Chemical Calculators - Supercomputer Molecules

PhotosToGo How many ways can two opposing knights be placed on a chessboard so they are not attacking each other? Could the answer be found with an RNA calculator?

Earlier this year, two other research groups have applied similar thinking to a second puzzle that asks the question, 'How many ways can two opposing knights be placed on a chessboard so they are not attacking each other?'

Laura Landweber collaborated with Richard Lipton, Dirk Faulhammer and Anthony Cukras to see whether they could solve this chess problem using DNA's chemical cousin ribonucleic acid (RNA). To make the experiment simpler they reduced the chessboard to a 3x3 grid and used different strands of RNA to form combinations each representing a location of the two knights on the board.

An enzyme - ribonuclease - was then used to seek out specific combinations of bases along the strands of RNA and cleaving those that do not match the correct answers to the problem. They came up with most of the answers in a very short time but the fact that it works alone demonstrates the potential of an RNA calculator.

Meanwhile, Lloyd Smith and his colleagues at the University of Wisconsin- Madison demonstrated a slightly different approach to the same puzzle using DNA itself. However, their system is built on a solid support, which lends itself better than dissolved molecules, to more direct connection to external devices, such as electronic components.

Of course Science Fiction writers got there first, the computer system of the latest Star Trek ship (Voyager) is biological - only a molecular system is small and powerful enough to run a ship of that complexity!

With logic gates adding up and strands of DNA solving age-old maths puzzles, it is perhaps only a few more years before chemistry will come up with a prescription for a molecular computer.Thorri Gunnlaugsson a former member of de Silva's research team and now heading his own group at Trinity College Dublin asks us to imagine a memory chip the size of a sugar cube carrying as much information as a thousand billion CD-ROMs or a molecular chip running a thousand times faster than the PC on your desktop. Sadly, there might then come a time when a computer crash doesn't just leave you frustrated by a blank screen but might soak your desktop too!