Losses of functional opsin genes, short-wavelength cone photopigments, and color vision—A significant trend in the evolution of mammalian vision

2013 ◽  
Vol 30 (1-2) ◽  
pp. 39-53 ◽  
Author(s):  
GERALD H. JACOBS
Keyword(s):  
Color Vision ◽  
Short Wavelength ◽  
Mammalian Species ◽  
Gene Families ◽  
Opsin Gene ◽  
Cone Type ◽  
Opsin Genes ◽  
Single Cone ◽  
Cone Pigments ◽  
Cone Photopigments

AbstractAll mammalian cone photopigments are derived from the operation of representatives from two opsin gene families (SWS1 and LWS in marsupial and eutherian mammals; SWS2 and LWS in monotremes), a process that produces cone pigments with respective peak sensitivities in the short and middle-to-long wavelengths. With the exception of a number of primate taxa, the modal pattern for mammals is to have two types of cone photopigment, one drawn from each of the gene families. In recent years, it has been discovered that the SWS1 opsin genes of a widely divergent collection of eutherian mammals have accumulated mutational changes that render them nonfunctional. This alteration reduces the retinal complements of these species to a single cone type, thus rendering ordinary color vision impossible. At present, several dozen species from five mammalian orders have been identified as falling into this category, but the total number of mammalian species that have lost short-wavelength cones in this way is certain to be much larger, perhaps reaching as high as 10% of all species. A number of circumstances that might be used to explain this widespread cone loss can be identified. Among these, the single consistent fact is that the species so affected are nocturnal or, if they are not technically nocturnal, they at least feature retinal organizations that are typically associated with that lifestyle. At the same time, however, there are many nocturnal mammals that retain functional short-wavelength cones. Nocturnality thus appears to set the stage for loss of functional SWS1 opsin genes in mammals, but it cannot be the sole circumstance.

Quantification of color vision with cone contrast sensitivity

2004 ◽  
Vol 21 (3) ◽  
pp. 483-485 ◽  
Author(s):  
JEFF RABIN
Keyword(s):  
Color Vision ◽  
Letter Recognition ◽  
Normal Color Vision ◽  
Novel Approach ◽  
Cone Type ◽  
Cone Function ◽  
Single Cone ◽  
Human Color Vision ◽  
Cone Photopigments ◽  
Cone Sensitivity

Human color vision is based fundamentally on three separate cone photopigments. Hereditary color deficiency, which affects up to 10% of males, results from an absorption shift or lack of L or M cone phototoreceptors. While hereditary S cone deficiency is rare, decreased S cone sensitivity occurs early in eye disease, underscoring the importance of quantifying S cone function. Our purpose is to describe a novel approach for quantifying human color vision based on the photopigments of normal color vision. Colored letters, visible to a single cone type, are presented in graded steps of cone contrast to determine the threshold for letter recognition. This approach quantifies normal color vision, indicates type and severity of hereditary deficiency, and reveals sensitivity decrements in various diseases.

scholarly journals Cone monochromacy and visual pigment spectral tuning in wobbegong sharks

2012 ◽  
Vol 8 (6) ◽  
pp. 1019-1022 ◽  
Author(s):  
Susan M. Theiss ◽  
Wayne I. L. Davies ◽  
Shaun P. Collin ◽  
David M. Hunt ◽  
Nathan S. Hart
Keyword(s):  
Visual Pigment ◽  
Molecular Basis ◽  
Colour Vision ◽  
Interspecific Variation ◽  
Single Class ◽  
Cone Type ◽  
Opsin Genes ◽  
Single Cone ◽  
The Difference ◽  
Absorbance Spectra

Much is known regarding the evolution of colour vision in nearly every vertebrate class, with the notable exception of the elasmobranchs. While multiple spectrally distinct cone types are found in some rays, sharks appear to possess only a single class of cone and, therefore, may be colour blind. In this study, the visual opsin genes of two wobbegong species, Orectolobus maculatus and Orectolobus ornatus , were isolated to verify the molecular basis of their monochromacy. In both species, only two opsin genes are present, RH1 (rod) and LWS (cone), which provide further evidence to support the concept that sharks possess only a single cone type. Examination of the coding sequences revealed substitutions that account for interspecific variation in the photopigment absorbance spectra, which may reflect the difference in visual ecology between these species.

Colour vision of domestic chicks

1999 ◽  
Vol 202 (21) ◽  
pp. 2951-2959 ◽  
Author(s):  
D. Osorio ◽  
M. Vorobyev ◽  
C.D. Jones
Keyword(s):  
Motion Detection ◽  
Short Wavelength ◽  
Colour Vision ◽  
Gallus Gallus ◽  
Cone Photoreceptor ◽  
Long Wavelength ◽  
Domestic Chicks ◽  
Cone Type ◽  
Single Cone ◽  
Wavelength Light

The colour vision of domestic chicks (Gallus gallus) was investigated by training them to small food containers decorated with tilings of grey and coloured rectangles. Chicks learn to recognise the colour quickly and accurately. Chicks have four types of single-cone photoreceptor sensitive to ultraviolet, short-, medium- or long-wavelength light. To establish how these receptors are used for colour vision, stimuli were designed to be distinguished only by specific combinations of receptors. We infer (1) that all four single cones are used, and (2) that their outputs are encoded by at least three opponency mechanisms: one comparing the outputs of ultraviolet- and short-wavelength-sensitive receptors, one comparing the outputs of medium- and long-wavelength receptors and a third comparing of the outputs of short- and long- and/or medium-wavelength receptors. Thus, the chicks have tetrachromatic colour vision. These experiments do not exclude a role for the fifth cone type, double cones, but other evidence suggests that these cones serve luminance-based tasks, such as motion detection, and not colour recognition.

South American Weakly Electric Fish (Gymnotiformes) Are Long-Wavelength-Sensitive Cone Monochromats

2016 ◽  
Vol 88 (3-4) ◽  
pp. 204-212 ◽  
Author(s):  
Da-Wei Liu ◽  
Ying Lu ◽  
Hong Young Yan ◽  
Harold H. Zakon
Keyword(s):  
Short Wavelength ◽  
Electric Fish ◽  
Sister Group ◽  
Weakly Electric Fish ◽  
Opsin Gene ◽  
South American ◽  
Long Wavelength ◽  
Cone Opsin ◽  
Opsin Genes ◽  
Weakly Electric

Losses of cone opsin genes are noted in animals that are nocturnal or rely on senses other than vision. We investigated the cone opsin repertoire of night-active South American weakly electric fish. We obtained opsin gene sequences from genomic DNA of 3 gymnotiforms (Eigenmannia virescens, Sternopygus macrurus, Apteronotus albifrons) and the assembled genome of the electric eel (Electrophorus electricus). We identified genes for long-wavelength-sensitive (LWS) and medium-wavelength-sensitive cone opsins (RH2) and rod opsins (RH1). Neither of the 2 short-wavelength-sensitive cone opsin genes were found and are presumed lost. The fact that Electrophorus has a complete repertoire of extraretinal opsin genes and conservation of synteny with the zebrafish (Danio rerio) for genes flanking the 2 short-wavelength-sensitive opsin genes supports the supposition of gene loss. With microspectrophotometry and electroretinograms we observed absorption spectra consistent with RH1 and LWS but not RH2 opsins in the retinal photoreceptors of E. virescens. This profile of opsin genes and their retinal expression is identical to the gymnotiform's sister group, the catfish, which are also nocturnally active and bear ampullary electroreceptors, suggesting that this pattern likely occurred in the common ancestor of gymnotiforms and catfish. Finally, we noted an unusual N-terminal motif lacking a conserved glycosylation consensus site in the RH2 opsin of gymnotiforms, a catfish and a characin (Astyanax mexicanus). Mutations at this site influence rhodopsin trafficking in mammalian photoreceptors and cause retinitis pigmentosa. We speculate that this unusual N terminus may be related to the absence of the RH2 opsin in the cones of gymnotiforms and catfish.

scholarly journals Foxq2 determines blue cone identity in zebrafish

2021 ◽  
Author(s):  
Yohey Ogawa ◽  
Tomoya Shiraki ◽  
Yoshitaka Fukada ◽  
Daisuke Kojima
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Mammalian Species ◽  
Photoreceptor Cells ◽  
Transcriptional Network ◽  
Opsin Gene ◽  
Cone Photoreceptor ◽  
Loss Of Function ◽  
Knock Out ◽  
Opsin Genes

In vertebrates, daylight vision is mediated by a combination of spectrally distinct cone photoreceptor cells. Most vertebrate lineages retain a tetrachromatic cone system in which each cone photoreceptor subtype expresses one of four cone opsins: UV- (SWS1), blue- (SWS2), green- (RH2), and red-sensitive (LWS) opsins. Each cone subtype identity is established by a transcriptional network directing selective opsin gene expression in single photoreceptors. Our knowledge is limited regarding gene expression mechanisms for the middle wavelength-sensitive opsin genes, sws2 and rh2, because they are absent in mammalian species such as mouse, whose visual system has been extensively studied. Our previous studies identified homeobox transcription factors, Six6 and Six7, as crucial regulators of both sws2 and rh2 gene expression in zebrafish. Yet it remains unclear how these two opsin genes are selectively expressed in a cone subtype-specific manner. Here we pursued loss-of-function studies on transcription factors expressed predominantly in zebrafish cone photoreceptors and found that sws2 expression requires a forkhead box transcription factor, Foxq2, which is retained in many vertebrates having sws2 gene. A quantitative gene expression analysis using purified pools of the four cone subtypes revealed that foxq2 was expressed only in SWS2 cone subtype. foxq2 expression was abrogated in six6a/six6b/six7 knock-out zebrafish, which is deficient in SWS2 cone subtype. Forced expression of foxq2 fully restored sws2 expression in six7 knock-out fish without affecting rh2 expression. We propose a core transcriptional network that determines SWS2 cone subtype identity in the tetrachromatic vertebrate.

Genetics and Evolution of Color Vision in Primates

2019 ◽  
Author(s):  
Gerald H. Jacobs
Keyword(s):  
Color Vision ◽  
Nonhuman Primates ◽  
Field Studies ◽  
Opsin Gene ◽  
Central Feature ◽  
Motion Cues ◽  
Central Processing ◽  
Situational Variables ◽  
Cone Photopigments ◽  
Species Specific

Color is a central feature of human perceptual experience where it functions as a critical component in the detection, identification, evaluation, placement, and appreciation of objects in the visual world. Its role is significantly enhanced by the fact that humans evolved a dimension of color vision beyond that available to most other mammals. Many fellow primates followed a similar path and in recent years the basic mechanisms that support color vision—the opsin genes, photopigments, cone signals, and central processing—have been the subjects of hundreds of investigations. Because of the tight linkage between opsin gene structure and the spectral sensitivity of cone photopigments, it is possible to trace pathways along which color vision may have evolved in primates. In turn, such information allows the development of hypotheses about the nature of color vision and its utility in nonhuman primates. These hypotheses are being critically evaluated in field studies where primates solve visual problems in the presence of the full panoply of photic cues. The intent of this research is to determine which aspects of these cues are critically linked to color vision and how their presence facilitates, impedes, or fails to influence the solutions. These investigations are challenging undertakings and the emerging literature is replete with contradictory conclusions. But steady progress is being made and it appears that (a) some of the original ideas about there being a restricted number of tasks for which color vision might be optimally utilized by nonhuman primates (e. g., fruit harvest) were too simplistic and (b) depending on circumstances that can include both features of proximate visual stimuli (spectral cues, luminance cues, size cues, motion cues, overall light levels) and situational variables (social cues, developmental status, species-specific traits) the utilization of color vision by nonhuman primates is apt to be complex and varied.

scholarly journals Processing of the S-cone signals in the early visual cortex of primates

2013 ◽  
Vol 31 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Youping Xiao
Keyword(s):  
Visual Cortex ◽  
Color Vision ◽  
Short Wavelength ◽  
Nonhuman Primates ◽  
Striate Cortex ◽  
Color Perception ◽  
Visual Pathway ◽  
Visual Features ◽  
Area V2 ◽  
Early Visual Cortex

AbstractThe short-wavelength-sensitive (S) cones play an important role in color vision of primates, and may also contribute to the coding of other visual features, such as luminance and motion. The color signals carried by the S cones and other cone types are largely separated in the subcortical visual pathway. Studies on nonhuman primates or humans have suggested that these signals are combined in the striate cortex (V1) following a substantial amplification of the S-cone signals in the same area. In addition to reviewing these studies, this review describes the circuitry in V1 that may underlie the processing of the S-cone signals and the dynamics of this processing. It also relates the interaction between various cone signals in V1 to the results of some psychophysical and physiological studies on color perception, which leads to a discussion of a previous model, in which color perception is produced by a multistage processing of the cone signals. Finally, I discuss the processing of the S-cone signals in the extrastriate area V2.

The visual pigments of the bottlenose dolphin (Tursiops truncatus)

1998 ◽  
Vol 15 (4) ◽  
pp. 643-651 ◽  
Author(s):  
JEFFRY I. FASICK ◽  
THOMAS W. CRONIN ◽  
DAVID M. HUNT ◽  
PHYLLIS R. ROBINSON
Keyword(s):  
Color Vision ◽  
Bottlenose Dolphin ◽  
Visual Pigments ◽  
Nucleotide Position ◽  
Long Wavelength ◽  
Terrestrial Mammals ◽  
Cone Opsin ◽  
Cone Pigments ◽  
The Common

To assess the dolphin's capacity for color vision and determine the absorption maxima of the dolphin visual pigments, we have cloned and expressed the dolphin opsin genes. On the basis of sequence homology with other mammalian opsins, a dolphin rod and long-wavelength sensitive (LWS) cone opsin cDNAs were identified. Both dolphin opsin cDNAs were expressed in mammalian COS-7 cells. The resulting proteins were reconstituted with the chromophore 11-cis-retinal resulting in functional pigments with absorption maxima (λmax) of 488 and 524 nm for the rod and cone pigments respectively. These λmax values are considerably blue shifted compared to those of many terrestrial mammals. Although the dolphin possesses a gene homologous to other mammalian short-wavelength sensitive (SWS) opsins, it is not expressed in vivo and has accumulated a number of deletions, including a frame-shift mutation at nucleotide position 31. The dolphin therefore lacks the common dichromatic form of color vision typical of most terrestrial mammals.

The Visual Opsin Gene Repertoires of Teleost Fishes: Evolution, Ecology, and Function

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Zuzana Musilova ◽  
Walter Salzburger ◽  
Fabio Cortesi
Keyword(s):  
Sensory System ◽  
Photoreceptor Cells ◽  
Opsin Gene ◽  
Annual Review ◽  
Specific Gene ◽  
Publication Date ◽  
Teleost Fishes ◽  
Opsin Genes ◽  
The Rich ◽  
Species Specific

Visual opsin genes expressed in the rod and cone photoreceptor cells of the retina are core components of the visual sensory system of vertebrates. Here, we provide an overview of the dynamic evolution of visual opsin genes in the most species-rich group of vertebrates, teleost fishes. The examination of the rich genomic resources now available for this group reveals that fish genomes contain more copies of visual opsin genes than are present in the genomes of amphibians, reptiles, birds, and mammals. The expansion of opsin genes in fishes is due primarily to a combination of ancestral and lineage-specific gene duplications. Following their duplication, the visual opsin genes of fishes repeatedly diversified at the same key spectral-tuning sites, generating arrays of visual pigments sensitive from the ultraviolet to the red spectrum of the light. Species-specific opsin gene repertoires correlate strongly with underwater light habitats, ecology, and color-based sexual selection. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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