Biosynthesis of 11-cis-retinoids and retinyl esters by bovine pigment epithelium membranes

Biochemistry ◽  
1987 ◽  
Vol 26 (24) ◽  
pp. 7938-7945 ◽  
Author(s):  
Brian S. Fulton ◽  
Robert R. Rando
Keyword(s):  
Pigment Epithelium ◽  
Retinyl Esters

scholarly journals RPE65 and the Accumulation of Retinyl Esters in Mouse Retinal Pigment Epithelium

2017 ◽  
Vol 93 (3) ◽  
pp. 844-848 ◽  
Author(s):  
Colleen Sheridan ◽  
Nicholas P. Boyer ◽  
Rosalie K. Crouch ◽  
Yiannis Koutalos
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinyl Esters

On the mechanism of isomerization of ocular retinoids by the crayfish Procambarus clarkii.

1997 ◽  
Vol 200 (3) ◽  
pp. 625-631
Author(s):  
R Srivastava ◽  
T H Goldsmith
Keyword(s):  
Convergent Evolution ◽  
Procambarus Clarkii ◽  
Pigment Epithelium ◽  
Synthetase Activity ◽  
Acyl Transferase ◽  
Phenylmethylsulfonyl Fluoride ◽  
Retinyl Esters ◽  
Vertebrate Eye ◽  
Ester Synthetase ◽  
Hydrolysis Of

The eyes of some crustaceans store substantial amounts of retinyl esters, with most of the retinol in the 11-cis configuration. Earlier work in this laboratory suggested that in lobster and crayfish the mechanism of isomerization of retinol to the 11-cis form involves the hydrolysis of all-trans retinyl esters. Although this is the same process as that occurring in the vertebrate eye, it is different from the retinal photoisomerase reaction known in other arthropods, specifically diurnal insects (Hymenoptera and probably Diptera). Using homogenates of crayfish, we have tested this proposed mechanism by inhibiting retinyl ester synthetase activity in the presence of exogenous all-trans retinol. Inhibition of lecithin:retinol acyl transferase with 5 mumol l-1 retinyl bromoacetate or 2 mmol l-1 phenylmethylsulfonyl fluoride blocks the formation of both all-trans and 11-cis retinyl esters as well as 11-cis retinol, as shown by direct assay and by the decrease in counts derived from tritiated all-trans retinol. The similarity of this isomerization to the mechanism in vertebrate pigment epithelium is thus an interesting example of convergent evolution in the biochemistry of visual pigments, in which the pigments themselves (the opsins) are largely conserved across phyla.

Retinyl esters in the vertebrate neuroretina

1989 ◽  
Vol 256 (1) ◽  
pp. R255-R258 ◽  
Author(s):  
K. A. Rodriguez ◽  
A. T. Tsin
Keyword(s):  
Visual Pigment ◽  
High Performance ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinyl Palmitate ◽  
Visual Pigments ◽  
Pigment Synthesis ◽  
Retinyl Ester ◽  
Retinyl Ester Hydrolase ◽  
Retinyl Esters

High-performance liquid chromatography (HPLC) was employed to measure retinyl esters in the vertebrate retina. Both retina and retinal pigment epithelium (RPE) from frog, chicken, and bovine eyes were studied. In comparison to the RPE, the retina possessed a significant level of 11-cis and all trans retinyl palmitate. Using a sensitive radioassay, we also detected the presence of retinyl ester hydrolase (REH) activity in homogenates prepared from both retina and RPE. The rate of retinyl ester hydrolysis in these retinas was sufficiently high to supply retinal chromophores for the metabolic renewal and for the regeneration of visual pigments. In comparison to retinyl esters in the RPE, retinyl esters in the retina are located much closer to the sites of visual pigment synthesis and regeneration. Hence it is possible that these retinyl esters play a more important role in the visual cycle than those in the RPE.

scholarly journals Diacylglycerol O-Acyltransferase Type-1 Synthesizes Retinyl Esters in the Retina and Retinal Pigment Epithelium

PLoS ONE ◽  
2015 ◽  
Vol 10 (5) ◽  
pp. e0125921 ◽  
Author(s):  
Joanna J. Kaylor ◽  
Roxana A. Radu ◽  
Nicholas Bischoff ◽  
Jacob Makshanoff ◽  
Jane Hu ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinyl Esters

Formation and storage of 11-cis retinol in the eyes of lobster (Homarus) and crayfish (Procambarus)

1996 ◽  
Vol 13 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Ranjana Srivastava ◽  
Daniel Lau ◽  
Timothy H. Goldsmith
Keyword(s):  
Pigment Epithelium ◽  
Chain Polyunsaturated Fatty Acid ◽  
Isomerase Activity ◽  
Decapod Crustacea ◽  
Mechanisms Of Formation ◽  
Retinyl Esters ◽  
And Storage ◽  
Dependent Processes ◽  
Long Chain ◽  
Storage Reserves

AbstractModes of storage and mechanisms of formation of 11-cis retinoids in the eyes of animals vary widely among the major phyla. We here describe evidence from two species of macruran decapod crustacea that point to different processes from those known in insects, the other group of arthropods for which there is extensive data. The eyes of the lobster (Homarus) contain about 300 pmol of retinal, somewhat less free retinol, and variable amounts (up to 1000+ pmol) of two retinyl esters, over 90% of which contain retinol in the 11-cis configuration. The major ester contains the long chain, polyunsaturated fatty acid docosahexaenoate (C22:6), but retinyl oleate (C18:1) is also present. Crayfish (Procambarus) contain the same retinyl esters, although in much smaller amounts. Homogenates of the eyes of both species are capable of isomerizing all-trans retinyl docosahexaenoate to the 11-cis configuration without using the energy of light. Crude fractionation of homogenates shows isomerase activity associated with membranes. The reaction mechanism has not been explored in detail, but on the basis of present evidence it may be similar to that found in vertebrate pigment epithelium. It is clearly different from the light-dependent processes known in insects (Hymenoptera and Diptera) and cephalopod mollusks, where isomerization takes place at the level of the aldehyde and 11-cis retinyl esters are not present as major storage reserves.

XRF and PIXE Analysis of light and Dark Adapted Ocular Tissue

1982 ◽  
Vol 40 ◽  
pp. 190-191
Author(s):  
B. J. Panessa ◽  
H. W. Kraner ◽  
J. B. Warren ◽  
K. W. Jones
Keyword(s):  
Trace Metals ◽  
Pigment Epithelium ◽  
Nerve Impulse ◽  
Light Response ◽  
Ocular Tissue ◽  
Emission Spectrometry ◽  
Retinol Dehydrogenase ◽  
Pixe Analysis ◽  
X Ray ◽  
Optimal Function

During photoexcitation the retina requires specific electrolytes and trace metals for optimal function (Na, Mg, Cl, K, Ca, S, P, Cu and Zn). According to Hagins (1981), photoexcitation and generation of a nerve impulse involves the movement of Ca from the rhodopsin-ladened membranes of the rod outer segment (ROS) to the plasmalemma, which in turn decreases the in-flow of Na into the photoreceptor, resulting in hyperpolarization. In toad isolated retinas, the presence of Ba has been found to increase the amplitude and prolong the delay of the light response (Brown and Flaming, 1978). Trace metals such as Cu, Zn and Se are essential for the activity of the metalloenzymes of the retina and retina pigment epithelium (RPE) (i.e. carbonic anhydrase, retinol dehydrogenase, tyrosinase, glutathione peroxidase, superoxide dismutase...). Therefore the content and fluctuations of these elements in the retina and choroid are of fundamental importance for the maintenance of vision. This paper presents elemental data from light and dark adapted frog ocular tissues examined by electron beam induced x-ray microanalysis, x-ray fluorescence spectrometry (XRF) and proton induced x-ray emission spectrometry (PIXE).

High-resolution scanning electron microscopy (HRSEM) of mitochondria from various rat tissues

1988 ◽  
Vol 46 ◽  
pp. 14-15
Author(s):  
P.J. Lea ◽  
M.J. Hollenberg
Keyword(s):  
Electron Microscopy ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Rat Hepatocytes ◽  
Three Dimensions ◽  
Objective Lens ◽  
Rat Tissues ◽  
Thin Sections ◽  
Reconstruction Methods ◽  
Scanning Electron

Our current understanding of mitochondrial ultrastructure has been derived primarily from thin sections using transmission electron microscopy (TEM). This information has been extrapolated into three dimensions by artist's impressions (1) or serial sectioning techniques in combination with computer processing (2). The resolution of serial reconstruction methods is limited by section thickness whereas artist's impressions have obvious disadvantages.In contrast, the new techniques of HRSEM used in this study (3) offer the opportunity to view simultaneously both the internal and external structure of mitochondria directly in three dimensions and in detail.The tridimensional ultrastructure of mitochondria from rat hepatocytes, retinal (retinal pigment epithelium), renal (proximal convoluted tubule) and adrenal cortex cells were studied by HRSEM. The specimens were prepared by aldehyde-osmium fixation in combination with freeze cleavage followed by partial extraction of cytosol with a weak solution of osmium tetroxide (4). The specimens were examined with a Hitachi S-570 scanning electron microscope, resolution better than 30 nm, where the secondary electron detector is located in the column directly above the specimen inserted within the objective lens.

Ultrastructural Changes of Smoooth Endoplasmic Reticulum in the Retinal Pigment Epithelium by Choline Chloride

1972 ◽  
Vol 30 ◽  
pp. 58-59
Author(s):  
Kazushige Hirosawa ◽  
Eichi Yamada
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cell ◽  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Choline Chloride ◽  
Retinal Pigment ◽  
Ultrastructural Changes ◽  
Lower Vertebrate ◽  
Visual Cells ◽  
Pigment Epithelial

The pigment epithelium is located between the choriocapillary and the visual cells. The pigment epithelial cell is characterized by a large amount of the smooth endoplasmic reticulum (SER) in its cytoplasm. In addition, the pigment epithelial cell of some lower vertebrate has myeloid body as a specialized form of the SER. Generally, SER is supposed to work in the lipid metabolism. However, the functions of abundant SER and myeloid body in the pigment epithelial cell are still in question. This paper reports an attempt, to depict the functions of these organelles in the frog retina by administering one of phospholipid precursors.

Morphological and elemental analysis of isolated incubated frog retina-choroid

1984 ◽  
Vol 42 ◽  
pp. 298-299
Author(s):  
B. J. Panessa-Warren ◽  
J. B. Warren ◽  
H. W. Kraner
Keyword(s):  
Elemental Analysis ◽  
Pigment Epithelium ◽  
Human Retina ◽  
Healthy Individuals ◽  
Anterior Portion ◽  
Pathological Conditions ◽  
Frog Retina ◽  
Isolated Retina ◽  
Vertebrate Eye ◽  
Retina Pigment Epithelium

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.

Sign in / Sign up

Export Citation Format

Share Document