miR-19a mimic is able to partially rescue heart/fin defects induced by MO-Tbx5.
(A–C) Analysis of 72hpf Tbx5a morphants. miR-19a or miR-Ct mimics, at the reported doses, were co-injected with 1.5 ng of MO-Tbx5a in Tg(Myl7:EGFP) embryos. The percentage of embryos with the indicated heart (A) or pectoral fin (B) defects was averaged across multiple independent experiments carried out in double blind. The total number of analyzed Tbx5 morphant embryos were as follows: not co-injected n = 100; miR-Ct co-injected n = 272 (0.5 ng), n = 214 (0.25 ng), n = 164 (0.125ng); miR-19a co-injected n = 200 (0.5ng), n = 132 (0.25 ng), n = 260 (0.125 ng). For each miR-19a mimic dose, the equivalent dose of miR-Ct was always injected as control. For all tested doses, differences between miR-Ct and miR-19a were significant (Fisher’s test P < 0,0001). In (C) images representative of the different phenotypes. Red scale bar = 10 µm, hts, heartstring; v, ventricle; a, atrium. White arrows indicate cardiac chambers, black arrow and star indicate fin presence and absence respectively. (D) Embryos injected with the indicated mix of morpholino and miRNA mimics were followed for 11 days, daily recording the number of surviving embryos. Curves were compared by long-rank test analysis. The total number of analyzed embryos were as follows: miR-Ct co-injected n = 60 (0.5 ng), n = 116 (0,25 ng); miR-19a co-injected n = 71 (0,5 ng), n = 97 (0,25 ng). (E,F) Analysis of 72hpf Tbx5b morphants co-injected with 4 ng of Tbx5b morpholino and 0.25 ng of miR-19a or miR-Ct mimics. hts: heartstring phenotype; mild defects: general cardiac defects; WT: wild type heart. NO fins: pectoral fins absence, WT fins: wild type pectoral fins.