Fig. 4

Ca²⁺ Propagation in the Beating Heart Is Deficient in the Absence of Functional Desmin

(A) Snapshots from videos corresponding to the 4D reconstructions of a single heartbeat in Tg(myl7:GalFF; UAS:Gcamp3.0) WT, desma^sa5−/−, and ct122aRGt 48-hpf embryos ( Movies S5, S6, and S7) show perturbations in the Ca²⁺ signal at the ventricle tip in the absence of functional Desma. Scale bar, 30 μm.

(B) Ca²⁺ intensity plots and quantification of the amplitude of the Ca²⁺ peak upon contraction in four different regions of the heart: (1) inflow tract; (2) atrium outer curvature; (3) ventricle proximal outer curvature; and (4) ventricle distal outer curvature. The amplitude is significantly reduced in region 3 of the desma^sa5−/− and in regions 3 and 4 of the ct122aRGt (n = 5 embryos, n ≥ 10 cells for each condition). Plots correspond to a representative example of each condition. Note that the heart-contraction sequences for each condition are not starting at the same moment of the contraction cycle. Gray arrows indicate the direction of blood flow through the heart. ct122aRGt indicates desma^ct122aRGt homozygous embryos.

The error bars correspond to the SEM.