May 26, 2009

So-called junk DNA may not be junk at all

U.S. scientists studying the genetics of the pond organism Oxytricha have determined so-called junk DNA might not be so junky after all.

The researchers said scientists have long been perplexed by junk DNA -- extensive strands of genetic material that dominate the genome, but seem to lack specific functions.

Now researchers from Princeton and Indiana Universities have discovered DNA sequences from regions of what had been viewed as the dispensable genome are actually performing functions central for the organism. They determined the genes spur a nearly acrobatic rearrangement of the entire genome that is necessary for the organism to grow.

Genes called transposons in the single-celled Oxytricha produce cell proteins known as transposases. During development, the transposons appear to first influence hundreds of thousands of DNA pieces to regroup. Then, when no longer needed, the organism erases the transposases from its genetic material, paring its genome to 5 percent of its original load.

The transposons actually perform a central role for the cell, Princeton Professor Laura Landweber, an author of the study, said. They stitch together the genes in working form.

The study that included Mariusz Nowacki, Brian Higgins, Genevieve Maquilan, Estienne Swart and Thomas Doak appeared in the May 15 edition of Science.