Vitamin A

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.


First slide is a figure I show in the vision lecture of my sophomore physiology class.

Second slide is a figure I show in the vision lecture of my senior neuroscience class


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.