Optimized miRNA-Seq faithfully captures miRNAs from biological samples. (A) Deep sequencing data of mapped miRNA reads cloned from total RNA isolated from mouse brain and (B) heart. The most cloned miRNAs are shown with the cloning frequencies. (C) Deep sequencing data of miRNA reads for cistronic miRNAs obtained from mouse heart and brain. Note the highly similar representation of each cistronic miRNA by read numbers across four orders of magnitude, except for the miR-451/144 cluster.