Fig. 3

Fig. 3 Rescue of scube2−/−phenotype by scube2FLandscube2EGFΔ3-6mRNAs. (A) The Scube2FL protein is predicted to closely resemble the wild-type Scube2 with 9 EGF-like domains, while the Scube2EGFΔ3-6 peptide only has 5 EGF-like domains. (B) Morphological analysis of scube2−/− larvae at 30 hpf following 0.2 M KCl injection showed that all scube2−/− larvae exhibited a curled body axis (19/19). Injection of scube2FL mRNA restored a straight body axis in most larvae (23/26), while injection of scube2EGFΔ3-6 mRNA did not rescue normal morphology, with most larvae remaining curled (17/20). The difference between the control group (injected with 0.2 M KCl) and the scube2FL mRNA group was statistically significant (Fisher's exact test with Bonferroni correction, p < 0.001). No significant difference was observed between the control and scube2EGFΔ3-6 mRNA groups (p = 0.681). (C) Slow muscle immunostaining in scube2−/− embryos at 30 hpf following rescue with scube2FL or scube2EGFΔ3-6 mRNAs revealed that injection of either scube2FL or scube2EGFΔ3-6 mRNA led to a significant increase in slow muscle fibre number compared to the control. The increase was greater in scube2−/−embryos rescued with scube2FL than with scube2EGFΔ3-6 (ANOVA with Bonferroni correction, p < 0.0001).