Fig. S1

Injection of morpholinos that block Dicer cleavage of pre-miR-143 phenocopy MO¹⁴³-injected embryos. (A-F) Embryos injected with two morpholinos that block Dicer cleavage on the guide (gDi¹⁴³; A-C) or star (sDi¹⁴³; D-F) strands of pre-miR-143 exhibit deflated, non-contractile ventricles and enlarged atria (C,F) that closely mimic hearts in MO¹⁴³-injected embryos (as shown in Fig. 2F). (G) Diagram of pre-miR-143 and the target sites for three morpholinos used to inhibit Dicer and Drosha cleavage (MO¹⁴³) or Dicer cleavage alone (gDi¹⁴; sDi¹⁴³). (H) gDi¹⁴³ and sDi¹⁴³ interfere with miR-143 biosynthesis. Northern analysis of miR-143 in total RNA samples isolated from WT, gDi¹⁴³ or sDi¹⁴³ animals at ∼2.5 dpf. No mature miR-143 can be visualized in morphants, whereas the presence of an internal ribosomal RNA (rRNA) band appears unaltered.