Expression of a non-human sno-lncRNA in RPL13A region in mouse. (A) A highly expressed sno-lncRNA was indicated in mouse ESC transcriptomes. Top, normalized read densities of poly(A)-/ribo- (red) and poly(A)+ RNA-seq (black) in mouse ESCs. Note two ends of this sno-lncRNA (indicated below) map precisely to the intron-imbedded SNORD33 and SNORD34. (B) Northern blot validation of this sno-lncRNA in mouse cell lines. This sno-lncRNA was highly expressed in mouse R1 cells, but less expressed in other mouse cell lines (NIH 3 T3, VDβ and MEF) with probes for parent RPL13A exon (black bar, left panel) or SNORD33 (blue bar, right panel) by Northern blots. Top, a schematic drawing of RPL13A gene (black bars) and intron-embedded snoRNAs (SNORD35, SNORD34 and SNORD33, from left to right, blue bars). Note that the NB probe recognizing SNORD33 can also visualize other mouse snoRNAs due to the sequence similarity of snoRNAs. (C) Recapitulation of RPL13A region sno-lncRNA in NIH 3 T3 cells. Top, a schematic drawing of mouse sno-lncRNA flanked by its full length intron and exons in expression vector. Bottom, Northern blots of recapitulated mouse sno-lncRNA with probes recognizing different regions. NT, no transfection; EV, empty vector. Note that endogenous RPL13A region sno-lncRNA is lowly expressed in NIH 3T3 cells.