Electronic Microscopy of Olygomerous Ferments

Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Helical Structure of Hair Cell Stereocilia Tip Links In the Chinchilla Cochlea

Outer-hair-cell stereocilia tip-link structure in the chinchilla cochlea was studied by transmission electron microscopy using tannic acid and Ruthenium red/Alcian blue histochemical procedures. Tannic acid and Ruthenium red/Alcian blue treatments showed the tip link as a compact strand of filaments 9–12 nm thick. Fourier analysis of tip-link images showed that the strand is a three-start helical bundle of fine, coiled filaments which had an axial period of 22.5 ± 1.5 nm. Each of three coiled filaments in the strand showed globular structures, 4.3 ± 0.3 nm in diameter. The globular structures may correspond to individual protein subunits or they may be repeating identical domains of one polypeptide. The three filaments of the helical array may provide a rigidity to the tip link during stereocilia deflections. Alternatively, changes in the subunit or domain structure of each filament may result in a lengthening or shortening of the tip-link strand

Electron microscopy and image analysis of the GroEL-like protein and its complexes with glutamine synthetase from pea leaves

The molecular structure of groEL-like protein from pea leaves has been studied by electron microscopy and image analysis of negatively stained particles. Over 1500 molecular projections were selected and classified by multivariate statistical analysis. It was shown that the molecule consists of 14 subunits arranged in two layers with 72 point group symmetry. Side view projections of the molecule show a four-striation appearance, which subdivides both layers of seven subunits into two halves; this may be explained by a two-domain structure of the subunits. The presence in protein preparations of projections corresponding to one layer of subunits or half-molecules is consistent with the molecular structure suggested. Electron microscopic evidence for a specific association of GroEL-like protein and octameric glutamine synthetase, which was co-purified with this protein, was obtained

The Structure of Tip Links and Kinocilial Links in Avian Sensory Hair Bundles

Recent studies have indicated that the tip links and kinocilial links of sensory hair bundles in the inner ear have similar properties and share a common epitope, and that cadherin 23 may also be a component of each link type. Transmission electron microscopy was therefore used to study and compare the fine structure of the tip links and kinocilial links in avian sensory hair bundles. Tannic acid treatment revealed a thin strand, 150¿200nm long and 8¿11nm thick, present in both link types. Fourier analysis of link images showed that the strand of both link types is formed from two filaments coiled in a helix-like arrangement with an axial period of 20¿25nm, with each filament composed of globular structures that are ~4nm in diameter. Differences in the radius and period of the helix-like structure may underlie the observed variation in the length of tip and kinocilial links. The similar helix-like structure of the tip links and kinocilial links is in accord with the presence of a common cell-surface antigen (TLA antigen) and similarities in the physical and chemical properties of the two link types. The spacing of the globular structures comprising each filament of the two link types is similar to the 4.3nm center-to-center spacing reported for the globular cadherin repeat, and is consistent with the suggestion that cadherin 23 is the tip link

Pathologic changes of the peripheral vestibular system secondary to Chronic Otitis media

To evaluate the histopathologic changes of dark, transitional, and hair cells of the vestibular system in human temporal bones from patients with chronic otitis media. Study Design Comparative human temporal bone study. Setting Otopathology laboratory. Subjects and Methods To compare the density of vestibular dark, transitional, and hair cells in temporal bones with and without chronic otitis media, we used differential interference contrast microscopy. In the chronic otitis media group (as compared with the age-matched control group), the density of type I and type II hair cells was significantly decreased in the lateral semicircular canal, saccule, and utricle (P .1). The findings of our study suggest that the decrease in the number of vestibular sensory cells and dark cells could be the cause of the clinical symptoms of imbalance of some patients with chronic otitis media1553494500United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute on Deafness & Other Communication Disorders (NIDCD