(A) Schematic structure of the zebrafish tmem88a gene shows three exons and two introns. TALEN pairs TAL1 (green) and TAL2 (magenta) were designed and assembled to target the coding region of exon2. There is a ScaI endonuclease restriction site within the spacer region (orange). (B) A tmem88a mutant line with an 8 bp deletion (Δ8) was generated. (C) Predicted translated sequences of wild-type Tmem88a and Tmem88aΔ8 show frame-shift after residue 48 (red), causing truncation of the protein and loss of the trans-membrane domains (blue) and the Dishevelled-binding domain (teal). (D) Brightfield images of control Tg(fli1a:egfp) and tmem88aΔ8 embryos at 24 hpf (n = 67, n = 53 respectively), 2 dpf (n = 54, n = 35), and 5 dpf (n = 51, n = 18) as labelled. (E) Sequence alignment shows that the tmem88a e2i2 SBMO is specific to tmem88a and illustrates a 9 bp mismatch with tmem88b mRNA.