Processors Toolkit

Researchers create DNA-based computer

Rupert Goodwins ZDNet.co.uk

Published: 22 Nov 2001 18:24 GMT

Israeli scientists have made a breakthrough in DNA computing, according to a report in Nature magazine. The system, designed by Ehud Shapiro and colleagues at the Weizmann Institute, uses DNA to carry out any calculation and requires little human intervention. Until now, DNA processors have needed intensive tending and have been limited to specific problems.

The system emulates a Turing machine, which is one of the fundamental concepts in computing. Such a machine examines data step by step, making decisions on what to do next based on that data. In theory, any Turing machine can do any computing problem. In nature, DNA molecules work in a very similar way, unzipping and recombining according to information coded into sequences of chemicals.

The Weizmann system works by encoding input data and software into double-stranded DNA molecules, and mixing them with two enzymes. One enzyme breaks down the input data DNA into snippets of varying length, according to the patterns in it. The other recombines these snippets, based on their patterns and those of the software DNA. This process continues down the input strand until it's finished, at which point an output molecule is created that encodes the final state of the system.

Because this system represents a Turing machine, it can be used for a very wide range of problems. Although DNA processing is slow at the level of individual molecules -- typically between 500 and 1000 bits per second, or many millions of times slower than current silicon processors -- it is intrinsically massively parallel. Shapiro and his co-workers estimate that they could run a trillion processes simultaneously in a wineglass, carrying out a billion operations a second while using under a nanowatt.

Although this invention is a major advance in DNA computation, it's still far from being useful. By silicon standards, the process has a high error rate and is hard to adapt to complex problems. However, Nature reports, the major potential may lie in intelligent systems that operate within cells, detecting or fixing problems or delivering precisely targeted drugs.

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