ABSTRACT
The recent past has seen the rapid identification of thousands of microRNAs (miRNAs) encoded by various metazoan organisms as well as some viruses, and it is very likely that many more still await discovery. Most of the hitherto-known miRNAs have been identified via the cloning and sequencing of small RNAs. While very powerful, this approach is not without its limitations: especially those miRNAs that are of low abundance, or which are only expressed in certain cell types or only during brief periods of organismal development, or are easily missed in cloning-based screens. Thus, alternative means of miRNA discovery are needed.
