Dyad lengths. (A) TEM images under the indicated conditions, arrows indicate dyads’ extent. Scale bar = 50 nm. (B) Violin plots of the dyad lengths. ** indicates a significant difference between the given mutant and its ISO-treated counterpart (P < 0.01). In the non-ISO-treated hearts, dyads in the S2814D mouse were significantly longer than all others (***, P < 0.001).