Figure 3. Searching for a cluster of imprinted genes on the X chromosome.

(A) qRT–PCR of X-linked genes in male and female blastocysts. It should be noted that very weak expression levels of Xist, Jpx, Ftx, Zcchc13 were detected in male blastocysts when additional PCR cycles were carried out. (B) The expression levels of Chic, Tsx, Xite, Tsix, Xist, Jpx, Ftx, Zcchc13, Rlim1/Rnf12, Slc16a2, C77370 were quantified by qRT–PCR in female and male mouse blastocysts. The ratios of the number of cDNA copies for each gene to that of cDNA copies for a housekeeping gene, β-actin, are indicated as expression levels. Expressions of Xite and Scl16a2 were not detected at the blastocyst stage (data not shown). Results are expressed as the mean ± SD (n = 3). The statistical significance of differences between sample means was determined by Student’s t-test. *P<0.01.