FIG. 1.
Ectopic X inactivation upon Xist induction in the embryo. (A) Generation of the inducible TX allele. The tet operator sequence (green) was introduced into the SacII site upstream of the P1 promoter of Xist. The probe XB1K is indicated. (B) Doxycycline (dox)-induced DNA binding of the transactivator protein nls-rtTA results in Xist expression. (C and D) Northern blot analysis of X-linked (C) and erythroid cell-specific (D) gene transcripts in male TX/Y R26rtTA/rtTA embryos, in which Xist was induced with doxycycline (+) for 4 days starting at the indicated time point. (E) Lateral view of TX/Y R26rtTA/rtTA embryos (+) after Xist induction for 4 days after the time point shown. Untreated (−) embryos were used as control.