Suppression of sept7b leads to defects in left–right asymmetry and hydrocephaly. (A–C) In situ hybridization of spaw in control (ctrl) embryos at the 20-somite stage (A) and in embryos treated with the sept7b TBMO (B,C). Spaw is expressed in the left lateral plate mesoderm in control embryos (A), whereas spaw expression is bilateral (B) or in the right lateral plate (C) in sept7b morphants, as indicated by arrows. (D–F) In situ hybridization of cmlc2 in a control embryo at the 30-somite stage (D) and in sept7b TBMO morphants (E,F). Cmlc2 expression shows the heart tube looping to the left in control embryos (D), whereas cmlc2 expression is in the center (E) or looping to the right (F) in sept7b morphants, as indicated by arrows. (G) The number of control and sept7b morphant embryos with spaw expression on the left side, right side, bilaterally or absent. (H) The number of control and sept7b-morphant embryos with cmcl2 expression on the left side, in the center or on the right side. (I,J) 2-dpf control embryos (I). (J) sept7b morphant (TBMO) at 2 dpf shows hydrocephaly (arrow). (K,L) Histological sections stained with hematoxylin–eosin of 4-dpf control (K) and TBMO-injected (L) zebrafish larvae show hydrocephalus in the morphants (arrow). (M,N) Immunofluorescence staining for acetylated tubulin (red) reveals misorientation, shortening and a reduced number of cilia in 30-hpf zebrafish that had been injected with the TBMO (N) compared with the control (M). Scale bars: 130μm (A–F); 100μm (K,L); 10μm (M,N).
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