Biologists still have no clear idea how many active genes there are coding for proteins in humans and other organisms, even though for some species the genomes have been completely sequenced. This is because many of the genes and their protein products have only been predicted by computer algorithms that are at this time imperfect.

While most RNAs work to create, package, and transfer proteins as determined by the cell’s immediate needs, miniature pieces of RNA, called microRNAs (miRNAs) regulate gene expression. Recently, researchers from the University of Pennsylvania School of Medicine determined how miRNAs team up with a regulatory protein to halt protein production. Results of the study were published recently in Cell.

Three teams of scientists say they have produced the equivalent of embryonic stem cells, at least in mice. Their procedure makes ordinary skin cells behave like stem cells. If the same can be done with human cells a big if the procedure could lead to breakthrough medical treatments without the contentious ethical and political debates surrounding the use of embryos.