Fig. 3.

Absence of X-inactivation in female C57BL/6 inbred Dicer KO ES cells. (A) Semiquantitative RT-PCR analysis of mRNA levels of ES cell markers (Oct4, Nanog, Klf4) and differentiation markers (Hnf4, Gata4) at the indicated day of RA-induced differentiation. Hprt served as loading control. (B) As in A except that Xist and Tsix RNA strand specific reverse transcription reactions were performed. (C) Phase contrast images depicting the morphological changes induced in ES cells after 4 days in RA-containing medium. (D) FISH for Xist RNA 6 days after RA addition by using a single stranded RNA probe, merged with Hoechst staining of nuclei. (E) Images depict FISH for the X chromosome in differentiating cultures 4 days after RA addition (green = X paint) counterstained with Hoechst.