Figure 1. Reduction of Fibronectin matrix enhances neural tube convergence but abrogates bilaterally symmetric paraxial mesoderm morphogenesis.
(A) A schematic of the zebrafish tailbud and two transverse sections at the anterior and posterior ends of the presomitic mesoderm (PSM, cyan). The left and right PSM flank the neural tube (NT, magenta) and notochord (NC). The neural tube and PSMs converge along the medial-lateral axis, and the anterior tailbud is further converged than the less developed posterior tailbud. (B–E) Transverse sections 160 μm posterior to the last somite boundary at 12–14 somite stage in wt (B), cdh2-/- (C), MZ itgα5-/- (D), and cdh2-/-; MZ itgα5-/- (E). Sections were reconstructed at a distance of 160–180 μm from last somite boundary after wholemount labeling for fibronectin (red) and nuclei (grey). Yellow dotted lines delineate neural tube contours. White arrowheads indicate locations of tissue detachment (also see Figure 1—figure supplement 2E and F). Dorsal is to the top. Scale bars = 70 μm. (F) Quantification of the medial-lateral length of the neural tube (as indicated by red double arrow) along the anterior-posterior axis starting from the last somite boundary. Quantifications were performed on transverse sections spaced every 20 μm. Dots represent means and error bars represent SD. Sample size: n = 10 PSMs on five embryos for each genotype. (G) Quantification of left-right asymmetry in PSM area. Each dot denotes an absolute difference in left and right PSM areas at each transverse section. Sample size: n = 75 sections from five embryos for each genotype. ***p<0.0005, T-test. cdh2-/- vs WT, p=0.79; MZ itgα5-/- vs WT, p=2.51e-4; MZ itgα5-/-;cdh2-/- vs WT, p=3.34e-10.
Figure 1—figure supplement 1. Reduction of cell-ECM interactions leads to precocious neural tube convergence and rescues cdh2 mutant neural tube convergence defects.
Figure 1—figure supplement 2. Reduction of cell matrix interactions provokes a precocious neural tube convergence and generates left-right asymmetries in the PSM|NT interfacial length and angle.
