Cambridge University scientists say they have seen four-stranded DNA at work in human cells for the first time.The famous “molecule of life”, which carries our genetic code, is more familiar to us as a double helix.But researchers tell the journal Nature Chemistry that the “quadruple helix” is also present in our cells, and in ways that might possibly relate to cancer.

They suggest that control of the structures could provide novel ways to fight the disease.

“The existence of these structures may be loaded when the cell has a certain genotype or a certain dysfunctional state,” said Prof Shankar Balasubramanian from Cambridge’s department of chemistry.

“We need to prove that; but if that is the case, targeting them with synthetic molecules could be an interesting way of selectively targeting those cells that have this dysfunction,” he told BBC News.

It will be exactly 60 years ago in February that James Watson and Francis Crick famously burst into the pub next to their Cambridge laboratory to announce the discovery of the “secret of life”.

What they had actually done was describe the way in which two long chemical chains wound up around each other to encode the information cells need to build and maintain our bodies.

Today, the pair’s modern counterparts in the university city continue to work on DNA’s complexities.

Balasubramanian’s group has been pursuing a four-stranded version of the molecule that scientists have produced in the test tube now for a number of years.

It is called the G-quadruplex. The “G” refers to guanine, one of the four chemical groups, or “bases”, that hold DNA together and which encode our genetic information (the others being adenine, cytosine, and thymine).

The G-quadruplex seems to form in DNA where guanine exists in substantial quantities.

And although ciliates, relatively simple microscopic organisms, have displayed evidence for the incidence of such DNA, the new research is said to be the first to firmly pinpoint the quadruple helix in human cells.

In 1953, Cambridge researchers Watson and Crick published a paper describing the interweaving ‘double helix’ DNA structure – the chemical code for all life. Now, in the year of that scientific landmark’s 60th Anniversary, Cambridge researchers have published a paper proving that four-stranded ‘quadruple helix’ DNA structures – known as…