hace1‐morphant embryos display specific cardiac phenotypes that can be rescued by human HACE1 mRNA while the vasculature remains intact. A: The looping defect that results from hace1 knockdown results in either misalignment of the atrium and the ventricle (the ventricle is located on the left side [white arrow], “inverted”) in ii or a tubular heart (“straight') in iii. Scale bar = 250 µm. B: Diagrammatic representation of each phenotype is included adjacent to a fluorescent image of a Tg(myl7::eGFP) hace1‐morphant embryo with the associated phenotype. C: Bar graphs showing the percent of each of the representative anatomic phenotypes shown in panels A and B (colors correspond to the respective phenotypes; n = 90–130 embryos for each group in 3 replicates; lateral views at 48 hpf; **P < 0.0001). D: Bar graphs showing the heart rate in hace1 and control morpholino‐injected embryos under the conditions indicated (n = 30–40 embryos for each group; * denotes a significant difference between the two groups of hace1 morphants, which also differ significantly with all other groups included in this panel at *P < 0.05). Movies capturing the differences in heart rates can be found in Supp. Movie S1. E: Fluorescence imaging of the 48‐hpf Tg(fli1a::eGFP) embryos injected with either control or hace1 morpholino demonstrates an intact vascular structure (lateral views) with a nonsignificant (ns) difference between the percentage of embryos with normal vasculature shown in F (n = 3, P > 0.05). Scale bar = 250 µm.
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