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Fig. 4
Maternal-zygotic frv mutants exhibit myocardial and endocardial fusion defects that are rescued by myocardial tmem2 expression. (A,B) Lateral views of zebrafish maternal (Mfrv) and maternal-zygotic (MZfrv) frv mutant siblings reveal body length and yolk extension defects in MZfrv embryos at 24 hpf. (C,D,G-J) Dorsal views depict myl7 expression at 20 somites (som) and 26 hpf. (E,F) Dorsal views depict endocardial expression of Tg(kdrl:GRCFP) (arrowheads) at 24 hpf. (K-N) Dorsal views depict endocardial expression of cdh5 (arrows) at 28 hpf In Mfrv embryos, expression of Tg(myl7:tmem2-gfp) has no effect on myocardial or endocardial morphogenesis (G,H,K,L), whereas in MZfrv embryos expression of Tg(myl7:tmem2-gfp) rescues both myocardial and endocardial fusion (I,J,M,N). Non-transgenic (non-tg) and transgenic siblings were distinguished by examination of fluorescence before fixation. Comparable results were obtained with two independent transgenic founders. Scale bars: 50 μm.