Photo-labile Pigments of the Chicken Retina

@article{Wald1937PhotolabilePO,
  title={Photo-labile Pigments of the Chicken Retina},
  author={George Wald},
  journal={Nature},
  year={1937},
  volume={140},
  pages={545-546}
}
  • G. Wald
  • Published 1 September 1937
  • Biology
  • Nature
THOUGH visual purples of the retinal rods have been known for sixty years1,2, nothing has been learned directly of analogous substances in the cones. In the chicken retina, which contains principally cones, attempts to identify photo-labile pigments heretofore have failed2. I have extracted from it two such pigments. 

IODOPSIN, A RED‐SENSITIVE CONE VISUAL PIGMENT IN THE CHICKEN RETINA *

The rapid dark adaptation of cones compared with rods has been explained by the rapid regeneration of iodopsin from 11‐cis retinal and opsin, which has a unique chloride‐binding site whose chloride ion serves for the red‐shift of the absorption maximum of iodipsin.

Cyanopsin, a Visual Pigment of Retinal Origin

It would be satisfying to observe whether there exists a natural iodopsin in situ to which the 620 pigment is related by a simple change of prosthetic group.

The Visual Cells and Visual Pigments of the Vertebrate Eye

This chapter deals with the manifold types of visual receptors throughout the various vertebrate groups, and the possible biological significance of this multiplicity, and attempts to sort out some ecological and phylogenetic relations suggested by the properties and distribution of these photopigments.

The Regeneration and Renewal of Visual Pigment in Vertebrates

The process underlying the restoration of colour is called regeneration and is the principal topic of this chapter.

Chemistry of Visual Processes

Experiments are described to describe experiments which seem to reconcile divergent findings, as between Wald and Lythgoe, and to provide a basis for discussing in chemical terms Granit’s discoveries, concerning the electro-physiology of retinal elements.

Photochemistry of Iodopsin

The only action of light on the pigment of cone vision, iodopsin, is to isomerize its chromophore from 11-cis to all-trans, which initiates bleaching, and its immediate product is a more intense pigment.

Visual Pigments of Goldfish Cones

The spectral maxima of photoproducts, combined with other evidence, indicate that retinene2 is the chromophore of all three cone pigments, consistent with the notion that visual pigment concentration within the outer segments is about the same for frog rods and goldfish cones.
...

References

SHOWING 1-4 OF 4 REFERENCES

Carotenoids of the Chicken Retina

The cones of many bird and reptile retinas contain brilliantly coloured oil globules, which may serve as a mechanism for colour vision in birds and reptiles.

Visual Purple System in Fresh-water Fishes

  • G. Wald
  • Environmental Science
    Nature
  • 1937
The visual purple of mammals, birds, amphibians, and certain marine fishes absorbs light maximally at 500 mμ and participates with retinene and vitamin A in a retinal cycle, and is referred to specifically as rho-dopsin.

THE VISIBILITY OF MONOCHROMATIC RADIATION AND THE ABSORPTION SPECTRUM OF VISUAL PURPLE

It is shown that the shift of the high intensity visibility curve toward the red actually occurs, and is about 7 or 8 µµ in extent, and it is deduced that the absorption spectrum of visual purple as measured directly in water solution should not coincide with its position in the rods, because of the greater density and refractive index of the rods.