A new dimension for genome studies
Scientists have long known that DNA is arranged in a double helix. But if the double helix did not fold further, each cell's genome would be two meters long — far too large to fit into the nucleus of a human cell, which is about a hundredth of a millimeter in diameter. A new paper from scientists at MIT, the Broad Institute of Harvard and MIT, University of Massachusetts Medical School and Harvard University, reveals the three-dimensional structure of the human genome and answers the thorny question of how each of our cells stows some three billion base pairs of DNA. The work, reported in this week's issue of Science, may also explain how cells control which stretches of DNA are transcribed and which remain silent. Furthermore, the new technique could allow researchers to study how gene expression changes as cells develop or become cancerous, says Thomas Tullius,...