Since 1976 (Stark & Zitzmann, 1976), a major thrust of the Stark lab research has concerned vitamin A deprivation and replacement. Vitamin A deprivation decreases rhodopsin in Drosophila rhabdomeres as inferred by spectroscopy, P-face particle density in freeze-fracture microscopy and electroretinographic (ERG) sensitivity (Harris et al, 1977). Carrot juice proved to be optimal in replacement experiments. Our first organized documentation of vitamin A replacement therapy was in 1991 (Sapp et al, 1991a): (1) cross-sectional area of rhabdomeres increased to asymptote at 2 days; (2) EM immunogold increased at 1 day and reached asymptote at 2 or 3 days; (3) absorbance difference recovered somewhat at 6 and 12 hr, most of the way at 1 day, and pretty much reached asymptote at 2 days. ERG sensitivity increased 100-fold within a few hours and reached asymptote at 3 days (Chen & Stark, 1992). Rhabdomeric P-face particle count showed an increase at 12.5 hr and reached the control (replete) count at 1 to two days (Stark & White, 1995); increases were also noted in the plasmalemma adjacent to the rhabdomeric membrane.

 

In summary, deprivation decreases rhodopsin without cell death and replacement synchronizes a massive de novo synthesis, export and deployment of rhodopsin witnessed by immunogold decoration of rough endoplasmic reticulum (Sapp et al, 1991b). Increased opsin gene transcription was suggested by promoter-reporter studies (Sun et al, 1993), northern blot analysis (Picking et al, 1996) and antibody staining (Shim et al, 2001).

 

Although this labıs focus has been on Drosophila, it is noteworthy that vitamin A deprivation decreases rhodopsin in rats and mice and that replacement effects a full recovery (Katz et al, 1991) (Katz et al, 1993) (Liou et al, 1998).

 

Imaging the photoreceptive organelle in the eyes of living Drosophila has expedited these studies in past and present studies (Stark & Thomas, 2004).

 

 

 

Chen DM, Stark WS (1992) Electrophysiological sensitivity of carotenoid deficient and replaced Drosophila. Vis Neurosci 9: 461-469

 

Harris WA, Ready DF, Lipson ED, Hudspeth AJ, Stark WS (1977) Vitamin A deprivation and Drosophila photopigments. Nature (Lond) 266: 648-650

 

Katz ML, Chen D-M, Stientjes HJ, Stark WS (1993) Photoreceptor recovery in retinoid-deprived rats after vitamin A replenishment. Exp Eye Res 56: 671-682

 

Katz ML, Kutryb M, Norberg N, Gao CL, White RH, Stark WS (1991) Maintenance of opsin density in photoreceptor outer segments of retinoid-deprived rats. Invest Ophthalmol Vis Sci 32: 1968-1980

 

Liou GI, Matragoon S, Chen D-M, Gao C, Fei Y, Katz M, Stark WS (1998) Visual sensitivity and interphotoreceptor retinoid-binding protein in the mouse: Regulation by vitamin A. FASEB J 12: 129-138

 

Picking WL, Chen D-M, Lee RD, Vogt ME, Polizzi JL, Marietta RG, Stark WS (1996) Control of Drosophila opsin gene expression by carotenoids and retinoic acid: Northern and western analyses. Exp Eye Res 63: 493-500

 

Sapp RJ, Christianson JS, Maier L, Studer K, Stark WS (1991a) Carotenoid replacement therapy in Drosophila: recovery of membrane, opsin and visual pigment. Exp Eye Res 53: 73-79

 

Sapp RJ, Christianson JS, Stark WS (1991b) Turnover of membrane and opsin in visual receptors of normal and mutant Drosophila. J Neurocytol 20: 597-608

 

Shim K, Zavarella KM, Thomas CF, Shortridge RD, Stark WS (2001) Evidence for indirect control of phospholipase C (PLC-beta) by retinoids in Drosophila phototransduction. Mol Vis 7: 216-221

 

Stark WS, Thomas CF (2004) Microscopy of multiple visual receptor types in Drosophila. Mol Vis 10: 943-955

 

Stark WS, White R, H. (1995) Carotenoid replacement in Drosophila: Freeze fracture electron microscopy. J Neurocytol sub: mitted

 

Stark WS, Zitzmann WG (1976) Isolation of adaptation mechanisms and photopigment spectra by vitamin A deprivation in Drosophila. J Comp Physiol 105: 15-27

 

Sun D, Chen DM, Harrelson A, Stark WS (1993) Increased expression of chloramphenicol acetyltransferase by carotenoid and retinoid replacement in Drosophila opsin promoter fusion stocks. Exp Eye Res 57: 177-187