Retinyl and 3-dehydroretinyl esters in the crayfish retina.
We have studied chemical nature and localization of retinyl esters stored in the retina of the crayfish, Procambarus clarkii, which has a rhodopsin-porphyropsin visual pigment system. The crayfish kept at 10 degrees C in the constant dark had 3-dehydroretinal along with retinal in the retina as the chromophore of visual pigment. Both retinyl and 3-dehydroretinyl esters were found in the retina, more than 95% of them in the 11-cis configuration. Of three kinds of fatty acid detected in the esters, the major component (about 80%) was the polyunsaturated fatty acid, docosahexaenoic acid (C22 = 6). Observations with electron and fluorescence microscopy and the results of fractionation experiments showed that the esters were stored in photoreceptor cells as oil droplets. The ratio of 3-dehydroretinal/retinal as visual pigment chromophore was always higher than that of 3-dehydroretinol/retinol in the stored esters. This result suggests a mechanism of selective utilization of 3-dehydroretinol for the chromophore of visual pigment in the crayfish retina.
Suzuki
T
T
Department of Pharmacology, Hyogo College of Medicine, Japan.
Maeda
Y
Y
Toh
Y
Y
Eguchi
E
E
D000818:Animals; D003400:Astacoidea / Q000378:metabolism*; D008854:Microscopy, Electron; D012160:Retina / Q000378:metabolism* / Q000648:ultrastructure; D012168:Retinal Pigments / Q000032:analysis; D012243:Rhodopsin / Q000032:analysis; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000032:analysis*
D012168:Retinal Pigments; C024366:vitamin A2; D014801:Vitamin A; C010507:porphyropsin; D012243:Rhodopsin