Fig. 3

swirl and snailhouse double mutant analysis. Phenotypes observed in embryos from crosses between swirl; din double heterozygous fish (A–F). (A) Wild type embryo at the 5-somite stage (dorsal to the right, anterior up). (B) A swirl mutant embryo at the 5-somite stage. Morphogenetic movements have driven the somitic tissue (arrowhead) and the tail bud off the yolk. These mutants die by the 14-somite stage (~ 16 hpf). (C) Wild type embryo at 1 dpf displaying a single ventral tail fin (arrowhead). (D) The weakly dorsalized, dominant swirl phenotype is characterized by a partial loss of the ventral tail fin (absent between the arrowheads). (E) din mutant embryos have multiple ventral tail fins (arrowhead) and a large edema posterior to the yolk extension (arrow). (F) The dominant dorsalized swirl mutant phenotype is epistatic to din, as evident by the absence of the ventral tail fin (arrowheads) in this din-/- ;swr+/- embryo. However some aspects of ventralization are still present, such as a minor edema (arrow) and a multiplicated ventral tail fin tip (arrowhead in the inset, which is a slightly different view). For snh double mutant analysis, 3 classes of 1 dpf phenotypes were observed in embryos from crosses between snh; din double heterozygous fish; wild type embryos as in A, din mutant embryos as in E and snh mutant embryos (G). snh embryos are truncated posteriorly and the trunk tissue is twisted above the yolk (arrowhead). Phenotypes observed in embryos from crosses of swirl;ogon double heterozygous fish (H and I). Wild type and swirl mutant embryos were observed identical to those in A, B, and C. (H) ogon mutants at 1 dpf exhibit multiple ventral tail fins (arrowhead) and an edema posterior to the yolk extension (arrow) as well as a swelling of the hindbrain ventricle (white arrowhead). (I) The dominant dorsalized swirl phenotype is epistatic to ogon as evidenced by embryos with a gap in the ventral tail fin (arrow), which also display an ogon head phenotype (white arrowhead) and multiplicated ventral tail fin tip (black arrowhead).