Transgene copy number is positively correlated with Jpx and Xist expression.

(A) Transgenic Tg(Jpx) and Tg(Jpx, Xist) mouse lines generated in this study. F, female; M, male. In line 03.4, a semicolon separates different transgenic Jpx and Xist copy numbers. (B) The ratio of transgenic (TG) to wildtype (WT) mice for females and males obtained from five representative transgenic lines, arranged from low to high copy number for each transgene construct.**, P<0.01; ***, P<0.001, from a binomial test for the expected situation of equal TG and WT animals, independently for males and females. (C) Number of animals included in the analysis. (D) Jpx (red bars) and Xist (green bars) expression levels in mouse embryonic fibroblasts (mEFs) isolated from female embryos (top) and male embryos (bottom). Left panel: Tg(Jpx) mouse lines. Right panel: Tg(Jpx, Xist) mouse lines. Data plotted are average expression levels normalized to housekeeping gene Gapdh, ± standard error of biological replicates. A one-tailed t-test was used to compare the expression in transgenic and wildtype samples. *, P<0.05; **, P<0.01; ***, P<0.001. (E) Number of embryos collected and used in the expression analysis. The ‘+’ denotes the number of wildtype animals used when wildtype littermates were unavailable; expression was averaged between such wildtype animals from separate litters.