Fig. 7

Med12 functions with Cas/Sox32 and Foxa2 to regulate endodermal organ development. (A–C) Embryos from med12^s432 heterozygote incrosses injected with cas mRNA were harvested at 90% epiboly and analyzed for sox17 expression. med12^s432 homozygous mutant embryos overexpressing cas mRNA showed decreased induction of sox17 expression (C) compared to med12 heterozygous (B) and wild-type (A) embryos. (D–H′) Embryos from wild-type crosses and med12^s432 heterozygote incrosses injected with foxa2 MO were harvested at 48 hpf and analyzed for foxa3 expression. Wild-type foxa3 expression reveals structures such as the liver (black arrow), pancreas (black arrowhead), and swim bladder (white arrowhead) (D). med12^s432 mutants show an ambiguous ductal morphology (black bracket) and defective development of endodermal organs (E). foxa2 MO-injected embryos showed slight perturbation of organ development (F), while med12^s432 heterozygous embryos injected with foxa2 MO showed a more severe malformation of organs (G), and med12^s432 homozygous mutant embryos injected with foxa2 MO showed an almost complete absence of accessory organs, exhibiting a solid endodermal rod (H, H′). (I–K) Confocal projections of larvae from med12^s432 heterozygote outcrosses in the Tg (fabp1a:dsRed, elastase:GFP; insulin:dsRed) heterozygote line injected with foxa2 MO (J and K) and analyzed at 96 hpf. While foxa2 MO-injected larvae showed slight perturbation of liver and exocrine pancreas (J), med12^s432 heterozygous larvae with foxa2 MO injection showed a more severe malformation of these organs (K). Images A–C are dorsal views, anterior to the top; D–H′ are dorsal views, anterior to the left; I–K are ventral views, anterior to the top.