Figure 1

G1- and S-phase cell-cycle gene expression in fin buds of sonic-you mutant correlates with the Fgf signaling status. Wild-type embryos and sonic-you mutant embryos (in which the zebrafish shh gene is disrupted) at 32 hpf (A-L) and 38 hpf (M-Y) were analysed for expression of the Shh target patched1(ptc1) (A, G, M; T), the Fgf target pea3 (B, H, N, U), the cell-cycle genes cyclinD1, pcna, and mcm5 (C-E, I-K, O-R, V-X), and replication protein A1(ra1) (F, L, S, Y). The Shh target ptc1 was expressed in the posterior part of wild-type fin buds at 32 and 38 hpf stages (A, M), but its expresssion was absent in sonic-you mutant fin buds (G, T). The Fgf signaling target pea3 was expressed at comparable levels in wild-type and sonic-you fin buds at 32 hpf stage (B, H). At 38 hpf pea3 was still strongly expressed in the wild-type fin buds (N), but almost completely downregulated in the sonic-you mutant fin buds (U). cyclinD1, pcna and mcm5 were expressed strongly in both wild-type and sonic-you fin buds at 32 hpf stage (C-E, I-K). At 38 hpf these genes were still strongly expressed in the wild-type fin buds (O-R), but downregulated in the sonic-you mutant fin buds (V-X). Expression of ra1 was similar in both wild-type and sonic-you fin buds at 32 and 38 hpf stages.