The tapetum lucidum of gars (Lepisosteidae) and its role as a reflector

1974 ◽  
Vol 52 (12) ◽  
pp. 1523-1530 ◽  
Author(s):  
Richard T. Wang ◽  
J. A. Colin Nicol
Keyword(s):  
Optical Density ◽  
Light Absorption ◽  
Visual Pigment ◽  
Retinal Pigment ◽  
Scotopic Vision ◽  
Underwater Light ◽  
Tapetum Lucidum ◽  
Dim Light ◽  
Lake Waters

Eyes of four species of gars were studied, namely, alligator (Lepisosteus spatula Lacépède), spotted (L. oculatus (Winchell)), shortnose (L. platostomus Rafinesque), and longnqse (L. osseus (L.)). The retina is duplex, a yellow tapetum lucidum is present, rods and retinal pigment move, and the tapetum is uncovered in dim light. The visual pigment is a porphyropsin, λmax 523, and the optical density of the pigment in the retina is 0.22. Transmission through the retina is low at short wavelengths and rises steeply above 460 nm. Reflectance from the tapetum is diminished in the blue, and rises progressively at longer wavelengths to reach a maximum (70%) at about 650 nm. Underwater illumination was measured in waters where gars occur. In lake waters maximal transmissivity occurred at 375 nm and the transmission per meter ranged from 76 to 62%. In rivers and bays, transmission was maximal at long wavelengths, ≥600 nm, and the transmission per meter ranged from 37% to 0.001%; these waters sometimes were stained, and were fairly turbid to very muddy. The yellow tapetum is an efficient reflector of underwater light, the greater part of the energy of which occurs at long wavelengths. It is calculated that the tapetum increases light absorption in the retina by 30%. In muddy rivers inhabited by gars, scotopic vision involving the tapetum probably operates during the daytime at depths of 2 m or less.

Studies on the eyes of gars (Lepisosteidae) with special reference to the tapetum lucidum

1973 ◽  
Vol 51 (5) ◽  
pp. 501-508 ◽  
Author(s):  
J. A. C. Nicol ◽  
H. J. Arnott
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Visible Spectrum ◽  
Tapetum Lucidum ◽  
Tubular System ◽  
Noteworthy Feature ◽  
Membrane Bound ◽  
Dim Light ◽  
Ammoniacal Silver ◽  
Pigment Epithelial Cells

Eyes of gars (Lepisosteus) possess a yellow tapetum lucidum which is located in processes of the pigment epithelium. A yellow reflecting pigment is involved, enclosed in tapetal spheres each about 240 nm in diameter. Retinomotor movements take place: in darkness (or dim light) the black retinal pigment retracts, exposing the tapetum, and the rods shorten; in the light the pigment migrates inwards, obscuring the tapetum, and the rods elongate. The tapetal pigment is soluble in water, dilute acid, and alkali, and insoluble in organic solvents; it is rendered insoluble (to water) by heavy metals; and it stains with reagents used to visualize phenolic compounds (ferric–ferricyanide; ammoniacal silver nitrate). A method of extracting the pigment is described, and the ultraviolet/visible spectrum shown. The refractive index is high (n23 1.59) and that, in conjunction with the size and arrangement of the tapetal spheres, is conducive to backscatter. A second noteworthy feature of the pigment epithelial cells is the presence of an extensive Golgi apparatus consisting of many dictyosomes interconnected by a complicated tubular system of smooth membranes. The tubules exhibit periodic swellings or vesiculations in which the tapetal spheres individually are formed. Comparisons are made with a similar Golgi complex in Styela, and with membrane-bound vesicles, derived from Golgi and concerned with formation of ommochrome granules, in Drosophila.

scholarly journals Peropsin, a novel visual pigment-like protein located in the apical microvilli of the retinal pigment epithelium

1997 ◽  
Vol 94 (18) ◽  
pp. 9893-9898 ◽  
Author(s):  
H. Sun ◽  
D. J. Gilbert ◽  
N. G. Copeland ◽  
N. A. Jenkins ◽  
J. Nathans
Keyword(s):  
Retinal Pigment Epithelium ◽  
Visual Pigment ◽  
Pigment Epithelium ◽  
Retinal Pigment

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.

Selective utilization of serum vitamin A for visual pigment synthesis

1989 ◽  
Vol 142 (1) ◽  
pp. 207-214
Author(s):  
A. T. Tsin ◽  
S. N. Gentles ◽  
E. A. Castillo
Keyword(s):  
Vitamin A ◽  
Visual Pigment ◽  
Carassius Auratus ◽  
High Performance ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Serum Vitamin ◽  
Pigment Synthesis ◽  
Goldfish Carassius Auratus ◽  
Vitamin A2

Two groups of goldfish (Carassius auratus) were subjected to light and temperature conditions known to promote a contrast in their scotopic visual pigment compositions. After 3 weeks, the porphyropsin/rhodopsin ratio in the neuroretina of these goldfish ranged from 99% porphyropsin in one group to 59% in the other. Samples of blood, liver and retinal pigment epithelium (RPE) were also removed from these animals and analysed by high-performance liquid chromatography (HPLC) for vitamin A composition. There was consistently more vitamin A2 than vitamin A1 (over 50% vitamin A2) in both vitamin A alcohol and vitamin A esters extracted from the liver and the RPE. In contrast, only 30% of all vitamin A extracted from the blood was vitamin A2. These observations suggest that it is mainly vitamin A1 that is transported in the blood, whereas vitamin A2 is selectively retained in the liver and in the RPE and used to form porphyropsin in the eye.

scholarly journals Increased Macular Pigment Optical Density and Visual Acuity following Consumption of a Buttermilk Drink Containing Lutein-Enriched Egg Yolks: A Randomized, Double-Blind, Placebo-Controlled Trial

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Sanne M. van der Made ◽  
Elton R. Kelly ◽  
Aize Kijlstra ◽  
Jogchum Plat ◽  
Tos T. J. M. Berendschot
Keyword(s):  
Visual Acuity ◽  
Optical Density ◽  
Dark Adaptation ◽  
Retinal Pigment ◽  
Elderly Subjects ◽  
Macular Pigment Optical Density ◽  
Daily Consumption ◽  
Double Blind ◽  
Double Blind Placebo ◽  
Egg Yolks

Purpose. To study the effect of 1-year daily consumption of a dairy drink containing lutein-enriched egg yolks on macular pigment optical density (MPOD) and visual function parameters in elderly subjects with ocular drusen and/or retinal pigment abnormalities.Methods. One hundred and one subjects were recruited to participate in this randomized, double-blind, placebo-controlled parallel intervention trial. Statistical analyses were performed with 46 subjects in the lutein group and 43 in the control group. MPOD, best corrected visual acuity (BCVA, logMAR), and dark adaptation were measured at the start of the study, after 6 months and after 12 months. Plasma lutein and zeaxanthin concentrations were assessed at baseline and at the end of the study.Results. In the lutein group, plasma lutein concentrations increased significantly from 205 ng/mL at baseline to 399 ng/mL after twelve months of intervention. MPOD increased significantly from 0.45 to 0.52 and BCVA improved significantly from −0.04 to −0.09 LogMar. Differences in rod dark adaptation rate between both groups were not significant.Conclusion. Daily consumption of a dairy drink containing lutein-enriched egg yolks for one year improves visual acuity, MPOD, and plasma lutein concentration in elderly subjects with drusen and/or retinal pigment epithelial abnormalities.

scholarly journals The potential retinal hazards of curing light use for dentists

2021 ◽  
Vol 2 (2) ◽  
pp. 77-84
Author(s):  
Nicole M Putnam ◽  
Sara Thomas ◽  
Grace Liao ◽  
Emily Bennett ◽  
Anne Breen ◽  
...  
Keyword(s):  
Blue Light ◽  
Optical Density ◽  
Light Exposure ◽  
Retinal Pigment Epithelial Cell ◽  
Retinal Pigment ◽  
Macular Pigment ◽  
Control Group ◽  
Macular Pigment Optical Density ◽  
Curing Light ◽  
Ocular Health

Background: Many recent studies have focused on the potential hazards of blue light exposure to ocular health. One group with a unique blue light exposure risk is dentists, who use curing lights that emit intense blue light during restorative procedures. During these procedures, dentists often experience brief ocular exposure to these lights. The purpose of the present study was to explore whether such exposures may have an effect on the vision and ocular health of dentists. Methods: A group of 12 dentists who had experienced curing light exposure over a period of 10 or more years were compared to a group of eight control subjects with no such exposure. The subjects were tested for visual acuity and contrast sensitivity. Their retinas were examined using fundus imaging and optical coherence tomography. Macular pigment optical density was measured. The likelihood that brief blue light exposure could lead to ocular effects was further explored by subjecting a retinal pigment epithelial cell (RPE) line to such exposures. Results: Although no visual defects or ocular pathologies were found in either group, the dentist group differed from the control group in having increased macular thickness (P < 0.02), a higher incidence of macular vessel tortuosity (P < 0.05), and greater variance in their macular pigment optical density values (P < 0.01). RPE cells that received blue light exposure similar to those sustained by dentists demonstrated a change in physiology. Conclusions: Retinal changes were found in dentists, which, while not pathological in themselves, are associated with some retinal pathologies. Further studies are necessary to determine whether these signs correlate with the degree of curing light exposure and to determine whether they eventually develop into pathological conditions.

scholarly journals Dim-Light Sensitivity of Cells in the Awake Cat's Lateral Geniculate and Medial Interlaminar Nuclei: A Correlation With Behavior

2009 ◽  
Vol 102 (2) ◽  
pp. 841-852 ◽  
Author(s):  
Incheol Kang ◽  
Joseph G. Malpeli
Keyword(s):  
Temporal Frequency ◽  
Light Sensitivity ◽  
Scotopic Vision ◽  
Lateral Geniculate ◽  
Cell Class ◽  
Behavioral Sensitivity ◽  
Dim Light ◽  
Y Cells ◽  
Dorsal Lateral Geniculate ◽  
Contrast Thresholds

Contrast thresholds of cells in the dorsal lateral geniculate (LGNd) and medial interlaminar (MIN) nuclei of awake cats were measured for scotopic and mesopic vision with drifting sine gratings (1/8, 2, and 4 cycles/deg [cpd]; 4-Hz temporal frequency). Thresholds for mean firing rate (F0) and temporally modulated responses (F1) were derived with receiver-operating-characteristic analyses and compared with behavioral measures recently reported by Kang and colleagues. Behavioral sensitivity was predicted by the neural responses of the most sensitive combinations of cell class and response mode: Y-cell F1 responses for 1/8 cpd, X-cell F1 responses for 2 cpd, and Y-cell F0 responses for 4 cpd. All previous estimates of neural scotopic increment thresholds in animal models fell between Weber's law (proportional to retinal illuminance) and the deVries–Rose law (proportional to the square root of illuminance). However, psychophysical experiments suggest that under appropriate conditions human scotopic vision follows the deVries–Rose law. If behavioral sensitivity is assumed to be determined by the most sensitive class of cells, this discrepancy is resolved. Under scotopic conditions, off-center Y cells were the most sensitive and these followed the deVries–Rose law fairly closely. MIN Y cells were, on average, 0.25 log units more sensitive than LGNd Y cells under scotopic conditions, supporting a previous proposal that the MIN is a specialization of the carnivore for dim-light vision. We conclude that both physiologically and behaviorally, cat and human scotopic vision are fundamentally similar, including adherence to the deVries–Rose law for detection of Gabor functions.

The vitamin a transporter STRA6 adjusts the stoichiometry of chromophore and opsins in visual pigment synthesis and recycling

2021 ◽  
Author(s):  
Srinivasagan Ramkumar ◽  
Vipul M Parmar ◽  
Ivy Samuels ◽  
Nathan A Berger ◽  
Beata Jastrzebska ◽  
...  
Keyword(s):  
Vitamin A ◽  
Visual Pigment ◽  
Binding Protein ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinol Binding Protein ◽  
Marker Genes ◽  
Cone Photoreceptors ◽  
Pigment Synthesis ◽  
Deficient Mice

Abstract The retinal pigment epithelium of the vertebrate eyes acquires vitamin A from circulating retinol binding protein for chromophore biosynthesis. The chromophore covalently links with an opsin protein in the adjacent photoreceptors of the retina to form the bipartite visual pigment complexes. We here analyzed visual pigment biosynthesis in mice deficient for the retinol binding protein receptor STRA6. We observed that chromophore content was decreased throughout the life cycle of these animals, indicating that lipoprotein-dependent delivery pathways for the vitamin cannot substitute for STRA6. Changes in the expression of photoreceptor marker genes, including a down-regulation of the genes encoding rod and cone opsins, paralleled the decrease in ocular retinoid concentration in STRA6-deficient mice. Despite this adaptation, cone photoreceptors displayed absent or mislocalized opsins at all ages examined. Rod photoreceptors entrapped the available chromophore but exhibited significant amounts of chromophore-free opsins in the dark-adapted stage. Treatment of mice with pharmacological doses of vitamin A ameliorated the rod phenotype but did not restore visual pigment synthesis in cone photoreceptors of STRA6-deficient mice. The imbalance between chromophore and opsin concentrations of rod and cone photoreceptors was associated with an unfavorable retinal physiology, including diminished electrical responses of photoreceptors to light, and retinal degeneration during aging. Together, our study demonstrates that STRA6 is critical to adjust the stoichiometry of chromophore and opsins in rod cone photoreceptors and to prevent pathologies associated with ocular vitamin A deprivation.

Retinyl esters in the vertebrate neuroretina

1989 ◽  
Vol 256 (1) ◽  
pp. R255-R258 ◽  
Author(s):  
K. A. Rodriguez ◽  
A. T. Tsin
Keyword(s):  
Visual Pigment ◽  
High Performance ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinyl Palmitate ◽  
Visual Pigments ◽  
Pigment Synthesis ◽  
Retinyl Ester ◽  
Retinyl Ester Hydrolase ◽  
Retinyl Esters

High-performance liquid chromatography (HPLC) was employed to measure retinyl esters in the vertebrate retina. Both retina and retinal pigment epithelium (RPE) from frog, chicken, and bovine eyes were studied. In comparison to the RPE, the retina possessed a significant level of 11-cis and all trans retinyl palmitate. Using a sensitive radioassay, we also detected the presence of retinyl ester hydrolase (REH) activity in homogenates prepared from both retina and RPE. The rate of retinyl ester hydrolysis in these retinas was sufficiently high to supply retinal chromophores for the metabolic renewal and for the regeneration of visual pigments. In comparison to retinyl esters in the RPE, retinyl esters in the retina are located much closer to the sites of visual pigment synthesis and regeneration. Hence it is possible that these retinyl esters play a more important role in the visual cycle than those in the RPE.

scholarly journals The quantitative analysis of the photochemical bleaching of visual purple solutions in monochromatic light

1936 ◽  
Vol 156 (887) ◽  
pp. 158-170 ◽  
Keyword(s):  
Quantitative Analysis ◽  
Experimental Error ◽  
Wave Length ◽  
Monochromatic Light ◽  
Scotopic Vision ◽  
Monomolecular Reaction ◽  
The Subject ◽  
Dim Light ◽  
Kinetics Of ◽  
Adsorption Curve

In 1851 Muller noticed that under certain condition the rods of the frog's retina were coloured red. In 1876 Boll found that the retina bleached on exposure to light. This bleaching is now known to be due to the decolouration of a light sensitive pigment, visual purple or rhodopsin. It is generally accepted that this pigment place an important part in scotopic vision, i. e ., vision in dim light. Visual purple can be extracted from dark-adapted retinae by a number of reagents, including solutions of the salts and digitonin. The solutions of the pigments so obtained have been the subject of several spectrophotometric investigations. Trendelenburg in 1904 determined the adsorption curve of rabbits visual purple (maximum 507 mμ .) and also the relative efficiencies of different wave-lengths in bleaching the solutions. He established the similarity between the relative efficiencies and the human scotopic luminosity curve, as determined by him, for the same source of light. The adsorption curve has been determined by a number of other observers who find the maximum of adsorption of visual purple to be at about 500 for mammals, amphibia, etc., and at a variable wave-length for fish. Recently Hecht has studied the bleaching of visual purple solutions in white light. He showed that weak solutions bleach according to the Kinetics of a monomolecular reaction, the velocity constant being proportional to the intensity of the bleaching light and independent of the temperature within experimental error. In the present work the bleaching of visual purple in monochromatic light has been studied and, by means of absolute determinations of the light intensity, it has been found possible to apply fundamental photochemical principles to this reaction.

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