Expression of G1- and S-phase cell-cycle genes fails to correlate with the status of Shh signaling in fin buds. Wild-type embryos were treated with 100 μM cyclopamine (cyA) (G-L, T-Y) or with the carrier 0,5% ethanol (EtOH) (A-F, M-S) for 6 hours from 34 to 40 hpf (A-L) or for 13 hours from 34 to 47 hpf (M-Y) and analysed for the expression of ptc1, pea3, cyclinD1, pcna, mcm5 and ra1. Expression of ptc1 was nearly completely lost after both 6 hours (A, G) and 13 hours (M, T) inhibition pulses. A 6-hour Hedgehog signaling inhibition led to a small change in pea3 expression in fin buds (B, H). Comparably small changes in expression after 6-hour Hedgehog signaling inhibition were observed for cyclinD1, pcna, mcm5 and ra1 (C-F, I-L). After 13-hour Hedgehog signaling inhibition, fin bud pea3 expression was strongly decreased (N, U). Likewise, expression of cyclinD1, pcna and mcm5 in fin buds was strongly downregulated (O-R, V-X). Expression of ra1gene was only mildly affected by 13-hour cyclopamine treatment (S, Y).
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