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Title : DNA computer is a step closer
Author : Roger Highfield, Science Editor, Electronic Telegr
Date :

SCIENTISTS intrigued by the prospect of developing a DNA computer have
overcome an important hurdle blocking its development, they reported
yesterday.

A test tube full of DNA, which carries our genetic blueprint, could process
more information than all of today's super-computers combined, yet would use
only a billionth of the energy a laptop requires. Seven feet of DNA coiled
up inside each of our cells serves as the instructions for nature's most
complex program - the human mind and body. However, problems run today by
cabinet-size super-computers would demand a mass of DNA the size
of the Sun to carry out.

Yesterday Prof Mitsu Ogihara, of the University of Rochester, New York,
proposed a method that slashes the volume of DNA needed for most problems to
a single test tube. In computer simulations, the new formula can tackle a
problem many billions of times more complex than those solved by other
proposed DNA computers.

Currently there is no good method to winnow out "good" computing DNA - the
strands with the correct sequences of chemical code that would serve as the
computer's memory.

"Instead of creating all the candidates at the beginning and then finding
the ones we want, we build the strands gradually, continually eliminating
strands that we cannot use," said Prof Ogihara. "In this way we cut down
dramatically the amount of DNA needed."

A DNA computer works in much the same way as a conventional computer, where
information is stored as "zeroes" or "ones" based on the spin of magnetic
particles on discs. In a DNA computer, the sequence of chemical "letters" in
a molecule of DNA encodes information that could be accessed and altered
with cut-and-paste biochemical techniques widely used today.

One pound of DNA could have the capacity to store more information than all
the computers ever built, and a test tube has the capacity to store 10
million times more information than the most powerful super-computer.

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