scholarly journals Actin filaments in sensory hairs of inner ear receptor cells.

1977 ◽  
Vol 75 (2) ◽  
pp. 339-343 ◽  
Author(s):  
A Flock ◽  
H C Cheung

Receptor cells in the ear are excited through the bending of sensory hairs which project in a bundle from their surface. The individual stereocilia of a bundle contain filaments about 5 nm in diameter. The identity of these filaments has been investigated in the crista ampullaris of the frog and guinea pig by a technique of decoration with subfragment-1 of myosin (S-1). After demembranation with Triton X-100 and incubation with S-1, "arrowhead" formation was observed along the filaments of the stereocilia and their rootlets and also along filaments in the cuticular plate inside the receptor cell. The distance between attached S-1 was 35 nm and arrowheads pointed in towards the cell soma. It is concluded that the filaments of stereocilia are composed of actin.

1962 ◽  
Vol 15 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Åke Flock ◽  
Jan Wersäll

The morphology of the hair bundles on top of the receptor cells in the lateral line organ of the teleost fish Lota vulgaris is described. Each receptor cell shows a distinct morphological polarization. Two groups of receptor cells can be distingiushed, one consisting of cells polarized towards the head, the other consisting of cells polarized towards the tail. In the crista ampullaris all cells are polarized in the same direction. An hypothesis is proposed for the function of the receptor cells in the lateral line organ and the labyrinth based on a correlation of morphological and functional polarization.


1983 ◽  
Vol 11 (3) ◽  
pp. 249-260 ◽  
Author(s):  
Åke Flock ◽  
Steven Orman

1990 ◽  
Vol 95 (5) ◽  
pp. 891-910 ◽  
Author(s):  
P Hochstrate ◽  
K Hamdorf

The process of light adaptation in blowfly photoreceptors was analyzed using intracellular recording techniques and double and triple flash stimuli. Adapting flashes of increasing intensity caused a progressive reduction in the excitability of the photoreceptors, which became temporarily suppressed when 3 x 10(6) quanta were absorbed by the cell. This suppression was confirmed by subsequently applying an intense test flash that photoactivated a considerable fraction of the 10(8) visual pigment molecules in the cell. The period of temporary desensitization is referred to as the refractory period. The stimulus intensity to render the receptor cell refractory was found to be independent of the extracellular calcium concentration over a range of 10(-4) and 10(-2) M. During the refractory period (30-40 ms after the adapting flash) the cell appears to be "protected" against further light adaptation since light absorption during this period did not affect the recovery of the cell's excitability. Calculations showed that the number of quantum absorptions necessary to induce receptor refractoriness is just sufficient to photoactivate every microvillus of the rhabdomere. This coincidence led to the hypothesis that the refractoriness of the receptor cells is due to the refractoriness of the individual microvilli. The sensitivity of the receptor cells after relatively weak adapting flashes was reduced considerably more than could be accounted for by the microvilli becoming refractory. A quantitative analysis of these results suggests that a photoactivated microvillus induces a local adaptation over a relatively small area of the rhabdomere around it, which includes several tens of microvilli. After light adaptation with an intense flash, photoactivation of every microvillus by the absorption of a few quanta produced only a small receptor response whereas photoactivation of every rhodopsin molecule in every microvillus produced the maximum response. The excitatory efficiency of the microvilli therefore increases with the number of quanta that are absorbed simultaneously.


1987 ◽  
Vol 36 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Sally E. Williams ◽  
David E. Smith ◽  
Jochen Schacht

1965 ◽  
Vol 25 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Åke Flock ◽  
Arndt J. Duvall

The bundle of sensory hairs protruding from the top of each receptor cell in the vestibular and lateral line organs in the teleost fish (burbot) Lota vulgaris is composed of a number of stereocilia and one kinocilium located in the periphery of the bundle. The ultrastructure of the kinocilium and its basal body is described. It is found that the kinocilium is morphologically polarized by the asymmetric arrangement of its component fibers and of the basal body by the presence of a basal foot. Peripheral fibers 5 and 6 of the kinocilium and the basal foot of the basal body are oriented away from the stereocilia; that is, in a direction coinciding with the direction of excitatory stimulation. The findings are discussed in terms of directional sensitivity.


1977 ◽  
Vol 83 (1-6) ◽  
pp. 85-91 ◽  
Author(s):  
Å. Flock ◽  
B. Flock ◽  
E. Murray

Author(s):  
Robert F. Dunn

Receptor cells of the cristae in the vestibular labyrinth of the bullfrog, Rana catesbiana, show a high degree of morphological organization. Four specialized regions may be distinguished: the apical region, the supranuclear region, the paranuclear region, and the basilar region.The apical region includes a single kinocilium, approximately 40 stereocilia, and many small microvilli all projecting from the apical cell surface into the lumen of the ampulla. A cuticular plate, located at the base of the stereocilia, contains filamentous attachments of the stereocilia, and has the general appearance of a homogeneous aggregation of fine particles (Fig. 1). An accumulation of mitochondria is located within the cytoplasm basal to the cuticular plate.


Author(s):  
Bert Ph. M. Menco

Vertebrate olfactory receptor cells are specialized neurons that have numerous long tapering cilia. The distal parts of these cilia line the interface between the external odorous environment and the luminal surface of the olfactory epithelium. The length and number of these cilia results in a large surface area that presumably increases the chance that an odor molecule will meet a receptor cell. Advanced methods of cryoprepration and immuno-gold labeling were particularly useful to preserve the delicate ultrastructural and immunocytochemical features of olfactory cilia required for localization of molecules involved in olfactory signal-transduction. We subjected olfactory tissues to freeze-substitution in acetone (unfixed tissues) or methanol (fixed tissues) followed by low temperature embedding in Lowicryl K11M for that purpose. Tissue sections were immunoreacted with several antibodies against proteins that are presumably important in olfactory signal-transduction.


1992 ◽  
Vol 67 (02) ◽  
pp. 252-257 ◽  
Author(s):  
Anne M Aakhus ◽  
J Michael Wilkinson ◽  
Nils Olav Solum

SummaryActin-binding protein (ABP) is degraded into fragments of 190 and 90 kDa by calpain. A monoclonal antibody (MAb TI10) against the 90 kDa fragment of ABP coprecipitated with the glycoprotein lb (GP lb) peak observed on crossed immunoelectrophoresis of Triton X-100 extracts of platelets prepared without calpain inhibitors. MAb PM6/317 against the 190 kDa fragment was not coprecipitated with the GP lb peak under such conditions. The 90 kDa fragment was adsorbed on protein A agarose from extracts that had been preincubated with antibodies to GP lb. This supports the idea that the GP Ib-ABP interaction resides in the 90 kDa region of ABP. GP lb was sedimented with the Triton-insoluble actin filaments in trace amounts only, and only after high speed centrifugation (100,000 × g, 3 h). Both the 190 kDa and the 90 kDa fragments of ABP were sedimented with the Triton-insoluble actin filaments.


1987 ◽  
Vol 103 (5) ◽  
pp. 204-211 ◽  
Author(s):  
B. Erlandsson ◽  
H. Hakanson ◽  
A. Ivarsson ◽  
P. Nilsson ◽  
J. Wersall

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