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 43 Effect of Mushroom Probiotic (Coriolus Versicolor) on Galectin Gene Secretion in Goat Blood

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 71-72
Author(s):  
Kingsley E Ekwemalor ◽  
Emmanuel K Asiamah ◽  
Sarah Adjei-Fremah ◽  
Eboghoye ElukaOkoludoh ◽  
Mulumebet Worku
Keyword(s):  
Plasma Protein ◽  
Cold Water ◽  
Cold Treatment ◽  
Coriolus Versicolor ◽  
Control Group ◽  
Plasma Protein Concentration ◽  
Treatment Groups ◽  
Total Plasma Protein ◽  
Evolutionarily Conserved ◽  
Effect Of Treatment

Abstract Galectins (GAL) constitute an evolutionarily conserved family of β-galactoside-binding proteins that are secreted. They are involved in the regulation of homeostasis, innate and adaptive immune responses to infectious challenge. The mushroom Coriolus versicolor (CV) has been reported to boost suppressed immune function, extending the survival rate and improving quality of life in man. The objective of this study was to evaluate the effect of mushroom probiotics on the secretion of Galectins in goat blood. Ten BoerXSpanish female goats (5 weeks of age) were used for this study. Powdered CV was soaked in cold water and sterile filtered. Following initial screening for infection, goats were assigned to two groups of five (n = 10). Goats were drenched daily with 10 mL cold (treatment I) extract for 4 weeks. A control group of five age-matched goats received sterile water (treatment II). Blood samples were collected on a weekly basis. The concentration plasma protein was determined by using Pierce BCA kit (Thermo Scientific Pierce, Rockford, IL). Galectins-1, -3, -8, -9 and -12 concentration was detected by using a commercial ELISA kits (ABclonal Biotechnology, Woburn, MA). There was an effect of treatment in total plasma protein concentration when compared to the control group (P < 0.02). Galectins tested were secreted in both control and treatment groups. Treatment with CV decreased the concentration of Gal-1, 8 and 9 and increased the concentration of Gal-3 and -12 (P < 0.05). Results from this study indicate that mushroom probiotics can modulate the secretion of GAL.

scholarly journals Direct Action of Light in Naturally Pigmented Muscle Fibers

1962 ◽  
Vol 46 (2) ◽  
pp. 333-342 ◽  
Author(s):  
Howard H. Seliger
Keyword(s):  
Visual Pigment ◽  
Absorption Maximum ◽  
Pupil Diameter ◽  
Direct Action ◽  
Pigment Epithelium ◽  
Action Spectrum ◽  
Square Root ◽  
Light Reaction ◽  
First Order ◽  
Iris Sphincter

Contraction due to light in excised eel irises appears to follow a simple first order law. The action spectrum for contraction has a maximum which agrees with the eel rhodopsin absorption maximum. Inasmuch as rhodopsin is the rod pigment-opsin complex and the iris sphincter pupillae evolves from the pigment epithelium of the retina in the region of the iris, the muscle pigment might be the same as the visual pigment. In the human eye the contraction of the iris sphincter is activated only by light incident on the retina and the pupil diameter varies inversely with the square root of the light intensity. The inverse first power relation observed in the present experiments suggests a more primitive origin for the light reaction in eel irises. Relaxation is a much slower process and can be approximated as the sum of two first order processes.

scholarly journals Peropsin, a novel visual pigment-like protein located in the apical microvilli of the retinal pigment epithelium

1997 ◽  
Vol 94 (18) ◽  
pp. 9893-9898 ◽  
Author(s):  
H. Sun ◽  
D. J. Gilbert ◽  
N. G. Copeland ◽  
N. A. Jenkins ◽  
J. Nathans
Keyword(s):  
Retinal Pigment Epithelium ◽  
Visual Pigment ◽  
Pigment Epithelium ◽  
Retinal Pigment

scholarly journals INHERITED RETINAL DYSTROPHY IN THE RAT

1962 ◽  
Vol 14 (1) ◽  
pp. 73-109 ◽  
Author(s):  
John E. Dowling ◽  
Richard L. Sidman
Keyword(s):  
Pigment Epithelium ◽  
Light And Electron Microscopy ◽  
Retinal Dystrophy ◽  
Photoreceptor Cells ◽  
Pigment Cells ◽  
Membrane Thickness ◽  
Outer Segments ◽  
Progressive Loss ◽  
Retinal Rods ◽  
Microscopy Data

Retinal dystrophies, known in man, dog, mouse, and rat, involve progressive loss of photoreceptor cells with onset during or soon after the developmental period. Functional (electroretinogram), chemical (rhodopsin analyses) and morphological (light and electron microscopy) data obtained in the rat indicated two main processes: (a) overproduction of rhodopsin and an associated abnormal lamellar tissue component, (b) progressive loss of photoreceptor cells. The first abnormality recognized was the appearance of swirling sheets or bundles of extracellular lamellae between normally developing retinal rods and pigment epithelium; membrane thickness and spacing resembled that in normal outer segments. Rhodopsin content reached twice normal values, was present in both rods and extracellular lamellae, and was qualitatively normal, judged by absorption maximum and products of bleaching. Photoreceptors attained virtually adult form and ERG function. Then rod inner segments and nuclei began degenerating; the ERG lost sensitivity and showed selective depression of the a-wave at high luminances. Outer segments and lamellae gradually degenerated and rhodopsin content decreased. No phagocytosis was seen, though pigment cells partially dedifferentiated and many migrated through the outer segment-debris zone toward the retina. Eventually photoreceptor cells and the b-wave of the ERG entirely disappeared. Rats kept in darkness retained electrical activity, rhodopsin content, rod structure, and extracellular lamellae longer than litter mates in light.

JAM-C maintains VEGR2 expression to promote retinal pigment epithelium cell survival under oxidative stress

2017 ◽  
Vol 117 (04) ◽  
pp. 750-757
Author(s):  
Xin Jia ◽  
Chen Zhao ◽  
Qishan Chen ◽  
Yuxiang Du ◽  
Lijuan Huang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment Epithelium ◽  
Cell Survival ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelium Cell ◽  
Photoreceptor Cells ◽  
Rpe Cells

SummaryJunctional adhesion molecule-C (JAM-C) has been shown to play critical roles during development and in immune responses. However, its role in adult eyes under oxidative stress remains poorly understood. Here, we report that JAM-C is abundantly expressed in adult mouse retinae and choroids in vivo and in cultured retinal pigment epithelium (RPE) and photoreceptor cells in vitro. Importantly, both JAM-C expression and its membrane localisation are downregulated by H2O2-induced oxidative stress. Under H2O2-induced oxidative stress, JAM-C is critically required for the survival of human RPE cells. Indeed, loss of JAM-C by siRNA knockdown decreased RPE cell survival. Mechanistically, we show that JAM-C is required to maintain VEGFR2 expression in RPE cells, and VEGFR2 plays an important role in keeping the RPE cells viable since overexpression of VEGFR2 partially restored impaired RPE survival caused by JAM-C knockdown and increased RPE survival. We further show that JAM-C regulates VEGFR2 expression and, in turn, modulates p38 phosphorylation. Together, our data demonstrate that JAM-C plays an important role in maintaining VEGR2 expression to promote RPE cell survival under oxidative stress. Given the vital importance of RPE in the eye, approaches that can modulate JAM-C expression may have therapeutic values in treating diseases with impaired RPE survival.

Selective utilization of serum vitamin A for visual pigment synthesis

1989 ◽  
Vol 142 (1) ◽  
pp. 207-214
Author(s):  
A. T. Tsin ◽  
S. N. Gentles ◽  
E. A. Castillo
Keyword(s):  
Vitamin A ◽  
Visual Pigment ◽  
Carassius Auratus ◽  
High Performance ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Serum Vitamin ◽  
Pigment Synthesis ◽  
Goldfish Carassius Auratus ◽  
Vitamin A2

Two groups of goldfish (Carassius auratus) were subjected to light and temperature conditions known to promote a contrast in their scotopic visual pigment compositions. After 3 weeks, the porphyropsin/rhodopsin ratio in the neuroretina of these goldfish ranged from 99% porphyropsin in one group to 59% in the other. Samples of blood, liver and retinal pigment epithelium (RPE) were also removed from these animals and analysed by high-performance liquid chromatography (HPLC) for vitamin A composition. There was consistently more vitamin A2 than vitamin A1 (over 50% vitamin A2) in both vitamin A alcohol and vitamin A esters extracted from the liver and the RPE. In contrast, only 30% of all vitamin A extracted from the blood was vitamin A2. These observations suggest that it is mainly vitamin A1 that is transported in the blood, whereas vitamin A2 is selectively retained in the liver and in the RPE and used to form porphyropsin in the eye.

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.

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