erbb2 mutant develops HL phenotypes (A) Schematic of method utilized for obtaining compact myocardial wall and myofibril measurements. (B,C) Mid-chamber confocal sections of control and erbb2^−/− hearts, respectively. (B’,C’) Magnified high-resolution images of compact myocardial wall and trabecular regions marked by dotted box in B, C. Yellow arrows point to length of CM along compact myocardial wall. White arrows point to trabeculae. (D,E) Maximal projection of confocal Z-stacks of ventricle. (D’-D”’, E’-E”’) Magnified high-resolution images of compact myocardium outlined in white in D and E revealing sarcomere structures of two CMs in control and erbb2^−/− ventricles, respectively. (F–H) Quantification of compact myocardial wall thickness (n = 6–10), Z-line length (n = 9–10), and distance between Z-lines (n = 8–10), at 3, 5, and 7 dpf from control and erbb2^−/− hearts. (I) Expression of nppa in whole hearts isolated from erbb2 control or erbb2^−/− larvae (n = 10–15). Data are represented as mean ± SEM. *p ≤ 0.05, **p = 0.0025, ***p = 0.0004 and ****p < 0.0001 by Student’s t test. v, ventricle; a, atrium.

Inhibition of TOR signaling attenuates erbb2 mutant HL phenotypes (A) Schematic of experimental design. (B,D,F,H,J,L,N,P) Mid-chamber confocal sections of control and erbb2^−/− hearts treated with DMSO or rapamycin at 5 and 7 dpf. (B’,D’,F’,H’,J’,L’,N’,P’) Magnified high-resolution images of compact myocardial wall and trabecular regions marked by dotted box in (B,D,F,H,J,L,N,P). Yellow arrows point to length of CM along compact myocardial wall. White arrows point to trabeculae. (C-C’,E-E’,G-G’,I-I’) Magnified high-resolution images of compact myocardium revealing sarcomere structures of CMs at 5 dpf. (K-K’,M-M’,O-O’,Q-Q’) Magnified high-resolution images of compact myocardium revealing sarcomere structures of CMs at 7 dpf. (R–T) Quantification of compact myocardial wall thickness (n = 7–15), Z-line length (n = 5–10), and distance between Z-lines (n = 5–12) at 5 and 7 dpf from DMSO or rapamycin-treated control and erbb2^−/− hearts. Data are represented as mean ± SEM. **p = 0.0035, ***p = 0.0003, and ****p < 0.0001 by Student’s t test.

ZFIN is incorporating published figure images and captions as part of an ongoing project. Figures from some publications have not yet been curated, or are not available for display because of copyright restrictions.

erbb2 mutant HL phenotypes result from the absence of trabecular formation (A) Schematic of transplantation experiment resulting in transplanted blastomeres from Tg(myl7:mKateCAAX);Tg(myl7:Cypher-EGFP) erbb2 control or erbb2^−/− donors into Tg(myl7:rasGFP); Tg(myl7:Cypher-EGFP) wild-type hosts. (B-B”,E-E”) Mid-chamber confocal sections of control and erbb2^−/− donor CMs, respectively, in wild-type host ventricle. (B”’,E”’) Magnified high-resolution images of compact myocardial wall and trabecular regions marked by dotted box in B”, E”. Yellow arrows point to length of donor CM (yellow line) along compact myocardial wall. White arrow heads point to length of host CM (white line) along compact myocardial wall. White arrows point to trabeculae. (C,F) Maximal projection of confocal Z-stacks of ventricle. (D,G) Magnified high-resolution images of compact myocardium, revealing sarcomere structures of control and erbb2^−/− donor CMs, respectively, in wild-type host ventricle at 5 dpf. (H–J) Quantification of cross-sectional area of erbb2 control donor and erbb2^−/− donor CMs (H), erbb2 control donor and host CMs (I), and erbb2^−/− donor and host CMs at 5 dpf (J). (K) Quantification of Z-line length of erbb2 control donor and erbb2^−/− donor CMs at 5 dpf. (L) Quantification of distance between Z-lines of erbb2 control donor and erbb2^−/− donor CMs at 5 dpf. Data are represented as mean ± SEM.

erbb2 mutant exhibits more pronounced HL phenotype overtime.

(A,B,E,F) Mid-chamber confocal sections of erbb2 control and erbb2^-/- hearts at 3 and 7 dpf. (A',B',E',F') Magnified high-resolution images of compact myocardial wall and trabecular regions marked by dotted box in A,B,E,F. Yellow arrows point to length of CM (white line) along compact myocardial wall. White arrows point to trabeculae. (C-C'',D-D'',G-G",H-H") Magnified high-resolution images of compact myocardium, revealing sarcomere structures of two CMs. (I, J) Representative images of whole-mount in situ hybridization of nppa in erbb2 control and erbb2^-/- hearts, respectively. (I', J') Magnified images of heart region marked by dotted box in I and J. (n = 12).