text: The scientific community has been quick to harness RNA silencing as a research tool. The strategic targeting of mRNA can provide a large amount of information about gene function and its ability to be turned on and off. Induced RNA silencing can serve as a controlled method for suppressing gene expression. Since the machinery is conserved across most eukaryotes, these experiments scale well to a range of model organisms. In practice, expressing synthetic short hairpin RNAs can be used to reach stable knock-down. If promoters can be made to express these designer short hairpin RNAs, the result is often potent, stable, and controlled gene knock-down in both in vitro and in vivo contexts. Short hairpin RNA vector systems can be seen as roughly analogous in scope to using cDNA overexpression systems. Overall, synthetic and natural small RNAs have proven to be an important tool for studying gene function in cells as well as animals.
  Bioinformatics approaches to identify small RNAs and their targets have returned several hundred, if not thousands of, small RNA candidates predicted to affect gene expression in plants, C. elegans, D. melanogaster, zebrafish, mouse, rat, and human. These methods are largely directed to identifying small RNA candidates for knock-out experiments but may have broader applications. One bioinformatics approach evaluated sequence conservation criteria by filtering seed complementary target-binding sites. The cited study predicted that approximately one third of mammalian genes were to be regulated by, in this case, miRNAs.