Figure 5.

Robo1 Fn1–3 domains are individually dispensable for the receptor’s midline repulsive function. (A–F) Stage 16 embryos stained with anti-FasII (green) and anti-HRP (magenta). Lower images show FasII channel alone of the same embryos. In robo1 mutant embryos, FasII-positive axons ectopically cross the midline in every segment (B, arrow with asterisk). This phenotype is rescued by a robo1 genomic rescue transgene expressing full-length Robo1 (C) or any of the Fn 1–3 Robo1 deletion variants (D–F). Bar graph shows quantification of ectopic crossing in the genotypes shown (A–F). Error bars indicate SE. Each rescue variant was compared to robo1¹, robo1::robo1 embryos (C) by a Student’s t-test, with a Bonferroni correction for multiple comparisons. Number of embryos scored for each genotype is shown in parentheses. n.s, not significant.