Fig. 5

Bmp inhibition rescues Engrailed(+) muscle cells and cxcl12a expression in glypican4^fr6. (A-C′) In situ hybridization shows expression of the Chemokine ligand cxcl12a in siblings (A-A′), glypican4^fr6 No-turning mutants (B-B′) and glypican4^fr6 U-turning mutants (C-C′) along the embryo trunk. (A′-C′) Higher magnification images of (A-C). (d-F) Engrailed (4D9) immunostaining reveals that, compared to siblings (D), glypican4^fr6 No-turning mutants (E) and glypican4^fr6 U-turning mutants (F) have a considerably diminished number of MPCs and MFFs. (G) Quantification of 4D9-positive muscle pioneer cells per somite at 24 hpf (p-values (t-test) for Control vs. No-turn=0.0036, Control vs. U-turn=5.09721×10⁻¹², No-turn vs. U-turn=0.00065). Error bars represent standard error. (H-K) In control (H-I) and glypican4^fr6 mutant (J-K) embryos inhibition of Bmp signaling with 10 μM Dorsomorphin induces the formation of MPCs and MFFs along the myoseptum. (L-O′) Bmp inhibition results in the upregulation of cxcl12a expression along the myoseptum in siblings (L-M′) and restores cxcl12a expression in glypican4^fr6 mutants (N-O′) along the embryo trunk. (L′-O′) Higher magnification images of (L-O). (P-T) Inhibition of Bmp signaling does not affect primordium migration (P-Q) but significantly rescues the migration of glypican4^fr6 mutants (R-S). (T) Quantification of primordia that have completed migration after Bmp inhibition, Fisher Exact Probability Test, Sibling-DMSO vs. Siblings-Dorsomorphin =0.31; glypican4^fr6-DMSO vs. glypican4^fr6-Dorsomorphin=0.04. Hours post treatment (hpt).