Figure 1: Strategy for preparing the Dkk3-EGFP transgene and Northern hybridization analysis of EGFP expression in adult mouse organs. (a) A schema of the modified BAC integrated with the EGFP-pA cassette into the first exon of the mouse Dkk3 gene. (b) Northern hybridization analysis of total RNA (retina, 10  𝜇 g; other tissues, 20  𝜇 g) isolated from adult organs in the BAC-Dkk3-EGFP mouse. The hybridization signal was obtained with the EGFP probe. The lower panel shows ethidium bromide staining of the RNA. (c) Northern blot analysis using a Dkk3 probe for wild-type mouse tissues. (d, e) Photographs of the adult BAC-Dkk3-EGFP mouse, which displays “green eyes” even under the room light because of the intense expression of EGFP in the retina.