Ostreococcus SECIS elements. (a) The most characteristic features of O. tauri and O. lucimarinus SECIS elements are a long mini-stem and an unpaired G preceding the SECIS quartet (core). A SelT SECIS element is shown as a typical example (left structure). Only two exceptions were found, including a type I SECIS element in SelH (middle structure) and a SECIS element with an unpaired A nucleotide preceding the SECIS core (right structure). (b) Alignment of nucleotide sequences of all O. tauri SECIS elements. Location of the SECIS core is indicated. Conserved nucleotides are highlighted. Black and grey highlighting shows sequence conservation.