Similar DNA Molecules Able to Recognize Each Other

Chroniton brings us a story about research into DNA which has shown that free-floating DNA strands are able to seek out similar strands without the assistance of other chemicals. From Imperial College London: "The researchers observed the behaviour of fluorescently tagged DNA molecules in a pure solution. They found that DNA molecules with identical patterns of chemical bases were approximately twice as likely to gather together than DNA molecules with different sequences. Understanding the precise mechanism of the primary recognition stage of genetic recombination may shed light on how to avoid or minimise recombination errors in evolution, natural selection and DNA repair. This is important because such errors are believed to cause a number of genetically determined diseases including cancers and some forms of Alzheimer's, as well as contributing to ageing."

Here's another question ...

[ScrewMaster]

are there any other compounds, perhaps naturally-occurring compounds that exhibit similar behavior? If so, that might go aways towards explaining how the first primordial single-celled organisms came about.

Why is this surprising?

[istartedi]

If I had two strands of magnets, arranged with random orders of polarity, identical strands would be able to stick together along the entire length in a "head to tail" fashion. Dissimilar strands would have "weak spots" where they didn't want to stick together. If you wiggled them, they'd be more likely to come aparts.

At the molecular level, electrical forces (analogous to the magetic attraction above) and thermal forces (analogous to the wiggling) dominate but the analogy is similar. This just doesn't seem like such an amazing thing to me.

Come on, let's try it. It probably won't be as cool as using mouse traps and ping-pong balls to demonstrate chain reactions; but it might still be interesting.

Re:Summary is wrong. Controversial conclusions.

[Anonymous Coward]

I thank the previous poster for clearing up what the authors are claiming. Hybridization between complementary single stranded DNA strands are highly specific and are used in a variety of assays like Northern blots, and PCR. These techniques can pick out the complementary molecule in a sea of other non-related DNA fragments. It is highly specific and has a huge dynamic range, in the sense that your target molecule can be an exceedingly minor species in a whole gamish of other DNA species and still be specifically detected.

The claim that identical double stranded fragments have a mere 2x increased chance of association over an unrelated DNA strand, even if it pans out, seems to me to be of little practical consequence to the life cycle of a cell. The background of the whole genome would swamp out the effect of such a weak difference in free energy; i.e. the dynamic range of the interaction would not be sufficient.