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. 2013 Jan 31;8(1):e55345. doi: 10.1371/journal.pone.0055345

Figure 2. XIST structure and transcription in Meishan and WC placentas; expression of a short isoform in the Meishan breed.

Figure 2

Swine XIST was discovered and annotated from reciprocal BLAT with bovine XIST as it is not annotated in the current pig 9.2 genome assembly. (A) Specifically, we identified BAC CH242-76N1 (GI: 219925014) that contained porcine XIST. Biochemical studies involving mutated or truncated XIST transcripts revealed the A-repeat region as the functional element responsible for X-chromosome inactivation [65]. We mapped Affymetrix probesets and the corresponding ESTs to porcine XIST and designed a series of RT-qPCRs (bracketed numbers) to validate microarray results (Table 1). (B) Agarose gel electrophoresis depicting representative PCR assays to amplify regions of genomic DNA or cDNA from D25 MS or WC fetuses for the chromosomal interval SSCX: 58,375,000-58,400,000 based on the assembly (SGSC Sscrofa9.2/susScr2 and BAC CH242-76N1 (GI: 219925014). A postive control for genomic DNA isolation is shown for COL10. For analysis of placental RNA isolation and cDNA generation, we performed reverse-transcription PCR with exon-spanning primers for the positive control RPL18 (Figure 2B, bottom panel, lanes 2+3). The short XIST isoform was absent from additional MS gestations (Table 1).