RETINOID METABOLISM AND CONVERSION OF RETINOL TO DEHYDRORETINOL IN THE CRAYFISH (PROCAMBARUS-CLARKII) RETINA

1. Activities of retinylester hydrolase (REHase) and retinol dehydroge nase (RDHase) were detected in the crayfish retina which has two visua l pigment chromophores and three stored retinoids. 2. RDHase and 11-ci s REHase activities were localized to rhabdomal fraction and enzymes w ere specific to 11-cis isomers of substrates. Overall reaction from re tinylester to retinal was highly specific to 11-cis isomers and this r eaction was not selective between retinol and dehydroretinol. 3. When 11-cis [H-3]-retinol was incubated with retina homogenates, radioactiv ity was detected in 11-cis dehydroretinol. 4. These results suggest th at retinol is converted to dehydroretinol after hydrolysis of retinyle sters.