Discovery of All Five Nucleobases in Asteroid Ryugu
—The building blocks of DNA and RNA are universally present in two carbonaceous asteroids—

Key points of results

• All five nucleobases that make up DNA and RNA—purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil)—have been conclusively identified in samples from asteroid Ryugu.
• The relative abundance of purine and pyrimidine nucleobases in Ryugu reflects their formation pathways. A clear correlation between the purine-to-pyrimidine ratio and ammonia abundance led us to propose a new molecular indicator of non-biological nucleobase evolution.
• The confirmed presence of all five nucleobases in two carbonaceous asteroids, Ryugu and Bennu, indicates that the fundamental components of genetic material were likely produced universally during the formation of the solar system, providing important direct evidence for early chemical evolution.

For more details, please see the Nature Astronomy link:
10.1038/s41550-026-02791-z

The “Ryugu Emaki” illustration showing the discovery of all five nucleobases in samples returned from asteroid Ryugu.