Perhaps you are a scientist. And perhaps you have wondered how badly the popular press could possibly mangle your research. Wonder no more: we have discovered a new maximum.
Behold this research summary in The Daily Galaxy, and be amazed!
It’s about a paper in the ACS Journal of Physical Chemistry B. It’s straightforward physical chemistry using some cool tools to image the formation of double helices of DNA: it’s simply addressing the question of how complementary strands align themselves in solution. It’s physical chemistry, OK? It’s about tiny molecular interactions…until the Daily Galaxy gets ahold of it. Now it’s about how DNA uses telepathy.
DNA has been found to have a bizarre ability to put itself together, even at a distance, when according to known science it shouldn’t be able to. Explanation: None, at least not yet.
Scientists are reporting evidence that contrary to our current beliefs about what is possible, intact double-stranded DNA has the “amazing” ability to recognize similarities in other DNA strands from a distance. Somehow they are able to identify one another, and the tiny bits of genetic material tend to congregate with similar DNA. The recognition of similar sequences in DNA’s chemical subunits, occurs in a way unrecognized by science. There is no known reason why the DNA is able to combine the way it does, and from a current theoretical standpoint this feat should be chemically impossible.
In the study, scientists observed the behavior of fluorescently tagged DNA strands placed in water that contained no proteins or other material that could interfere with the experiment. Strands with identical nucleotide sequences were about twice as likely to gather together as DNA strands with different sequences. No one knows how individual DNA strands could possibly be communicating in this way, yet somehow they do. The “telepathic” effect is a source of wonder and amazement for scientists.
Cue the theremins, everyone, and bring on the reanimated corpse of Rod Serling to narrate this sucker. Audience, say “OOOOOoooooOOOOOOOOooOOH!”
Oh, wait. Read the actual paper, first. It turns out that not only are the scientists not mystified, but they provide a reasonable explanation for the phenomenon, and go on to give some alternatives, even. None of them involve molecular telepathy. They actually are amazed at the ability of these molecules to align…at distances of one whole nanometer!
Pay especially careful to the first sentence of the following paragraph. If you are a journalist writing a summary of a paper, claiming that it says no one knows how the two molecules recognize each other, you should probably read more closely a paragraph that begins, “We hypothesize that the origin of this recognition may be as follows.” It’s a clue that an explanation will follow.
We hypothesize that the origin of this recognition may be as follows. In-register alignment of phosphate strands with grooves on opposing DNA minimizes unfavorable electrostatic interactions between the negatively charged phosphates and maximizes favorable interactions of phosphates with bound counterions. DNAs with identical sequences will have the same structure and will stay in register over any juxtaposition length. Nonhomologous DNAs will have uncorrelated sequence-dependent variations in the local pitch that will disrupt the register over large juxtaposition length. The register may be restored at the expense of torsional deformation, but the deformation cost will still make juxtaposition of nonhomologous DNAs unfavorable. The sequence recognition energy, calculated from the corresponding theory is consistent with the observed segregation within the existing uncertainties in the theoretical and experimental parameters. This energy is ˜1 kT under the conditions utilized for the present study, but it is predicted to be significantly amplified, for example, at closer separations, at lower ionic strength, and in the presence of DNA condensing counterions.
So, their preferred explanation is that there are electrostatic interactions between the molecules that favor pairs that fit together well. Not telepathy. As cautious investigators, they also suggest some alternative explanations; perhaps telepathy will appear here? Or maybe elves?
Presently, we cannot exclude other mechanisms for the observed segregation. For instance, sequence-dependent bending of double helices may also lead to homology recognition by affecting the strand-groove register of two DNA molecules in juxtaposition. The juxtaposition of bent, nonhomologous DNAs may also be less energetically favorable under osmotic stress, since it may reduce the packing density of spherulites. In addition, formation of local single-stranded bubbles and base flipping may cause transient cross-hybridization between the molecules, as proposed to explain Mg2+ induced self-assembly of DNA fragments with the same sequence and length. We consider it to be rather unlikely in this instance, since the probability of bubble formation in unstressed linear DNA of the studied length is very small in contrast to the case where topological strain is relieved by bubble formation in small circular DNA molecules. Furthermore, bubble formation would distort the cholesteric order of spherulites and we see no evidence of this in spherulites composed of a single type of DNA molecule.
I’m so disappointed. Telepathy isn’t mentioned once in the whole danged paper, and there aren’t even tiny diaphanous fairies tugging at the molecules. And no, the Intelligent Designer doesn’t appear, either.
Baldwin GS, Brooks NJ, Robson RE, Wynveen A, Goldar A, Leikin S, Seddon JM, Kornyshev AA (2008) DNA Double Helices Recognize Mutual Sequence Homology in a Protein Free Environment. J. Phys. Chem. B 112(4):1060-1064.