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.

scholarly journals Inherited colour vision deficiencies: From Dalton to molecular genetics

2005 ◽  
Vol 133 (11-12) ◽  
pp. 521-527
Author(s):  
Dragana Cvetkovic ◽  
Dobrosav Cvetkovic
Keyword(s):  
Molecular Basis ◽  
Colour Vision ◽  
Molecular Genetic ◽  
Regulatory Region ◽  
Cone Opsin ◽  
Opsin Genes ◽  
The Difference ◽  
Vision Defects ◽  
Hybrid Genes ◽  
Cone Opsins

In recent years, great advances have been made in our understanding of the molecular basis of colour vision defects, as well as of the patterns of genetic variation in individuals with normal colour vision. Molecular genetic analyses have explained the diversity of types and degrees of severity in colour vision anomalies, their frequencies, pronounced individual variations in test results, etc. New techniques have even enabled the determination of John Dalton?s real colour vision defect, 150 years after his death. Inherited colour vision deficiencies most often result from the mutations of genes that encode cone opsins. Cone opsin genes are linked to chromosomes 7 (the S or ?blue? gene) and X (the L or ?red? gene and the M or ?green? gene). The L and M genes are located on the q arm of the X chromosome in a head-to-tail array, composed of 2 to 6 (typically 3) genes - a single L is followed by one or more M genes. Only the first two genes of the array are expressed and contribute to the colour vision phenotype. The high degree of homology (96%) between the L and M genes predisposes them to unequal recombination, leading to gene deletion or the formation of hybrid genes (comprising portions of both the L and M genes), explaining the majority of the common red-green colour vision deficiencies. The severity of any deficiency is influenced by the difference in spectral sensitivity between the opsins encoded by the first two genes of the array. A rare defect, S monochromacy, is caused either by the deletion of the regulatory region of the array or by mutations that inactivate the L and M genes. Most recent research concerns the molecular basis of complete achromatopsia, a rare disorder that involves the complete loss of all cone function. This is not caused by mutations in opsin genes, but in other genes that encode cone-specific proteins, e.g. channel proteins and transducin.

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.

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.

Position of a 'green-red' hybrid gene in the visual pigment array determines colour-vision phenotype

10.1038/8798 ◽  
1999 ◽  
Vol 22 (1) ◽  
pp. 90-93 ◽  
Author(s):  
Takaaki Hayashi ◽  
Arno G. Motulsky ◽  
Samir S. Deeb
Keyword(s):  
Visual Pigment ◽  
Colour Vision ◽  
Hybrid Gene

A Window Fourier-Domain Infrared Search System

1989 ◽  
Vol 43 (8) ◽  
pp. 1311-1316 ◽  
Author(s):  
Jeffrey W. Sherman ◽  
James A. de Haseth ◽  
David G. Cameron
Keyword(s):  
Visual Inspection ◽  
Fourier Domain ◽  
Search System ◽  
Matching Algorithm ◽  
The Difference ◽  
Difficult Cases ◽  
Absorbance Spectra ◽  
Infrared Search System ◽  
Magnitude Improvement ◽  
Infrared Data

A search system is presented that utilizes Fourier-domain infrared data. This system removes or nulls features from infrared absorbance spectra that are found to be dominant and similar in the spectra of interest. This method enhances spectral differences. An example of one such region that is commonly nulled is the C-H stretch region of the spectra. These bands occur in organic compounds and, while generally being quite strong, contribute little to differentiation between spectra. More than one region may be nulled with this system, and the regions are chosen by visual inspection of the spectra of interest. The nulled spectra are then transformed into the Fourier domain, where data in the region that is 55–155 points displaced from the centerburst are extracted and normalized. Finally, a complete library search is performed on the normalized Fourier-domain data. The actual matching algorithm uses a simple dot product calculation, and excellent search results are obtained. This method can be used to distinguish similar compounds that are not easily distinguished by other infrared search methods. In the most difficult cases, a minimum of two-orders-of-magnitude improvement in the difference in dot products is observed when the results of full bandpass spectra are compared with the results of spectra that had one or more regions nulled.

Visual pigments, oil droplets and cone photoreceptor distribution in the european starling (Sturnus vulgaris)

1998 ◽  
Vol 201 (9) ◽  
pp. 1433-1446 ◽  
Author(s):  
N S Hart ◽  
J C Partridge ◽  
I C Cuthill
Keyword(s):  
Visual Pigment ◽  
Sturnus Vulgaris ◽  
European Starling ◽  
Visual Pigments ◽  
Double Cone ◽  
Temporal Region ◽  
Oil Droplets ◽  
Tetrazolium Chloride ◽  
Oil Droplet ◽  
Single Cone

Microspectrophotometric measurements of retinal photoreceptors from the European starling (Sturnus vulgaris) revealed four classes of single cone, containing visual pigments with wavelengths of maximum absorbance (<IMG src="/images/symbols/lambda.gif" WIDTH="8" HEIGHT="12" ALIGN="BOTTOM" NATURALSIZEFLAG= "3">max) at 563, 504, 449 and close to 362 nm. The two longer-wave-sensitive single cones contained brightly coloured oil droplets which cut off light below 572 and 514 nm, respectively. The 449 nm <IMG src="/images/symbols/lambda.gif" WIDTH="8" HEIGHT="12" ALIGN="BOTTOM" NATURALSIZEFLAG="3">max pigment was associated with a 'colourless' oil droplet with peak measured absorptance below 400 nm. The ultraviolet-sensitive visual pigment was paired with a transparent oil droplet which showed no significant absorption above 350 nm. A single class of double cone was identified, both members of which contained the longwave-sensitive (<IMG src="/images/symbols/lambda.gif" WIDTH="8" HEIGHT= "12" ALIGN="BOTTOM" NATURALSIZEFLAG="3">max 563 nm) visual pigment. The principal member of the double cone contained an oil droplet with a topographically variable cut-off wavelength below 471 nm; the oil droplet found in the accessory member was only measured in the ventral retina and displayed three distinct peaks of absorption at approximately 430, 450 and 480 nm. Rod photoreceptors had a <IMG src="/images/symbols/lambda.gif" WIDTH="8" HEIGHT="12" ALIGN="BOTTOM" NATURALSIZEFLAG="3">max at 503 nm. A new polynomial for fitting visual pigment templates to ultraviolet-sensitive visual pigment data is given. Topographic density measurements of the different cone classes were made using Nitroblue-tetrazolium chloride to label selectively bleached photoreceptors. The two classes of shortwave-sensitive single cone were more abundant in the dorsal retina, and longwave-sensitive single cones were notably less abundant in the dorso-temporal region of the retina, which subserves binocular vision.

scholarly journals Designing bioinspired surfaces for water collection from fog

2018 ◽  
Vol 377 (2138) ◽  
pp. 20180269 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Flat Surface ◽  
Unit Area ◽  
Water Repellency ◽  
Vertical Axis ◽  
Collection Rate ◽  
Flat Surfaces ◽  
Single Cone ◽  
Water Collection ◽  
The Difference ◽  
Conical Surfaces

A systematic study is presented on various water collectors, bioinspired by desert beetles, desert grass and cacti. Three water collecting mechanisms including heterogeneous wettability, grooved surfaces, and Laplace pressure gradient, were investigated on flat, cylindrical, conical surfaces, and conical array. It is found that higher water repellency in flat surfaces results in higher water collection rate and inclination angle (with respect to the vertical axis) has little effect. Surfaces with heterogeneous wettability have higher water collection rate than surfaces with homogeneous wettability. Both cylindrical and conical surfaces resulted in comparable water collection rate. However, only the cone transported the water droplets to its base. Heterogeneity, higher inclination and grooves increased the water collection rate. A cone has a higher collection rate per unit area than a flat surface with the same wettability. An array of cones has higher collection rate per unit area than a single cone, because droplets in a conical array coalesce, leading to higher frequency of droplets falling. Adding heterogeneity further increases the difference. Based on the findings, scaled-up designs of beetle-, grass- and cactus-inspired surfaces and nets are presented. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’.

scholarly journals Molecular basis of the altered antigenic expression of RhD in weak D(Du) and RhC/e in RN phenotypes

Blood ◽  
1996 ◽  
Vol 87 (11) ◽  
pp. 4853-4861 ◽  
Author(s):  
C Rouillac ◽  
P Gane ◽  
J Cartron ◽  
PY Le Pennec ◽  
JP Cartron ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Molecular Genetic ◽  
Low Frequency ◽  
State Level ◽  
Polymerase Chain Reaction Analysis ◽  
Low Grade ◽  
Molecular Genetic Basis ◽  
Group Locus ◽  
The Difference ◽  
D Antigen

The RH blood group locus is composed of two sequence-related genes, RHD and RHCE, encoding the D, Cc, and Ee antigens in common Rh-positive phenotypes. In this report, we have analyzed the molecular basis of Rh antigens expression in weak D (Du) and RN donors, in whom there is a severe reduction of the D and C/e antigens, respectively. Genomic and transcript analysis of three unrelated low-grade weak D (Du) variants indicated that the very low expression of the D antigen is not the result of rearrangement or mutation in the coding sequence of the RHO gone. Accordingly, weak D (Du) erythrocytes should carry a normal RhD polypeptide, which is in agreement with the observation that these variants never produce anti-D antibodies. Comparative polymerase chain reaction analysis showed a lower steady-state level of RhD transcripts in weak D (Du) reticulocytes, as compared with normal RhD-positive controls, thus providing direct evidence that the difference between the D antigen of D-positive and weak D (Du) red blood cells is quantitative only. Conversely, analysis of the molecular genetic basis of the RN phenotype Indicated that the severely decreased expression of the RhC and Rhe antigens in three variants is associated with a qualitative alteration identified as a segmental DNA exchange between the RHCE and RHD genes. These genomic rearrangements, which resulted in hybrid RhCe-D-Ce proteins expressing the low frequency Rh32 but not the high incidence Rh46 antigens, involved either axon 4 alone or both exons 3 and 4. These findings show that an identical phenotypical alteration of Rh antigens (reduced expression) may result either from a quantitative or a qualitative alteration of the RH genes expression.

Sign in / Sign up

Export Citation Format

Share Document