Follow the nitrogen to extraterrestrial life

[Astronuc]

The narrow search for water may miss important clues, say USC geobiologists

The great search for extraterrestrial life has focused on water at the expense of a crucial element, say geobiologists at the University of Southern California.

Writing in the Perspectives section of the May 5 issue of Science, four USC researchers propose searching for organic nitrogen as a direct indicator of the presence of life. Nitrogen is essential to the chemistry of living organisms.

Even if NASA were to find water on Mars, its presence only would indicate the possibility of life, said Kenneth Nealson, Wrigley Professor of earth sciences in the USC College of Letters, Arts and Sciences.

"It's hard to imagine life without water, but it's easy to imagine water without life," Nealson said.

The discovery of nitrogen on the Red Planet would be a different story.

"If you found nitrogen in abundance on Mars, you would get extremely excited because it shouldn't be there," Nealson said.

The reason has to do with the difference between nitrogen and carbon, the other indispensable organic element.  Unlike carbon, nitrogen is not a major component of rocks and minerals. This means that any substantial organic nitrogen deposits found in the soil of Mars, or of another planet, likely would have resulted from biological activity.

read more at - http://www.spaceref.com/news/viewsr.html?pid=20503

 

[remcook]

ehm...Titan?
There are also inorganic ways to form nitrogen. surely, not all earth's nitrogen is produced by life?
maybe i should read it more closely, but I don't see what they mean.

[Astronuc]

I believe the presence of nitrogen infers the potential for "amino acids", which are so-called because they have an amine group (NH₂). - http://en.wikipedia.org/wiki/Amino_acid

Nitrogen is also a component of the nucleobases, the two purines adenine and guanine, and the two pyrimidines, thymine and cytosine, all 4 of which are constituents of DNA, and the pyrimidine uracil, which replaces thymine in RNA.  But it is not so simple.

http://en.wikipedia.org/wiki/Adenine
http://en.wikipedia.org/wiki/Guanine

http://en.wikipedia.org/wiki/Thymine
http://en.wikipedia.org/wiki/Cytosine
http://en.wikipedia.org/wiki/Uracil

http://en.wikipedia.org/wiki/DNA - DNA has 4 bases - A, G, C, T
http://en.wikipedia.org/wiki/RNA - RNA has 4 bases - A, G, C, U