Fig. 3

Transplanting wild-type MPs at the HMS rescues PAC formation in netrin 1a morphants. (A) Scheme for heterochronic transplants. Rhodamine Dextran (RhDx) is injected into one-cell stage fli1a:egfp^y1 zebrafish embryos (donor). netrin1aSBMO is injected into one-cell stage fli1a:egfp^y1 embryos (host). Cells are transferred from the RhDx embryo at 4 hpf to the netrin 1a morphant host at 3 hpf at a location fated to include MPs. (B-G) Lateral views showing fli1a:egfp^y1 and the lineage marker (RhDx) in two transplanted embryos. The PAC (arrows, B,E) forms in the same hemisegments that receive transplanted wild-type MPs (arrowheads, C,F). Confocal projections. (H) Quantitation of rescue in netrin 1a morphants showing presence of the PAC (partial or complete) in hemisegments that either received wild-type transplanted MPs or were populated only by morphant host MPs. Host MPs only, 42±9%; transplanted donor MPs, 78±10%. All values are mean±s.e.m.; P-value determined by Wilcoxon signed rank test. n, number of hemisegments (number of embryos). A, anterior; D, dorsal; MP, muscle pioneer. Scale bar: 50 μm.