Fig. 4

Parhyale opsin reporters. a Design of the PhOpsin1:EGFP-CAAX and PhOpsin2:mKate-CAAX reporters. The genomic fragments of PhOpsin1 and PhOpsin2 are 1.6 and 3.1 kb long, respectively, including upstream sequences, promoters (arrow) and 5′UTRs. The PhOpsin2:mKate-CAAX reporter also includes the endogenous start codon of PhOpsin2 (ATG), part of the coding sequence of PhOpsin2 (in black, interrupted by an intron) and the T2A self-cleaving peptide sequence (in blue), both cloned in frame with the mKate-CAAX coding sequence. b Fluorescence microscopy in a live transgenic embryo carrying both reporters. Three ommatidia are visible in the field of view, with EGFP-CAAX (green) and mKate-CAAX (magenta) fluorescence localised in the rhabdom. The mKate channel also shows autofluorescence of pigment granules. c, c′, c″ Higher magnification view of a single ommatidium, revealing the star-shaped pattern of the rhabdom. EGFP-CAAX (green) localises in most of the rhabdom, whereas mKate-CAAX (magenta) is restricted to one tip. d Longitudinal view of an ommatidium of a transgenic adult carrying the PhOpsin2:mKate-CAAX reporter. The structure of the ommatidium is revealed by brightfield microscopy (in grey). The mKate signal (magenta) extends through the entire length of the rhabdom, from proximal (near the nuclear layer, NL) to distal (near the crystalline cone, CC). Scale bars, 5 μm