Researchers are first to see DNA 'blink'

February 17, 2017

Many of the secrets of cancer and other diseases lie in the cell's nucleus. But getting way down to that level -- to see and investigate the important genetic material housed there -- requires creative thinking and extremely powerful imaging techniques.

Vadim Backman and Hao Zhang, nanoscale imaging experts at Northwestern University, have developed a new imaging technology that is the first to see DNA "blink," or fluoresce. The tool enables the researchers to study individual biomolecules as well as important global patterns of gene expression, which could yield insights into cancer.

Backman will discuss the tool and its applications -- including the new concept of macrogenomics, a technology that aims to regulate the global patterns of gene expression without gene editing -- Friday (Feb. 17) at the American Association for the Advancement of Science (AAAS) annual meeting in Boston.

The talk, "Label-Free Super-Resolution Imaging of Chromatin Structure and Dynamics," is part of the symposium "Optical Nanoscale Imaging: Unraveling the Chromatin Structure-Function Relationship," which will be held from 1 to 2:30 p.m. Eastern Time Feb. 17 in Room 206, Hynes Convention Center.

The Northwestern tool features six-nanometer resolution and is the first to break the 10-nanometer resolution threshold. It can image DNA, chromatin and proteins in cells in their native states, without the need for labels.

For decades, textbooks have stated that macromolecules within living cells, such as DNA, RNA and proteins, do not have visible fluorescence on their own.

"People have overlooked this natural effect because they didn't question conventional wisdom," said Backman, the Walter Dill Professor of Biomedical Engineering in the McCormick School of Engineering. "With our super-resolution imaging, we found that DNA and other biomolecules do fluoresce, but only for a very short time. Then they rest for a very long time, in a 'dark' state. The natural fluorescence was beautiful to see."

Backman, Zhang and collaborators now are using the label-free technique to study chromatin -- the bundle of genetic material in the cell nucleus -- to see how it is organized. Zhang is an associate professor of biomedical engineering at McCormick.

"Insights into the workings of the chromatin folding code, which regulates patterns of gene expression, will help us better understand cancer and its ability to adapt to changing environments," Backman said. "Cancer is not a single-gene disease."

Current technology for imaging DNA and other genetic material relies on special fluorescent dyes to enhance contrast when macromolecules are imaged. These dyes may perturb cell function, and some eventually kill the cells -- undesirable effects in scientific studies.

In contrast, the Northwestern technique, called spectroscopic intrinsic-contrast photon-localization optical nanoscopy (SICLON), allows researchers to study biomolecules in their natural environment, without the need for these fluorescent labels.

Backman, Zhang and Cheng Sun, an associate professor of mechanical engineering at McCormick, discovered that when illuminated with visible light, the biomolecules get excited and light up well enough to be imaged without fluorescent stains. When excited with the right wavelength, the biomolecules even light up better than they would with the best, most powerful fluorescent labels.

"Our technology will allow us and the broader research community to push the boundaries of nanoscopic imaging and molecular biology even further," Backman said.
-end-


Northwestern University

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.