Figure 4

(A, B) Single-plane images of snai1b+/+ embryos injected with myl7:GFP (A) or with myl7:desmb-p2a-GFP (B) at 50 hpf. (C) A higher percentage of CMs extrude when overexpressing desmb (n = 23) compared with control (n = 15) (magenta arrowheads in B, B?). (D?D?, F?F?, H?H?) Orthogonal projections in the YZ plane of hearts from 52 hpf embryos injected with myl7:desmb-p2a-GFP and immunostained for ?-catenin epitope ?-18, GFP, and BFP (D?D?), p-myosin, GFP, and Alcama (F?F?), or Desmin, GFP, and Alcama (H?H?). Close-up of boxed areas of desmb-overexpressing and adjacent wild-type CMs (D?, F?, H?). (E?E?, G?G?, I?I?) Fluorescence intensity profile (FIP) (E, G, I) and mean fluorescence intensity (mFI) (E?, G?, I?) of ?-catenin epitope ?-18 (E?E?), p-myosin (G?G?), and Desmin (I?I?) in CMs that overexpress desmb (magenta arrowheads) and CMs that do not overexpress desmb (white arrowheads). ?-catenin epitope ?-18, p-myosin, and Desmin immunostaining signals are enriched in the basal domain in desmb overexpressing CMs. FIP: desmb OE CMs, (E) N = 132, (G) N = 120, (I) N = 88; desmb OE extruding CMs, (E) N = 47, (G) N = 54, (I) N = 49; control CMs, (E) N = 153, (G) N = 133, (I) N = 86. mFI: desmb OE CMs, (E?) N = 49, (G?) N = 65, (I?) N = 63; desmb OE extruding CMs, (E?) N = 33, (G?) N = 60, (I?) N = 59; control CMs, (E?) N = 55, (G?) N = 62, (I?) N = 64. Plot values represent means ± S.D. (C) or means ± S.E.M. (E, G, I). In the violin plots (E?, G?, I?), solid black lines indicate median. p-values determined by Mann?Whitney U (C) or Kruskal?Wallis (E?, G?, I?) test. Scale bars: 20 µm (A?B?, D, F, H); 2 µm (D?, F?, H?). V: ventricle; A: atrium; ap: apical; ba: basal; n: number of embryos; N: number of CMs. See also Figure 4?figure supplements 1?3.