Fig. 4. Gata4 deficient embryos express early endoderm markers but organogenesis fails. (A) Shown are representative semi-quantitative RT-PCR results for the early endoderm markers Sox17 and FoxA2. Assays used either 2 or 1 µg of RNA, isolated for the RT reaction at 28 hpf or 48 hpf, as indicated. We consistently found no significant difference in the expression levels comparing control (WT) and morphant (MO) embryos. (B) RT-PCR assays were also performed using RNA isolated at 4 dpf for markers of differentiated intestine (I-fabp), liver (transferrin), and pancreas (elastaseB). (C-J) Representative embryos are shown following in situ hybridization to detect transferrin RNA, comparing control (WT) and morphant (MO) embryos at 2 dpf (C,D), 3 dpf (E,F), 4 dpf (G,H) and 5 dpf (I,J). In all cases, the morphant embryos develop with a small patch of transferrin-positive cells (arrowheads in MO panels), but this patch fails to grow when compared with controls (arrows in WT panels). Views are dorsal, anterior to the left.