Knock-down of smp results in reduced transcription of cell cycle-associated genes while increased expression of msxb, msxc and shh. (A) The graph of the measurements from real-time quantitative RT-PCR shows fold changes in the transcription of genes associated with the cell cycle between antisense-morpholino-transfected and mismatch-morpholino-transfected regenerating fin lobes. (B) A graph shows fold change expression of several developmental genes after transfection of antisense-morpholino into cells of the regenerating fin. The numbers in parenthesis represent the number of individual replicates. (C) In situ hybridization with msxb probe show expression in untransfected fins. (D) Knock-down of smp expanded the msxb expression domain in the regenerating fin. (E) In regenerating fins of wild-type fish, shh is present in a defined region of basal epithelium that overlies distal margin of new developing scleroblasts. (F–H) shh expression in smp-morphant fins expanded dramatically to the underlying mesenchyme. Three sections from three different experiments are shown. (I) shh expression in untransfected and antisense-morpholino-transfected lobes by whole mount of caudal fins at 3 dpa. (J) The untransfected lobe shows shh expression in the regenerating fin rays as doublets (red arrows). A clearly discernible gap lacking shh transcript is between these doublets. (K) Antisense-morpholino transfected lobe at high-magnification shows a single shh expression domain (red arrows). Dashed lines (black arrows in H) show amputation planes. Scale bars equal 75 μm. (**: p < 0.005; *:p < 0.05 in Student's t-test).
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