Fig. 2 cas mutants do not express molecular markers of endoderm differentiation. Wild-type (A, C, E) and cas mutant (B, D, F) embryos were examined at the 25-somite stage (21.5 hpf) for expression of axial (A, B), fkd7 (C, D), and gata4 (E, F). (A) axial is expressed in the ventral neuroectoderm and anterior endoderm (arrowhead); endodermal axial expression is absent from cas mutants (B). Similarly, fkd7 and gata4 are expressed in the endoderm of wild-type (arrowheads in C, E) but not cas mutant (D, F) embryos. fkd7 is also expressed in the floor plate and hypochord (C), which is posteriorly shortened in cas mutants (arrow in D). Endodermal gata4 expression defines a region of the gut tube that will form the liver. Myocardial gata4 expression (arrow in E) illustrates the cardia bifida present in cas mutants (arrows in F). (A–D) Lateral views, anterior to the left, dorsal to the top; (E, F) dorsal views, anterior to the left.
Reprinted from Developmental Biology, 215(2), Alexander, J., Rothenberg, M., Henry, G.L., and Stainier, D.Y.R., casanova plays an early and essential role in endoderm formation in zebrafish, 343-357, Copyright (1999) with permission from Elsevier. Full text @ Dev. Biol.