Figure 2. Capturing dynamic changes in RNA modifications.

High resolution mass spectra of stable isotope labeled nucleosides from cell culture. (a) Labeling of compounds used for stable isotope labeling in cell culture. Grey circles indicate the positions of isotopes (¹³C, ¹⁵N, or ²H/D). (b) Merged high resolution mass spectra of the four canonical nucleosides of total tRNA after labeling of HEK 293 cells with shown compounds for 7 days. Background signals are marked with asterisks. (c) Merged high resolution mass spectra of three exemplary modifications (m⁵C, m⁷G, and m¹A) in total tRNA after stable isotope labeling of HEK 293 cells for 7 days. Figure adapted with permission from Reference (14); copyright 2021 The Authors. Abbreviations: tRNA, transfer ribonucleic acid; HEK 293, Human embryonic kidney 293; m⁵C, 5-methylcytidine; m⁷G, 7-methylguanosine; m¹A, 1-methyladenosine.