spaw and lefty1 expression phenotypes. (A-F′′)Time course of single color, double in situ hybridizations for spaw and lefty1 from 10-18 somites in posterior (A-F), mid-LPM (A′-F′), left lateral (A′-F′) and anterior LPM (A′′-F′′) views. (A-A′′) False-colored images of zebrafish embryos from B-B′′ depicting the domains of spaw and lefty1. In situ hybridizations of spaw or lefty1 alone confirm the reported phenotypes. Arrows, boundary of detectable spaw expression; brackets, ectopic spaw across the midline; arrowheads, lefty1 in the diencephalon; asterisks, lefty1 in the cardiac mesoderm. L, left; R, right.

Characterization of the bmp4^Y180* allele. (A) Bmp4 protein with location of the Y180^* mutation indicated. RAKR, cleavage sequence. (B) Sequence comparisons of cDNA from wild type (wt) and bmp4^Y180* mutants. (C-G) Zebrafish embryos at 24-36 hours post-fertilization (hpf). (C) WT embryo. (D) bmp4^Y180* mutant with absent ventral fin (arrow) and cloaca defects (arrowhead). (E) Uninjected embryo. (F) Embryo injected with bmp4 RNA exhibiting V4 ventralization. (G) Embryo injected with bmp4^Y180* RNA lacking morphological defects.

Characterization of the novel bmp4^S355* and bmp4^C365S mutant alleles. (A) Diagram of the Bmp4 protein with locations of the S355* and C365S mutations indicated. (C,E) Sequence results from PCR amplification of the bmp4 gene from cDNA obtained from wild type (wt), bmp4^C365S (C) and bmp4^S355* (E) mutants confirming the identity and location of genetic lesions. (B,D,F-J) Brightfield images of zebrafish at 24-36 hpf. (B) WT embryo. (D) bmp4^C365S mutant with no obvious defects in the ventral fin or cloaca. (F) bmp4^S355* mutant exhibiting significant loss of the ventral fin (arrow). (G) Uninjected embryo. (H) Embryo injected with 50 pg of S355* RNA exhibiting no morphological defects. (I,J) Embryos injected with 50 pg of C365S RNA displaying C2-C3 (I) and C4 (J) dorsalization. Images of WT and uninjected embryos are duplicated from Fig. 2.

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