STENTER AND BLEPHARISMA PHOTORECEPTORS - STRUCTURE AND FUNCTION

Stentor coeruleus and Blepharisma japonicum are single cell ciliates, and yet they can detect light with high efficiency, exhibiting well-de fined photophobic responses. The photoreceptors that are responsible f or the light-avoiding behavior have been identified as stentorin and b lepharismin (or oxyblepharismin) respectively. The structure of stento rin was determined to be octahydroxydiisopropyl-naphathodianthrone, an d that of blepharismin, although not fully elucidated, is also a hyper icin analogue. The photochemistry of this class of novel photoreceptor s is unknown; however, proton and/or electron transfer may play a sign ificant role in the primary photoprocess. G-proteins and phosphodieste rase appear to be invoked in the sensory signal transduction and ampli fication.