Highly conserved snoRNA ends from sno-lncRNAs . (A) Conservation analysis of sno-lncRNAs and other lncRNAs. sno-lncRNAs (11 of human sno-lncRNAs summarized in Table 1) are less conserved than other reported lncRNAs  or lincRNAs . The median phastCons score was labeled to indicate the average conservation level. (B) Conservation analysis of nearby exons, snoRNA ends and internal sequences of sno-lncRNAs. snoRNA ends exhibit much higher conservation than nearby exons and internal sequences. The median phastCons score was labeled to indicate the average conservation level. (C) Sequence conservation analysis of PWS region in different species with VISTA browser. PWS region snoRNAs (SNORD116 cluster, light blue) exhibit a remarkably higher conservation across species than SNURF-SNRPN exons and introns. Y-axis, species selected for comparing (left panel) and conservation levels (right panel); Red bars, human PWS region sno-lncRNAs; Blue circles, human PWS region snoRNAs (SNORD116 cluster); Black bars, exons of human PWS region sno-lncRNA host gene (SNURF-SNRPN). Colors of conserved regions were labeled by VISTA according to UCSC annotations (exons in blue and introns in red). Note that sno-lncRNA4 was previously identified as PWCR1 mRNA or small nucleolar RNA (snord116-20) according to UCSC annotation (blue). An analysis of all five PWS region sno-lncRNAs and their flanking sequences was highlighted in Additional file 3.