15:30 〜 15:45
[PPS08-07] 液体クロマトグラフ―超高分解能質量分析計を用いた地球外物質中核酸塩基の検出
★招待講演
キーワード：核酸塩基、炭素質隕石、小惑星リュウグウ
Since the detection of nucleobases in carbonaceous meteorites more than 60 years ago, their possible contributions to chemical evolution in space and to the emergence of genetic functions on the early Earth have been discussed. However, among five DNA/RNA nucleobases (uracil, cytosine, thymine, guanine, and adenine), only uracil, adenine, and guanine have been detected in meteorites so far, which renders the above hypothesis uncertain. We suspect that the non-detection of cytosine and thymine could be due to some technical issues applied in previous studies. In the present study, we analyzed aqueous extracts from carbonaceous meteorites (Murchison, Tagish Lake, and Murray) and returned samples from the asteroid (162173) Ryugu using state-of-the art analytical techniques for the detection of tiny amounts of nucleobases in such extraterrestrial materials.
We detected all five DNA/RNA nucleobases including thymine and cytosine in aqueous extracts from a ~2 g of the three carbonaceous meteorite for the first time with the concentration ranging from 4-72 ng/g-meteorite. After careful evaluation, we concluded that the detected nucleobases are indigenous to the meteorite. Their detection would be mainly due to the fine-tuned analytical method without a loss of nucleobases during wet chemical procedures.
We also detected an RNA nucleobase, uracil, from the Ryugu samples. The concentration of uracil was comparable to that in other carbonaceous meteorites. Since the Ryugu is the freshest sample of CI-type carbonaceous asteroids, it is no doubt that the detected uracil is extraterrestrial in origin. Other nucleobases were not detected in the sample, which would be due the low sample amount (~10 mg) allocated to the present study. In addition to uracil, other nitrogen (N)-heterocyclic molecules including nicotinic acid, also known as Vitamin B3, were detected in the Ryugu samples. The detection uracil in the Ryugu samples strongly suggests that nucleobases are ubiquitous in the Solar system and implies its contribution to prebiotic chemistry on the Earth.
We detected all five DNA/RNA nucleobases including thymine and cytosine in aqueous extracts from a ~2 g of the three carbonaceous meteorite for the first time with the concentration ranging from 4-72 ng/g-meteorite. After careful evaluation, we concluded that the detected nucleobases are indigenous to the meteorite. Their detection would be mainly due to the fine-tuned analytical method without a loss of nucleobases during wet chemical procedures.
We also detected an RNA nucleobase, uracil, from the Ryugu samples. The concentration of uracil was comparable to that in other carbonaceous meteorites. Since the Ryugu is the freshest sample of CI-type carbonaceous asteroids, it is no doubt that the detected uracil is extraterrestrial in origin. Other nucleobases were not detected in the sample, which would be due the low sample amount (~10 mg) allocated to the present study. In addition to uracil, other nitrogen (N)-heterocyclic molecules including nicotinic acid, also known as Vitamin B3, were detected in the Ryugu samples. The detection uracil in the Ryugu samples strongly suggests that nucleobases are ubiquitous in the Solar system and implies its contribution to prebiotic chemistry on the Earth.