Scientists decipher the 3-D structure of the human genome

A contiguous stretch of DNA chain inside a fractal globule packs into a compact, unknotted structure, making it easy to pack and unpack. Image by X. Robert Bao, Leonid A. Mirn, and Maxim Imakaev

(PhysOrg.com) -- Scientists have deciphered the three-dimensional structure of the human genome, paving the way for new insights into genomic function and expanding our understanding of how cellular DNA folds at scales that dwarf the double helix.

In a paper featured this week on the cover of the journal Science, they describe a new technology called Hi-C and apply it to answer the thorny question of how each of our cells stows some three billion base pairs of DNA while maintaining access to functionally crucial segments. The paper comes from a team led by scientists at Harvard University, the Broad Institute of Harvard and MIT, University of Massachusetts Medical School, and the Massachusetts Institute of Technology.

"We've long known that on a small scale, DNA is a double helix," says 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 and in the laboratory of Eric Lander at the Broad Institute. "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 researchers report two striking findings. First, the human genome is organized into two separate compartments, keeping active genes separate and accessible while sequestering unused DNA in a denser storage compartment. Chromosomes snake in and out of the two compartments repeatedly as their DNA alternates between active, gene-rich and inactive, gene-poor stretches.
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:wow:


Thanks so much for posting.

Wow.

If you have ever seen the way some model multi-dimensionality implied by the certain String Theory, it looks something like this. A way of creating an enormous amount of open surface area. This is really amazing.