Re: News: A simple fusion to jump-start evolution

On Dec 19, 12:03=A0am, "Robert Karl Stonjek" <rston...@xxxxxxxxxxxxxx>
wrote:
A simple fusion to jump-start evolution
December 18th, 2008 in General Science / Biology

With the aid of a straightforward experiment, researchers have provided s=
ome
clues to one of biology's most complex questions: how ancient organic
molecules came together to form the basis of life.

Specifically, this study, appearing online this week in JBC, demonstrated
how ancient RNA joined together to reach a biologically relevant length.

RNA, the single-stranded precursor to DNA, normally expands one nucleic b=
ase
at a time, growing sequentially like a linked chain. The problem is that =
in
the primordial world RNA molecules didn't have enzymes to catalyze this
reaction, and while RNA growth can proceed naturally, the rate would be s=
o
slow the RNA could never get more than a few pieces long (for as nucleic
bases attach to one end, they can also drop off the other).

Ernesto Di Mauro and colleagues examined if there was some mechanism to
overcome this thermodynamic barrier, by incubating short RNA fragments in
water of different temperatures and pH.

They found that under favorable conditions (acidic environment and
temperature lower than 70 C), pieces ranging from 10-24 in length could
naturally fuse into larger fragments, generally within 14 hours.

The RNA fragments came together as double-stranded structures then joined=
at
the ends. The fragments did not have to be the same size, but the efficie=
ncy
of the reactions was dependent on fragment size (larger is better, though
efficiency drops again after reaching around 100) and the similarity of t=
he
fragment sequences.

The researchers note that this spontaneous fusing, or ligation, would a
simple way for RNA to overcome initial barriers to growth and reach a
biologically important size; at around 100 bases long, RNA molecules can
begin to fold into functional, 3D shapes.

Article link:http://www.jbc.org/cgi/content/abstract/M805333200v1

Source: American Society for Biochemistry and Molecular Biologyhttp://www=
...physorg.com/news148844248.html

Posted by
Robert Karl Stonjek

But the writer is trying to get to RNA. Why would nature want to get
to RNA?
There was no direction here. Instead there was some reason why longer
lengths of RNA were more stable
and long lasting in that environment. That's the question to ask.

.

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