Fig. 1

Fig. 1 Myocardial snai1b expression at the BV annulus and in the ventricle during trabeculation.

a A zebrafish embryo (left panel) at 5 dpf, and its heart is highlighted. Right panel illustrates the two-chambered cardiac anatomy. b At 6 dpf, confocal imaging of hearts of Tg(snai1b:EGFP; myl7:mCherry) larvae. The intensity of snai1b expression (green, arrow) was highest at the BV annulus (n = 5). c At 5 dpf, confocal imaging of hearts from Tg(myl7:mCherry-zCdt1) embryos (n = 7) demonstrates that snai1b fluorescence (colored squares) was colocalized to CM nuclei. Upper panel provides a view of the BV annulus from the BA. d During trabeculation (56–96 hpf), snai1b:EGFP signal is concentrated around the BV annulus. Isoproterenol (ISO) treatment at 1 dpf induced snai1b activation in the ventricular CMs. e Whole-mount in situ hybridization of snai1b mRNA in the Tg(snai1b:EGFP; myl7:mCherry) reporter line reveals a significant increase of both EGFP⁺ and mRNA⁺ CMs in ISO-treated hearts. (see Supplementary Figs. 1 and 2 for staining images). All values are displayed with mean and standard deviation (SD). p-value is displayed for each comparison. The number of hearts analyzed in each is displayed in (d). Ordinary two-way ANOVA followed by Šídák’s multiple comparisons test on the means was applied to determine statistical significance. Source data are provided as a Source Data file. Anatomic labels: BA bulbus arteriosus, V ventricle, BV bulbus-ventricular annulus, Ch chest wall, AV atrioventricular canal.