Corporate Banner
Satellite Banner
Technology
Networks
Scientific Communities
 
Become a Member | Sign in
Home>News>This Article
  News
Return

X-rays Used to Examine How DNA Protects Itself from UV Light

Published: Tuesday, June 24, 2014
Last Updated: Tuesday, June 24, 2014
Bookmark and Share
Scientists have made detailed observations of a “relaxation response” that protects these molecules, and the genetic information they encode, from UV damage.

The experiment at the Department of Energy’s SLAC National Accelerator Laboratory focused on thymine, one of four DNA building blocks. Researchers hit thymine with a short pulse of ultraviolet light and used a powerful X-ray laser to watch the molecule’s response: A single chemical bond stretched and snapped back into place within 200 quadrillionths of a second, setting off a wave of vibrations that harmlessly dissipated the destructive UV energy.

The international research team reported the results June 23 in Nature Communications.

While protecting the genetic information encoded in DNA is vitally important, the significance of this result goes far beyond DNA chemistry, said Philip Bucksbaum, director of the Stanford PULSE Institute and a co-author of the report.

“The new tool the team developed for this study provides a new window on the motion of electrons that control all of chemistry,” he said. “We think this will enhance the value and impact of X-ray free-electron lasers for important problems in biology, chemistry and physics.”

Light Becomes Heat
Researchers had noticed years ago that thymine seemed resistant to damage from UV rays in sunlight, which cause sunburn and skin cancer. Theorists proposed that thymine got rid of the UV energy by quickly shifting shape. But they differed on the details, and previous experiments could not resolve what was happening.

The SLAC experiment took place at the Linac Coherent Light Source (LCLS), a DOE Office of Science user facility, whose bright, ultrashort X-ray laser pulses can see changes taking place at the level of individual atoms in quadrillionths of a second.

Scientists turned thymine into a gas and hit it with two pulses of light in rapid succession: first UV, to trigger the protective relaxation response, and then X-rays, to detect and measure the response. 

“As soon as the thymine swallows the light, the energy is funneled as quickly as possible into heat, rather than into making or breaking chemical bonds,” said Markus Guehr, a DOE Early Career Program recipient and senior staff scientist at PULSE who led the study. “It’s like a system of balls connected by springs; when you elongate that one bond between two atoms and let it loose, the whole molecule starts to tremble.”

Ejected Electrons Signal Changes
The X-rays measured the relaxation response indirectly by stripping away some of the innermost electrons from atoms in the thymine molecule. This sets off a process known as Auger decay that ultimately ejects other electrons. The ejected electrons fly into a detector, carrying information about the nature and state of their home atoms.

By comparing the speeds of the ejected electrons before and after thymine was hit with UV, the researchers were able to pinpoint rapid changes in a single carbon-oxygen bond: It stretched when hit with UV light and shortened 200 quadrillionths of a second later, setting off vibrations that continued for billionths of a second.

“This is the first time we’ve been able to distinguish between two fundamental responses in the molecule – movements of the atomic nuclei and changes in the distribution of electrons – and time them within a few quadrillionths of a second,” said the paper’s first author, Brian McFarland, a postdoctoral researcher who has since moved from SLAC to Los Alamos National Laboratory.

Guehr said the team plans more experiments to further explore the protective relaxation response and extend the new method, called time-resolved Auger spectroscopy, into other scientific realms.


Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,500+ scientific posters on ePosters
  • More Than 3,800+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Scientists Prove X-ray Laser Can Solve Protein Structures from Scratch
Study shows for the first time that X-ray lasers can be used to generate a complete 3-D model of a protein without any prior knowledge of its structure.
Friday, November 29, 2013
X-ray Laser Explores New Uses for DNA Building Blocks
The founding father of DNA nanotechnology – a field that forges tiny geometric building blocks from DNA strands – recently came to SLAC to get a new view of these creations using powerful X-ray laser pulses.
Monday, March 18, 2013
Scientific News
Health Risks of Saturated Fats Aggravated by Immune Response
Research shows that the presence of saturated fats resulted in monocytes migrating into the tissues of vital organs.
Changing the Biological Data Visualisation World
Scientists at TGAC, alongside European partners, have created a cutting-edge, open source community for the life sciences.
NIH Study Finds Calorie Restriction Lowers Some Risk Factors for Age-Related Diseases
Two-year trial did not produce expected metabolic changes, but influenced other life span markers.
Immunotherapy Agent Benefits Patients with Drug-Resistant Multiple Myeloma in First Human Trial
Daratumumab proved generally safe in patients, even at the highest doses.
Low-level Arsenic Exposure Before Birth Associated with Early Puberty in Female Mice
Study examine whether low-dose arsenic exposure could have similar health outcomes in humans.
Inciting an Immune Attack On Cancer Cells
A new minimally invasive vaccine that combines cancer cells and immune-enhancing factors could be used clinically to launch a destructive attack on tumors.
‘Mutation-Tracking’ Blood Test for Breast Cancer
Scientists have developed a blood test for breast cancer able to identify which patients will suffer a relapse after treatment, months before tumours are visible on hospital scans.
Cellular Contamination Pathway for Heavy Elements Identified
Berkeley Lab scientists find that an iron-binding protein can transport actinides into cells.
Intensity of Desert Storms May Affect Ocean Phytoplankton
MIT study finds phytoplankton are extremely sensitive to changing levels of desert dust.
Common ‘Heart Attack’ Blood Test May Predict Future Hypertension
Small rises in troponin levels may have value as markers for subclinical heart damage and high blood pressure.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!