Knockdown of gata4 can rescue partially the mga morphant brain degeneration, but not the gut phenotype. A-C: Shown are representative embryos at 24 hpf that are wildtype (A), morphant injected with only the mga-specific MO1 (B), or injected first with MO1 and subsequently with the gata4 morpholino (C). The ratios shown represent the number of embryos with a grossly normal brain structure in a representative experiment (which was reproduced several times). Note that the brain degeneration present in 100% of the single morphants (B) is rescued in a significant percentage (33%) of the co-injected embryos (C). D-F: Similar results showing that the morphological rescue correlates with an abrogation of apoptosis measured by TUNEL staining. The representative 24-hpf embryos are WT (D), MO1 morphants (E), or co-injected with MO1 and gata4 morpholino (F). G-L: Shown are representative embryos stained for transcripts encoding the liver marker transferrin at 3 dpf (G-I) or 4 dpf (J-L). Embryos are wildtype (WT) control (G, J), MO1-injected (H, K), or co-injected with MO1 and gata4 morpholino (I, L). M-O: A similar analysis was performed at 4 dpf using a probe for ifabp to stain the gut. In contrast to the rescue for brain morphogenesis, knockdown of gata4 failed to rescue the liver or gut phenotype in the mga morphant background. Views (A-F) and (M-O) are lateral, dorsal to the top, anterior to the left). G-L: Views are dorsal, anterior to the left. L, liver; G, gut.
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