Examples of novel miRNAs annotated in this study. (A) sblock6825/mir-4984 and (B) sblock66958/mir-4982 are novel miRNA loci that generate specific miRNA/miRNA* duplex species and had at least some reads in AGO1-IP libraries. mir-4982 approaches the lower limit for read accumulation needed for confident annotation. (C) sblock87333 is an example of a “candidate” miRNA locus that was not assigned a miRNA gene name at present. It exhibits heterogeneous 5p arm species (pink), and its dominant 3p arm is 20 nt in length, which is not typical for known miRNAs. Nevertheless, the 3p species clearly exhibit a preferred 5′ end, and several versions of the 3p species extending to 22 nt were present in head AGO1-IP data (GSM488489); one of the 5p reads would potentially pair with this duplex in an appropriate fashion. Therefore, this locus may eventually prove to be a genuine miRNA locus.
