Hawaii Astrobiologists find Martian clay contains Chemical Organics

Electron microscope image showing the 700-million-year-old Martian clay veins containing boron (100 µm = one tenth of a millimeter).

Researchers from the University of Hawaii at Manoa NASA Astrobiology Institute (UHNAI) have discovered high concentrations of boron in a Martian meteorite.

When present in its oxidized form (borate), boron may have played a key role in the formation of RNA, one of the building blocks for life.

The work was published on June 6 in PLOS One.

The Antarctic Search for Meteorites team found the Martian meteorite used in this study in Antarctica during its 2009-2010 field season.

The minerals it contains, as well as its chemical composition, clearly show that it is of Martian origin.

Using the ion microprobe in the W. M. Keck Cosmochemistry Laboratory at UH, the team was able to analyze veins of Martian clay in the meteorite.

After ruling out contamination from Earth, they determined boron abundances in these clays are over ten times higher than in any previously measured meteorite.

"Borates may have been important for the origin of life on Earth because they can stabilize ribose, a crucial component of RNA. In early life RNA is thought to have been the informational precursor to DNA," said James Stephenson, a UHNAI postdoctoral fellow.

RNA may have been the first molecule to store information and pass it on to the next generation, a mechanism crucial for evolution.

Although life has now evolved a sophisticated mechanism to synthesize RNA, the first RNA molecules must have been made without such help.

One of the most difficult steps in making RNA nonbiologically is the formation of the RNA sugar component, ribose. Previous laboratory tests have shown that without borate the chemicals available on the early Earth fail to build ribose.

However, in the presence of borate, ribose is spontaneously produced and stabilized.

This work was born from the uniquely interdisciplinary environment of UHNAI. The lead authors on the paper, Stephenson, an evolutionary biologist, and Lydia Hallis, a cosmochemist who is also a UHNAI postdoctoral fellow, first came up with the idea over an after-work beer.

"Given that boron has been implicated in the emergence of life, I had assumed that it was well characterized in meteorites," said Stephenson.

"Discussing this with Dr. Hallis, I found out that it was barely studied. I was shocked and excited. She then informed me that both the samples and the specialized machinery needed to analyze them were available at UH."

More information: 
Stephenson, J. D., Hallis, L. J., Nagashima K., and Freeland, S. J. 2013, "Boron Enrichment in Martian Clay," PLoS ONE 8(6): e64624. dx.doi.org/10.1371/journal.pone.0064624