jnk1 and jnk2 are required for early establishment of the midline barrier. (A) Schematic of zebrafish embryo at 13-14 ss. Lateral view. lefty1 (lft1) expression (blue) extends anteriorly from the base of the notochord (red). Arrowhead indicates the anterior limit of expression. Representative images of mRNA in situ hybridisation of lft1 at 13-14 ss in (B) wild type, and (C) MZjnk1a, (D) MZjnk1b, (E) MZjnk1a;MZjnk1b, (F) MZjnk2, (G) MZjnk1a;MZjnk1b;Zjnk2 and (H) MZjnk3 mutant embryos. Arrowheads indicate the anterior limit of lft1 expression in the notochord. (I) Quantification of the average length of lft1 expression at 13-14 ss. Loss of jnk1a results in ∼50% reduction in average length of lft1 domain. MZjnk1b, MZjnk1a;MZjnk1b, MZjnk2 and MZjnk1a;MZjnk1b;Zjnk2 mutants display a more dramatic and similar reduction in the extent of lft1 propagation in the notochord. lft1 expression is unaffected in MZjnk3 mutants. (B-H) Lateral view, anterior is towards the top. (I) Data are mean±s.e.m., Brown-Forsythe and Welch ANOVA, multiple comparisons, with notations denoting result of test between wild type and respective mutant. n=6 clutches. Minimum clutch sizes: wild type, n=82; MZjnk1a, n=73; MZjnk1b, n=61; MZjnk1a;MZjnk1b, n=78; MZjnk2, n=59; MZjnk3, n=69; MZjnk1a;MZjnk1b;Zjnk2, n=37. (B-H) Lateral views, anterior leftwards. ns, not significant. *P<0.05, ****P<0.0001.
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