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Clues for space-based chirality

1st April 2013


Over the last four years, a team of researchers carefully analysed samples of meteorites with an abundance of carbon, called carbonaceous chondrites. They looked for the amino acid isovaline and discovered that three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety - as much as a record 18 percent more in the often-studied Murchison meteorite. "Finding more left-handed isovaline in a variety of meteorites supports the theory that amino acids brought to the early Earth by asteroids and comets contributed to the origin of only left-handed based protein life on Earth," said Dr. Daniel Glavin of NASA's Goddard Space Flight Center in Greenbelt, Md. Their findings validate and extend the research first reported a decade ago by Drs. John Cronin and Sandra Pizzarello of Arizona State University, who were first to discover excess isovaline in the Murchison meteorite, believed to be a piece of an asteroid.

The Scientist Live Audio Mailbag presented the questions submitted by readers to Dr. Jason Dworkin who worked on the study with Glavin. 

Why did you choose to search the meteorites for isovaline specifically? The release glossed over it but I am interested in more detail, if possible. (Spencer C., Dundee, Scotland)

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According to the release, 'The researchers looked for the amino acid isovaline and discovered that three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety - as much as a record 18 percent more in the often-studied Murchison meteorite.' Why is 18% statistically significant? It does not actually seem like enough to for the basis of an assumption that chiral assymettry was brought via meteorites. (Arthur P., London, England)

Listen now.

How can you tell if a microbe is terrestrial or extra-terrestrial? (Jennifer E., St. Louis, USA)

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You say, 'The team discovered meteorites with more water also had greater amounts of left-handed isovaline. 'This gives us a hint that the creation of extra left-handed amino acids had something to do with alteration by water.'' Can you explain how you conclude that the creation of extra left-handed amino acids is tied to water? (Petr N., Budapest, Hungary)

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Would life forms based on right handed forms of amino acids function differently than left handed ones? (Lorenzo P., Bologna, Italy)

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What other amino acids are found in outerspace? Do they function similarly when not under Earth-conditions? (Michelle K., New York, USA)

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What is the next line of research for your lab? (Ed.)

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For more information regarding the study and Dr. Rasgon's research, visit his webpage:

http://astrobiology.gsfc.nasa.gov/analytical/ 





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