NASA Reproduces a Building Block of Life in Laboratory

NASA Reproduces a Building Block of Life in Laboratory

NASA scientists studying the origin of life have reproduced uracil, a key component of our hereditary material, in the laboratory. They discovered that an ice sample containing pyrimidine exposed to ultraviolet radiation under space-like conditions produces this essential ingredient of life.

Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the basic structure for uracil, part of a genetic code found in ribonucleic acid (RNA). RNA is central to protein synthesis, but has many other roles.

"We have demonstrated for the first time that we can make uracil, a component of RNA, non-biologically in a laboratory under conditions found in space," said Michel Nuevo, research scientist at NASA's Ames Research Center, Moffett Field, Calif. "We are showing that these laboratory processes, which simulate occurrences in outer space, can make a fundamental building block used by living organisms on Earth."

Nuevo is the lead author of a research paper titled “Formation of Uracil from the Ultraviolet Photo-Irradiation of Pyrimidine in Pure Water Ices,” Astrobiology vol. 9 no. 7, published Oct. 1, 2009.

NASA Ames scientists have been simulating the environments found in interstellar space and the outer solar system for years. During this time, they have studied a class of carbon-rich compounds, called polycyclic aromatic hydrocarbons (PAHs), which have been identified in meteorites, and are the most common carbon-rich compound observed in the universe. PAHs typically are six-carbon ringed structures that resemble fused hexagons, or a piece of chicken wire.

Pyrimidine also is found in meteorites, although scientists still do not know its origin. It may be similar to the carbon-rich PAHs, in that it may be produced in the final outbursts of dying, giant red stars, or formed in dense clouds of interstellar gas and dust.

“Molecules like pyrimidine have nitrogen atoms in their ring structures, which makes them somewhat whimpy. As a less stable molecule, it is more susceptible to destruction by radiation, compared to its counterparts that don’t have nitrogen,” said Scott Sandford, a space science researcher at Ames. “We wanted to test whether pyrimidine can survive in space, and whether it can undergo reactions that turn it into more complicated organic species, such as the nucleobase uracil.”

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