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article imageClearest DNA image ever is generated

By Tim Sandle     Dec 14, 2014 in Science
A new full-genome map indicates how DNA is folded within the nuclei of human cells has been produced using a type of nuclear cartography,which uses PCR to examine for DNA fragments.
Scientists have created the highest-resolution map to date of how the human genome folds within the nucleus.
Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. DNA is nucleic acid, which a macro-molecule essential for life (DNA contains the instructions needed for an organism to develop, survive and reproduce.) Almost all DNA molecules consist of two biopolymer strands coiled around each other to form a double helix.
Scientists created their map using an updated version of a previously published method called Hi-C. First, they crosslinked the DNA in cells with formaldehyde to preserve its 3-D structure. Next, they treated the DNA with restriction enzymes, cutting it into tiny pieces. They then added biotin markers to the ends of the cut DNA, followed by ligase, which binds together any free DNA ends that are in close proximity. Finally, the researchers sheared the DNA and pulled down biotin-marked fragments, which they sequenced.
The new images show the genome’s 3-D structure, including the fact that it forms around 10,000 loops. It also shows how genome structure influences gene expression, as looping DNA brings promoters and enhancers into close proximity. The work covers one mouse and eight human cell types. In genetics, a promoter is a region of DNA that initiates transcription of a particular gene. An enhancer is a short region of DNA that can be bound with proteins (activators) to activate transcription of a gene or genes. Transcription is the first step of gene expression, the process by which information from a gene is used in the synthesis of proteins.
Bing Ren, a professor of cellular and molecular medicine at the University of California, San Diego has described the new images as "a landmark in the field of genome architecture." The images are ten times better resolution than any previously published work.
The images and associated research have been published in the science journal Cell. The paper is called "A 3D map of the human genome at kilobase resolution reveals principles of chromatin looping."
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