Scientists detect full set of genetic building blocks in Ryugu samples

Tuesday 17 - 07:00

By: Dakir Madiha

Scientists detect full set of genetic building blocks in Ryugu samples

Scientists have identified all five canonical nucleobases, the molecular units that encode genetic information, in samples returned from the asteroid Ryugu. The findings, published on March 15 in Nature Astronomy, support the theory that carbon-rich asteroids delivered key chemical ingredients to early Earth.

A research team led by Toshiki Koga of the Japan Agency for Marine-Earth Science and Technology analyzed two Ryugu samples collected by the Japan Aerospace Exploration Agency’s Hayabusa2 mission. The study confirmed the presence of adenine, guanine, cytosine, thymine and uracil, the complete set of nucleobases used in DNA and RNA. Earlier analyses in 2023 had detected only uracil and vitamin B3, with other bases likely below detection limits at the time.

The discovery makes Ryugu the second asteroid where all five nucleobases have been directly confirmed. In January 2025, Japanese researchers reported the same full set in samples from asteroid Bennu, returned by NASA’s OSIRIS-REx mission, at concentrations five to ten times higher than those found in Ryugu.

Comparisons between Ryugu, Bennu and two well-studied meteorites, Murchison and Orgueil, revealed distinct chemical patterns. Ryugu showed roughly equal amounts of purines and pyrimidines, while Bennu and Orgueil were richer in pyrimidines and Murchison was dominated by purines. Researchers found a strong link between these ratios and ammonia levels, suggesting that the chemical environment inside asteroid parent bodies influences nucleobase formation.

The detection of thymine alongside uracil is significant for theories about the origin of life. The RNA world hypothesis proposes that RNA preceded DNA, with uracil considered easier to form under prebiotic conditions. Finding both molecules together indicates that asteroid chemistry can produce a full set of genetic components rather than favoring one pathway.

Researchers said the consistent detection of all five nucleobases in carbon-rich asteroids points to a widespread process across the solar system. The results strengthen the idea that asteroid impacts may have supplied early Earth with the organic materials needed for prebiotic chemistry and the eventual emergence of life.