12. Non-coding RNAs—comparison of biogenesis in plants and animals

Regulation of gene expression via small non-coding RNAs (ncRNAs) is one of the most ancient mechanisms, and it appears to exist throughout all domains and kingdoms of life. In most of the species analyzed to date, small silencing RNAs are characterized by their short length (approximately 20 to 30 nt), their association with members of the Argonaute (Ago) family of proteins, and their capacity to reduce gene expression by several independent mechanisms. At the same time, there exist longer small ncRNAs. The expression of ncRNAs might also lead to an increase in gene expression. Some ncRNA classes might have common regulatory pathways. Moreover, similar types of ncRNAs may be derived from single- or double-stranded RNA precursors, and diffe....