scholarly journals The evolution of rod photoreceptors

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160074 ◽  
Author(s):  
Ala Morshedian ◽  
Gordon L. Fain
Keyword(s):  
Entire Range ◽  
Selection Pressure ◽  
Outer Segment ◽  
Bright Light ◽  
Protein Isoforms ◽  
Single Photons ◽  
Rod Photoreceptors ◽  
Present Evidence ◽  
Dim Light ◽  
Novel Protein

Photoreceptors in animals are generally of two kinds: the ciliary or c-type and the rhabdomeric or r-type. Although ciliary photoreceptors are found in many phyla, vertebrates seem to be unique in having two distinct kinds which together span the entire range of vision, from single photons to bright light. We ask why the principal photoreceptors of vertebrates are ciliary and not rhabdomeric, and how rods evolved from less sensitive cone-like photoreceptors to produce our duplex retina. We suggest that the principal advantage of vertebrate ciliary receptors is that they use less ATP than rhabdomeric photoreceptors. This difference may have provided sufficient selection pressure for the development of a completely ciliary eye. Although many of the details of rod evolution are still uncertain, present evidence indicates that (i) rods evolved very early before the split between the jawed and jawless vertebrates, (ii) outer-segment discs make no contribution to rod sensitivity but may have evolved to increase the efficiency of protein renewal, and (iii) evolution of the rod was incremental and multifaceted, produced by the formation of several novel protein isoforms and by changes in protein expression, with no one alteration having more than a few-fold effect on transduction activation or inactivation. This article is part of the themed issue ‘Vision in dim light’.

Effect of hydroxylamine on the subcellular distribution of arrestin (S-antigen) in rod photoreceptors

1994 ◽  
Vol 11 (3) ◽  
pp. 561-568 ◽  
Author(s):  
Nancy J. Mangini ◽  
Grady L. Garner ◽  
Tinging L. Okajima ◽  
Larry A. Donoso ◽  
David R. Pepperberg
Keyword(s):  
Visual Pigment ◽  
Driving Force ◽  
Outer Segment ◽  
Processing System ◽  
Bright Light ◽  
Photoreceptor Outer Segment ◽  
Rod Photoreceptors ◽  
Average Value ◽  
Secondary Antibodies ◽  
Microscopic Image Processing

AbstractThe immunocytochemical labeling of arrestin (S-antigen) in photoreceptors of the ovine retina was examined following incubation of the retina with hydroxylamine (NH2OH), an agent known to inhibit the phosphorylation of photoactivated rhodopsin. Intact, isolated retinas bathed in medium containing 20 mM NH2OH, or in control medium lacking NH2OH, were maintained in darkness or exposed to bright light for 3 min (dark-adapted and light-adapted conditions, respectively); further incubated in darkness for 10 min; and then fixed and prepared for cryosectioning. Cryosections were incubated with anti-S-antigen monoclonal antibody MAb A2G5; with secondary antibodies that were conjugated with horseradish peroxidase; and with either 3–amino-9–ethyl carbazole or diaminobenzidine as chromogen. Anti-arrestin labeling in cryosections was then analyzed densitometrically using a light-microscopic image processing system. In dark-adapted control retinas, labeling density of the photoreceptor outer segment (OS) layer (0.061 ± 0.004; average ± S.e.m.) was less than that of the inner segment (IS) layer (0.138 ± 0.011). In light-adapted control retinas, OS labeling density (0.139 ± 0.007) exceeded IS labeling density (0.095 ± 0.005). Incubation with NH2OH eliminated this light-dependent increase in labeling of the OS relative to that of the IS, i.e. eliminated the increase in relative OS/IS labeling. Densities of labeling were 0.110 ± 0.006 (OS) and 0.183 ± 0.006 (IS) in NH2OH-treated dark-adapted retinas vs. 0.078 ± 0.004 (OS) and 0.182 ± 0.008 (IS) in NH2OH-treated light-adapted retinas. Anti-arrestin labeling was also examined in retinas that were exposed to 3 min or 13 min of bright light and then immediately fixed. Among retinas incubated in the absence of NH2OH, an increase in OS/IS labeling density was evident after 3 min of illumination, and retinas illuminated for 13 min exhibited an even larger increase in OS/IS labeling. An increase in OS/IS labeling was also exhibited by NH2OH-treated retinas that had been illuminated for 3 min; by comparison with dark-adapted NH2OH-treated controls (average value of OS/IS labeling: 0.60), OS/IS labeling in these illuminated retinas was 0.97. However, OS/IS labeling in NH2OH-treated retinas that had been illuminated for 13 min (average value: 0.35) was lower than that of the dark-adapted controls. The results indicate that, within intact rods, NH2OH inhibits the light-dependent increase in OS/IS anti-arrestin labeling that is ordinarily expressed at long times (~10 min) after major bleaching of the visual pigment. Among the possible bases for the effect of NH2OH are a reduction in the driving force for the movement of arrestin from the inner to the outer segment and/or a facilitation of the degradation of arrestin in the outer segment.

scholarly journals The 9-methyl group of retinal is essential for rapid Meta II decay and phototransduction quenching in red cones

2009 ◽  
Vol 134 (2) ◽  
pp. 137-150 ◽  
Author(s):  
Maureen E. Estevez ◽  
Alexander V. Kolesnikov ◽  
Petri Ala-Laurila ◽  
Rosalie K. Crouch ◽  
Victor I. Govardovskii ◽  
...  
Keyword(s):  
Visual Pigment ◽  
Molecular Mechanisms ◽  
Bright Light ◽  
Rapid Response ◽  
Rapid Decay ◽  
Rod Photoreceptors ◽  
Methyl Group ◽  
Response Recovery ◽  
Electrophysiological Recordings ◽  
Dim Light

Cone photoreceptors of the vertebrate retina terminate their response to light much faster than rod photoreceptors. However, the molecular mechanisms underlying this rapid response termination in cones are poorly understood. The experiments presented here tested two related hypotheses: first, that the rapid decay rate of metarhodopsin (Meta) II in red-sensitive cones depends on interactions between the 9-methyl group of retinal and the opsin part of the pigment molecule, and second, that rapid Meta II decay is critical for rapid recovery from saturation of red-sensitive cones after exposure to bright light. Microspectrophotometric measurements of pigment photolysis, microfluorometric measurements of retinol production, and single-cell electrophysiological recordings of flash responses of salamander cones were performed to test these hypotheses. In all cases, cones were bleached and their visual pigment was regenerated with either 11-cis retinal or with 11-cis 9-demethyl retinal, an analogue of retinal lacking the 9-methyl group. Meta II decay was four to five times slower and subsequent retinol production was three to four times slower in red-sensitive cones lacking the 9-methyl group of retinal. This was accompanied by a significant slowing of the recovery from saturation in cones lacking the 9-methyl group after exposure to bright (>0.1% visual pigment photoactivated) but not dim light. A mathematical model of the turn-off process of phototransduction revealed that the slower recovery of photoresponse can be explained by slower Meta decay of 9-demethyl visual pigment. These results demonstrate that the 9-methyl group of retinal is required for steric chromophore–opsin interactions that favor both the rapid decay of Meta II and the rapid response recovery after exposure to bright light in red-sensitive cones.

If You’re Happy and You Know it Stay Alert: The Effects of Lighting on Vigilance Performance and Affective State

2021 ◽  
Vol 65 (1) ◽  
pp. 854-858
Author(s):  
Lauren E. Monroe ◽  
Samantha L. Smith
Keyword(s):  
Affective State ◽  
Light Condition ◽  
Bright Light ◽  
Extended Period ◽  
Light Therapy ◽  
Speed Of Information Processing ◽  
Attention Tasks ◽  
High Workload ◽  
Dim Light ◽  
Over Time

Vigilance, or sustained attention tasks involve detecting critical signals, embedded amid more frequent neutral signals, over an extended period of time. A decline in performance, engagement, and arousal over time, as well as high workload and stress, are common outcomes of such tasks. Exposure to broad-spectrum or short wavelength bright light has been found to positively impact alertness, speed of information processing, and mood, but has not been extensively explored in the vigilance domain. The present study explored whether a light therapy lamp could mitigate the negative vigilance outcomes found in both performance and affective state. Results indicated that the therapy light did not prevent a decline in detection of critical signals over time, nor significantly impact workload, sleepiness, or subjective stress state compared to a dim light condition. However, mood questionnaire results suggest that lighting may impact separate constructs of arousal and tiredness, warranting further research.

Treatment of Seasonal Affective Disorder with Light in the Evening

1985 ◽  
Vol 147 (4) ◽  
pp. 424-428 ◽  
Author(s):  
Steven P. James ◽  
Thomas A. Wehr ◽  
David A. Sack ◽  
Barbara L. Parry ◽  
Norman E. Rosenthal
Keyword(s):  
Sleep Deprivation ◽  
Affective Disorder ◽  
Seasonal Affective Disorder ◽  
Bright Light ◽  
Early Morning ◽  
Antidepressant Effect ◽  
Comparison Study ◽  
Female Patients ◽  
Dim Light ◽  
Effect Of Light

A cross-over comparison study of exposure, in the evenings only, to bright versus dim light was carried out on nine female patients with seasonal affective disorder. A significant antidepressant effect of the bright lights was shown. No consistent observable effects were produced by the dim lights. These results support earlier studies demonstrating the efficacy of bright light given morning and evening. The antidepressant effect of light is not mediated by sleep deprivation, and the early morning hours are not crucial for a response.

scholarly journals Adapting-bump model for eccentric cells of Limulus.

1980 ◽  
Vol 76 (5) ◽  
pp. 539-557 ◽  
Author(s):  
F Wong ◽  
B W Knight
Keyword(s):  
Light Intensity ◽  
Power Spectrum ◽  
Entire Range ◽  
Correlation Factor ◽  
Noise Model ◽  
Average Shape ◽  
Noise Data ◽  
Dim Light ◽  
Data Yield ◽  
Poisson Shot Noise

Light-evoked intracellular voltage noise records have been obtained from Limulus eccentric cells, from threshold light intensity to an intensity .10(5) times threshold. These data are analyzed in terms of a simple "adapting-bump" noise model. It is shown how the model yields a data reduction procedure that slightly generalizes the familiar use of Campbell's theorem for Poisson shot noise: the correlative effect of adaptation amends Campbell's theorem by a single multiplicative factor, which may be estimated directly from the power spectrum of the noise data. The model also permits direct estimation of the bump shape from the power spectrum. The bump shape estimated from noise at dim light is in excellent agreement with the average shape of bumps observed directly in the dark. The data yield a bump rate that is linear with light up through about 50 times threshold intensity but that falls short of linearity by a factor of 35 at the brightest light. The bump height decreases as the -0.4 power of light intensity across the entire range. Bump duration decreases by a factor of 2 across the entire range, and the adaptation correlation factor descends from unity to about one-third. The modest change of the adaptation correlation shows that naive application of Campbell's theorem to such data is adequate for rough estimation of the model's physiological parameters. This simple accounting for all the data gives support to the adapting-bump model.

The relationship between ambient lighting conditions, absolute dark-adapted thresholds, and rhodopsin in black and hypopigmented mice

2004 ◽  
Vol 21 (6) ◽  
pp. 925-934 ◽  
Author(s):  
GERARD H. DALY ◽  
JESSICA M. DILEONARDO ◽  
NATALIE R. BALKEMA ◽  
GRANT W. BALKEMA
Keyword(s):  
Bright Light ◽  
Visual Sensitivity ◽  
Segment Length ◽  
Single Strain ◽  
Photoreceptor Layer ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Dim Light ◽  
Albino Mice ◽  
The Relationship

Significant variation in absolute dark-adapted thresholds is observed both within and between strains of mice with differing ocular pigmentation levels. Differences in threshold within a single strain are related to the Williams' photostasis effect, that is, photoreceptor rhodopsin levels are dependent upon ambient lighting conditions. To examine threshold differences among strains, we equalized rhodopsin levels by maintaining albino mice (c2J/c2J) at 2 × 10−4 cd/m2 (dim light) and black mice at 2 × 102 cd/m2 (bright light). This resulted in ocular rhodopsin levels for albino mice (albino—dim) of 494 ± 11 pmoles/eye and rhodopsin levels for black mice (black—bright) of 506 ± 25 pmoles/eye. For comparison, rhodopsin levels in black mice maintained in dim light are 586 ± 46 pmoles/eye and 217 ± 46 pmoles/eye in albino mice maintained in bright light. We found similar dark-adapted thresholds (6.38 log cd/m2vs. 6.47 log cd/m2)) in albino and black mice with equivalent rhodopsin determined with a water maze test. This suggests that dark-adapted thresholds are directly related to rhodopsin levels regardless of the level of ocular melanin. The number of photoreceptors, photoreceptor layer thickness, and outer segment length did not differ significantly between albino (dark) and black mice (bright). These results demonstrate that the visual sensitivity defect found in hypopigmented animals is secondary to abnormal rhodopsin regulation and that hypopigmented animals have either an improper input to the photostasis mechanism or that the photostasis mechanism is defective.

scholarly journals The discovery of the ability of rod photoreceptors to signal single photons

2018 ◽  
Vol 150 (3) ◽  
pp. 383-388 ◽  
Author(s):  
Edward N. Pugh
Keyword(s):  
Visual System ◽  
Molecular Mechanism ◽  
Single Photon ◽  
Visual Environment ◽  
Single Photons ◽  
Rod Photoreceptors ◽  
Subsequent Research ◽  
Visual Threshold ◽  
Reliable Transmission

Vertebrate rod photoreceptors evolved the astonishing ability to respond reliably to single photons. In parallel, the proximate neurons of the visual system evolved the ability to reliably encode information from a few single-photon responses (SPRs) as arising from the presence of an object of interest in the visual environment. These amazing capabilities were first inferred from measurements of human visual threshold by Hecht et al. (1942), whose paper has since been cited over 1,000 times. Subsequent research, in part inspired by Hecht et al.’s discovery, has directly measured rod SPRs, characterized the molecular mechanism responsible for their generation, and uncovered much about the specializations in the retina that enable the reliable transmission of SPRs in the teeth of intrinsic neuronal noise.

scholarly journals A novel cellular structure in the retina of insectivorous birds

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Luke P. Tyrrell ◽  
Leandro B. C. Teixeira ◽  
Richard R. Dubielzig ◽  
Diana Pita ◽  
Patrice Baumhardt ◽  
...  
Keyword(s):  
Cellular Structure ◽  
Bird Species ◽  
Insectivorous Birds ◽  
Visual Channel ◽  
Oil Droplets ◽  
Rod Photoreceptors ◽  
Dim Light ◽  
Retinal Structure ◽  
The Many ◽  
Ecological Differences

Abstract The keen visual systems of birds have been relatively well-studied. The foundations of avian vision rest on their cone and rod photoreceptors. Most birds use four cone photoreceptor types for color vision, a fifth cone for achromatic tasks, and a rod for dim-light vision. The cones, along with their oil droplets, and rods are conserved across birds – with the exception of a few shifts in spectral sensitivity – despite taxonomic, behavioral and ecological differences. Here, however, we describe a novel photoreceptor organelle in a group of New World flycatchers (Empidonax spp.) in which the traditional oil droplet is replaced with a complex of electron-dense megamitochondria surrounded by hundreds of small, orange oil droplets. The photoreceptors with this organelle were unevenly distributed across the retina, being present in the central region (including in the fovea), but absent from the retinal periphery and the area temporalis of these insectivorous birds. Of the many bird species with their photoreceptors characterized, only the two flycatchers described here (E. virescens and E. minimus) possess this unusual retinal structure. We discuss the potential functional significance of this unique sub-cellular structure, which might provide an additional visual channel for these small predatory songbirds.

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