Fig. 7

Terminal Protein Na⁺/K⁺-ATPase Is Required for Luminal Inflation but Not for OAA Dissolution

(A) In 30-hpf nok^m520 mutants, Na⁺/K⁺-ATPase α failed to enrich at the midline region in the neural tissue (arrowheads) but still enriched in the otic vesicle (arrows).

(B) Brain ventricle inflation was blocked by ouabain treatment (arrows; 26-ss).

(C) Ouabain did not prevent Na⁺/K⁺-ATPase α from enriching apically with Nok in the neural tissue (26-ss).

(D and E) TEM revealed that in ouabain-treated embryos, the PAAs persisted (black arrows), whereas the OAAs were not detectable on the opposing apical cell membranes (arrowheads). (E) Magnification of the boxed region in (D). The red arrow indicates the midline direction.

(F) Diagrams summarize that pioneer, intermediate, and terminal proteins regulate zebrafish neurulation through the three steps.

(G) A diagram illustrates the three core elements that underlie symmetry formation: symmetry, asymmetry, and opposing configuration. Also see Figure S7.