Appearance of a methylated ribonucleic acid on illumination of Euglena gracillis cells grown in the dark.

Investigation of the methylation of nucleic acids by [Me-(3)H]methionine after illumination of Euglena cells grown in the dark has shown that a high-molecular-weight nucleic acid fraction undergoes methylation after exposure to light for 60-120min. This methylated nucleic acid fraction was isolated both by sucrose-density-gradient centrifugation and exclusion chromatography on Sephadex G-200. The fraction was shown to consist of a preformed RNA that is present in cells grown in the dark and which on illumination is transmethylated by methionine.