Genetic 'telepathy'? A bizarre new property of DNA
January 28, 2008Scientists are reporting evidence that intact, double-stranded DNA has the “amazing” ability to recognize similarities in other DNA strands from a distance. And then like friends with similar interests, the bits of genetic material hangout or congregate together. The recognition — of similar sequences in DNA’s chemical subunits — occurs in a way once regarded as impossible, the researchers suggest in a study scheduled for the Jan. 31 issue of ACS’ Journal of Physical Chemistry B.
Geoff S. Baldwin, Sergey Leikin, John M. Seddon, and Alexei A. Kornyshev and colleagues say the homology recognition between sequences of several hundred nucleotides occurs without physical contact or presence of proteins, factors once regarded as essential for the phenomenon.
This recognition may help increase the accuracy and efficiency of the homologous recombination of genes — a process responsible for DNA repair, evolution, and genetic diversity. The new findings thus may shed light on ways to avoid recombination errors, which underpin cancer, aging, and other health problems.
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.
“Amazingly, the forces responsible for the sequence recognition can reach across more than one nanometer of water separating the surfaces of the nearest neighbor DNA,” said the authors.
Source: ACS
Nov 10, 2009 |
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That may explain why the strands move. But how does that explain the direction of movement? What properties of molecular resonant frequencies would cause "like" strands to be attracted rather than say repulsed from each other?
And I wonder if someone could chime in as to the magnitude or importance of this effect when judged within the class of known mechanisms for DNA interaction.
Regardless. Assuming the experiment is sound, it looks like it will be a very interesting paper to read. And an interesting subject to investigate further.
Say you have a strand:
A-T
T-A
C-G
G-C
G-C
C-G
T-A
And then you take the exact same strand of DNA and line itself up with itself:
A-T A-T
T-A T-A
C-G C-G
G-C G-C
G-C G-C
C-G C-G
T-A T-A
Notice how the "opposite" bound base ends up next to the "original" base. If one assumes that the attractions are bi-directional (a C attracts G, so G attract C), then it's simply a matter of lining up opposite bases next to each other and having them attract one another (Electrically? Opposites attract).
Whereas if part of the strand were reversed, or sections were reversed, then some sections would NOT line up correctly, and might net a neutral or repulsive force (depending on rotational alignment along the axis, perhaps).
For example (using [yes] as attractive and [no] as repulsive):
(Original example)
A-T [Yes] A-T
T-A [Yes] T-A
C-G [Yes] C-G
G-C [Yes] G-C
G-C [Yes] G-C
C-G [Yes] C-G
T-A [Yes] T-A
more neutral sample:
A-T [No] T-A
T-A [Yes] G-C
C-G [No] T-A
G-C [No] C-G
G-C [Yes] G-C
C-G [Yes] C-G
T-A [No] A-T
The original example might have been highly attractive, whereas the second example (directly above) would be more mixed, composed of partly attractive pairings and slightly repulsive pairings. Thus it would not be as good a match as the more similar strand...
I'm tending to think of these as something more like an electric/magnetic "combination key." The more attractive pairings you get (in sequence), the more they are drawn together. The more "random" the pairings (the worse the sequential match), the less likely they are to be attracted? Or something like that...
But, maybe that's oversimplified? Makes sense to me, but may not work like that in reality.
Anybody know the properties of this fluorescent stuff? Possibly the behaviour is induced by the dyes?