Meeting Abstract
There are several photosensing systems in epigeal crayfish that operate simultaneously. The eyes, brain, and caudal photoreceptor (CPR) are known to generate responses to light. While the opsin in the long-wavelength sensitive photoreceptor cells in the main rhabdom has been identified as a typical crustacean long-wavelength sensitive opsin, we have now discovered the opsin responsible for light detection in the short-wavelength receptor, the eighth retinular cell which lies distal to the main rhabdom. Here, we characterize the short-wavelength sensitive opsin in the crayfish retina, and provide evidence that both opsins are expressed throughout the central nervous system of the crayfish, Procambarus clarkii. We used RT-PCR to identify the short-wavelength sensitive opsin in the retina, and to detect both opsin transcripts in the brain and each ganglion of the ventral nerve cord. We used immunohistochemistry to label the short- and long-wavelength opsins in the retina and throughout the CNS, including the sixth abdominal ganglion where the CPR exists. We hypothesize that visual opsins are involved in photoreception throughout the central nervous system. Furthermore, our results suggest the presence of a more extensive system of photoreceptors than previously recognized.
