Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists see DNA get 'sunburned' for the first time

02.02.2007
For the first time, scientists have observed DNA being damaged by ultraviolet (UV) light.

Ohio State University chemists and their colleagues in Germany used a special technique to watch strands of DNA in the laboratory sustain damage in real time.

They observed the most common chemical reaction among a family of reactions on the DNA molecule that are linked to sunburn, and discovered that this key reaction happens with astounding speed -- in less than one picosecond, or one millionth of one millionth of a second.

Scientists are studying UV damage to understand the role it plays in sunburn and diseases such as skin cancer. This new finding, reported in the current issue of the journal Science, shows that the damage depends greatly on the position of the DNA at the moment the UV strikes the molecule.

... more about:
»DNA »chemical reaction »reaction »sunburn »sustain »thymine

UV light excites the DNA molecule by adding energy, said Bern Kohler, associate professor of chemistry at Ohio State. Some exited energy states last a long time, and others a short time. The energy often decays away harmlessly, but occasionally it triggers a chemical reaction that alters the DNA's molecular structure.

Previously, scientists believed that the longer a DNA molecule was excited by UV energy, the greater the chance that it would sustain damage. So long-lived excited states were thought to be more dangerous than short-lived ones. But this study shows that the most common UV damage is caused by a very short-lived excited state.

"The speed of this reaction has important consequences for understanding how DNA is damaged by UV light," said Kohler. "In this study, we didn't see any evidence that long-lived energy states are responsible for damage. Now it seems more likely that short-lived states cause the most common chemical damage to DNA."

That damage consists of two tiny molecular bonds that form where they shouldn't -- between two thymine bases stacked together among the billions of bases in the DNA double helix.

DNA employs some chemical reactions of its own to heal itself. But when DNA sustains too much damage, it can't replicate properly. Badly damaged cells simply die -- the effect that gives sunburn its sting. Scientists also believe that chronic damage creates mutations that lead to diseases such as skin cancer.

For this study, the chemists used a technique called transient absorption to observe the DNA damage. Transient absorption is based on the idea that molecules absorb light at specific wavelengths, and it allows researchers to study events that happen in less than a picosecond.

They took specially designed strands of DNA -- ones made solely of thymine bases, in order to boost the chance of observing a reaction between adjacent thymines -- and exposed them to UV light. Then they timed the reactions that caused the new thymine bonds to form.

Kohler stressed that he and his colleagues examined damage to isolated DNA strands, not DNA within a cell. Sunburn results from a series of chemical reactions in a living cell, and so this experiment did not allow them to see a cell sustain sunburn.

This is, however, the first time anyone has observed the initial molecular events behind damage to DNA. Kohler thinks the results might make scientists attack the problem of UV damage in a new way.

DNA in a cell is always moving, he explained. It bends and twists one way or another because it is a relatively flexible molecule. This flexibility enables the normal chemical reactions that are constantly happening in the cell. Each shape-shift can require anywhere from a few to several hundred picoseconds to complete.

That's fast, but this new study shows that UV damage happens many times faster. On the timescale that the unwanted bonds form, even a rapidly moving DNA molecule would essentially appear frozen.

That means that whether or not two thymine bases are damaged depends on the position of the DNA during the extremely brief time required for it to absorb UV light. Either two thymine bases are lined up in just the right way to bond when the UV hits, or they're not.

"This insight explains why some pairs of thymine bases get damaged more frequently than others, and it suggests that scientists can understand damage patterns to DNA by studying the factors that influence how the bases are arranged in space," Kohler said.

"In our efforts to understand photo-damage, this new result shifts our attention to the DNA structure, and the kinds of arrangements that exist at the moment DNA absorbs light."

His coauthors on the paper include Carlos E. Crespo-Hernandez, a former postdoctoral researcher at Ohio State ; and Wolfgang J. Schreier, Tobias E. Schrader, Florian O. Koller, Peter Gilch, Wolfgang Zinth, Vijay N. Swaminathan, and Thomas Carell, all of Ludwig Maximilians University in Munich .

The research was funded in part by the National Institute of General Medical Science at the National Institutes of Health, and by the Alexander von Humboldt Foundation of Germany.

Bern Kohler | EurekAlert!
Further information:
http://www.chemistry.ohio-state.edu

Further reports about: DNA chemical reaction reaction sunburn sustain thymine

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>