scholarly journals β-ionone activates and bleaches visual pigment in salamander photoreceptors

2009 ◽  
Vol 26 (3) ◽  
pp. 267-274 ◽  
Author(s):  
TOMOKI ISAYAMA ◽  
S.L. McCABE ENGLAND ◽  
R.K. CROUCH ◽  
A.L. ZIMMERMAN ◽  
C.L. MAKINO
Keyword(s):  
Visual Pigment ◽  
Outer Segment ◽  
Binding Pocket ◽  
Visual Pigments ◽  
Rods And Cones ◽  
Cyclic Nucleotide Gated Channels ◽  
Circulating Current ◽  
High Concentrations ◽  
Flash Response ◽  
Complete Regeneration

AbstractVision begins with photoisomerization of 11-cis retinal to the all-trans conformation within the chromophore-binding pocket of opsin, leading to activation of a biochemical cascade. Release of all-trans retinal from the binding pocket curtails but does not fully quench the ability of opsin to activate transducin. All-trans retinal and some other analogs, such as β-ionone, enhance opsin’s activity, presumably on binding the empty chromophore-binding pocket. By recording from isolated salamander photoreceptors and from patches of rod outer segment membrane, we now show that high concentrations of β-ionone suppressed circulating current in dark-adapted green-sensitive rods by inhibiting the cyclic nucleotide-gated channels. There were also decreases in circulating current and flash sensitivity, and accelerated flash response kinetics in dark-adapted blue-sensitive (BS) rods and cones, and in ultraviolet-sensitive cones, at concentrations too low to inhibit the channels. These effects persisted in BS rods even after incubation with 9-cis retinal to ensure complete regeneration of their visual pigment. After long exposures to high concentrations of β-ionone, recovery was incomplete unless 9-cis retinal was given, indicating that visual pigment had been bleached. Therefore, we propose that β-ionone activates and bleaches some types of visual pigments, mimicking the effects of light.

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.

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.

scholarly journals Vitamin A activates rhodopsin and sensitizes it to ultraviolet light

2011 ◽  
Vol 28 (6) ◽  
pp. 485-497 ◽  
Author(s):  
SADAHARU MIYAZONO ◽  
TOMOKI ISAYAMA ◽  
FRANÇOIS C. DELORI ◽  
CLINT L. MAKINO
Keyword(s):  
Vitamin A ◽  
Uv Light ◽  
Electrical Response ◽  
Bright Light ◽  
Binding Pocket ◽  
Outer Segments ◽  
Circulating Current ◽  
Retinal Chromophore ◽  
Flash Response

AbstractThe visual pigment, rhodopsin, consists of opsin protein with 11-cis retinal chromophore, covalently bound. Light activates rhodopsin by isomerizing the chromophore to the all-trans conformation. The activated rhodopsin sets in motion a biochemical cascade that evokes an electrical response by the photoreceptor. All-trans retinal is eventually released from the opsin and reduced to vitamin A. Rod and cone photoreceptors contain vast amounts of rhodopsin, so after exposure to bright light, the concentration of vitamin A can reach relatively high levels within their outer segments. Since a retinal analog, β-ionone, is capable of activating some types of visual pigments, we tested whether vitamin A might produce a similar effect. In single-cell recordings from isolated dark-adapted salamander green-sensitive rods, exogenously applied vitamin A decreased circulating current and flash sensitivity and accelerated flash response kinetics. These changes resembled those produced by exposure of rods to steady light. Microspectrophotometric measurements showed that vitamin A accumulated in the outer segments and binding of vitamin A to rhodopsin was confirmed in in vitro assays. In addition, vitamin A improved the sensitivity of photoreceptors to ultraviolet (UV) light. Apparently, the energy of a UV photon absorbed by vitamin A transferred by a radiationless process to the 11-cis retinal chromophore of rhodopsin, which subsequently isomerized. Therefore, our results suggest that vitamin A binds to rhodopsin at an allosteric binding site distinct from the chromophore binding pocket for 11-cis retinal to activate the rhodopsin, and that it serves as a sensitizing chromophore for UV light.

Movement of retinal along cone and rod photoreceptors

1994 ◽  
Vol 11 (2) ◽  
pp. 389-399 ◽  
Author(s):  
Jing Jin ◽  
Gregor J. Jones ◽  
M. Carter Cornwall
Keyword(s):  
Cell Body ◽  
Dark Adaptation ◽  
Visual Pigment ◽  
Outer Segment ◽  
Light Adaptation ◽  
Rod Photoreceptors ◽  
Rod Outer Segment ◽  
Rods And Cones ◽  
Outer Segments ◽  
Rod Cell

AbstractSingle isolated photoreceptors can be taken through a visual cycle of light adaptation by bleaching visual pigment, followed by dark adaptation when supplied with 11–cis retinal. Light adaptation after bleaching is manifested by faster response kinetics and a permanent reduction in sensitivity to light flashes, presumed to be due to the presence of bleached visual pigment. The recovery of flash sensitivity during dark adaptation is assumed to be due to regeneration of visual pigment to pre-bleach levels. In previous work, the outer segments of bleached, light-adapted cells were exposed to 11–cis retinal. In the present work, the cell bodies of bleached photoreceptors were exposed. We report a marked difference between rods and cones. Bleached cones recover sensitivity when their cell bodies are exposed to 11–cis retinal. Bleached rods do not. These results imply that retinal can move freely along the cone photoreceptor, but retinal either is not taken up by the rod cell body or retinal cannot move from the rod cell body to the rod outer segment. The free transfer of retinal along cone but not along rod photoreceptors could explain why, during dark adaptation in the retina, cones have access to a store of 11–cis retinal which is not available to rods. Additional experiments investigated the movement of retinal along bleached rod outer segments. The results indicate that retinal can move along the rod outer segment, but that this movement is slow, occurring at about the same rate as the regeneration of visual pigment.

scholarly journals Adaptation of a deep-sea cephalopod to the photic environment. Evidence for three visual pigments.

1988 ◽  
Vol 92 (1) ◽  
pp. 55-66 ◽  
Author(s):  
S Matsui ◽  
M Seidou ◽  
S Horiuchi ◽  
I Uchiyama ◽  
Y Kito
Keyword(s):  
Deep Sea ◽  
Visual Pigment ◽  
Small Area ◽  
High Performance ◽  
Outer Segment ◽  
High Sensitivity ◽  
Photoreceptor Cells ◽  
High Performance Liquid Chromatographic ◽  
Visual Pigments ◽  
Environmental Light

Watasenia scintillans, a bioluminescent deep-sea squid, has a specially developed eye with a large open pupil and three visual pigments. Photoreceptor cells (outer segment: 476 micron; inner segment: 99 micron) were long in the small area of the ventral retina receiving downwelling light, whereas they were short (outer segment: 207 micron; inner segment: 44 micron) in the other regions of the retina. The short photoreceptor cells contained the visual pigment with retinal (lambda max approximately 484 nm), probably for the purpose of adapting to their environmental light. The outer segment of the long photoreceptor cells consisted of two strata, a pinkish proximal area and a yellow distal area. The visual pigment with 3-dehydroretinal (lambda max approximately 500 nm) was located in the pinkish proximal area, giving high sensitivity at longer wavelengths. A newly found pigment (lambda max approximately 471 nm) was in the yellow distal area. The small area of the ventral retina containing two visual pigments is thought to have a high and broad spectral sensitivity, which is useful for distinguishing the bioluminescence of squids of the same species in their environmental downwelling light. These findings were obtained by partial bleaching of the extracted pigment from various areas of the retina and by high-performance liquid chromatographic analysis of the chromophore, complemented by microscopic observations.

Age-related changes in the visual pigments of the white sturgeon (Acipenser transmontanus)

1993 ◽  
Vol 71 (8) ◽  
pp. 1552-1557 ◽  
Author(s):  
E. R. Loew ◽  
A. J. Sillman
Keyword(s):  
Visual Pigment ◽  
Visual Pigments ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Disulfonic Acid ◽  
Fluorescent Substance ◽  
Rods And Cones ◽  
Age Related ◽  
Juvenile Sturgeon ◽  
Spectral Absorbance

Using in situ microspectrophotometry, the spectral absorbance characteristics of the photoreceptors in the retinas of larval, juvenile, and adult white sturgeon (Acipenser transmontanus) were determined. The adult has one type of rod, containing a visual pigment with maximum spectral absorbance (λmax) near 540 nm. There are three types of cones, morphologically identical but distinguished from one another by containing either a blue-sensitive (λmax 464 nm), green-sensitive (λmax 531 nm), or red-sensitive (λmax 605 nm) visual pigment. Juvenile sturgeon have visual pigments similar to those of the adult. However, no evidence could be found for the presence of either blue-sensitive or red-sensitive cones in larval white sturgeon through the age of 10 weeks. Larval sturgeon up to about 10 weeks yielded only green-sensitive rods and cones. The absence of red-sensitive cones in the larvae, and their presence in older fish, was confirmed by the use of 4,4′-diisothiocyanato-stilbene-2,2′-disulfonic acid, a fluorescent substance that binds selectively to photoreceptors sensitive to long-wavelength light. Regardless of age, all visual pigments are based on vitamin A2. Also regardless of age, white sturgeon retinas yielded no evidence for the presence of photoreceptors sensitive to ultraviolet light.

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 Unique retinal binding pocket of primate blue-sensitive visual pigment

2020 ◽  
Author(s):  
Yuki Nonaka ◽  
Shunpei Hanai ◽  
Kota Katayama ◽  
Hiroo Imai ◽  
Hideki Kandori
Keyword(s):  
Ftir Spectroscopy ◽  
Low Temperatures ◽  
Visual Pigment ◽  
Binding Pocket ◽  
Visual Pigments ◽  
Unique Property ◽  
Light Perception ◽  
Physiological Temperature ◽  
Retinal Binding Pocket ◽  
Isomeric States

ABSTRACTThe visual pigments of humans contain 11-cis retinal as the chromophore of light perception, and its photoisomerization to the all-trans form initiates visual excitation in our eyes. It is well known that three isomeric states of retinal (11-cis, all-trans, and 9-cis) are in photoequilibrium at very low temperatures such as 77 K. Here we report the lack of formation of the 9-cis form in monkey blue (MB) at 77 K, as revealed by light-induced difference FTIR spectroscopy. This indicates that the chromophore binding pocket of MB does not accommodate the 9-cis form, even though it accommodates the all-trans form by twisting the chromophore. Mutation of the blue-specific tyrosine at position 265 into tryptophan, which is highly conserved in other animal rhodopsins, led to formation of the 9-cis form in MB, suggesting that Y265 is one of the determinants of the unique photochemistry in blue pigments. We also found that 9-cis retinal does not bind to MB opsin, implying that the chromophore binding pocket does not accommodate the 9-cis form at physiological temperature. The unique property of MB is discussed based on the present results.

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

The photoreceptors and visual pigments in the retina of the white sturgeon, Acipenser transmontanus

1990 ◽  
Vol 68 (7) ◽  
pp. 1544-1551 ◽  
Author(s):  
A. J. Sillman ◽  
M. D. Spanfelner ◽  
E. R. Loew
Keyword(s):  
Vitamin A ◽  
Visual Pigment ◽  
Visual Pigments ◽  
Spectrophotometric Analysis ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Light Regimen ◽  
Cone Pigment ◽  
Spectral Absorbance

The photoreceptors in the retina of the white sturgeon, Acipenser transmontanus (Chondrostei), were studied by means of scanning electron microscopy, in situ microspectrophotometry, and spectrophotometric analysis of visual pigment extracts. The white sturgeon retina is simple in that it contains only two morphologically distinct photoreceptors. The retina is dominated by rods with large outer segments, but there is a substantial population (40%) of single cones. Evidence was found for only one rod visual pigment and one cone visual pigment. Peak spectral absorbance (λmax) of the rod pigment is near 539 nm, whereas λmax of the cone pigment is near 605 nm. Both visual pigments are porphyropsin types with chromophores based on vitamin A2. No detectable rhodopsin based on vitamin A1 is ever present, regardless of season or light regimen. The results are discussed in terms of the sturgeon's behavior, as well as the implications for the evolution of color vision.

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