A milestone in small RNA biology—piRNA biogenesis from start to finish

PIWI-interacting RNAs, or piRNAs for short, are a class of 'small regulatory RNAs'—tiny pieces of nucleic acid just 22–30 nucleotides in length. They may be small, but with their associated Argonaute proteins, piRNAs have the power to 'silence' transposable elements, so called egoistic genes found in the genomes of plants, fungi, and animals. piRNA-guided silencing can act on chromatin to block transposon transcription, or by destroying transposon mRNAs in order to block their transl