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Figure 2.
(A–D) Confocal projection images of the heart of Tg(myl7:BFP-CAAX); Tg(cdh5:Gal4ff); Tg(UAS:LIFEACT-GFP);±Tg(UAS:irsp53dn-p2a-tagRFP) zebrafish at 48 (A–B) and 72 (C–D) hours post-fertilization (hpf). (A–B) Endocardial protrusions (white arrows) and touchdowns (white asterisks) are reduced in embryos with endothelial overexpression of irsp53dn. (C–D) Cardiac trabeculation (arrowheads) is reduced in larvae with endothelial overexpression of irsp53dn; (C’–D) 3D rendering. (E) Quantification of the number of endocardial protrusions in wild-type and in embryos with endothelial overexpression of irsp53dn at 48 hpf. (F-F’) Illustration of the division of the 48 hpf ventricle into four regions (F). Distribution and average number of endocardial protrusions in different regions of mid-sagittal sections of the ventricle from 48 hpf wild-type and irsp53dn embryos (F’). (G–G’) Illustration of the division of the 72 hpf ventricle into the outer and inner curvature (G). Quantification of the percentage of trabecular cardiomyocytes (CMs) in the outer curvature of wild-type and irsp53dn larvae at 72 hpf (G’). (H–H’) 72 hpf larvae with endothelial overexpression of irsp53dn display a reduced number of myl7:mVenus-Gmnn+ CMs (yellow arrows) in their ventricle. (I) Quantification of the number of mVenus-Gmnn+ CMs in the ventricle of wild-type and irsp53dn larvae at 72 hpf. All images are ventral views, anterior to the top. V, ventricle; A, atrium. Data in graphs expressed as mean ± SEM.
Blocking endocardial protrusion formation reduces cardiac trabeculation.