Fig. 4

nodal mutations suppress lefty1^-/-;lefty2^-/- mutant defects.

(A–F’’) Lateral views of embryos with indicated genotypes at 1 day post-fertilization (dpf). Embryos are progeny from an incross of cyc^m294/+;lft1^-/-;lft2^+/- (A–C’’) or sqt^cz35/+;lft1^-/-;lft2^+/- (D–F’’) adults, and were genotyped after imaging (see Materials and methods for details). In contrast to lft1^-/-;lft2^-/- mutants (A’’, D’’), nodal^+/-;lft1^-/-;lft2^-/- mutants (B’’, E’’) have long tails and well-defined heads, and some nodal^-/-;lft1^-/-;lft2^-/- mutants (C’’,F’’) have eyes in addition to full-length tails. nodal^-/-;lft1^-/-;lft2^-/- and nodal^+/-;lft1^-/-;lft2^-/- mutants are not viable. cyc homozygotes exhibit the expected curved body axis (Sampath et al., 1998) (C,C’), but curvature is reduced in cyc^-/-;lft1^-/-;lft2^-/- embryos (C’’). (G–L’’’) In situ hybridization assessing expression of endodermal (sox32/casanova) (G–I’’’) or mesodermal (noto/floating head) (J–L’’’) genes in the indicated genotypes (dorsal views). Mesendoderm upregulation is less pronounced in sqt^-/-;lft1^-/-;lft2^-/- compared to lft1^-/-;lft2^-/- mutants. (M–N) 72 embryos from a cyc^+/-;lft1^-/-;lft2^+/- incross (M) and 84 embryos from a sqt^+/-;lft1^-/-;lft2^+/- incross (N) were scored and imaged at 1 dpf, and subsequently genotyped. Number of embryos of each genotype with the indicated phenotype at 1 dpf is shown. Together, these results demonstrate that loss of sqt or cyc can suppress lft1^-/-;lft2^-/- mutant phenotypes.