[piRNAs: Biology and Bioinformatics].

The discovery of small noncoding RNAs and their roles in a variety of regulatory mechanisms have led many scientists to look at the principles of functioning of the cells on a completely different side. Small RNA molecules play key roles in important processes such as the co- and posttranscriptional regulation of gene expression, epigenetic modification of DNA and histones and antiviral protection. piRNA is one of the most numerous, although the least-studied class of small noncoding RNAs. piRNA is highly expressed in the germ line of most eukaryotes and its main function is to regulate the activity of mobile elements during embryonic development. Moreover, recent studies reveal moderate activity of piRNA in somatic cells. However, the mechanisms of piRNA biogenesis and function are still poorly understood and are the object of intensive researches. This review presents actual information about the biogenesis and various functions of piRNA, as well as bioinformatical aspects of this field of molecular biology.