Fig. 3.

Representative genes of a specific profile of transcriptional activity during X-imprinted inactivation assayed by RNA FISH in female embryos. (A) Representative gene silenced at the blastocyst stage. Gla primary transcripts (red) shown by specific RNA FISH at 8-cell (Upper Left), 16-cell (Upper Right), and blastocyst (Bottom Left) stages. Two Gla signals, with 1 within the Xist domain (green), could be seen in the majority of the blastomeres at the 8-cell and 16-cell stages, whereas only 1 signal could be observed in the majority of the blastomeres at the blastocyst stage. For each cell stage, a representative blastomere is shown. Bottom Right: Kinetics of expression of the 6 genes Slc25a5, Lamp2, Atrx, Gla, Fgd1, and Pdha1 silenced from the blastocyst stage. (B) Representative gene escaping to silence. Atp6ap2 primary transcripts (red) shown by specific RNA FISH at 8-cell (Upper Left), 16-cell (Upper Right), and blastocyst (Bottom Left) stages. Two Atp6ap2 signals, with 1 within the Xist domain (green), could be seen in the majority of the blastomeres throughout the preimplantation stages. For each cell stage, a representative blastomere is shown. Bottom Right: Kinetics of expression of the 5 genes Atp6ap2, Utx, Mecp2, Huwe1, and Jarid1c escaping from silencing.