(Press-News.org) Oxidative stress is believed to cause a number of diseases. Up to now, it has been common practice to measure oxidative stress levels by determining the oxidation state of a small molecule called glutathione in cell extracts. Scientists from the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) have been the first to discover that cells under stress deposit their oxidized glutathione in a cellular waste repository. This protects cells from oxidative stress – and questions the validity of the conventional measuring method.
Cancer, Alzheimer's, arteriosclerosis– the list of diseases which have been linked to oxidative stress is long and even includes the very process of aging. Oxidative stress is caused by so-called reactive oxygen compounds, which include the notorious "free radicals". If a cell is exposed to more reactive oxygen compounds than it can instantly degrade, it is under oxidative stress. As a result, important components such as proteins, DNA and lipids are oxidized and thus get damaged.
To determine whether a cell is under oxidative stress, scientists often analyze the oxidation state of glutathione. Glutathione is a small molecule which gets oxidized to protect the cell from reactive oxygen compounds. In theory, the amount of oxidized glutathione should therefore indicate whether a cell is healthy or under oxidative stress. However, researchers in the team of Associate Professor (PD) Dr. Tobias Dick have demonstrated that this hypothesis, which is the basis of a large number of scientific studies, is deceptive.
"Up to now, it was necessary to destroy the cells in order to measure the amount of oxidized glutathione," Tobias Dick explains. "However, this means that any spatial resolution is lost." Therefore, virtually nothing was known about where exactly oxidized glutathione is found in the cells. Scientists have presumed that it remains in the cytoplasm, where it is formed.
To find out more about the whereabouts of glutathione in the cell, Tobias Dick and co-workers developed biosensors which indicate the oxidation state of glutathione in intact cells by releasing light signals. In yeast cells, the researchers were able, for the first time, to follow the path of oxidized glutathione through the living cell in real time. They were surprised to find that, rather than remaining in the cytoplasm, it promptly gets locked up in a safe depot, the vacuole.
The cytoplasm, where all important cellular metabolic processes happen, is thus reliably protected from oxidative damage. Cells that would have been considered to be under oxidative stress using the conventional method appeared entirely healthy in their cytoplasm. Tobias Dick and his team could subsequently show that this is not only true for yeast cells but also for various mammalian cells and also for cancer cells.
These results mean that – contrary to previously held beliefs – the level of oxidative glutathione does not indicate whether or not a cell is under oxidative stress. "Therefore, it is important to re-evaluate prior studies that have established a link between oxidative stress and various diseases based on the conventional method."
INFORMATION:
A picture for this press release is available at:
http://www.dkfz.de/de/presse/pressemitteilungen/2012/images/66-hefe-wt1.jpg
Picture caption: A biosensor tracks oxidized glutathione in the vacuole of yeast cells.
Source: Tobias Dick, German Cancer Research Center
Bruce Morgan, Daria Ezeriņa, Theresa N.E. Amoako, Jan Riemer, Matthias Seedorf and Tobias P. Dick: Multiple glutathione disulfide removal pathways mediate cytosolic redox homeostasis. Nature Chemical Biology 2012, DOI: 10.1038/NCHEMBIO.1142
The German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) with its more than 2,500 employees is the largest biomedical research institute in Germany. At DKFZ, more than 1,000 scientists investigate how cancer develops, identify cancer risk factors and endeavor to find new strategies to prevent people from getting cancer. They develop novel approaches to make tumor diagnosis more precise and treatment of cancer patients more successful. Jointly with Heidelberg University Hospital, DKFZ has established the National Center for Tumor Diseases (NCT) Heidelberg where promising approaches from cancer research are translated into the clinic. The staff of the Cancer Information Service (KID) offers information about the widespread disease of cancer for patients, their families, and the general public. The center is a member of the Helmholtz Association of National Research Centers. Ninety percent of its funding comes from the German Federal Ministry of Education and Research and the remaining ten percent from the State of Baden-Württemberg.
Imagine a solid ball rolling down a slightly inclined ramp. What could be perceived as child's play is the focus of serious theoretical research by Manoj Chaudhury and Partho Goohpattader, two physicists from Lehigh University, Bethlehem, Pensylvania, USA. Their study, which is about to be published in EPJ E, has one thing in common with childhood behaviour. It introduces a mischievous idea, namely studying the effect of random noise, such as vibrations, on the ball. They found it could lower the energy barrier to set the ball in motion.
The authors used a ramp with ...
A protected area network should ensure the maintenance of biodiversity, but climate is changing rapidly, thereby creating further demand for the protected area network to be efficient in preserving biota. Due to climate change species ranges are expected to move polewards, which poses challenges to the protected area network.
Population changes of different bird species groups according to their habitat preferences in boreal protected areas in Finland were studied on the basis of large-scale bird censuses carried out in 1981 and in 2000. Mean temperatures rose clearly ...
Washington D.C., December 17, 2012 – A study published in the December 2012 issue of the Journal of the American Academy of Child and Adolescent Psychiatry found that adolescents who experienced food insecurity in the past year have a higher prevalence of mental disorders than adolescents whose families have reliable access to food.
Using data from the National Comorbidity Survey Replication Adolescent Supplement (NCS-A), a group of researchers led by Dr. Katie McLaughlin, of Boston Children's Hospital and Harvard Medical School, examined 6,483 adolescents aged 13-17 ...
AUGUSTA, Ga. – Telestroke networks that enable the remote and rapid diagnosis and treatment of stroke can improve the bottom line of patients and hospitals, researchers report.
A central hub hospital delivering rapid stroke diagnosis and treatment partnering with typically smaller spoke hospitals in need of those services means more patients recover better and the network – and hospitals – make money, according to a study in the American Heart Association journal Circulation: Cardiovascular Quality and Outcomes.
"We measure stroke treatment in reduced disability and ...
JACKSONVILLE, Fla. — A research team led by scientists at Mayo Clinic in Florida have decoded the entire pathway that regulates leakiness of blood vessels — a condition that promotes a wide number of disorders, such as heart disease, cancer growth and spread, inflammation and respiratory distress.
They say their findings, published online Dec. 17 in the Journal of Cell Biology, suggest that several agents already being tested for other conditions might reverse vessel leakiness.
"Now that we understand a lot more about the pathway that leads to leaky blood vessels, ...
BUFFALO, N.Y. — Coral colonies that suffered tissue damage in The Bahamas were still producing low numbers of eggs four years after the injuries occurred, according to new research by University at Buffalo scientists. Tiny sperm-producing factories called spermaries were also in short supply.
The slow recovery was a surprise, said UB geology professor Howard Lasker, PhD, who led the study on the coral species Antillogorgia elisabethae.
"The really interesting finding was that four years later, these colonies were still displaying an effect," Lasker said. "They don't ...
ROCHESTER, Minn. -- It appears that long, arduous hours in the hospital are causing more than stress and fatigue among doctors-in-training -- they're crashing, or nearly crashing, their cars after work, according to new Mayo Clinic research. Nearly half of the roughly 300 Mayo Clinic residents polled during the course of their residencies reported nearly getting into a motor vehicle crash during their training, and about 11 percent were actually involved in a traffic accident.
The study, recently published in Mayo Clinic Proceedings, found that residents attributed the ...
Stratum ventilation systems have been touted as a much more energy efficient system for cooling buildings such as school rooms and offices in hotter climes based on the provisions of the recent ANSI/ASHRAE 55-2010. They may also reduce the risk of the spread of airborne diseases according to a study to be published early next year in the journal World Review of Science, Technology and Sustainable Development.
This approach to cooling small and medium-sized rooms in a building has come to the fore as a low-cost alternative to high-energy air-conditioning systems particularly ...
This press release is available in German.
In the period of atmospheric nuclear testing in the 1950s and 1960s significant amounts of uranium-236 were distributed world-wide. Despite this, uranium-236 has mostly eluded detection and clear attribution to this source. A team of three researchers based in Austria and Australia lead by Stephan Winkler have identified the bomb-pulse of this isotope in corals from the Caribbean Sea. Uranium is readily dissolved in seawater, and therefore is carried by ocean currents. This makes uranium-236 and ideal tool for investigating ...
This press release is available in German.
The gonad is well known to be important for reproduction but also affects animal life span. Removal of germ cells – the sperm and egg producing cells – increases longevity of the roundworm Caenorhabditis elegans. However, the underlying molecular mechanisms were a mystery. Now scientists at the Cologne-based Max Planck Institute for Biology of Ageing, have discovered that germ cell removal flips a "molecular switch" that extends the life span by using components of a "developmental clock".
The roundworm Caenorhabditis elegans ...
