Cone Pigments and Vision in the Mouse

2008 ◽  
pp. 353-373
Author(s):  
Gerald H. Jacobs
Keyword(s):  
Cone Pigments

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.

scholarly journals Color Tuning Mechanism of Human Red, Green, and Blue Cone Pigments: SAC-CI Theoretical Study

2009 ◽  
Vol 82 (9) ◽  
pp. 1140-1148 ◽  
Author(s):  
Kazuhiro Fujimoto ◽  
Jun-ya Hasegawa ◽  
Hiroshi Nakatsuji
Keyword(s):  
Theoretical Study ◽  
Color Tuning ◽  
Tuning Mechanism ◽  
Cone Pigments

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.

scholarly journals Stiles-Crawford effect and the bleaching of cone pigments

1971 ◽  
Vol 217 (1) ◽  
pp. 231-242 ◽  
Author(s):  
J. R. Coble ◽  
W. A. H. Rushton
Keyword(s):  
Cone Pigments

A Hospital-Based Cross-Sectional Study to Estimate the Prevalence and Sex Distribution of Colour Vision Deficiency among School Going Children Attending a Tertiary Eye Care Center in Kolkata City, West Bengal, India

2021 ◽  
Vol 8 (32) ◽  
pp. 2962-2967
Author(s):  
Rinki Saha ◽  
Indrajit Sarkar ◽  
Tamojit Chatterjee ◽  
Sandip Samaddar ◽  
Suman Chandra Sen
Keyword(s):  
School Children ◽  
Colour Vision ◽  
Care Center ◽  
Cross Sectional Study ◽  
Sex Distribution ◽  
Cross Sectional ◽  
Colour Vision Deficiency ◽  
Cone Pigments ◽  
Normal Colour ◽  
Colour Blindness

BACKGROUND Colour vision is a function of three types of cone pigments present in the retina. Colour vision deficiency is an important disorder of vision that may pose a handicap to the performance of an affected individual. The prevalence of colour blindness varies in different geographical areas. The identification and estimation of the prevalence of colour vision deficiency in school-going children will help to educate and guide the caregivers to help the children in selecting their profession. This study was done to estimate the prevalence, sex distribution, and types of colour vision deficiency among school-going children of 5 to 15 years. METHODS A cross-sectional observational study was done among 500 students to evaluate the colour vision during the period from 1st January 2018 to 30th June 2019 at the Regional Institute of Ophthalmology, Kolkata. Ishihara’s pseudo isochromatic colour vision chart 38th edition was used to assess the school children for colour vision status. The children who were found to be colour blind were further classified into degree and types of colour vision deficiency. RESULTS A total of 500 students (250 male & 250 female) of surrounding schools, in the age group of 5 years to 15 years, were screened. 480 students (96 %) had normal colour vision while 20 (4 %) students were found to have defective colour vision. Prevalence (4 %) for colour blindness was found to be higher in males (3.6 %) than females (0.4 %). It was observed that out of 20 (4 %) colour-blind subjects 3.6 % were protanopes and 0.4 % were deuteranopes. CONCLUSIONS The present study shows the prevalence of colour blindness found to be quite low (4 %) and more common in males (3.6 %) in comparison to females (0.4 %). Protanomaly (3.6 %) was more common than deuteranomaly (0.4 %). KEYWORDS Colour Blindness, Protanomaly, Deuteranomaly, School Children

scholarly journals Comparative analysis of the decay of meta-intermediate, the formation of opsin and the regeneration between rod and cone pigments

2003 ◽  
Vol 43 (supplement) ◽  
pp. S188
Author(s):  
S. Kuwayama ◽  
H. Imai ◽  
T. Morizumi ◽  
Y. Shichida
Keyword(s):  
Comparative Analysis ◽  
Cone Pigments

Photic Environment, Visual Pigments, and the Limits of the Visible Spectrum

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 160-160
Author(s):  
V I Govardovskii
Keyword(s):  
Visible Spectrum ◽  
Blue Shift ◽  
Short Wave ◽  
Visual Pigments ◽  
Limiting Factor ◽  
Spectral Position ◽  
Dark Noise ◽  
Water Fish ◽  
Cone Pigments ◽  
Purkinje Shift

The limits of the visible spectrum are set by the light available for vision, and by the visual pigment absorbance. The hundreds of visual pigments studied to the present day have absorbance maxima spread within the range from 350 to 620 nm. Yet this diversity is used for vision quite nonuniformly: rod and cone visual pigments are tightly clustered around a few preferred positions in the spectrum, eg near 500 nm in the rods of land animals. The so-called ‘sensitivity hypothesis’ assumes that the clustering is to maximise the number of absorbed photons available in the animals' light environment. In most cases, however, visual pigments are substantially more short-wave (blue-shifted) than is necessary for maximum quantal absorption. Examples of the ‘blue shift’ are the Purkinje shift during cone - rod transition in dark adaptation, the hypsochromic shift of rod visual pigments in deep-water fish, and a similar shift in the cone pigments of geckos and some snakes as a result of evolutionary adaptation to nocturnal habits. It is argued that an important limiting factor in vision is the dark noise produced by thermal isomerisation of the chromophore. Measurements of the dark noise in rods with different visual pigments show that the noise increases steeply when the absorbance maximum is shifted to longer wavelengths, thus precluding the use of long-wave pigments for vision at low intensities. The optimum spectral position of a pigment may be that which ensures a maximum light-to-noise ratio in a particular photic environment.

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