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Greetings fellow Luciferians. I know many of you haven't a clue as to
who I am, but I am one of you. Haven't been able to contribute since I
voluntarily attached the time-sucking leech that is Amazon.com to my
jugular, but I try to read the Virus digest often enough to maintain a
passing familiarity with the major threads. I hope to rejoin this
community sometime in the future. Save me a seat. -KMO
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From: "Pat Shepard" <c604016@showme.missouri.edu>
To: "Kevin O'Connor" <kmo@amazon.com>
Subject: Interesting Story
Date: Sat, 26 Apr 1997 09:26:28 -0500
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Thought you might be interested in this (from
http://sciencenow.sciencemag.org)
Lifeless Evolution
If there is one theme uniting life-forms from the lowliest virus to the
loftiest primate, it's that they all evolve. Now some lifeless strands of
RNA are doing the same thing in a California laboratory. The animated
molecules, described in today's issue of Science,* promise to be a powerful
new tool in understanding the concept of evolution.
For several years, biochemists have been enticing ribozymes--RNA strands
that catalyze chemical reactions--to "evolve" by creating a batch of
different RNA molecules and selecting the best catalyzers among them. The
fittest molecules are copied, mutated to create new variants, and so on
through many cycles of selection. But the process requires human
intervention and takes a long time. Besides, says Gerald Joyce, a
biochemist at The Scripps Research Institute in La Jolla, California, it
"has an artificial feel to it."
Joyce and Scripps colleague Martin Wright set out to eliminate the
artificial selection step. The duo devised a replication "engine": a set of
enzymes, including RNA polymerase, that makes copies of the ribozymes. For
any ribozyme to access the engine, it must first attach to a string of
nucleotides, which activate the RNA polymerase. The polymerase doesn't copy
the ribozyme perfectly; it introduces variations, which are the raw
material of evolution. Ribozymes that attach more tightly and quickly to
the nucleotides are more likely to get replicated. "The ones with the best
access to the machine have the most progeny," says Andrew Ellington, a
biochemist at Indiana University in Bloomington. "It's survival of the
fittest; the molecules are duking it out." Because ribozymes replicate in a
matter of minutes, the population changes quickly over time, so long as it
has a steady supply of nucleic acids.
"It's a neat system," says Ellington. "You feed the thing and it takes
off." Indeed, the replicating ribozymes, which could be used to model
evolutionary processes, bear an uncanny resemblance to reproducing
life-forms. Says Ellington, they evolve in test tubes "just like bacteria"
do.
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