Fig. 1

Fig. 1 Assembly of thin filaments in the embryonic zebrafish heart. (A) Shown are images of 10 S embryos after two-color immunostaining to label Tm (green) and F-actin (red). Tm and F-actin networks are co-localized within the cardiac progenitor cells (outlined by dashed lines), which are labeled by Tm staining. The F-actin network also extends to the neighboring cells beyond the cardiac progenitor cells. (B) Shown are images of two-color immunostaining using the Zn5 antibody to label cell membrane (green) and phalloidin to label thin filaments (red). The thin filament network in the ventricle appears to associate with the cell membrane at both 24 S and 48 hpf. (C and D) Shown are images of 24 S, 26 S, and 48 hpf embryos after immunostaining using either anti-Tm (C) or anti-tnnt2 antibody (D). Both anti-Tm and anti-tnnt2 antibodies revealed a continuous filament network at 24 S, which becomes striated at 26 S, and lateral growth forming mature thin filaments at 48 hpf. Insets in (A, C, D) are of the same image at higher magnification. Insets at top are of networks, and insets at bottom are of myofibrils. Brackets, continuous thin filaments. Arrowheads, periodic dots of thin filaments after striation. Arrows, mature thin filaments after lateral growth. Scale bar = 20 μm.