Figure 5.

Dox-controlled inducible and reversible regulation of endogenous Nmyc expression. (a) Real-time PCR quantification of endogenous Nmyc expression in E10.5d embryos of wild-type, Nmyc^TRE/TRE and Nmyc^TRE/TRE:tTS whose mothers reared on drinking water containing 0 mg/ml dox (−dox) or 2 mg/ml dox (+dox). (b) Real-time PCR measurement shows dox-dependent reversible regulation of endogenous Nmyc expression in Nmyc^TRE/TRE:tTS mice. The pregnant mice were exposed to dox-containing (2 mg/ml) drinking water for 10 days beginning at E0.5d, followed by no exposure to dox for 14 days (+→− dox group), and followed by access to dox-containing drinking water again for 7 days (+→-→+ dox group). Nmyc expression was normalized to Nmyc^TRE/TRE levels. (c) Nmyc^TRE/TRE:tTS embryos whose mothers without dox exposure died at E11.5d. However, prenatal exposure to dox for at least 1 day led to Nmyc^TRE/TRE:tTS embryo survival. (d) Nmyc^TRE/TRE and Nmyc^TRE/TRE:tTS embryo from same litter at E11.5d from a mother without dox exposure. (e) Differences in body weight were observed in Nmyc^TRE/TRE:tTS mice depended on the different dose and duration of dox treatment on their mother. Body weight was normalized to Nmyc^TRE/WT:tTS (n = 13–24 for each genotype in the different exposure duration groups). (f) Nmyc^TRE/TRE:tTS mice were smaller at 2 days postnatal than littermates of other genotypes. The mother had been exposed to drinking water containing 0.5 mg/ml dox for 1 day at E0.5d. Scale bar is 1000 µm.