Figure 6. Switching of imprinted to random X-inactivation in E3.5 embryos lacking maternal EED.

See also Figure 6—figure supplement 1. (A,B) Allele-Specific Xist RNA FISH in Eed^fl/+ and Eed^m-/- male and female E3.0-E3.5 blastocyst embryos. Xist RNA expressed from the maternal X-chromosome is indicated in red and from the paternal X-chromosome in white. Representative embryos are depicted. Nuclei are stained blue with DAPI. Scale bars, 20 µm.

Figure 6—figure supplement 1. Characterization of allele-specific Xist RNA FISH probe in cells and embryos.

(A) Female Trophoblast stem (TS) cells (top panel) and extraembryonic endoderm (XEN) stem cells (bottom panel) stained with an allele-specific Xist RNA FISH probe. Both TS cells and XEN cells express Xist from and undergo imprinted X-inactivation of the paternal X-chromosome (Kunath et al., 2005; Tanaka et al., 1998). The TS cells are derived from a cross of JF1 Mus molossinus dam with a 129/S1-derived Mus musculus sire. The XEN cells are generated from a cross of 129/S1 Mus musculus dam and JF1 Mus molossinus-derived sire. In the TS cells, the paternal-X is therefore Mus musculus derived while in the XEN cells the paternal-X is JF1 Mus molossinus derived. Mus musculus-specific Xist RNA FISH probe detects the complimentary Xist RNA in red and the Mus molossinus-specific Xist RNA FISH probe detects its complimentary Xist RNA in white. (B) Eed^fl/+ female E3.5 embryos stained with the same allele-specific Xist RNA FISH probe as in (A). Top panels, representative stained embryo derived from a cross of Eed^fl/fl;X^JF1X^JF1 Mus molossinus-derived dam with a Mus musculus sire. Bottom panels, representative stained embryo from an Eed^fl/fl Mus musculus-derived dam with a JF1 Mus molossinus-derived sire (this embryo is also shown in Figure 6A). Due to imprinted X-inactivation, both E3.5 embryos are expected to express Xist RNA from their paternal X-chromosome.