Characterization of unspliced Dxz4 transcript. (a) Schematic map of a Dxz4 monomer. The internal VNTR is represented by the black box. Below it are indicated six intervals (i to vi) assessed by reverse-transcription PCR (RT-PCR). The RT-PCR results for i to vi are given as images of ethidium bromide-stained agarose gels for NIH/3T3 complementary DNA (cDNA). Samples include water (W), RNA incubated with (+RT) and without (-RT) reverse transcriptase, and genomic DNA. (b) RNA FISH results of direct-labeled Spectrum-Orange or Spectrum-Green probes for regions i to vi in NIH/3T3 cells. Signals are indicated by white arrows merged with DAPI (black and white). (c) Strand-specific quantitative RT-PCR analysis of Dxz4 expression in two independent male and female samples. Graph shows fold expression of dxz4 in sense (left) and anti-sense (right) primed cDNA relative to cDNA prepared with no gene-specific primer. Error bars show standard deviation. (d) RNA FISH analysis of unspliced Dxz4 (red) and Xist RNA (green) merged with DAPI (black and white) in female cells. Dxz4 indicated by the white arrowheads and inactive X chromosome-specific transcript (Xist) by the white arrows. (e) Frequency of Dxz4 RNA FISH signals overlapping Xist in female cells.