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August 22, 2011
Volume 89, Number 34
p. 38

Nucleobases From Space

Exotic purines present the strongest evidence yet that meteorites could have delivered DNA building blocks to Earth

Carmen Drahl

Purine
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NASA/Goddard Space Flight Center
Lines Of Evidence NASA Goddard research physical scientist Michael P. Callahan explains the data that convinced the team that the meteorites' exotic purines were made in space, rather than just being earthly contaminants.

Filmed and edited by Carmen Drahl/C&EN
STEP BY STEP Callahan walks through the procedure for extracting and detecting nucleobases in meteorites.
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This 1-cm meteorite fragment is shown with purines the NASA team detected that are rare or absent in biology. NASA/Goddard Space Flight Center
This 1-cm meteorite fragment is shown with purines the NASA team detected that are rare or absent in biology.

In a bid to answer a decades-old question, a multi-institution team has presented the strongest evidence yet that nucleobases, the building blocks of DNA, could have been made on meteorites in space and delivered to a primordial Earth (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1106493108). Researchers have been finding amino acids and nucleobases—the molecules of life—in meteorites for some time. While they’ve confirmed the amino acids’ extraterrestrial origins, purine and pyrimidine nucleobases found in the space rocks could always be explained as earthly contamination. Michael P. Callahan of NASA’s Goddard Space Flight Center and colleagues have now analyzed a dozen meteorites found in Antarctica and elsewhere with high-resolution liquid chromatography-mass spectrometry. In two meteorites they detected traces of purines that are rare or absent in biology. The team didn’t find those exotic purines in ice and soil found near the meteorites. But laboratory reactions of ammonia, water, and hydrogen cyanide, which are all present in meteorites, produced the entire purine suite. The team is continuing to make measurements in additional meteorites, Callahan says.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2011 American Chemical Society
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Lines Of Evidence

NASA Goddard research physical scientist Michael P. Callahan explains the data that convinced the team that the meteorites' exotic purines were made in space, rather than just being earthly contaminants.

NASA/Goddard Space Flight Center

Step By Step

Callahan walks through the procedure for extracting and detecting nucleobases in meteorites.

Filmed and edited by Carmen Drahl/C&EN
Chemical & Engineering News
ISSN 0009-2347
Copyright © 2011 American Chemical Society
  • Print this article
  • Email the editor

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