Cone opsins expressed in adult cod.

In situ hybridization shows that adult cod express both subtypes of SWS2; SWS2A and SWS2B, while only one RH2A subtype, the RH2A-1 is expressed in the retina. The SWS2A opsin (A and D) seems to be expressed in a higher number of transcripts in each photoreceptor cell compared with the SWS2B opsin (B and E). Both SWS2A and SWS2B expressing photoreceptors are found at some distance apart, and appear to form a regular pattern. The green RH2A-1 opsin (C and F) dominates in the retina of adult cod with only a few cells lacking expression. Scale bar, 20 µm.