Fig. 4

Tracing individual MPs during regeneration in chimeric animals. Blastula transplantations were performed with Tg(mitfa:gfp) zebrafish embryos injected with rhodamine dextran as donors and alb embryos injected with mitfa-MO as recipients. (A-E′) Red and green channel are shown in A-E, green channel only in A′-E′. Starting at 60 hpf (A,A′), we imaged a clone appearing at the site of a rhodamine-labelled DRG (asterisk) from which a peripheral axon extends ventrally (arrow). The arrowhead in A,A′ points to a GFP-positive cell located at the ventral side of the myotome. Another labelled cell appears at 70 hpf at the site of the DRG (arrowhead in B,B′). This cell divides, and the two daughter cells migrate dorsally (blue arrowhead) and ventrally (white arrowhead) along a spinal nerve (C,C′). The dorsally migrating cell divides once (blue arrowheads in D-E2), its progeny arrive at the dorsal side of the larva. The ventrally migrating cell divides once (white arrowheads in D-E2). (F-H′) The daughter cells, after reaching a position along the ventral stripe close to a cell that arrived there earlier, melanise (arrowheads in G-H′). Complete time-lapse imaging is shown in supplementary material Movies 2, 3. The region marked in E′ is shown in more detail in G, and the boxed area in G is enlarged in H,H′. (I-J′′) Chimeric adult fish that had developed several donor-derived melanophores at the lateral stripe in late larval stages. These display vertical streaks of donor-derived melanophores spanning the entire flank from dorsal to ventral, including the fins, enlarged in I′,J′ J′′. These streaks appeared in the same rostrocaudal position as the larval melanophores.