Known and novel miRNA genes. (a) MiRNA expression classifies E. electricus tissues. Tissue distance matrix based on miRNA expression. MiRNA expression values for 8 tissues were filtered, normalized and log2 transformed as described in Methods. Values shown are Euclidean distances. Tree is derived from complete linkage hierarchical clustering. (b) Normalized sequencing read counts for conserved and novel E. electricus miRNAs. (c) Heatmap and complete linkage hierarchical clustering of novel miRNA log2-transformed and median-centered expression values in E. electricus tissues demonstrates tissue-specific expression patterns. Log2 values are clamped between −3 and +3.