Figure 1. Adult retinal phenotypes of α-Cre;Dll1^CKO/CKO conditionally mutants.

A) Deletion strategy for α-Cre-mediated removal of Dll1 and activation of GFP expression from the Z/EG transgene. B) α-Cre;Dll1^CKO/+ and α-Cre;Dll1^CKO/CKO adult eyes and optic nerves appear identical to Dll1^CKO/CKO control littermates. No Dll1 heterozygous phenotypes were found by gross inspection or histology (n=6). C–D) Histologic sections of P21 eyes highlighted thinner retinal tissue with rosetting in the absence of Dll1 (n=9). E–F) Anti-GFP/DAPI double label of α-Cre;Z/EG;Dll1^CKO/+ and α-Cre;Z/EG;Dll1^CKO/CKO P21 retinal sections. In the distal retina, the α-Cre lineage (GFP-marked) in both control and Dll1^CKO/CKO mutants is interspersed with GFP-negative cells (DAPI only), even within rosettes. This is vastly different than the segregation of wild type and mutant cells found in α-Cre;Z/EG;Rbpj^CKO/CKO eyes (Riesenberg et al., 2009). Anterior is right in B, scleral is up in C–F. Scale bars = 500μm in B, 20 μm in C,E. α= Pax6 intronic α enhancer; P0 = Pax6 promoter, IRES = internal ribosome binding site; pA = poly A sequence; DSL= Delta/Serrate/Lag domain; TM = transmembrane-spanning domain; ONL = outer nuclear layer, INL = inner nuclear layer, GCL = ganglion cell layer.