shootin1 mutants display reduced migration speed of the PLLP. (a) Schematic structures of shootin1 and shootin3 proteins of the shootin1 and shootin3 single mutants. Frameshift mutations in shootin1 and shootin3 resulted in premature stop codons after amino acid positions 47 and 26, respectively. The gray boxes indicate amino acids added by the frameshift mutations; numbers in brackets indicate the numbers of these additional residues. CC1-3: coiled-coil domain; PR: proline-rich domain. (b) Representative time-lapse images of wild-type control, shootin1−/− single mutant, shootin3−/− single mutant and shootin1−/−;shootin3−/− double mutant embryos carrying the SAIGFF213A;UAS:GFP construct. Time-lapse images of a shootin1−/−;shootin3−/−double mutant embryo into which shootin1 and shootin3 mRNAs were injected are also presented at the bottom. Arrows indicate the leading edges of PLLPs. Scale bars: 50 μm. (c) Migration speeds of PLLP in wild-type control (n = 21), shootin1−/− single mutant (n = 26), shootin3−/− single mutant (n = 15) and shootin1−/−;shootin3−/− double mutant (n = 23) embryos at 32–38 hpf obtained from the analyses in (b). (d) Rescue analyses of the PLLP migration in the shootin1;shootin3 double mutants. shootin1 and shootin3 mRNAs were injected into the shootin1−/−;shootin3−/− double knockout (DKO) mutant embryos (DKO + mRNA, n = 25). Data for the uninjected wild-type (WT) and DKO mutant embryos in (d) are shared with those in (c). Data for (c) and (d) represent mean ± SEM. Statistical significance of the differences is indicated with asterisks (***P < 0.01; **P < 0.02; *P < 0.05; ns, nonsignificant).