Fig. 1

An inducible Cre/loxP-based genetic system for long-term fate mapping of zebrafish NC. (A) Schematic of the two constructs used to generate (1) a NC-specific ER^T2-Cre driver line [(–4.9kb)sox10 zebrafish promoter] and (2) a ubiquitous reporter line [(–3kb)rps9 promoter from Takifugu rubripes] that enables detection of the recombination events during the early phases of NC differentiation. (3) DsRed excision after Cre-mediated recombination. (B) Time window for tamoxifen induction (16-24 hpf). (C-H) Tg(sox10:ER^T2-Cre;rps9:switch) embryos at 36 hpf, treated with tamoxifen (C,E,G) or with ethanol as control (D,F,H). (C-L′) Maximum intensity projections (MIPs) of confocal stacks. (C) GFP⁺ recombined cells in the branchial arch region (arrow) and cmlc:GFP marker (circled). (E) Hindbrain area with recombined cells in the otic epithelium (arrow) and along the dorsal neural tube, characterized by an epithelial, pre-delamination shape (arrowhead). (G) Sagittal section of the trunk with GFP⁺ melanoblasts and sympathetic neuron precursors flattened along the dorsal aorta walls (arrowhead) and the ventral notochord (arrow). (D,F,H) In the uninduced controls, no recombined cells are detectable. (I,J) Developing viscerocranium in 4-dpf Tg(sox10:ER^T2-Cre;β-actin:switch) larvae showing labeled chondrocytes that are absent in the control. The eyes, which show red autofluorescence, are circled. (K-L′) Tg(sox10:ER^T2-Cre;EF1α:switch) induced embryos (36 hpf) showing (K,K′) labeled pharyngeal arches (1-7) and (L,L′) pigment precursors (a), motor axon glia (b), dorsal root ganglia (DRG) progenitors (c), glia along the lateral line (d) and dorsal melanoblasts (e). The anteroposterior (AP) and dorsoventral (DV) axes are indicated.