DNA found in Outer Space

DNA in Meteorite

Ever thought of building blocks of DNA to be found in space? If no then this article is going to prove helpful to you for NASA-funded researchers have discovered that building blocks of DNA, the molecule that carries the genetic instructions for development of life, in meteorites, which were likely created in space.
The researchers witness this theory that a "kit" of ready made parts created in space and delivered to Earth by meteorite and comet impacts that helped the origin of life. Dr. Michel Callhan of NASA's Goddard Space Flight Center, greenbelt, Md states that, "People have been discovering components of DNA in meteorites since 1960s, but researchers were unsure whether they were really created in space or if instead they came from contamination by terrestrial life." He also adds "For the first time, we have three lines of evidence that together give us confidence these DNA building blocks actually were created in space."

The discovery also changes the chemistry inside asteroids and comets stating that these are capable of making building blocks of essential biological molecules. For instance, these scientist at the Goddard Astrobiological Analytical Laboratory have found amino acids in samples of comet Wild 2 from NASA's Stardust mission, and in various carbon-rich meteorites. Amino acids are used to make proteins, the main component of nucleus and used in structures like hair to enzymes.

The Goddard team, in New York ground up samples of twelve carbon-rich meteorites, nine of which were collected from Antarctica. They extracted each samples with a solution of formic acid and ran through a liquid chromatograph. They further analyzed the chemical structure of compounds of the samples using a mass spectrometer.From the analysis the team found adenine and guanine, the components of nucleobases, which are building blocks of DNA. They also found Hypoxanthine and Xanthine. Adenine and guanine connect with two other nucleobases to form the rungs of the spiral ladder resembled by DNA. They are part of of the code protein which cellular machinery to produce. Hypoxanthine and xanthine are not found in DNA, but are used in other biological processes. Also, in two of the meteorites, the team discovered for the first time trace amounts of three molecules related to nucleobases: purine, 2,6-diaminopurine, and 6,8-diaminopurine. These compounds have the same base molecules as nucleobases but with a structure added or removed.

The three evidence to prove the team's findings are:-

1. The above mentioned three nucleobase-related molecules, called nucleobase analogs, provide the evidence that the compounds in the meteorites came from space and not terrestrial contamination.

2. The second piece of evidence to show the possibility of terrestrial contamination as a source of these molecules was collected from a 8 Kg sample of ice from Antarctica. The amounts of the two nucleobases added with amount of hypoxanthine and xanthine, found in ice were much lower than in the meteorites. Moreover none of the nucleobase analogs were discovered in the sample of ice. Also, from Australia soil sample were collected, where a meteorite with nucleobase analog molecules had fallen, for analysis. But the result was the same as the product from the sample of ice, no nucleobase analogs molecules.

3. The last piece of evidence found by the team is that these nucleobases -both the biological and non biological ones- were produced in a completely non-biological reaction. An identical suite of nucleobases and nucleobase analog analogs were generated in non biological reaction in lab containing hydrogen cyanide, ammonia, and water. This provides a plausible mechanism for their synthesis in the asteroid parent bodies, and supports the notion that they are extraterrestrial.

Callahan concludes that these meteorites seems to be a 'goldilocks' class of meteorite, the so-called CM2 meteorite, where conditions are just right to make more of these molecules.

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