PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

UGA physicist helps uncover new data on adenine, a crucial building block of life

2011-08-19
(Press-News.org) Athens, Ga. – Early Earth's atmosphere provided little shielding for ultraviolet light from space, so many prebiotic molecules, bombarded by it and light of other wavelengths, had a hard time surviving at all. But some molecules became photostable—able to withstand the assault and thrive as building blocks of life.

Five of the many molecules that survived the bombardment from UV light were the nucleic acid bases adenine, cytosine, guanine, thymine and uracil. Now, in just published research, a University of Georgia physicist and a collaborator in Germany have shown that one of these building blocks of DNA and RNA, adenine, has an unexpectedly variable range of ionization energies along its reaction pathways.

This means that understanding experimental data on how adenine survives exposure to UV light is much more complicated than previously thought. It also has far-reaching implications for spectroscopic measurements of heterocyclic compounds—those with atoms of at least two different elements in their rings.

"Photoprotection relies on the conversion of potentially harmful UV radiation into heat and has to operate on ultrafast time scales to compete over pathways that lead to the destruction of the biomolecule," said Susanne Ullrich, assistant professor in physics in the UGA department of physics and astronomy, part of the Franklin College of Arts and Sciences. "Disentangling these pathways and their time scales is challenging and requires a very close collaboration between experimentalists and theorists."

The research is in the online journal Physical Chemistry Chemical Physics. Co-author of the paper is Mario Barbatti, a theorist at the Max-Planck Institute in Mulheim, Germany.

The quantum-chemical calculations create for the first time a new baseline on how time-resolved spectroscopic techniques based on photoionization can be most reliably used to study this class of molecules.

"Photostable organic molecules participated in the complex molecular evolution that led to the formation of life," said Ullrich. "Because of the significance of nucleic acid bases as the genetic coding material, the photophysics of nucleobases has received considerable theoretical and experimental attention. This new work can help clarify inconsistencies researchers have always found in studying photoionization and photoelectron spectra of adenine."

Ullrich and her team used a technique called time-resolved photoionization with femtosecond (a quadrillionth of a second) resolution to unravel the mechanisms that protect adenine against UV damage. For the spectroscopic measurements, they employ a state-of-the-art femtosecond laser and custom-built photoelectron and photoion spectrometer.

Adenine is vaporized and transported into the spectrometer in a supersonic jet expansion. A pump pulse excites the sample of molecules, and finally a probe pulse is used to examine the sample after an adjustable delay time.

This examination is based on the process of photoionization that removes an electron from the molecule. The kinetic energy of the released photoelectron is measured in the spectrometer and provides the spectroscopic information needed to establish the photoprotection mechanism of adenine. Interpretation, however, heavily relies on the knowledge of ionization potentials (IP) along the relaxation pathways. (Ionization potential is the energy needed to remove an electron from the molecule.)

There has been a longstanding divergence between theoretical and experimental results when it comes to studying the IP of adenine and understanding on which surface adenine "relaxes" after it is excited with UV light. Understanding it more clearly could give new insights into how this important building block of life has continued to exist with stability in a world with millions of genetic threats.

"To our surprise, we found there were significant variations in the ionization energy between two different regions on this pathway," said Barbatti. "Due to the general character of the three pathways we studied, we believe the IPs computed along them can be used as a general guide for helping with setup and analysis for further experiments, not only with adenine but other related compounds."

Before this work, little has been known about the behavior of ionization potentials along the main reaction pathways for gaseous adenine in an excited state. Calling that a "knowledge gap," Barbatti and Ullrich say the new findings have "implications for experimental setup and data interpretation."

### END


ELSE PRESS RELEASES FROM THIS DATE:

Study finds sex differences in mental illness

2011-08-19
WASHINGTON – When it comes to mental illness, the sexes are different: Women are more likely to be diagnosed with anxiety or depression, while men tend toward substance abuse or antisocial disorders, according to a new study published by the American Psychological Association. Published online in APA's Journal of Abnormal Psychology, the study looked at the prevalence by gender of different types of common mental illnesses. The researchers also found that women with anxiety disorders are more likely to internalize emotions, which typically results in withdrawal, loneliness ...

Embryo development obeys the laws of hydrodynamics

2011-08-19
Vincent Fleury, a researcher at the Paris Diderot University, studied the early stage of development when embryonic cells first form a flat sheet of cells before folding into a U-shape, resembling a folded pancake. He demonstrated that the formation of a chicken's head is a consequence of the collision between both sides of the embryo flowing at constant speed towards each other. This study captured for the first time on film highly accurate observations of how a chicken embryo evolves during its first two days of development, using time-lapse microscopy. Prior attempts ...

A quick way to grade grasses for ethanol yields

2011-08-19
This release is available in Spanish. U.S. Department of Agriculture (USDA) researchers have developed an inexpensive way to grade the ethanol potential of perennial grasses at the biorefinery's loading dock. That future has been made possible by a team of Agricultural Research Service (ARS) scientists, including Ken Vogel, Rob Mitchell, and Steve Masterson at Lincoln, Neb.; Hans Jung at St. Paul, Minn.; Bruce Dien at Peoria, Ill.; and Michael Casler at Madison, Wis. ARS is USDA's chief intramural scientific research agency, and this research supports the USDA priority ...

Headaches are common in year following traumatic brain injury, especially among females

Headaches are common in year following traumatic brain injury, especially among females
2011-08-19
New Rochelle, NY, August 18, 2011—Recurring headaches are common during the year following a traumatic brain injury (TBI), regardless of the severity of the TBI, and they tend to occur more often among females and those with a pre-TBI history of headache, according to an article in Journal of Neurotrauma, a peer-reviewed journal published by Mary Ann Liebert, Inc. The article is available free online at www.liebertpub.com/neu More than 70% of patients who had suffered a TBI reported having headaches during the first year after their injury. This finding is a result of ...

PET scans confirm effectiveness of estrogen-blocking drugs in breast cancer patients

2011-08-19
SEATTLE – For the first time, researchers at Seattle Cancer Care Alliance have demonstrated the feasibility of using serial positron emission tomography (PET) scans, using a special estrogen-containing isotope, to confirm the relative effectiveness of estrogen-blocking and estrogen-depleting therapy in patients with metastatic breast cancer. The results of the research are published online in Clinical Cancer Research. The PET scans, taken before, during and after hormonal therapy, confirmed the superior effectiveness of estrogen-receptor-blocking drugs such as tamoxifen ...

Disordered networks synchronise faster than small world networks

2011-08-19
In this study, Carsten Grabow and colleagues from the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, created a model to test the speed of synchronisation of complex networks in collaboration with the Warwick Complexity Centre, UK. They tested this model using three very different oscillators acting on complex networks, which are known as Kuramoto, Rössler and pulse-coupled oscillators. As a result, for all tested networks they showed that the structure of the coupling between network nodes determines the speed of synchronisation. In short: ...

New component of a plant steroid-activated pathway discovered

2011-08-19
Washington, D.C.— Plant biologists have been working for years to nail down the series of chemical signals that one class of plant hormones, called brassinosteroids, send from a protein on the surface of a plant cell to the cell's nucleus. New research from Carnegie scientists Tae-Wuk Kim and Zhiyong Wang, with contributions from the University of California San Francisco, isolated another link in this chain. Fully understanding the brassinosteroid pathway could help scientists better understand plant growth and help improve food and energy crop production. Brassinosteroids ...

Regenerative powers in the animal kingdom explored in special issue of the Biological Bulletin

Regenerative powers in the animal kingdom explored in special issue of the Biological Bulletin
2011-08-19
MBL, WOODS HOLE, MASS.—Why can one animal re-grow tissues and recover function after injury, while another animal (such as a human being) cannot? This is a central question of regenerative biology, a field that has captured the imagination of scientists and the public since the 18th century, and one that is finally gaining traction and momentum through modern methods of analysis. Regeneration of the eye lens in frogs; of neural tissue in the snail; of the spinal cord in the sea lamprey; of the entire viscera in the sea cucumber—these and other capacities of animal regeneration ...

3i and VantagePoint Invest $45m in TouchTunes Interactive Networks

2011-08-19
3i, an international investor focused on private equity, infrastructure and debt management, announced today that it has acquired a minority stake of newly issued shares in TouchTunes Interactive Networks, the world's largest digital interactive out-of-home entertainment provider, for $40 million. Current majority shareholder VantagePoint Capital Partners will invest an additional $5 million. The total investment will support TouchTunes' growth strategy and help bolster its product and service offering. Founded in 1998, TouchTunes is the world's largest digital interactive ...

Message to gay soldiers: It's your army too

Message to gay soldiers: Its your army too
2011-08-19
As the U.S. military prepares for the repeal of "Don't Ask Don't Tell" (DADT), policymakers are looking to other military bodies around the world that have successfully integrated gay, lesbian and bisexual (GLB) soldiers into military service. Now a new study from Tel Aviv University suggests that an integrated support and education dimension is essential to the successful assimilation of these soldiers into the U.S. armed forces. Dr. Guy Shilo of TAU's Bob Shapell School of Social Work has completed the only quantitative study detailing the LGB experience in the military. ...

LAST 30 PRESS RELEASES:

Study tracks chromium chemistry in irradiated molten salts

Scientists: the beautiful game is a silver bullet for global health

Being physically active, even just a couple of days a week, may be key to better health

High-fat diet promote breast cancer metastasis in animal models

A router for photons

Nurses and AI collaborate to save lives, reduce hospital stays

Multi-resistance in bacteria predicted by AI model

Tinker Tots: A citizen science project to explore ethical dilemmas in embryo selection

Sensing sickness

Cost to build multifamily housing in California more than twice as high as in Texas

Program takes aim at drinking, unsafe sex, and sexual assault on college campuses

Inability to pay for healthcare reaches record high in U.S.

Science ‘storytelling’ urgently needed amid climate and biodiversity crisis

KAIST Develops Retinal Therapy to Restore Lost Vision​

Adipocyte-hepatocyte signaling mechanism uncovered in endoplasmic reticulum stress response

Mammals were adapting from life in the trees to living on the ground before dinosaur-killing asteroid

Low LDL cholesterol levels linked to reduced risk of dementia

Thickening of the eye’s retina associated with greater risk and severity of postoperative delirium in older patients

Almost one in ten people surveyed report having been harmed by the NHS in the last three years

Enhancing light control with complex frequency excitations

New research finds novel drug target for acute myeloid leukemia, bringing hope for cancer patients

New insight into factors associated with a common disease among dogs and humans

Illuminating single atoms for sustainable propylene production

New study finds Rocky Mountain snow contamination

Study examines lactation in critically ill patients

UVA Engineering Dean Jennifer West earns AIMBE’s 2025 Pierre Galletti Award

Doubling down on metasurfaces

New Cedars-Sinai study shows how specialized diet can improve gut disorders

Making moves and hitting the breaks: Owl journeys surprise researchers in western Montana

PKU Scientists simulate the origin and evolution of the North Atlantic Oscillation

[Press-News.org] UGA physicist helps uncover new data on adenine, a crucial building block of life