scholarly journals Euphausiid visual pigments. The rhodopsins of Euphausia superba and Meganyctiphanes norvegica (Crustacea, Euphausiacea).

1982 ◽  
Vol 80 (3) ◽  
pp. 451-472 ◽  
Author(s):  
C J Denys ◽  
P K Brown
Keyword(s):  
Schiff Base ◽  
Euphausia Superba ◽  
Visual Pigments ◽  
Long Wavelength ◽  
Spectral Changes ◽  
Accessory Pigment ◽  
Meganyctiphanes Norvegica ◽  
Ph Dependent ◽  
Wavelength Light ◽  
Absorbance Spectra

The rhabdoms of Euphausia superba contain one digitonin-extractable rhodopsin, lambda max 485 nm. The rhodopsin undergoes unusual pH-dependent spectral changes: above neutrality, the absorbance decreases progressively at 485 nm and rises near 370 nm. This change is reversible and appears to reflect an equilibrium between a protonated and an unprotonated form of the rhodopsin Schiff-base linkage. Near neutral pH and at 10 degrees C, the rhodopsin is partiaLly converted by 420-nm light to a stable 493-nm metarhodopsin. The metarhodopsin is partially photoconverted to rhodopsin by long-wavelength light in the absence of NH2OH; in the presence of NH2OH, it is slowly converted to retinal oxime and opsin. The rhodopsin of Meganyctiphanes norvegica measured in fresh rhabdoms by microspectrophotometry has properties very similar to those of the extracted rhodopsin of E. superba. Its lambda max is 488 nm and it is partially photoconverted by short wavelength irradiation to a stable photoconvertible metarhodopsin similar to that of E. superba. In the presence of light and NH2OH, the M. norvegica metarhodopsin is converted to retinal oxime and opsin. Our results indicate that previous determinations of euphausiid rhodopsin absorbance spectra were incorrect because of accessory pigment contamination.

scholarly journals The diversity of opsins in Lake Baikal amphipods (Amphipoda: Gammaridae)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Polina Drozdova ◽  
Alena Kizenko ◽  
Alexandra Saranchina ◽  
Anton Gurkov ◽  
Maria Firulyova ◽  
...  
Keyword(s):  
Lake Baikal ◽  
Visual Pigments ◽  
Ancient Lake ◽  
Climate History ◽  
Habitat Depth ◽  
Long Wavelength ◽  
Evolutionary Scenario ◽  
Evolutionary Changes ◽  
Evolutionary Success ◽  
Multiple Species

Abstract Background Vision is a crucial sense for the evolutionary success of many animal groups. Here we explore the diversity of visual pigments (opsins) in the transcriptomes of amphipods (Crustacea: Amphipoda) and conclude that it is restricted to middle (MWS) and long wavelength-sensitive (LWS) opsins in the overwhelming majority of examined species. Results We evidenced (i) parallel loss of MWS opsin expression in multiple species (including two independently evolved lineages from the deep and ancient Lake Baikal) and (ii) LWS opsin amplification (up to five transcripts) in both Baikal lineages. The number of LWS opsins negatively correlated with habitat depth in Baikal amphipods. Some LWS opsins in Baikal amphipods contained MWS-like substitutions, suggesting that they might have undergone spectral tuning. Conclusions This repeating two-step evolutionary scenario suggests common triggers, possibly the lack of light during the periods when Baikal was permanently covered with thick ice and its subsequent melting. Overall, this observation demonstrates the possibility of revealing climate history by following the evolutionary changes in protein families.

scholarly journals Demonstration of epitaxial growth of strain-relaxed GaN films on graphene/SiC substrates for long wavelength light-emitting diodes

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ye Yu ◽  
Tao Wang ◽  
Xiufang Chen ◽  
Lidong Zhang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Light Emitting Diodes ◽  
Nitrogen Plasma ◽  
Biaxial Stress ◽  
Organic Chemical ◽  
Graphene Surface ◽  
Light Emitting ◽  
Long Wavelength ◽  
Pre Treatment ◽  
Wavelength Light

AbstractStrain modulation is crucial for heteroepitaxy such as GaN on foreign substrates. Here, the epitaxy of strain-relaxed GaN films on graphene/SiC substrates by metal-organic chemical vapor deposition is demonstrated. Graphene was directly prepared on SiC substrates by thermal decomposition. Its pre-treatment with nitrogen-plasma can introduce C–N dangling bonds, which provides nucleation sites for subsequent epitaxial growth. The scanning transmission electron microscopy measurements confirm that part of graphene surface was etched by nitrogen-plasma. We study the growth behavior on different areas of graphene surface after pre-treatment, and propose a growth model to explain the epitaxial growth mechanism of GaN films on graphene. Significantly, graphene is found to be effective to reduce the biaxial stress in GaN films and the strain relaxation improves indium-atom incorporation in InGaN/GaN multiple quantum wells (MQWs) active region, which results in the obvious red-shift of light-emitting wavelength of InGaN/GaN MQWs. This work opens up a new way for the fabrication of GaN-based long wavelength light-emitting diodes.

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.

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.

Regulation of Photoactivation in Vertebrate Short Wavelength Visual Pigments:  Protonation of the Retinylidene Schiff Base and a Counterion Switch

Biochemistry ◽  
2007 ◽  
Vol 46 (18) ◽  
pp. 5330-5340 ◽  
Author(s):  
Lavoisier S. Ramos ◽  
Min-Hsuan Chen ◽  
Barry E. Knox ◽  
Robert R. Birge
Keyword(s):  
Schiff Base ◽  
Short Wavelength ◽  
Visual Pigments

Visual pigments and oil droplets in diurnal lizards

2002 ◽  
Vol 205 (7) ◽  
pp. 927-938 ◽  
Author(s):  
Ellis R. Loew ◽  
Leo J. Fleishman ◽  
Russell G. Foster ◽  
Ignacio Provencio
Keyword(s):  
Visual Pigment ◽  
Visual Pigments ◽  
Anolis Carolinensis ◽  
Visual Cell ◽  
Oil Droplets ◽  
Oil Droplet ◽  
Long Wavelength ◽  
Apparent Color ◽  
Vitamin A2 ◽  
Insight Into

SUMMARY We report microspectrophotometric (MSP) data for the visual pigments and oil droplets of 17 species of Caribbean anoline lizard known to live in differing photic habitats and having distinctly different dewlap colors. The outgroup Polychrus marmoratus was also examined to gain insight into the ancestral condition. Except for Anolis carolinensis, which is known to use vitamin A2 as its visual pigment chromophore, all anoline species examined possessed at least four vitamin-A1-based visual pigments with maximum absorbance (λmax) at 564, 495,455 and 365 nm. To the previously reported visual pigments for A. carolinensis we add an ultraviolet-sensitive one withλ max at 365 nm. Five common classes of oil droplet were measured, named according to apparent color and associated with specific cone classes — yellow and green in long-wavelength-sensitive (LWS) cones,green only in medium-wavelength-sensitive (MWS) cones and colorless in short-wavelength-sensitive (SWS) and ultraviolet-sensitive (UVS) cones. MSP data showed that the colorless droplet in the SWS cone had significant absorption between 350 and 400 nm, while the colorless droplet in the UVS cone did not. The pattern for Polychrus marmoratus was identical to that for the anoles except for the presence of a previously undescribed visual cell with a rod-like outer segment, a visual pigment with a λmaxof 497 nm and a colorless oil droplet like that in the UVS cones. These findings suggest that anoline visual pigments, as far as they determine visual system spectral sensitivity, are not necessarily adapted to the photic environment or to the color of significant visual targets (e.g. dewlaps).

Light Trapping in Thin Film Silicon n-i-p Solar Cells - Gains and Losses

2008 ◽  
Vol 1101 ◽  
Author(s):  
Ruud E.I. Schropp ◽  
Hongbo Li ◽  
Jatin K. Rath ◽  
Ronald H. Franken
Keyword(s):  
Thin Film ◽  
Light Trapping ◽  
Structural Defects ◽  
Metallic Surface ◽  
Textured Surfaces ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Internal Surfaces ◽  
Gains And Losses ◽  
Wavelength Light

AbstractThin film silicon solar cell technology frequently makes use of rough or textured surfaces in order to enhance light absorption within the thin absorber layers by scattering and total internal reflection (“light trapping”). The rough morphology of the optically functional internal surfaces both in superstrate and substrate cells however, not only has a beneficial effect on light scattering properties, but on the other hand may also have deleterious effects on the microscopic structure of the deposited layers, in particular if these layers are nanocrystalline. The narrow valleys in the surface morphology may lead to structural defects, such as cavities and pinholes. By adjusting the morphology, these defects can be avoided.However, even when structural defects in layers directly deposited on rough interfaces are avoided, the obtained optically defined maximum current density is still much lower than expected. For instance, in n-i-p structures the rough interface (the textured back reflector consisting of nanostructured Ag coated with ZnO) is located at the back of the cell, where only long wavelength light is present. The natively textured Ag film is sputtered at elevated temperature and optimized for diffusely reflecting this long wavelength light. From experiments we infer that the nanostructured metallic surface also gives rise to plasmon absorption in the red and near IR, and that this leads to a parasitic absorption, i.e. at least part of the absorbed energy is not re-emitted to the active layers.

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