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Crop Biotech Update

Junk DNA: Anything but Junk, Scientists Say

June 5, 2009

There's more to junk DNA than previously thought, according to researchers at the USDA Agricultural Research Service and collaborators at Johns Hopkins University. As it turns out, what was first thought of as DNA with zero value in plants may actually be important regulator of gene expression and may be key in helping scientists produce better transgenic crops.

Bret Cooper and colleagues searched the junk DNA in the model plant Arabidopsis for short DNA segments that appeared as molecular patterns. When comparing these patterns to genes, the researchers found that 50 percent of the genes had the exact same sequences as the molecular patterns. These patterns, called pyknons, are important because they portend an unforeseen connection between coding and non-coding DNA. They have only been identified in the human genome so it is unknown whether pyknons have wider biological relevance or are simply a phenomenon of the human genome.

In an article published by Molecular BioSystems, Cooper and colleagues observed that most of these pyknons resemble small segments of RNA that regulate gene expression through gene silencing. According to them, this suggests that gene silencing RNA segments are converted back into DNA and are integrated into the intergenic space. Using information from pyknons, scientists can pinpoint genes that are controlled by gene silencing. There may also be some application for the improvement of transgenic plants by using the pyknon information.

 Read the original article at http://www.ars.usda.gov/is/pr/2009/090602.htm The paper published by Molecular BioSystems is available at http://dx.doi.org/10.1039/b903031j