'Telepathic' Genes Recognize Similarities In Each Other

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'Telepathic' Genes Recognize Similarities In Each Other

http://www.sciencedaily.com/releases/2008/01/080124103151.htm

Genes have the ability to recognise similarities in each other from a

distance, without any proteins or other biological molecules aiding

the process, according to new research. This discovery could explain

how similar genes find each other and group together in order to

perform key processes involved in the evolution of species.

This new study shows that genes -- which are parts of double-stranded

DNA with a double-helix structure containing a pattern of chemical

bases - can recognise other genes with a similar pattern of chemical

bases.

This ability to seek each other out could be the key to how genes

identify one another and align with each other in order to begin the

process of 'homologous recombination' -- whereby two double-helix DNA

molecules come together, break open, swap a section of genetic

information, and then close themselves up again.

Recombination is an important process which plays a key role in

evolution and natural selection, and is also central to the body's

ability to repair damaged DNA. Before now, scientists have not known

exactly how suitable pairs of genes find each other in order for this

process to begin.

The authors of the new study carried out a series of experiments in

order to test the theory, first developed in 2001 by two members of

this team, that long pieces of identical double-stranded DNA could

identify each other merely as a result of complementary patterns of

electrical charges which they both carry. They wanted to verify that

this could indeed occur without physical contact between the two

molecules, or the facilitating presence of proteins.

Previous studies have suggested that proteins are involved in the

recognition process when it occurs between short strands of DNA which

only have about 10 pairs of chemical bases. This new research shows

that much longer strands of DNA with hundreds of pairs of chemical

bases seem able to recognise each other as a whole without protein

involvement. According to the theory, this recognition mechanism is

stronger the longer the genes are.

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.

Professor ei Kornyshev from Imperial College London, one of the

study's authors, explains the significance of the team's

results: " Seeing these identical DNA molecules seeking each other out

in a crowd, without any external help, is very exciting indeed. This

could provide a driving force for similar genes to begin the complex

process of recombination without the help of proteins or other

biological factors. Our team's experimental results seem to support

these expectations. "

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. Understanding this

mechanism is also essential for refining precise artificial

recombination techniques for biotechnologies and gene therapies of

the future.

The team is now working on a set of further experiments to determine

exactly how these interactions work, including the predicted length

dependence. In addition, further studies are needed to ascertain

whether this interaction, discovered in a test tube, occurs in the

highly complex environment of a living cell.

The study was carried out by researchers at Imperial College London

and the National Institute of Health (NIH) in the USA. The work was

funded in the UK by the EPSRC and supported by the NIH Institute of

Child Health and Human Development.

Journal reference: Geoff S. Baldwin, J. , E.

Robson, Wynveen, Arach Goldar, Sergey Leikin, M. Seddon,

and ei A. Kornyshev. 'DNA Double Helices Recognize Mutual

Sequence Homology in a Protein Free Environment', Journal of Physical

Chemistry B, 23 January 2008.