Throwing the DNA switch

By BBC News Online's Jo Kettlewell

With the kind of precision that makes engineers drool, scientists can now manipulate DNA using remote control.

One could even imagine turning genes on and off electronically in the future

Professor Joseph Jacobson

By the mere flick of a switch, they can make small loops of the "life molecule" snap open and shut. This could advance the treatment of certain life threatening diseases in the future.

In particular, it might eventually enable doctors to switch genes on and off at will which, in theory, could revolutionise the way cancers are tackled.

The development is the latest example of so called nano-engineering, which involves the fabrication and control of structures that measure just a few millionths of a millimetre across.

Loops

The remote-controlled DNA is the work of Joseph Jacobson, of the Massachusetts Institute of Technology, Cambridge, US, and colleagues.

The researchers synthesised many strands of DNA just 38 bases, or "letters", in length. They structured them such that the last seven bases on either end were "complementary" and formed bonds with each other. This meant that the strands doubled over and joined, forming a loop.

Gold crystals measuring only 1.4 nanometres (billionths of a metre) across were attached to the loops to act as antennae and all the structures placed in solution.

The researchers then surrounded the solution with an oscillating magnetic field, inducing electric currents in the gold particles that heated up the surrounding DNA so much that the loops burst open. But when the magnetic field was switched off, the heat dissipated and the loops closed again, as the complementary bases rebonded.

Professor Joseph Jacobson told BBC News Online: "The reason we got into this was because nothing like it has ever been done before. We are interested in trying to control things electronically.

Gene control

"One could even imagine turning genes on and off electronically in the future", he added. And that, in a sentence, is the holy grail of many research doctors. One of the most feared diseases could be treated with far greater efficiency if this kind of control was possible.

If you could control these genes you could control cancer

Dr Harprett Wassan

Dr Harprett Wassan, a leading Oncologist at the Hammersmith hospital in London, UK, explained: "Cells contain things called oncogenes, or 'accelerators', which speed up cell growth, and suppressor genes, or 'brakes', which do the opposite."

Cancer occurs when oncogenes, the accelerators, get out of control, causing massive cell growth; or when suppressor genes, the brakes, jam and fail to stop it.

"If you could control these genes, you could control cancer," Dr Wassan told BBC News Online. By turning off overactive accelerator genes or turning on faulty brake genes the disease could, theoretically, be cured.

The therapeutic application is a long way off, but this discovery is undeniably a step in the right direction. "It sounds ingenious," said Dr Wassan.

The research was originally published in the journal Nature.