Characterization of the longer transcripts of 21U-RNAs. (a) A view of the longer and overlapping 21U-RNA reads. The number of reads shown in this figure was based on the computational output of the SOAP program  followed by removal of redundant sequences, and samples of all six developmental stages (embryo to young adult of hermaphrodites) were used as the input. The core consensus motif 'CTGTTTCA' and the mature 21U-RNA sequences are capitalized and highlighted in blue and red, respectively. (b) The proportion of longer 21U-RNAs of different length. The number of reads of each transcript was reflected in the result; for example, the length of an extension in a longer 21U-RNA with 3 bp extension to its 3' side and with 4 reads was calculated as 12 (3 × 4). (c) The abundance of longer 21U-RNAs during development. The left and right vertical axes represent the number of longer 21U-RNA reads (22 to 26 nucleotides) and that of mature 21U-RNAs with longer transcripts detected, respectively.