Fig. 8

The Sp consensus binding site cannot functionally replace the G/C-rich enhancer in vivo. (A and B) Transgenic zebrafish were created which harbor the Sp consensus (SpCon) binding site replacing the G/C-rich enhancer in the tuba1a:GFP transgene. (A) SpCon transgenic fish display nervous system restricted GFP expression at 48 h post fertilization similar to Wt promoter (Fig. 8A). Auto-fluorescence in the yolk is noted with an asterisk (*). (B) SpCon transgenic fish fail to re-express GFP during optic nerve regeneration. Wt tuba1a:GFP transgenic fish exhibit strong tuba1a (a) and GFP (b) expression in the retinal ganglion cell layer (GCL) 3 days following optic nerve injury. In addition, we observed variable and weak GFP expression in inner nuclear layer cells in this particular line of fish which may reflect the transgene insertion site. Uninjured SpCon transgenic (c and d) and 3 day post-nerve injury (e and f) retinal sections were stained for tuba1a expression (c and e) or imaged for fluorescence (d and f). Note the absence of GFP fluorescence in the GCL of the injured retina (f) while endogenous tuba1a expression is highly induced (e).