(A) Representative morphologies of smyhc1+/+, smyhc1R673H/+, and smyhc1R673H/R673H larvae at 2 dpf after 24 hour treatment with 0.25% DMSO (control) or 25 μM para-aminoblebbistatin. All larvae treated with para-aminoblebbistatin develop a slight dorsal tail curve and pericardial edema regardless of genotype. All para-aminoblebbistatin-treated smyhc1R673H/+ (n=9) and smyhc1R673H/R673H (n=3) larvae are indistinguishable from smyhc1+/+ unlike the untreated larvae which have markedly curved or distorted body axis. (B) Representative images of smyhc1+/+, smyhc1R673H/+, and smyhc1R673H/R673H larvae at 3dpf after 48 hour treatment with 0.25% DMSO (control) or 25 μM para-aminoblebbistatin. All larvae treated with para-aminoblebbistatin develop a slight dorsal tail curve and pericardial edema regardless of genotype. Para-aminoblebbistatin-treated smyhc1R673H/+ (n=9) and smyhc1R673H/R673H (n=3) larvae are indistinguishable from smyhc1+/+ unlike the untreated larvae which have markedly curved or distorted body axis. 