Microspectrophotometry of visual pigments

1972 ◽  
Vol 5 (3) ◽  
pp. 349-393 ◽  
Author(s):  
Stanley D. Carlson
Keyword(s):  
Vitamin A ◽  
Conformational Change ◽  
Visual Pigments ◽  
Visual Cells ◽  
Rods And Cones ◽  
Outer Segments ◽  
Pigment Molecule ◽  
Receptor Membrane ◽  
Covalently Bonded ◽  
Membrane Changes

Visual pigments are embedded in the disc membranes of the outer segments of vertebrate rods and cones and in the microvilli of invertebrate visual cells. The pigment molecule in both is a most fascinating aggregate of known (the ubiquitous II-cis isomer of vitamin A1 or A2-aldehyde = retinal1 or 2; Hubbard & Wald, 1952) covalently bonded to the unknown (a protein termed opsin) (Anderson, Hoffman & Hall, 1971). This conjugated molecule is called rhodopsin or dehydrorhodopsin (porphryopsin) when the prosthetic portion is retinall or 2 respectively. So sensitive is this sterically hindered, bent and twisted molecule to light that absorption of one photon can initiate its isomerization to the all trans form. This conformational change is but one (but the best known) of the factors leading to receptor membrane changes ushering in the visual impulse.

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.

scholarly journals THE VISUAL CELLS AND VISUAL PIGMENT OF THE MUDPUPPY, NECTURUS

1963 ◽  
Vol 19 (1) ◽  
pp. 79-106 ◽  
Author(s):  
Paul K. Brown ◽  
I. R. Gibbons ◽  
George Wald
Keyword(s):  
Visual Pigment ◽  
Main Role ◽  
Ciliary Process ◽  
Visual Cells ◽  
Rods And Cones ◽  
Pigment Epithelial ◽  
Outer Segments ◽  
Exciton Migration ◽  
Cytoplasmic Filaments ◽  
Crystalline Array

Electron microscopy of the visual cells of the mudpuppy Necturus have revealed several new or hitherto neglected features of organization: (a) A system of deeply staining micelles in virtually crystalline array, probably located in the lamellae of the rod outer segments. These particles may contain the visual pigment, porphyropsin. Counts of the micelles, and microspectrophotometric measurements of porphyropsin in the retina and single rods yield the estimate that each lamellar micelle may contain about 50 molecules of porphyropsin. (b) Systems of about 30 cytoplasmic filaments (here called dendrites), continuous with the cytoplasm of the inner segment, and standing like a palisade about the outer segments of the rods and cones. In the rods, one such filament stands in the mouth of each of the approximately 30 deep fissures that carve the outer segment into a radial array of lobules. (c) A system of deeply staining particles in the membranes of the dendrites, and another in the membranes of the pigment epithelial processes. It is suggested that these may have a part in interchanges of material with the outer segments. The ciliary process is found to penetrate more deeply than is commonly supposed into the outer segments of the rods and cones. The edge of each double-membrane disc in rods forms a differentiated rim structure, both around the disc circumference and bordering the fissures. These anatomical arrangements are summarized in Figs. 13 and 14, and the relevant measurements in Table I. The dilution of visual pigment in Necturus rods and cones and a general consideration of their microstructures make it seem unlikely that such typically solid state processes as exciton migration or photoconduction can transport the effects of light far from the site of absorption. Excitation must, therefore, be conveyed to the receptor as a whole by some axial structure. Among axial structures, the plasma membrane is most likely to be the site of nervous excitation. The ciliary process probably plays its main role in the embryogenesis and regeneration of outer segments; and the dendrites and pigment epithelial processes in exchanges of material with the outer segments and perhaps with one another.

scholarly journals Rhythmic daily shedding of outer-segment membranes by visual cells in the goldfish.

1978 ◽  
Vol 76 (3) ◽  
pp. 593-604 ◽  
Author(s):  
W T O'Day ◽  
R W Young
Keyword(s):  
Outer Segment ◽  
Dark Period ◽  
Pigment Epithelium ◽  
Light Period ◽  
Rhythmic Pattern ◽  
Light Cycle ◽  
Visual Cells ◽  
Rods And Cones ◽  
Outer Segments ◽  
Pigment Epithelial Cells

Goldfish were placed on a daily light cycle of 12 h light and 12 h darkness for 18 days or longer. The visual cells and pigment epithelium of the retina were then examined by microscopy at many intervals throughout the cycle. Goldfish rods and cones follow a rhythmic pattern in eliminating packets of photosensitive membranes from their outer segments. Rods shed membranes early in the light period. The detached membranes are ingested by pigment epithelial cells or by ameboid phagocytes, which degrade them during the remainder of the light period. Cones discard membranes from the ends of their outer segments early in the dark period. During the next several hours, this debris is digested by the pigment epithelium or by ameboid phagocytes. Thus, the disposal phase of the outer-segment renewal process is similar in rods and cones, but is displaced in time by about 12 h. There is evidence that this daily rhythm of membrane disposal in rods and cones is a general property of vertebrate visual cells.

scholarly journals RENEWAL OF GLYCEROL IN THE VISUAL CELLS AND PIGMENT EPITHELIUM OF THE FROG RETINA

1974 ◽  
Vol 62 (2) ◽  
pp. 378-389 ◽  
Author(s):  
Carol Bibb ◽  
Richard W. Young
Keyword(s):  
Pigment Epithelium ◽  
Lipid Synthesis ◽  
Plexiform Layer ◽  
Visual Cell ◽  
Oil Droplets ◽  
Visual Cells ◽  
Rods And Cones ◽  
Outer Segments ◽  
Frog Retina ◽  
Autoradiographic Analysis

The renewal of glycerol in the visual cells and pigment epithelium of the frog retina was studied by autoradiographic analysis of animals injected with [2-3H]glycerol. Assay of chloroform:methanol extracts showed that the labeled precursor was used mainly in lipid synthesis, although there was also some utilization in the formation of protein. Radioactive glycerol was initially concentrated in the myoid portion of rods and cones, indicating that this is the site of phospholipid synthesis in visual cells. The glycogen bodies (paraboloids) of accessory cones were also heavily labeled, suggesting the diversion of some glycerol into glycogenic pathways. In the pigment epithelium, only the oil droplets became significantly radioactive. The outer plexiform layer (which contains the visual cell synaptic bodies) and the cone oil droplets gradually accumulated considerable amounts of labeled material. Within 1–4 h, labeled molecules began to appear in the visual cell outer segments, evidently having been transported there from the myoid portion of the inner segment. Most of these were phospholipid molecules which became distributed throughout the outer segments, presumably replacing comparable constituents in existing membranes. In rods only, there was also an aggregation of labeled material at the base of the outer segment due to membrane biogenesis. These highly radioactive membranes, containing labeled molecules of lipid and protein, were subsequently displaced along the rod outer segments due to repeated membrane assembly at the base. The distribution of radioactivity supported the conclusion that membrane renewal by molecular replacement is more rapid for lipid than it is for protein.

Human visual pigments: microspectrophotometric results from the eyes of seven persons

1983 ◽  
Vol 220 (1218) ◽  
pp. 115-130 ◽  
Keyword(s):  
Colour Vision ◽  
Visual Pigments ◽  
Clinical Tests ◽  
Wave Fields ◽  
Rods And Cones ◽  
Outer Segments ◽  
Long Wave ◽  
Spectral Location ◽  
Absorbance Spectra

The material for this work was obtained from seven eyes removed because of malignant growths. Foveal and parafoveal samples of the retinas were taken and transverse measurements were made of the absorbance spectra of the outer segments of the rods and cones, using a Liebman microspectrophotometer. Four kinds of spectra were obtained with absorbance peaks at the following wavelengths: rods, 496.3 ± 2.3 nm ( n = 39); red cones, 558.4 ± 5.2 nm ( n = 58); green cones, 530.8 ± 3.5 nm ( n = 45); blue cones, 419.0 ± 3.6 nm ( n = 5). The distribution of the peaks was unimodal for the rods. For the red and green cones, however, there was evidence for bimodal distributions, with sub-population maxima at 563.2 ± 3.1 nm ( n = 27) and 554.2 ± 2.3 nm ( n = 31) for the reds and at 533.7 ± 2.1 nm ( n = 23) and 527.8 ± 1.8 nm ( n = 22) for the greens. A substantial difference in mean spectral location of the red cones was observed between patient 1 (561 nm) and patient 4 (553 nm). Both patients were classified as normal trichromats by all clinical tests of colour vision but there was a clear difference in their relative sensitivities to long-wave fields. In both direction and magnitude, this difference proved to be that required by the microspectrophotometric results.

The photoreceptors and visual pigments in the retina of a boid snake, the ball python (Python regius)

1999 ◽  
Vol 202 (14) ◽  
pp. 1931-1938 ◽  
Author(s):  
A.J. Sillman ◽  
J.K. Carver ◽  
E.R. Loew
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Visual Pigment ◽  
Outer Segment ◽  
Visual Pigments ◽  
Single Type ◽  
Python Regius ◽  
Rods And Cones ◽  
Outer Segments ◽  
Scanning Electron

The photoreceptors and visual pigments of Python regius were studied using microspectrophotometry and scanning electron microscopy. The retina contains rods and cones, with rods constituting at least 90 % of the photoreceptor population. The rods are of a single type with long, narrow outer segments and are tightly packed. The wavelength of maximum absorbance (λ max) of the visual pigment in the rods is in the region of 494 nm. Two distinct types of cone are present. The most common cone, with a stout but stubby outer segment, contains a visual pigment with λ max at approximately 551 nm. A relatively rare cone, with a long, slender outer segment, contains an ultraviolet-sensitive visual pigment with λ max at approximately 360 nm. All the visual pigments have chromophores based on vitamin A1. The results are discussed in relation to the behavior of P. regius.

Salamander rods and cones contain distinct transducin alpha subunits

2000 ◽  
Vol 17 (6) ◽  
pp. 847-854 ◽  
Author(s):  
JAMES C. RYAN ◽  
SERGEY ZNOIKO ◽  
LIN XU ◽  
ROSALIE K. CROUCH ◽  
JIAN-XING MA
Keyword(s):  
Amino Acid ◽  
Blot Analysis ◽  
Cellular Localization ◽  
Amino Acid Level ◽  
Single Copy ◽  
Lower Vertebrate ◽  
Rods And Cones ◽  
Sequence Identity ◽  
Outer Segments ◽  
Cone Pigments

The mammalian retina is known to contain two distinct transducins that interact with their respective rod and cone pigments. However, there are no reports of a nonmammalian species having two distinct transducins. In the present study, we report the cloning and cellular localization of two transducin α subunits (Gαt) from the tiger salamander. Through degenerate polymerase chain reaction (PCR) and subsequent screening of a salamander retina cDNA library, we have identified two forms of Gαt. When compared to existing sequences in GenBank, the cloned subunits showed high similarity to rod and cone transducins. The salamander Gαt-1 has 91.2–93.7% amino acid sequence identity to mammalian rod Gαt subunits and 79.7–80.9% to mammalian cone Gαts. The salamander Gαt-2 has 86.2–87.9% sequence identity to mammalian cone Gαts and 78.9–80.9% to mammalian rod Gαts at the amino acid level. The Gαt-1 cDNA encodes 350 amino acids while the Gαt-2 cDNA encodes 354 residues, which is typical for rod and cone Gαts, respectively, and we thus identified the Gαt-1 as rod and Gαt-2 as cone Gαt. Sequences identified as effector binding sites and GTPase activity regions are highly conserved between the two subunits. Genomic Southern blot analysis showed that rod and cone Gαt subunits are both encoded by single-copy genes. Northern blot analysis identified retina-specific transcripts of 3.0 kb for rod Gαt and 2.6 kb for cone Gαt. Immunohistochemistry in the flat-mounted salamander retina demonstrated that rod Gαt is localized to rods, predominantly in the outer segments; similarly, cone Gαt is localized to cone outer segments. The results confirm that the two sequences encode rod and cone transducins and demonstrate that this lower vertebrate contains two distinct transducins that are localized specifically to rod and cone photoreceptors.

Visual Pigments in Single Rods and Cones of the Human Retina

Science ◽  
1964 ◽  
Vol 144 (3614) ◽  
pp. 45-52 ◽  
Author(s):  
P. K. Brown ◽  
G. Wald
Keyword(s):  
Visual Pigments ◽  
Human Retina ◽  
Rods And Cones

Spectral absorbance, structure, and population density of photoreceptors in the retina of the lake sturgeon (Acipenser fulvescens)

2007 ◽  
Vol 85 (4) ◽  
pp. 584-587 ◽  
Author(s):  
A.J. Sillman ◽  
E.K. Ong ◽  
E.R. Loew
Keyword(s):  
Visual Pigment ◽  
Visual Pigments ◽  
Lake Sturgeon ◽  
Acipenser Fulvescens ◽  
Long Wavelength ◽  
Rods And Cones ◽  
The North ◽  
Spectral Absorbance ◽  
Dim Light ◽  
Scanning Electron

Lake sturgeon ( Acipenser fulvescens Rafinesque, 1817) photoreceptors were studied with scanning electron microscopy and microspectrophotometry. The retina contains both rods and cones, with cones estimated composing about 30% of the photoreceptor population. Only large single cones were identified and they are similar to those found in other species of the order Acipenseriformes. The rods are large, with long, broad outer segments, and are similar to the dominant rod found in other sturgeons and the North American paddlefish ( Polyodon spathula (Walbaum, 1792)). Mean (SD) rod packing density at 22 624 ± 3 509 rods/mm2 is low compared with those of other animals that function primarily in dim light. The visual pigment of the rods has a mean (SD) peak absorbance (λmax) at 541 ± 2 nm. Three different cone populations were identified: a long wavelength sensitive cone containing a visual pigment with λmax at 619 ± 3 nm; middle wavelength sensitive cone with λmax at 538 ± 1 nm; and short wavelength sensitive cone with λmax at 448 ± 1 nm. All the visual pigments are based on the vitamin A2 chromophore.

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