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Results for “Fluorescence Microscopy”

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At least 451 records · Page 25Linked to original sources
PubMed1996

A method for co-localization of tubular lysosomes and microtubules in macrophages: fluorescence microscopy of individual cells.

Routinely used procedures for chemical fixation often fail to preserve delicate membrane-bounded tubular structures in a variety of cell types. Fixation procedures commonly employed in immunocytochemical studies for localization of structural proteins, such as those found in cytoskeletal elements, may also degrade these tubular structures. Here we describe a procedure that preserves the elaborate tubular lysosome system found in stimulated macrophages and allows the subsequent immunofluorescence localization of microtubules in the same cells. Use of this methodology permits the assessment of the spatial relationship between tubular lysosomes and microtubules in macrophages.

Animals↗
PubMed1992

The localization of myosin I and myosin II in Acanthamoeba by fluorescence microscopy.

We used several fixation protocols and a panel of monoclonal antibodies to re-examine the localization of myosin I and myosin II in Acanthamoeba. Two monoclonal antibodies that bind to the head of myosin II stain a range of particles in the cytoplasm. The smallest and most numerous cytoplasmic particles are about the same size and intensity as myosin II minifilaments and are distributed throughout the endoplasm. The largest particles stain like myosin II thick filaments and are concentrated in the cleavage furrow of dividing cells and in the tail of locomoting cells. Five different monoclonal antibodies that bind to the myosin II tail also stain cytoplasmic particles but with a limited range of intensity. None of the myosin II monoclonal antibodies stains the contractile vacuole or plasma membrane. Two monoclonal antibodies to myosin I gave punctate cytoplasmic staining that did not correspond clearly to any of the phase-dense particles in the cytoplasm. In many, but not all, locomoting cells, the myosin I staining was concentrated at the leading edge. Both myosin I antibodies stained a single cytoplasmic vacuole of variable size that was presumed to be the contractile vacuole. The antibody that binds myosin IA but not myosin IB stained novel intercellular contacts and the antibody that binds both myosin IA and myosin IB stained the plasma membrane, especially the tips of filopodia.

Acanthamoeba↗
PubMed2004

Depth-variant maximum-likelihood restoration for three-dimensional fluorescence microscopy.

We derive an algorithm for maximum-likelihood image estimation on the basis of the expectation-maximization (EM) formalism by using a new approximate model for depth-varying image formation for optical sectioning microscopy. This new strata-based model incorporates spherical aberration that worsens as the microscope is focused deeper under the cover slip and is the result of the refractive-index mismatch between the immersion medium and the mounting medium of the specimen. Images of a specimen with known geometry and refractive index show that the model captures the main features of the image. We analyze the performance of the depth-variant EM algorithm with simulations, which show that the algorithm can compensate for image degradation changing with depth.

Algorithms↗
PubMed2005

Three-dimensional characterization of tethered microspheres by total internal reflection fluorescence microscopy.

Tethered particle microscopy is a powerful tool to study the dynamics of DNA molecules and DNA-protein complexes in single-molecule experiments. We demonstrate that stroboscopic total internal reflection microscopy can be used to characterize the three-dimensional spatiotemporal motion of DNA-tethered particles. By calculating characteristic measures such as symmetry and time constants of the motion, well-formed tethers can be distinguished from defective ones for which the motion is dominated by aberrant surface effects. This improves the reliability of measurements on tether dynamics. For instance, in observations of protein-mediated DNA looping, loop formation is distinguished from adsorption and other nonspecific events.

DNA↗
PubMedDate not supplied

Localization of wheat germ agglutinin lectin receptors on human sperm by fluorescence microscopy: utilization of different fixatives.

Wheat germ agglutinin (WGA) and Concanavalin A (Con A) seem to be the most widely studied of the lectins used to investigate sperm surface receptors. It has been reported that WGA receptors on human sperm membranes may be closely related to male fertility and that WGA receptor deficiency may cause human infertility. Although these claims may not be negated, there are many discrepancies in current literature regarding the localization and detection of human sperm WGA receptors. These discrepancies are probably the result of variations in the pretreatment of sperm before fixation and sperm-lectin interaction. This study investigated the effect of different fixation procedures on the localization of human sperm WGA receptors on normal spermatozoa. Comparative studies were performed on spermatozoa separated by wash-swim-up and fixed with 4% formaldehyde, 95% ethanol, or Bouin's solution, or nonfixed (air-dried) using fluorescein isothiocyanate-conjugated WGA. There were significant differences (p < .01) in the % WGA receptor localization following the different fixation procedures on samples receiving the same treatment previous to fixation. The different fixatives affect the plasma membrane to different degrees, resulting in an alteration of lectin receptor localization. To allow a better comparison and understanding of results, a standardized preparation procedure is recommended during studies using lectins as molecular probes. The results suggest than an aldehyde fixative may be the fixative of choice for sperm membrane studies.

Cell Membrane↗