an appropriate label into Drosophila tissue without perturbing the process. - [Read Fluorescent Reagents for Live Cell Imaging and Their Introduction into Cells]

Category: Cytoskeleton Protocols: Actin Myosin Protocols

The same GFP-tagged actin construct used in cell transfection experiments has been used to produce transgenic mice. Transgenic animals allow the imaging of brain tissue in the intact animal, as acutely cut slices or as organotypic slice cultures. They also serve as a source of cells for imaging neurons at high resolution in dispersed low-density cell culture. In contrast to cells transfected in culture, where the level of actin-GFP expression in neurons varies considerably, transgenic mice... - [Read Imaging Actin in Tissue Slices from Transgenic Mouse Brain Protocol]

Category: Molecular Imaging: Light Microscopy

Light Microscopy - Microscopes in Cell Biology. House Ear Institute. Fluorescence microscopy, Nomarski differential interference contrast, Comparison between phase contrast and interference contrast optical systems , Interference contrast, Phase contrast, Darkfield illumination, alignment of Kohler illumination system, Protocol for using oil immersion lenses, Use of immersion oil, Calculating the final magnification on the photomicrograph, vibration, The coverslip glass, Photomicroscopy. - [Read Light Microscopy - Microscopes in Cell Biology]

Category: C. elegans Protocols

At low magnification, dissection microscopes are useful, whereas at higher magnification and resolution, a wide range of optical methods can be used, including differential interference contrast (DIC) optics, phase contrast, fluorescence, polarized light, confocal, and dark field. - [Read Live Imaging of Caenorhabditis elegans: Observation of Nematodes and Data Collection Protocol]

Category: Microscopy Protocols: Optical Microscopy Protocols

Diffraction-limited optical microscopy requires that the spatial resolution of an image is limited by the wavelength of the incident light & by the numerical apertures of the condenser & objective lens systems.The development of near-field scanning optical microscopy (scanning near-field optical microscopy) has allowed for a imaging technique that retains the various contrast mechanisms afforded by optical microscopy methods while attaining spatial resolution beyond the optical diffraction limit - [Read Near-Field Scanning Optical Microscopy]