scholarly journals The visual pigment xenopsin is widespread in protostome eyes and impacts the view on eye evolution

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Clemens Christoph Döring ◽  
Suman Kumar ◽  
Sharat Chandra Tumu ◽  
Ioannis Kourtesis ◽  
Harald Hausen
Keyword(s):  
Visual Pigment ◽  
Photoreceptor Cells ◽  
Complex Situation ◽  
Eye Evolution ◽  
Molecular Components ◽  
Existing Data

Photoreceptor cells in the eyes of Bilateria are often classified into microvillar cells with rhabdomeric opsin and ciliary cells with ciliary opsin, each type having specialized molecular components and physiology. First data on the recently discovered xenopsin point towards a more complex situation in protostomes. In this study, we provide clear evidence that xenopsin enters cilia in the eye of the larval bryozoan Tricellaria inopinata and triggers phototaxis. As reported from a mollusc, we find xenopsin coexpressed with rhabdomeric-opsin in eye photoreceptor cells bearing both microvilli and cilia in larva of the annelid Malacoceros fuliginosus. This is the first organism known to have both xenopsin and ciliary opsin, showing that these opsins are not necessarily mutually exclusive. Compiling existing data, we propose that xenopsin may play an important role in many protostome eyes and provides new insights into the function, evolution, and possible plasticity of animal eye photoreceptor cells.

The effect of extrinsic factors on two distinctive rhodopsin–porphyropsin systems

1977 ◽  
Vol 55 (6) ◽  
pp. 1000-1009 ◽  
Author(s):  
William N. McFarland ◽  
Donald M. Allen
Keyword(s):  
Visual Pigment ◽  
Brook Trout ◽  
Pigment Epithelium ◽  
Cold Treatment ◽  
Continuous Light ◽  
Photoreceptor Cells ◽  
Pigment Composition ◽  
Extrinsic Factors ◽  
Treatment Groups ◽  
Species Groups

The effects of light, temperature, and thyroxine on the proportions of two visual pigments (rhodopsin and porphyropsin) are compared for three species of fishes in which the pigment proportions change oppositely in response to light (rainbow and brook trout vs. common shiners). In rainbow trout and common shiners higher temperatures reduced the proportions of porphyropsin in the retina, independent of photic conditions. The greatest differences between the warm and cold treatment groups, however, were obtained with a photoperiod as contrasted with continuous light or darkness. Capping of one eye in brook trout reduced porphyropsin independently of the uncapped eye. Thyroxine, which favors porphyropsin in both species groups, acted effectively only in the presence of light. It is suggested that a photoperiod, which produces both bleaching and photomechanical movements within the retina, enhances the exchange of vitamin A1 and A2 aldehydes between the photoreceptor cells and the pigment epithelium. Apparently light influences these processes oppositely in the different groups of fishes. A model to explain how photic conditions affect visual pigment composition in tadpoles (Bridges 1975) is extended to account for the opposite responses to light and darkness observed in different fishes.

scholarly journals Renewal of opsin in the photoreceptor cells of the mosquito.

1979 ◽  
Vol 74 (5) ◽  
pp. 565-582 ◽  
Author(s):  
P J Stein ◽  
J D Brammer ◽  
S E Ostroy
Keyword(s):  
Membrane Protein ◽  
Protein Metabolism ◽  
Gel Electrophoresis ◽  
Visual Pigment ◽  
Light Adaptation ◽  
Sodium Dodecyl ◽  
Photoreceptor Cells ◽  
Membrane Turnover ◽  
Photoreceptor Membrane ◽  
Perinuclear Cytoplasm

Mosquito rhodopsin is a digitonin-soluble membrane protein of molecular weight 39,000 daltons, as determined by sodium dodecyl sulfate gel electrophoresis. The rhodopsin undergoes a spectral transition from R515-520 to M480 after orange illumination. The visual pigment apoprotein, opsin, is the major membrane protein in the eye. Protein synthesis in the photoreceptor cells occurs in the perinuclear cytoplasm and the newly made protein is transported to the rhabdom. Light adaptation increases the rate of turnover of this rhabdomal protein. The turnover of electrophoretically isolated opsin is also stimulated by light adaptation. The changes observed in protein metabolism biochemically, are consistent with previous morphological observations of photoreceptor membrane turnover. The results agree with the hypothesis that the newly synthesized rhabdomal protein is opsin.

scholarly journals Evolution and the origin of the visual retinoid cycle in vertebrates

2009 ◽  
Vol 364 (1531) ◽  
pp. 2897-2910 ◽  
Author(s):  
Takehiro G. Kusakabe ◽  
Noriko Takimoto ◽  
Minghao Jin ◽  
Motoyuki Tsuda
Keyword(s):  
Visual Pigment ◽  
Photoreceptor Cells ◽  
Light Sensitivity ◽  
Visual Cycle ◽  
Interphotoreceptor Retinoid Binding Protein ◽  
New Genes ◽  
Ascidian Larva ◽  
Cycle Systems ◽  
Subcellular Compartmentalization ◽  
Cellular Compartments

Absorption of a photon by visual pigments induces isomerization of 11- cis -retinaldehyde (RAL) chromophore to all- trans -RAL. Since the opsins lacking 11- cis -RAL lose light sensitivity, sustained vision requires continuous regeneration of 11- cis -RAL via the process called ‘visual cycle’. Protostomes and vertebrates use essentially different machinery of visual pigment regeneration, and the origin and early evolution of the vertebrate visual cycle is an unsolved mystery. Here we compare visual retinoid cycles between different photoreceptors of vertebrates, including rods, cones and non-visual photoreceptors, as well as between vertebrates and invertebrates. The visual cycle systems in ascidians, the closest living relatives of vertebrates, show an intermediate state between vertebrates and non-chordate invertebrates. The ascidian larva may use retinochrome-like opsin as the major isomerase. The entire process of the visual cycle can occur inside the photoreceptor cells with distinct subcellular compartmentalization, although the visual cycle components are also present in surrounding non-photoreceptor cells. The adult ascidian probably uses RPE65 isomerase, and trans -to- cis isomerization may occur in distinct cellular compartments, which is similar to the vertebrate situation. The complete transition to the sophisticated retinoid cycle of vertebrates may have required acquisition of new genes, such as interphotoreceptor retinoid-binding protein, and functional evolution of the visual cycle genes.

scholarly journals Multiple visual pigments in a photoreceptor of the salamander retina.

1996 ◽  
Vol 108 (1) ◽  
pp. 27-34 ◽  
Author(s):  
C L Makino ◽  
R L Dodd
Keyword(s):  
Absorption Spectra ◽  
Visual Pigment ◽  
Photoreceptor Cells ◽  
Visual Pigments ◽  
Wavelength Band ◽  
Absorption Bands ◽  
Maximal Sensitivity ◽  
Retinal Chromophore ◽  
Wavelength Discrimination ◽  
Pigment Absorption

Although a given retina typically contains several visual pigments, each formed from a retinal chromophore bound to a specific opsin protein, single photoreceptor cells have been thought to express only one type of opsin. This design maximizes a cell's sensitivity to a particular wavelength band and facilitates wavelength discrimination in retinas that process color. We report electrophysiological evidence that the ultraviolet-sensitive cone of salamander violates this rule. This cell contains three different functional opsins. The three opsins could combine with the two different chromophores present in salamander retina to form six visual pigments. Whereas rods and other cones of salamander use both chromophores, they appear to express only one type of opsin per cell. In visual pigment absorption spectra, the bandwidth at half-maximal sensitivity increases as the pigment's wavelength maximum decreases. However, the bandwidth of the UV-absorbing pigment deviates from this trend; it is narrow like that of a red-absorbing pigment. In addition, the UV-absorbing pigment has a high apparent photosensitivity when compared with that of red- and blue-absorbing pigments and rhodopsin. These properties suggest that the mechanisms responsible for spectrally tuning visual pigments separate two absorption bands as the wavelength of maximal sensitivity shifts from UV to long wavelengths.

scholarly journals Vertebrate features revealed in the rudimentary eye of the Pacific hagfish (Eptatretus stoutii)

2020 ◽  
Author(s):  
Emily M. Dong ◽  
W. Ted Allison
Keyword(s):  
Ganglion Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
List Type ◽  
Eye Evolution ◽  
The Pacific ◽  
Pigmented Epithelium ◽  
Cell Layers ◽  
Eptatretus Stoutii

SUMMARYHagfish eyes are markedly basic compared to the eyes of other vertebrates, lacking a pigmented epithelium, a lens, and a retinal architecture built of three cell layers – the photoreceptors, interneurons & ganglion cells. Concomitant with hagfish belonging to the earliest-branching vertebrate group (the jawless Agnathans), this lack of derived characters has prompted competing interpretations that hagfish eyes represent either a transitional form in the early evolution of vertebrate vision, or a regression from a previously elaborate organ. Here we show the hagfish retina is not extensively degenerating during its ontogeny, but instead grows throughout life via a recognizable Pax6+ ciliary marginal zone. The retina has a distinct layer of photoreceptor cells that appear to homogeneously express a single opsin of the rh1 rod opsin class. The epithelium that encompasses these photoreceptors is striking because it lacks the melanin pigment that is universally associated with animal vision; notwithstanding, we suggest this epithelium is a homolog of gnathosome Retinal Pigment Epithelium (RPE) based on its robust expression of RPE65 and its engulfment of photoreceptor outer segments. We infer that the hagfish retina is not entirely rudimentary in its wiring, despite lacking a morphologically distinct layer of interneurons: multiple populations of cells exist in the hagfish inner retina that differentially express markers of vertebrate retinal interneurons. Overall, these data clarify Agnathan retinal homologies, reveal characters that now appear to be ubiquitous across the eyes of vertebrates, and refine interpretations of early vertebrate visual system evolution.HIGHLIGHTSHagfish eyes are degenerate but not degenerating, i.e. rudimentary but growingRetinal interneurons discovered implying ancestral hagfish had derived retinas & visionDespite lacking pigment, a Retinal Pigmented Epithelium homolog functions in hagfishRevised synapomorphies illuminate the dimly lit origins of vertebrate eye evolutionGRAPHICAL ABSTRACT

scholarly journals Physiological Properties of Rod Photoreceptor Cells in Green-sensitive Cone Pigment Knock-in Mice

2007 ◽  
Vol 130 (1) ◽  
pp. 21-40 ◽  
Author(s):  
Keisuke Sakurai ◽  
Akishi Onishi ◽  
Hiroo Imai ◽  
Osamu Chisaka ◽  
Yoshiki Ueda ◽  
...  
Keyword(s):  
Visual Pigment ◽  
Single Photon ◽  
Noise Analysis ◽  
Photoreceptor Cells ◽  
Molecular Properties ◽  
Rod Photoreceptor ◽  
Wild Type ◽  
Scotopic Vision ◽  
Signal Transduction Proteins ◽  
Single Photon Response

Rod and cone photoreceptor cells that are responsible for scotopic and photopic vision, respectively, exhibit photoresponses different from each other and contain similar phototransduction proteins with distinctive molecular properties. To investigate the contribution of the different molecular properties of visual pigments to the responses of the photoreceptor cells, we have generated knock-in mice in which rod visual pigment (rhodopsin) was replaced with mouse green-sensitive cone visual pigment (mouse green). The mouse green was successfully transported to the rod outer segments, though the expression of mouse green in homozygous retina was ∼11% of rhodopsin in wild-type retina. Single-cell recordings of wild-type and homozygous rods suggested that the flash sensitivity and the single-photon responses from mouse green were three to fourfold lower than those from rhodopsin after correction for the differences in cell volume and levels of several signal transduction proteins. Subsequent measurements using heterozygous rods expressing both mouse green and rhodopsin E122Q mutant, where these pigments in the same rod cells can be selectively irradiated due to their distinctive absorption maxima, clearly showed that the photoresponse of mouse green was threefold lower than that of rhodopsin. Noise analysis indicated that the rate of thermal activations of mouse green was 1.7 × 10−7 s−1, about 860-fold higher than that of rhodopsin. The increase in thermal activation of mouse green relative to that of rhodopsin results in only 4% reduction of rod photosensitivity for bright lights, but would instead be expected to severely affect the visual threshold under dim-light conditions. Therefore, the abilities of rhodopsin to generate a large single photon response and to retain high thermal stability in darkness are factors that have been necessary for the evolution of scotopic vision.

scholarly journals Co-expression of xenopsin and rhabdomeric opsin in photoreceptors bearing microvilli and cilia

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Oliver Vöcking ◽  
Ioannis Kourtesis ◽  
Sharat Chandra Tumu ◽  
Harald Hausen
Keyword(s):  
Visual Pigment ◽  
Photoreceptor Cell ◽  
Gene Loss ◽  
Photoreceptor Cells ◽  
Common Origin ◽  
Opsin Gene ◽  
Cell Type ◽  
Rods And Cones ◽  
Gene Structures ◽  
And Function

Ciliary and rhabdomeric opsins are employed by different kinds of photoreceptor cells, such as ciliary vertebrate rods and cones or protostome microvillar eye photoreceptors, that have specialized structures and molecular physiologies. We report unprecedented cellular co-expression of rhabdomeric opsin and a visual pigment of the recently described xenopsins in larval eyes of a mollusk. The photoreceptors bear both microvilli and cilia and express proteins that are orthologous to transporters in microvillar and ciliary opsin trafficking. Highly conserved but distinct gene structures suggest that xenopsins and ciliary opsins are of independent origin, irrespective of their mutually exclusive distribution in animals. Furthermore, we propose that frequent opsin gene loss had a large influence on the evolution, organization and function of brain and eye photoreceptor cells in bilaterian animals. The presence of xenopsin in eyes of even different design might be due to a common origin and initial employment of this protein in a highly plastic photoreceptor cell type of mixed microvillar/ciliary organization.

scholarly journals Adaptation of a deep-sea cephalopod to the photic environment. Evidence for three visual pigments.

1988 ◽  
Vol 92 (1) ◽  
pp. 55-66 ◽  
Author(s):  
S Matsui ◽  
M Seidou ◽  
S Horiuchi ◽  
I Uchiyama ◽  
Y Kito
Keyword(s):  
Deep Sea ◽  
Visual Pigment ◽  
Small Area ◽  
High Performance ◽  
Outer Segment ◽  
High Sensitivity ◽  
Photoreceptor Cells ◽  
High Performance Liquid Chromatographic ◽  
Visual Pigments ◽  
Environmental Light

Watasenia scintillans, a bioluminescent deep-sea squid, has a specially developed eye with a large open pupil and three visual pigments. Photoreceptor cells (outer segment: 476 micron; inner segment: 99 micron) were long in the small area of the ventral retina receiving downwelling light, whereas they were short (outer segment: 207 micron; inner segment: 44 micron) in the other regions of the retina. The short photoreceptor cells contained the visual pigment with retinal (lambda max approximately 484 nm), probably for the purpose of adapting to their environmental light. The outer segment of the long photoreceptor cells consisted of two strata, a pinkish proximal area and a yellow distal area. The visual pigment with 3-dehydroretinal (lambda max approximately 500 nm) was located in the pinkish proximal area, giving high sensitivity at longer wavelengths. A newly found pigment (lambda max approximately 471 nm) was in the yellow distal area. The small area of the ventral retina containing two visual pigments is thought to have a high and broad spectral sensitivity, which is useful for distinguishing the bioluminescence of squids of the same species in their environmental downwelling light. These findings were obtained by partial bleaching of the extracted pigment from various areas of the retina and by high-performance liquid chromatographic analysis of the chromophore, complemented by microscopic observations.

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