scholarly journals Dependency on light and vitamin A derivatives of the biogenesis of 3-hydroxyretinal and visual pigment in the compound eyes of Drosophila melanogaster.

1988 ◽  
Vol 92 (5) ◽  
pp. 587-600 ◽  
Author(s):  
K Isono ◽  
T Tanimura ◽  
Y Oda ◽  
Y Tsukahara
Keyword(s):  
Drosophila Melanogaster ◽  
Vitamin A ◽  
Visual Pigment ◽  
Absorption Maximum ◽  
Action Spectrum ◽  
Compound Eyes ◽  
Trans Form ◽  
Optimum Wavelength ◽  
Derivatives Of ◽  
Cis Isomer

When the fruitfly, Drosophila melanogaster, was reared on media deficient in carotenoids and retinoids, the level of 3-hydroxyretinal (the chromophore of fly rhodopsin) in the retina decreased to less than 1% compared with normal flies. The level of 3-hydroxyretinal increased markedly in flies that were given a diet supplemented with retinoids or carotenoids. The retinas of flies fed on all-trans retinoids and maintained in the dark predominantly contained the all-trans form of 3-hydroxyretinal, and showed no increase in the level of either the 11-cis isomer or the visual pigment. Subsequent illumination of the flies converted substantial amounts of all-trans 3-hydroxyretinal to its 11-cis isomer. The action spectrum of the conversion by illumination showed the optimum wavelength to be approximately 420 nm, which is significantly greater than the absorption maximum of free, all-trans 3-hydroxyretinal. Flies that were fed on carotenoids showed a rapid increase of the levels of 11-cis 3-hydroxyretinal and of visual pigment in the absence of light.

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 Utilization of retinoids in the bullfrog retina.

1982 ◽  
Vol 80 (6) ◽  
pp. 885-913 ◽  
Author(s):  
J I Perlman ◽  
B R Nodes ◽  
D R Pepperberg
Keyword(s):  
Vitamin A ◽  
Visual Pigment ◽  
Outer Segment ◽  
Rana Catesbeiana ◽  
Retinyl Palmitate ◽  
Visual Cycle ◽  
Trans Isomers ◽  
Isolated Retina ◽  
Cis Isomer

The capacity to generate 11-cis retinal from retinoids arising naturally in the eye was examined in the retina of the bullfrog, Rana catesbeiana. Retinoids, co-suspended with phosphatidylcholine, were applied topically to the photoreceptor surface of the isolated retina after substantial bleaching of the native visual pigment. The increase in photoreceptor sensitivity associated with the formation of rhodopsin, used as an assay for the appearance of 11-cis retinal in the receptors, was analyzed by extracellular measurement of the photoreceptor potential; in separate experiments using the isolated retina or receptor outer segment preparations, the formation of rhodopsin was measured spectrophotometrically. Treatments with the 11-cis isomers of retinal and retinol induced significant increases in both the rhodopsin content and photic sensitivity of previously bleached receptors. The all-trans isomers of retinyl palmitate, retinol, and retinal, as well as the 11-cis isomer of retinyl palmitate, were inactive by both the electrophysiological and spectrophotometric criteria for the generation of rhodopsin. Treatment with any one of the "inactive" retinoids did not abolish the capacity of subsequently applied 11-cis retinal or 11-cis retinol to promote the formation of rhodopsin. The data are discussed in relation to the interconversions of retinoids ("visual cycle of vitamin A") thought to mediate the regeneration of rhodopsin in vivo after extensive bleaching.

Restriction of P-element insertions at the Notch locus of Drosophila melanogaster

1987 ◽  
Vol 7 (4) ◽  
pp. 1545-1548
Author(s):  
M R Kelley ◽  
S Kidd ◽  
R L Berg ◽  
M W Young
Keyword(s):  
Drosophila Melanogaster ◽  
Dna Sequences ◽  
Consensus Sequence ◽  
P Element ◽  
Induced Mutations ◽  
P Elements ◽  
Target Dna ◽  
Complex Locus ◽  
Additional Level ◽  
Derivatives Of

P elements move about the Drosophila melanogaster genome in a nonrandom fashion, preferring some chromosomal targets for insertion over others (J. C. J. Eeken, F. H. Sobels, V. Hyland, and A. P. Schalet, Mutat. Res. 150:261-275, 1985; W. R. Engels, Annu. Rev. Genet. 17:315-344, 1983; M. D. Golubovsky, Y. N. Ivanov, and M. M. Green, Proc. Natl. Acad. Sci. USA 74:2973-2975, 1977; M. J. Simmons and J. K. Lim, Proc. Natl. Acad. Sci. USA 77:6042-6046, 1980). Some of this specificity may be due to recognition of a particular DNA sequence in the target DNA; derivatives of an 8-base-pair consensus sequence are occupied by these transposable elements at many different chromosomal locations (K. O'Hare and G. M. Rubin, Cell 34:25-36, 1983). An additional level of specificity of P-element insertions is described in this paper. Of 14 mutations induced in the complex locus Notch by hybrid dysgenesis, 13 involved P-element insertions at or near the transcription start site of the gene. This clustering was not seen in other transposable element-induced mutations of Notch. DNA sequences homologous to the previously described consensus target for P-element insertion are not preferentially located in this region of the locus. The choice of a chromosomal site for integration appears to be based on more subtle variations in chromosome structure that are probably associated with activation or expression of the target gene.

scholarly journals Theoretical Study of the Reaction of Formation of Some Free Phosphines by Stereoselective Hydrophosphination through DFT Method

2018 ◽  
pp. 1-10
Author(s):  
Kouadio Valery Bohoussou ◽  
Anoubilé Bénié ◽  
Mamadou Guy-Richard Koné ◽  
N’guessan Yao Silvère Diki ◽  
Kafoumba Bamba ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Chemical Reactivity ◽  
Dft Method ◽  
Trans Form ◽  
Dft Methods ◽  
Activation Barriers ◽  
Reactivity Descriptors ◽  
Chemical Reactivity Descriptors ◽  
Theoretical Results ◽  
Cis Isomer

In this work the formation of vinylphosphines was studied through the hydrophosphination reaction. The study aims to rationalize the stereoselectivity of these compounds using quantum DFT methods. This theoretical study of chemical reactivity was conducted at B3LYP/6-311 + G (d, p) level. Global chemical reactivity descriptors, stationary point energies and activation barriers were examined to foretell the relative stability of the stereoisomers formed. The various results obtained have revealed that the addition of arylphosphine to dihalogenoacetylene is stereospecific. The Trans form of vinylphosphines is more stable than the Cis form, when the substituent on phosphorus generates less or no π-conjugations. On the other hand, the Cis isomer is predominant when the aryl radical favors more π-conjugations. The theoretical results obtained are in agreement with the experimental results.

The photoreceptors and visual pigments in the retina of the white sturgeon, Acipenser transmontanus

1990 ◽  
Vol 68 (7) ◽  
pp. 1544-1551 ◽  
Author(s):  
A. J. Sillman ◽  
M. D. Spanfelner ◽  
E. R. Loew
Keyword(s):  
Vitamin A ◽  
Visual Pigment ◽  
Visual Pigments ◽  
Spectrophotometric Analysis ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Light Regimen ◽  
Cone Pigment ◽  
Spectral Absorbance

The photoreceptors in the retina of the white sturgeon, Acipenser transmontanus (Chondrostei), were studied by means of scanning electron microscopy, in situ microspectrophotometry, and spectrophotometric analysis of visual pigment extracts. The white sturgeon retina is simple in that it contains only two morphologically distinct photoreceptors. The retina is dominated by rods with large outer segments, but there is a substantial population (40%) of single cones. Evidence was found for only one rod visual pigment and one cone visual pigment. Peak spectral absorbance (λmax) of the rod pigment is near 539 nm, whereas λmax of the cone pigment is near 605 nm. Both visual pigments are porphyropsin types with chromophores based on vitamin A2. No detectable rhodopsin based on vitamin A1 is ever present, regardless of season or light regimen. The results are discussed in terms of the sturgeon's behavior, as well as the implications for the evolution of color vision.

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.

ISOMERIZATION OF 11-cis VITAMIN A IN VIVO

1960 ◽  
Vol 38 (11) ◽  
pp. 1219-1222 ◽  
Author(s):  
D. W. Stainer ◽  
T. K. Murray ◽  
J. A. Campbell
Keyword(s):  
Vitamin A ◽  
Intestinal Tract ◽  
Biological Potency ◽  
Oral Doses ◽  
Poor Absorption ◽  
Cis Isomer

Single oral doses of all-trans and 11-cis vitamin A acetate were given to young, vitamin A deficient rats and the proportion of cis isomer in the intestinal tract and liver measured. Some conversion of 11-cis to all-trans occurred in the stomach and intestine, and a mixture of the two isomers was absorbed and stored in the liver. The high proportion of cis isomer found in the liver stores 5 hours after a dose of 11-cis vitamin A disappeared completely in 23 days. Oral doses of both all-trans and 11-cis vitamin A produced greater liver stores than the same doses given subcutaneously. The relative biological potency of the 11-cis isomer was the same by either route, which indicated that the low potency of this isomer was not due only to poor absorption from the intestine.

Synthesis of a cis isomer of vitamin A aldehyde

2010 ◽  
Vol 68 (7) ◽  
pp. 609-612 ◽  
Author(s):  
W. Graham ◽  
D. A. van Dorp ◽  
J. F. Arens
Keyword(s):  
Vitamin A ◽  
Cis Isomer
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