Fig. 3. The Muscle-Specific Gene stac3 underlies the mi34 Phenotype.

(a) Diagram of the predicted wt Stac3 protein (top). Arrow denotes location of the stop codon. DNA sequence of corresponding regions of wt cDNA, wt genomic DNA, and stac3^mi34 cDNA showing that a missense mutation in a splice donor site lead to the inclusion of the intron (bracket) and stop codon (asterisk) in the mutant cDNA. (b) Stac3 protein appears not to be synthesized in mutants. Western blot of showing that anti-Stac3 labels a band from wt but not mutant embryos at 48 hpf. β actin was the loading control. (c) Stac3 co-localizes with RyR and DHPR_α1 in skeletal muscles. Left, side view of the trunk of 48 hpf embryos labeled with anti-Stac3 showing that both fast twitch and slow twitch express Stac3 in wt but not mutant embryos. Scale: 60 μm. Inset shows the brightfield image of the trunk of the mutant. Right, dissociated 48 hpf wildtype muscle fibers labeled with anti-Stac3 and anti-RyR or anti-DHPR_α1 showing that Stac3 co-localizes with RyR and DHPRα1. Scale: 10 μm.