Current research in vitamins
William S. Stark
Department of Biology
Saint Louis University
Vitamin A (retinol, an alcohol) is converted to retinal (retinene, is the lod term, an aldehyde), and this is bound to opsin, a G protein coupled receptor; this is the chromophore, giving color and light absorbing capability to the visual pigment rhodopsin.
Third slide is a picture of beta carotene, lutein and zeaxanthin, some carotenoids
Without vitamin A, there is no opsin in Drosophila visual membranes
My interests in vitamin A deprivation in Drosophila.
Serendipity, trying white corn meal, and using a retinoid
free medium, started me on a lifelong interest in vitamin A deprivation and
replacement. This picture
shows Freeze fracture EM of rhabdomeric microvilli of vitamin A replete and deprived Drosophila
Harris, W.A., Ready, D.F., Lipson, E.D., Hudspeth, A.J. and Stark, W.S. Vitamin A deprivation and Drosophila photopigments. Nature, 1977, 266, 648-650.
Vitamin A activates the opsin gene and turns on opsin synthesis in Drosophila.
My interests in vitamin A replacement therapy in Drosophila
A northern blot shows that various foods or food additives activate opsin gene transcription.
EM of rough endoplasmic reticulum shows high immunogold
labeling indicating that replacement synchronizes a massive synthesis and
export of rhodopsin.