Technique lets researchers see how and where DNA fits into cells
THURSDAY, Oct. 8 (HealthDay News) -- The 3-D structure of the human genome has been deciphered by U.S. researchers, an achievement that improves understanding of genomic function and reveals how two meters of DNA can be packed into each human cell.
The scientists used a new technology called Hi-C, which enabled them to conduct genomewide analysis of the proximity of individual genes.
"We've long known that on a small scale, DNA is a double helix," co-first author Erez Lieberman-Aiden, a graduate student in the Harvard-MIT Division of Health Science and Technology and a researcher at Harvard's School of Engineering and Applied Sciences, said in a Harvard news release. "But if the double helix didn't fold further, the genome in each cell would be two meters long. Scientists have not really understood how the double helix folds to fit into the nucleus of a human cell, which is only about a hundredth of a millimeter in diameter. This new approach enabled us to probe exactly that question."
The scientists discovered that the human genome is organized into two separate compartments -- one that keeps active genes accessible and another that sequesters unused DNA.
"Cells cleverly separate the most active genes into their own special neighborhood, to make it easier for proteins and other regulators to reach them," senior author Job Dekker, an associate professor of biochemistry and molecular pharmacology at University of Massachusetts Medical School, said in the news release.
The researchers also found that the human genome uses fractal globule architecture to pack about three billion base pairs of DNA into each cell without any knots or tangles that could interfere with a cell's ability to read its own genome.
"Nature's devised a stunningly elegant solution to storing information -- a super-dense, knot-free structure," senior author Eric Lander, director of the Broad Institute, a professor of biology at MIT and a professor of systems biology at Harvard Medical School, stated in the news release.
The study appears in the Oct. 9 issue of Science.
The U.S. National Human Genome Research Institute has more about genomics.
-- Robert Preidt
SOURCE: Harvard University, news release, Oct. 8, 2009
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