Direct imaging of intracellular RNA, DNA, and liquid-liquid phase separated membraneless organelles with Raman microspectroscopy

• Published in: Communications biology Vol. 5; no. 1; pp. 1383 - 9
• Main Authors: Samuel, Ashok Zachariah, Sugiyama, Kaori, Ando, Masahiro, Takeyama, Haruko
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 17.12.2022; Nature Publishing Group UK; Nature Portfolio
• Subjects: Amyloid; Biology; Biomolecular Condensates; Cell division; Cell lines; Cell Nucleus; Chromosomes; Deoxyribonucleic acid; DNA; DNA structure; Double-stranded; Interphase; Intracellular; Metaphase; Mitosis; Organelles; Raman spectroscopy; Ribonucleic acid; RNA; RNA - chemistry; Spectrum analysis
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-022-04342-4

Methodologies for direct intracellular imaging of RNA and DNA are necessary for the advancement of bioimaging. Here we show direct label-free imaging of RNA and DNA in single cells by isolating their accurate Raman spectra. Raman images of DNA from interphase cells show intact nucleus, while those from mitotic cells reveal condensed chromosome. The condensed chromosome images are accurate enough to assign the stage of mitotic cell division (e.g., metaphase). Raman spectral features indicate B-DNA double helical conformational form in all the cell lines investigated here. The Raman images of RNAs, on the other hand, reveal liquid-liquid phase separated (LLPS) membraneless organelles in interphase cells, which disappears during mitosis. Further, the Raman spectrum of proteins from the intracellular LLPS organelles indicates slight enrichment of amyloid-like secondary structural features. Vibrational imaging of intracellular DNA and RNA simultaneously would open myriad of opportunities for examining functional biochemical aspects of cells and organelles.