Trans-duplication of SNORA76 (A) and SNORA24 (B). Gray boxes represent gene regions and black lines intergenic regions. Green arrows show transcriptional orientation. Pink boxes represent exons and purple boxes introns. Open blue boxes show trans-duplicated regions. The nucleotide sequence of each trans-duplicated region is shown. SnoRNA sequences are colored yellow. Retroposed nucleotides, with the corresponding snoRNAs, are shown in lower case. Poly(A) sequences are shown as open boxes. TSD sequences are shaded. L1 consensus recognition sites (for T2A4 derivatives) are indicated as red bars above 5' sequences.