Figure 8 : Possible scenario for expansion and functional diversification of opsins in T. cystophora.

From: Cubozoan genome illuminates functional diversification of opsins and photoreceptor evolution

Figure 8

Our data and data from other studies39,60 show that Cnidarian intron-less opsins might have been derived from an ancient eumetazoan ciliary-like opsin containing introns by retro-transposition. Once anchored in the genome the ancient cnidopsin gene underwent several rounds of duplication, diversification and sensitivity tuning. Individual opsins were thus accommodated for distinct functions in diverse tissue photoreceptors - ocular, extraocular and larval. These opsins differ in stage- or tissue-expression, primary structure and also in subsequent cellular signaling – either via Gs-cAMP pathway or other G-protein pathways. For further information see Discussion.