Figure 7-figure supplement 1-source data 1.

(A) Schematic and verified exon 1 sequence of V5 epitope tag insertion into the N-terminus of the endogenous tjp1b locus. Bases in dark blue indicate V5 sequence. Light blue bases indicate the XbaI restriction enzyme cut site and the 5x glycine linker sequence. (B–H) Confocal images of Mauthner circuit neurons and stereotypical electrical synaptic sites of formation in 5-day-post-fertilization, V5-tjp1b heterozygous (B,C) and V5-tjp1b homozygous (D,E), and chimeric (F–H) zebrafish larvae. For chimeric larvae, the genotype of the donor cell (green, genotype1) and host (black, genotype2) varies and is noted above each set of images (genotype1 > genotype2). Animals are stained with anti-GFP (green), anti-zebrafish-Cx35.5 (cyan), anti-zebrafish-Cx34.1 (yellow), and anti-V5 (magenta). Images have been passed through a 3 × 3 median filter. Scale bar = 2 µm in all images. (F–H) Confocal images of M/CoLo sites of contact in 5-day-post-fertilization chimeric animals. In each set of images, GFP-expressing cells (Mauthner (F), CoLo (G), or both Mauthner and CoLo (H)) are derived from a V5-tjp1b^+/-; zf206Et donor. Animals are stained with anti-GFP (green), anti-zebrafish-Cx35.5 (cyan), anti-zebrafish-Cx34.1 (yellow), and anti-V5 (magenta). (I–J) Quantification of the number of stereotypical electrical synaptic structures labeled with both anti-Cx34.1 and anti-Cx35.5 in chimeric animals of the indicated genotypes with a GFP-positive Mauthner cell. The height of the bar represents the mean of the sampled data normalized to the wt>wt average, and circles represent the normalized value of each individual animal (CE synapses: wt>wt n = 8, tjp1b/ZO1b^-/->wt n = 16, wt>tjp1b/ZO1b^-/- n = 9; M/CoLo synapses: wt>wt n = 11, tjp1b/ZO1b^-/->wt n = 18, wt>tjp1b/ZO1b^-/- n = 9). Error bars are ± SEM. Associated experimental statistics can be found in Figure 7—figure supplement 1—source data 1.