This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers have developed fluorescent molecules that permit imaging of how DNA is packaged inside living cells at unprecedented resolution and, in preserved cells, at a resolution close to the width of the double helix itself. The team tested the fluorescent probes on slices of bowel tissue taken from three cancer patients.
These are ordinary wax-preserved samples, which is how almost all hospitals store patient biopsies. In the tumors, the DNA was noticeably looser and more spread out than in the healthy tissue sitting right beside it. Other studies have found that DNA unpacks steadily as cancer takes hold, and the researchers suggest that how loosely a cell's DNA is folded could eventually serve as a measure of how far a tumor has progressed or how aggressive it is.
Doctors currently examine these types of biopsies by eye, using a staining method more than a century old. The advance, described today in the journal Molecular Cell, raises the possibility that one day they could also look at how DNA occupies three-dimensional space inside cells as an additional clue for diagnosing and treating cancer. "With the same dye we can do two very different things.
In a living cell we can watch DNA moving, which tells us how chromatin, the natural state of DNA in cells, behaves. In a preserved cell we can zoom in until we are almost at the scale of the DNA molecule itself. Combining both approaches helps us see one of the main layers of control in human biology in unprecedented resolution," explains ICREA Research Professor Pia Cosma, senior author of the study.
Every cell in the human body holds 2 meters of DNA squeezed into a very small space. How tightly it is folded up decides which genes are switched on and which stay off. Almost all images of DNA folding come from cells that are already dead.
Powerful microscope techniques needed to track individual components of DNA in cells typically require treating samples with harsh chemicals and strong laser lights that living cells cannot survive. A team at the Centre for Genomic Regulation (CRG) in Barcelona, the City University of Hong Kong and the Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences) Southern Medical University found a way to overcome this challenge by designing fluorescent probes. Called HoTs, the dyes can navigate inside living cells on their own and stick to DNA.
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