Extraterrestrial Nucleobases?

This is interesting… An international group of researchers (UK, USA, Netherlands) have apparently confirmed the presence of two primitive nucleobases in meteorite samples. The Murcheson Meteorite crash landed in Australia nearly 50 years ago, and has been pored over by astrobiologists ever since. The reason being that this meteorite is a rare one. Carbonaceous chondrites (as these meteorites are alliteratively known) are full of interesting carbon-based chemicals. Many astrobiologists believe that meteorites like this one may seed young planets with the raw materials for life (a hypothesis known as Panspermia). It seems, they could be onto something.

The two chemicals, Uracil (a component of RNA) and Xanthine (a precursor to Guanine and Adenine in DNA) have been identified in samples from this meteorite. Ruling out terrestrial origins by the combination of isotopes in the sample, it seems highly likely that these biomolecules were indeed created inside this meteorite, or otherwise in space. Fascinating. The authors also point out that both of these chemicals are capable of self organisation, to some extent, due to the way the molecules stack themselves. Logically, this could have some significance for the formation of the first RNA and DNA, which are both essentially a big stack of nucleobases held together by a backbone. Perhaps the molecules stacked themselves first, and the backbones developed later…

Either way, as Mark Sephton at Imperial College London said in the press release, “Because meteorites represent left over materials from the formation of the solar system, the key components for life — including nucleobases — could be widespread in the cosmos. As more and more of life’s raw materials are discovered in objects from space, the possibility of life springing forth wherever the right chemistry is present becomes more likely.” I guess it now falls on the shoulders of us astrochemists to figure out how and where molecules like these might form in space…

On a slightly more personal note, xanthine is actually where I got the “Xan” in my online alias, “Invader Xan” from. Even more apt now — this actually is invader xanthine!

[ Ref – Martins et al (2008) ]

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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