Topology of the Outer Segment Membranes of Retinal Rods and Cones Revealed by a Fluorescent Probe

Science ◽  
1974 ◽  
Vol 185 (4157) ◽  
pp. 1176-1179 ◽  
Author(s):  
S. Yoshikami ◽  
W. E. Robinson ◽  
W. A. Hagins
Keyword(s):  
Fluorescent Probe ◽  
Outer Segment ◽  
Rods And Cones ◽  
Retinal Rods

scholarly journals Recoverin Regulates Light-dependent Phosphodiesterase Activity in Retinal Rods

2004 ◽  
Vol 123 (6) ◽  
pp. 729-741 ◽  
Author(s):  
Clint L. Makino ◽  
R.L. Dodd ◽  
J. Chen ◽  
M.E. Burns ◽  
A. Roca ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mechanism Of Action ◽  
Functional Role ◽  
Outer Segment ◽  
Phosphodiesterase Activity ◽  
Wild Type ◽  
Visual Transduction ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Flash Response

The Ca2+-binding protein recoverin may regulate visual transduction in retinal rods and cones, but its functional role and mechanism of action remain controversial. We compared the photoresponses of rods from control mice and from mice in which the recoverin gene was knocked out. Our analysis indicates that Ca2+-recoverin prolongs the dark-adapted flash response and increases the rod's sensitivity to dim steady light. Knockout rods had faster Ca2+ dynamics, indicating that recoverin is a significant Ca2+ buffer in the outer segment, but incorporation of exogenous buffer did not restore wild-type behavior. We infer that Ca2+-recoverin potentiates light-triggered phosphodiesterase activity, probably by effectively prolonging the catalytic activity of photoexcited rhodopsin.

scholarly journals THE RENEWAL OF PROTEIN IN RETINAL RODS AND CONES

1968 ◽  
Vol 39 (1) ◽  
pp. 169-184 ◽  
Author(s):  
Richard W. Young ◽  
Bernard Droz
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Electron Microscope ◽  
Golgi Complex ◽  
Outer Segment ◽  
Photoreceptor Cells ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Utilization Of Protein ◽  
Low Levels

The renewal of protein in retinal rods and cones has been analyzed by quantitative electron microscope radioautography in adult frogs injected with a mixture of radioactive amino acids. Protein synthesis occurs predominantly in the ergastoplasm, localized in the myoid region of the photoreceptor cells. Much of the newly formed protein next flows through the Golgi complex. In rods, a large proportion of the protein then moves past the mitochondria of the ellipsoid segment, passes through the connecting cilium into the outer segment, and is there assembled into membranous discs at the base of that structure. Discs are formed at the rate of 36 per day in red rods and 25 per day in green rods at 22.5° C ambient temperature. In cones, a small proportion of the protein is similarly displaced to the outer segment. However, no new discs are formed. Instead, the protein becomes diffusely distributed throughout the cone outer segment. Low levels of radioactivity have been detected, shortly after injection, in the mitochondria, nucleus, and synaptic bodies of rods and cones. Nevertheless, in these organelles, the renewal process also appears to involve the utilization of protein formed in the ergastoplasm of the myoid.

Freeze-Fracture Replication of Frozen Outer Segments of Rat Retinal Rods

1969 ◽  
Vol 27 ◽  
pp. 392-393
Author(s):  
Thomas S. Leeson ◽  
C. Roland Leeson
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Outer Segment ◽  
Freeze Fracture ◽  
X Ray Diffraction ◽  
X Ray ◽  
Outer Segments ◽  
Retinal Rods ◽  
Temperature Electron ◽  
Freeze Etching

Numerous previous studies of outer segments of retinal receptors have demonstrated a complex internal structure of a series of transversely orientated membranous lamellae, discs, or saccules. In cones, these lamellae probably are invaginations of the covering plasma membrane. In rods, however, they appear to be isolated and separate discs although some authors report interconnections and some continuities with the surface near the base of the outer segment, i.e. toward the inner segment. In some species, variations have been reported, such as longitudinally orientated lamellae and lamellar whorls. In cross section, the discs or saccules show one or more incisures. The saccules probably contain photolabile pigment, with resulting potentials after dipole formation during bleaching of pigment. Continuity between the lamina of rod saccules and extracellular space may be necessary for the detection of dipoles, although such continuity usually is not found by electron microscopy. Particles on the membranes have been found by low angle X-ray diffraction, by low temperature electron microscopy and by freeze-etching techniques.

scholarly journals ELECTRON MICROSCOPE OBSERVATIONS ON SYNAPTIC VESICLES IN SYNAPSES OF THE RETINAL RODS AND CONES

1956 ◽  
Vol 2 (3) ◽  
pp. 307-318 ◽  
Author(s):  
Eduardo De Robertis ◽  
Carlos M. Franchi
Keyword(s):  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Sharp Decrease ◽  
Albino Rabbit ◽  
Synaptic Membrane ◽  
Complete Darkness ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Filamentous Material ◽  
Rod Cell

The submicroscopic organization of the rod and cone synapses of the albino rabbit has been investigated with the use of the electron microscope. The most common rod synapse consists of an enlarged expansion of the rod fiber (the so called spherule) into which the dendritic postsynaptic fiber of the bipolar cell penetrates and digitates. The membrane surrounding the terminal consists of a double layer, the external of which is interpreted as belonging to the intervening glial cells. The synaptic membrane has a pre- and a postsynaptic layer with a total thickness of 180 to 300 A. The presynaptic layer is frequently denser and is intimately associated with the adjacent synaptic vesicles. The synaptic membrane shows processes constituted by foldings of the presynaptic layer. The entire spherule is filled with synaptic vesicles varying in diameter between 200 and 650 A with a mean of 386 A. In addition, the spherule contains a few large vacuoles near the rod fiber, interpreted as endoplasmic reticulum, and a matrix in which with high resolution a fine filamentous material can be observed. The postsynaptic fiber is homogeneous and usually does not show synaptic vesicles. In animals maintained in complete darkness for 24 hours vesicles appear to accumulate near the synaptic membrane and its processes. After 9 days there is a sharp decrease in size of the synaptic vesicles. A special rod synapse in which the dendritic postsynaptic expansion penetrates directly into the rod cell body has been identified. In line with Cajal's classification this type of synapse could be considered as a somatodendritic one. The cone synapse has a much larger terminal with a more complex relationship with the postsynaptic fiber. However, the same components recognized in the rod synapse can be observed. In animals maintained for 9 days in complete darkness there is also a considerable diminution in size of the synaptic vesicles.

scholarly journals Diffusion of calcium ions in retinal rods. A theoretical calculation.

1981 ◽  
Vol 77 (4) ◽  
pp. 475-487 ◽  
Author(s):  
S McLaughlin ◽  
J Brown
Keyword(s):  
Diffusion Coefficient ◽  
Adsorption Isotherm ◽  
Calcium Ions ◽  
Outer Segment ◽  
Effective Diffusion ◽  
Langmuir Adsorption Isotherm ◽  
Diffuse Double Layer ◽  
Langmuir Adsorption ◽  
Retinal Rods ◽  
Disk Membrane

The Fick diffusion equation is combined with the Langmuir adsorption isotherm and the relevant equations from the Gouy-Chapman theory of the electrical diffuse double layer to demonstrate that the effective diffusion coefficient of calcium ions, both in the cytoplasm of the rod outer segment and within the aqueous space bounded by the disk membrane, should be reduced by a factor of 10-100 because these ions adsorb to phospholipids present in the disk membrane.

Protein Sorting in Healthy and Diseased Photoreceptors

2019 ◽  
Vol 5 (1) ◽  
pp. 73-98 ◽  
Author(s):  
Yoshikazu Imanishi
Keyword(s):  
Signal Transduction ◽  
Membrane Protein ◽  
Outer Segment ◽  
Protein Sorting ◽  
Rods And Cones ◽  
Retinal Photoreceptor ◽  
Photoreceptor Neurons ◽  
Cellular Compartments ◽  
G Protein Coupled ◽  
Distinct Membrane

Rods and cones are retinal photoreceptor neurons required for our visual sensation. Because of their highly polarized structures and well-characterized processes of G protein–coupled receptor–mediated phototransduction signaling, these photoreceptors have been excellent models for studying the compartmentalization and sorting of proteins. Rods and cones have a modified ciliary compartment called the outer segment (OS) as well as non-OS compartments. The distinct membrane protein compositions between OS and non-OS compartments suggest that the OS is separated from the rest of the cellular compartments by multiple barriers or gates that are selectively permissive to specific cargoes. This review discusses the mechanisms of protein sorting and compartmentalization in photoreceptor neurons. Proper sorting and compartmentalization of membrane proteins are required for signal transduction and transmission. This review also discusses the roles of compartmentalized signaling, which is compromised in various retinal ciliopathies.

scholarly journals THE RENEWAL OF ROD AND CONE OUTER SEGMENTS IN THE RHESUS MONKEY

1971 ◽  
Vol 49 (2) ◽  
pp. 303-318 ◽  
Author(s):  
Richard W. Young
Keyword(s):  
Rhesus Monkey ◽  
Rhesus Monkeys ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Renewal Processes ◽  
Visual Cells ◽  
Rods And Cones ◽  
Outer Segments ◽  
Retinal Rod ◽  
Assembly Site

The renewal of retinal rod and cone outer segments has been studied by radioautography in rhesus monkeys examined 2 and 4 days after injection of leucine-3H. The cell outer segment consists of a stack of photosensitive, membranous discs. In both rods and cones some of the newly formed (radioactive) protein became distributed throughout the outer segment. Furthermore, in rods (but not in cones), there was a transverse band of concentrated radioactive protein slightly above the outer segment base 2 days after injection. This was due to the formation of new discs, into which labeled protein had been incorporated. At 4 days, these radioactive discs were located farther from the outer segment base. Repeated assembly of new discs had displaced them away from the basal assembly site and along the outer segment. Measurements of the displacement rate indicated that each retinal rod produces 80–90 discs per day, and that the entire complement of outer segment discs is replaced every 9–13 days. To compensate for the continual formation of new discs, groups of old discs are intermittently shed from the apical end of the cell and phagocytized by the pigment epithelium. Each pigment epithelial cell engulfs and destroys about 2000–4000 rod outer segment discs daily. The similarity between visual cells in the rhesus monkey and those in man suggests that the same renewal processes occur in the human retina.

PHOTOTRANSDUCTION IN RETINAL RODS AND CONES

Vision ◽  
2001 ◽  
Author(s):  
YIANNIS KOUTALOS ◽  
KEI NAKATANI ◽  
WEI-HONG XIONG ◽  
KING-WAI YAU
Keyword(s):  
Rods And Cones ◽  
Retinal Rods

scholarly journals THE FLICKER RESPONSE FUNCTION FOR THE TURTLE PSEUDEMYS

1939 ◽  
Vol 22 (3) ◽  
pp. 311-340 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf ◽  
Gertrud Zerrahn-Wolf
Keyword(s):  
Flash Intensity ◽  
Rods And Cones ◽  
Sensory Effects ◽  
Retinal Rods ◽  
Fixed Proportion ◽  
Order Of Magnitude ◽  
The Mean ◽  
Probability Integral ◽  
The Individual ◽  
Critical Intensity

1. At constant temperature, with a fixed proportion of light time in a flash cycle (namely, tL/tD = 1), the mean critical intensity for motor response to visual flicker by the turtle Pseudemys scripta follows a probability integral (log I) as a function of flash frequency F. The fit is close and satisfactory; certain quite minor but consistent deviations are adequately explained by features of the experiments. 2. The variation (σI) of critical I is directly proportional to the mean critical intensity (Im), over the entire explorable range. 3. These facts are consistent with the fact that the retina of this turtle is devoid of rods. It contains only cones, histologically, which, with their central representations, provide a single population of sensory effects. The properties of this population are compared with those of homologous populations deduced from corresponding measurements with other forms (various fishes; amphibian; man) which exhibit two such groups of sensory effects associated with the possession of retinal rods and cones. 4. Certain other formulations which have previously been applied to homologous data obtained with other organisms do not properly describe the Pseudemys measurements. 5. The use of a probability integral to describe the data of response to visual flicker for the dissection of the compound curves provided by animals possessing both rods and cones, is accordingly Justified. 6. Persisting differences among individuals of Pseudemys as regards the values of the critical flash intensity under various conditions of experimentation are of the same order of magnitude as are the transitory differences found in lots of other kinds of animals. 7. Determinations of mean critical flash frequency (Fm) at fixed levels of I lie slightly above determinations of Im at fixed values of I, as with other forms. The variation of critical flash frequency goes through a maximum as log I is increased; its height is lower than with certain other forms, in correlation with the low general slope of the F - log I curve (more properly, band). 8. These facts are consistent with the view that the dispersions of the individual critical intensities (and flash frequencies) are determined by organic variation rather than by "experimental error." 9. When the temperature is altered the F - log Im curve is shifted, with no change of Fmax. or of shape; the curve moves to lower intensities as the temperature is raised. 10. The reciprocal of the mean critical intensity, at fixed flash frequency, is a measure of excitability. With increase of temperature (12.5° to 36°) 1/Im for given F follows the Arrhenius equation, exhibiting a "break" at 29.5° (µ = 26,700, 12.5° to 29.5°; 12,400, 29.5° to 36°). This is explained by the necessary theory that, the number of elements of sensory effect required for the index response at fixed F being constant, the ease of their excitation is governed by temperature through its control of the velocity of an interrelated system of catalyzed processes common to all of the sensory elements concerned.

scholarly journals Revamped Outer Segment Structure and Photoresponse in Retinal Rods Over-expressing Rhodopsin

2009 ◽  
Vol 96 (3) ◽  
pp. 525a
Author(s):  
Xiao-Hong Wen ◽  
Lixin Shen ◽  
Richard S. Brush ◽  
Norman Michaud ◽  
Muayyad R. Al-Ubaidi ◽  
...  
Keyword(s):  
Outer Segment ◽  
Retinal Rods
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