April 2009
Volume 50, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2009
High Concentration of 11-cis Retinyl Esters in the Cone Outer Segments of the Chicken Retina
Author Affiliations & Notes
  • B. Y. Thackeray
    Family Practice, Corpus Christi Family Practice Residency, Corpus Christi, Texas
  • B. S. Betts
    Biology, University of Texas at San Antonio, San Antonio, Texas
  • A. R. Trevino
    Biology, University of Texas at San Antonio, San Antonio, Texas
  • A. Muniz
    Biology, University of Texas at San Antonio, San Antonio, Texas
  • A. T. C. Tsin
    Biology, University of Texas at San Antonio, San Antonio, Texas
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 3000. doi:
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      B. Y. Thackeray, B. S. Betts, A. R. Trevino, A. Muniz, A. T. C. Tsin; High Concentration of 11-cis Retinyl Esters in the Cone Outer Segments of the Chicken Retina. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3000.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : In contrast to the classical visual cycle, which accumulates all-trans retinyl esters in the retinal pigment epithelium (RPE), the novel cone visual cycle accumulates 11-cis retinyl esters within the retina for visual chromophore renewal and cone pigment regeneration. At present, the retinal location of these 11-cis retinyl esters is not known. 11-cis retinoids for cone visual pigment regeneration are critical for visual sensitivity. The purpose of this study is to determine the location of this 11-cis retinyl ester pool in the cone dominated chicken retina in order to further understand the pathway of cone pigment regeneration.

Methods: : Isolated chicken retinas free of RPE were exposed to ambient lighting for 20 min at 4°C. A percoll density gradient was used for separation and isolation of cone outer segment enriched fractions. Fractions were identified as cone or rod outer segments using light microscopy. Retinyl esters from cone, rod, and rod/cone enriched fractions, and from the remaining retina were extracted and analyzed by HPLC.

Results: : Microscopic examination of cone enriched fractions harvested from percoll gradients showed an excess of 90% cone outer segments (n=3), and this fraction accounted for 2% of the total retinal proteins recovered (n=2). Rod enriched fractions contained 80% rod outer segments (n=3), and accounted for 9% of the total retinal proteins recovered (n=2). The isolated chicken retina contains 750 pmol/mg 11-cis retinyl ester (Villazana-Espinoza 2006). In this study the cone outer segment enriched fraction contained the highest concentration of 11-cis retinyl esters (834.92 pmol/mg; n=2) whereas the rod outer segment enriched fraction contained only 54.86 pmol/mg (n=2). A similarly low concentration of 11-cis retinyl esters were observed in the gradient fraction containing a mixture of rod and cone outer segments (52.10 pmol/mg; n=2). The 11-cis retinyl ester concentration in remaining retina (cone and rod inner segments and other retinal cells; 113.61 pmol/mg; n=2) was also significantly lower than that in the cone outer segment.

Conclusions: : In this study we have demonstrated that in the enriched fraction of cone outer segments collected from percoll density gradient using isolated light adapted chicken retina, 11-cis retinyl esters exist at a significantly higher concentration than those in the rod outer segments and in all remaining retinal cells and cell components. Our data suggests that 11-cis retinyl esters may be accumulated in the cone outer segments during light adaptation in the chicken retina.

Keywords: retina • photoreceptors • retinoids/retinoid binding proteins 
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