seahorse mutants have a low level of left-right patterning defects. (A) At 20 somites, the majority of sea mutants have normal left-sided expression of southpaw and lefty1/2 in the lateral plate mesoderm, and lefty1 in the diencephalon (asterisk). southpaw is expressed lateral (marked with arrows) to the darker stained lefty1/2-expressing cells in the lateral plate. (B-G) The majority of sea mutants had correctly looped hearts (B) with the ventricle (white V) looped to the right of the atrium (white A) and correctly placed visceral organs (E) with the liver (white L) on the left and pancreas (white P) on the right. A low level of sea mutants display either situs inversus (complete reversal of organ positioning; C,F) or heterotaxia (random organ positioning; D,G). (H-J) sea mutants also display a low level of asymmetric defects in habenular expression of lov at 4 dpf. Although most mutants have the typical greater level of expression on the left (H), some mutants have reversed (I) or isomeric (J) expression. (A) Dorsal view, anterior towards the top. (B-D) Ventral views, anterior towards the top. (E-G) Dorsal views of the same embryos in B-D, anterior towards the top. (H-J) Dorsal views of the diencephalon, anterior towards the top. In all panels, black R indicates right, black L indicates left.
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