Prevalence of antisense miRs in Ciona. (a) In the scaffold 20 11-miR cluster, three miR loci have antisense reads that exactly match the sense miR/miR* products. (b) Secondary structures of Ci-mir-2217-1 and its associated antisense locus, miR-2217-1-as, both form highly symmetric hairpins, on which the miR and miR* products are indicated as lines. (c) In one case, we observed the antisense locus of Ci-mir-2246 produces not only miR/miR*, but also a 5p-moR product. (d) Secondary structures and product distribution of Ci-mir-2246 and Ci-mir-2246-as.