Fig. 2

DHPR tetrads are reduced and incomplete in stac3 mutants. (A?E) Freeze-fracture electron micrographs of 4-d postfertilization larvae showing DHPR particles in triadic clusters of WT (A), stac3^?/? expressing stac3^WT-EGFP (WT rescue) (B), stac3^?/? expressing stac3^NAM-mKate2 (NAM rescue) (C), stac3^?/? (D), and stac3^?/? injected with an antisense morpholino oligonucleotide against stac3 (stac3^?/? + MO) (E). (A??E?) Same as A?E, with yellow dots and purple shading added for clarity to denote, respectively, segments of T tubules with tetrad sites of DHPRs and segments of T tubules with no tetrad sites in muscle fibers of WT (A?), WT rescue (B?), NAM rescue (C?), stac3^?/? (D?), and stac3^?/? + MO (E?). (F) Illustration showing stereotypical DHPR particles in tetrad sites (labeled with yellow dots) along a T tubule and gaps with no tetrad sites (purple) as seen above. (G) Histogram showing that the particles per T-tubule length are decreased in NAM rescue, stac3^?/?, and stac3^?/? + MO muscles compared with WT and WT rescue. (ANOVA Tukey's; ***P < 0.001, **P < 0.01.) (H) Histogram showing that full tetrads per tetrad site are decreased in NAM rescue, stac3^?/?, and stac3^?/? + MO muscles compared with WT and WT rescue. ns, not significant. SEMs are indicated. (ANOVA Tukey's; ***P < 0.001, *P < 0.05.)