Genetic precursor and vitamin B3 found in Ryugu asteroid
Uracil and Vitamin B3 have been detected in material brought to Earth from the asteroid Ryugu.
It is not the first time that a precursor compound to a chemical compound present in all living cells has been detected in extraterrestrial material. Uracil, one of the four bases in ribonucleic acid (RNA), was detected in the Murchison meteorite that fell in Australia back in 1969. But the recent discovery of Uracil in pristine material returned from the near-Earth asteroid Ryugu by the Hyabusa2 spacecraft is highly significant, not least given that vitamin B3 (niacin) and other organic compounds associated with life were also found in the samples. The new findings1 indicate that nucleobases have an extraterrestrial origin, and were delivered to Earth by carbon-rich meteorites.
Hokkaido University chemist Yasuhiro Oba and colleagues analysed samples from two landing sites on Ryugu. The researchers’ detection of uracil, niacin and other organic molecules in pristine samples uncontaminated by terrestrial processes suggest that these compounds may have been generated by photochemical reactions in interstellar ice which was later incorporated into asteroids during the formation of the solar system. The delivery of these compounds to Earth through meteorite impact could have played a significant role in the emergence of early life.
We should soon see more such discoveries in extraterrestrial material of organic compounds associated with biology. I am particularly excited by the possibility that direct evidence of life will be found in material brought to Earth from Mars.
Oba et al., “Uracil in the carbonaceous asteroid (162173) Ryugu”, Nature Communications 14, 1292 (2023); doi:10.1038/s41467-023-36904-3.