Fig. 6

Gene expression analysis using in situ hybridization on whole-mount and longitudinal sections of EGFP (A, C, F, H, J) and chordin-injected rays (B, D, G, I, K) at 4 dpa/1 dpi. (A-D) runx2a and runx2b are both expressed within newly differentiating scleroblasts (arrowheads in panels A and C) in control regenerates and are both downregulated following chordin injection (B, D). (E-F) col10a1 expression on whole-mount 3 dpa regenerate (E) and 4 dpa regenerate 1 day following EGFP construct injection (F). At 3 dpa col10a1 is already strongly expressed in the entire fin ray and presents a stronger expression in the distal part of the regenerate. At 4 dpa/1 dpi, in the EGFP-injected fin rays, a similar strong expression is observed with a broad domain in the distal part of the regenerate. (G) In contrast, in the chordin-injected rays, col10a1 expression at 4 dpa/1 dpi is reduced and observed in a more restricted domain in the distal part of the regenerate. (H, I) ihha expression in the distal scleroblasts (arrowheads) of EGFP-injected rays (H) is unaffected in chordin-injected rays (I). (J, K) shh expression in the basal epidermal layer is unchanged in both EGFP (J) and chordin-injected rays (K). Asterisks in panels J and K indicate blood vessels. b, blastema; ble, basal layer of the epidermis; s, scleroblasts. Distal part of the regenerate is to the right (A-D, H-K) and to the top (E-G). Arrows indicate level of amputation. Arrowheads show expression of col10a1 in each ray in panels E-G. Scale bars: (A-D, H-K) = 25 μm, (E-G) = 100 μm.