The Ancient Splice of Life
Summary (Feb 25, 2005): One of the key motivations for revisiting the probability of life elsewhere in the universe is the surprising proclivity of life in hostile places on Earth. New findings suggest that modern organisms may have useless DNA fragments today that once saved their ancestors lives in extreme environments.
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The Ancient Splice of Life
based on Yale release  |
Traditional classification resembling a 'tree of life' organized into six kingdoms.
Credit: UCLA |
Yale scientists report in the journal Nature that the "missing" genes for tRNA in an ancient parasite are made up by splicing together sequences in distant parts of the DNA genome.
The research led by Professor
Dieter Söll in the
Department of Molecular Biophysics and Biochemistry at Yale focuses on the most ancient organism with a known genome sequence. Nanoarchaeum equitans, is a member of a new phylogenetic kingdom in the Archaea containing organisms that are primitive, parasitic and extremophile, or notable for living in the most extreme environments.
Surprisingly, Söll's team found that, although the genome of Nanoarchaeum lacks several intact tRNA genes, functional forms of those tRNAs can be made by copying from two distant DNA sequences -- and joining them.
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A 3D structure of RNA.
Credit: SpaceDaily |
The regions on the separate pieces, that allow them to find each other and splice, are somewhat similar to internal sequences found in tRNA genes of more complex organisms. These regions, termed introns, are sequences that are cut out of whole gene transcripts during the process of tRNA maturation. The known tRNA introns in organisms like yeast, however, appear to have no function. Therefore, modern tRNA introns might be remnants of an old essential process of tRNA biosynthesis.
"These results may point to extremophiles in the kingdom of Archaea as predecessors of more modern organisms that have gained a genetic load in the process of evolution," said Söll. "Or they may represent a specialization that has rid itself of genetic baggage to exist in extreme environments."
Understanding how primitive organisms like Nanoarchaea operate gives clues to -- but not proof of -- the relationship between modern and ancient organisms.
Related Web Pages
Could Opportunity Find Life on Mars?Evidence of bacteria on Europa? New Signs of Polar Life
NSF Life in Extreme Environments (
LEXEN) Program
Introduction to the Archaea - Life's extremists
Life without Volcanic Heat The Three Domains of Life Advances in our Understanding of Life Did Hades Freeze Over? Extreme EnvironmentsThe Unboilable Bug Note:
Extreme Life
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Friday, February 25, 2005
