Figure 2. Normalized read counts and their distribution according to the nucleotide length.

Fig. 1A shows that majority of trimmed reads were 21–23 nucleotides in length, the same size as miRNA. Fig. 1B shows the distribution of trimmed reads based on their mapping to miRNA, human genome, non-coding RNA (besides miRNA etc) and E coli genome. mm1, mm2 and mm3 represent alignment to miRBase with 0 or 1, 2 and 3 mismatches respectively. Note that the majority of aligned miRNA with 0 or 1 mismatch are distributed around 22 base pairs, the expected size of miRNA. hg19, human genome version 19; fRNAdb, functional RNA database.