Figure 5. Xenopsin is co-localised with acetylated tubulin and Gαi in extraocular ciliary phaosome cells and r-opsin is expressed with Gαq in eyes.

(A-E) Co-localization of acetylated tubulin and xenopsin is found throughout the cell (n, nucleus) (100% of acTub⁺ cells express xenopsin (in one cross section, n = 3 individual worms). (E) A cross section of a phaosome shows stronger xenopsin expression near the base of the cilia (n = 8 individuals); (F) r-opsin is expressed in photoreceptor cells (rpc) that extend from the pigment cup cells (pcc) to the optic lobe (ol) of the brain, together forming the cerebral eyes (ce); r-opsin is also expressed in the tentacular eyes (te) (n = 5 individuals); (G) Schematic of xenopsin and r-opsin expression in adult cross-section, with a diagram of a putative ciliary photoreceptor cell (ciliary phaosome cell, cpc) showing co-localization of xenopsin and acetylated tubulin. (H) The position of the putative ciliary photoreceptors (labeled with acetylated tubulin) in relation to the rhabdomeric photoreceptors (labeled with Gαq) (n = 3 individuals). (I and J) Gαi expression in the xenopsin⁺ cells including on the ciliary membranes (arrowheads).

Figure 5—figure supplement 1. G alpha subunit phylogeny and C terminal end alignment.

(A) IQ-TREE phylogenetic reconstruction of G alpha subunit relationships identifies those expressed in the Maritigrella crozieri larval transcriptome (red). Support for node is calculated using 1000 Ultrafast bootstrap replications as well as 1000 SH-aLRT replicates and approximate aBayes single branch testing. Scale bar unit for branch length is the number of substitutions per site. (B) Alignment of c terminal ends of Human and Maritigrella crozieri G alpha subunits. See Figure 1 additional data file for full amino acid sequences from all taxa.