Researchers have found that DNA which was previously though to be ‘junk’, could play a vital role in the evolution of the genome.It seems that tandem repeats influence the activity of neighbouring genes. How tightly local DNA wraps around nucleosomes is determined by these repeats. This packaging structure then dictates the extent to which genes can be activated. As these tandem repeats are very unstable the number present changes frequently during DNA replication. This changes the way DNA is packaged and activated.
These changes may allow organisms to tune the activity of their genes to match the environment. This is a vital principle for survival.
To test this idea scientists conducted a complex experiment testing tandem repeats in evolution using yeast cells as guinea pigs. It was found that when repeats were present near a gene it was “possible to select yeast mutants that show vastly increased activity of this gene”. When the tandem repeats were removed however this evolution was impossible.
As the researchers said “If this was the real world only cells with the repeats would be able to swiftly adapt to changes, thereby beating their repeat-less counterparts in the game of evolution. Their junk DNA saved their lives”.
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Link: http://www.medicalnewstoday.com/articles/151864.php
