The eyes have it

Scientists reveal how organic mercury can interfere with vision

2013-09-12

(Press-News.org) More than one billion people worldwide rely on fish as an important source of animal protein, states the United Nations Food and Agriculture Organization. And while fish provide slightly over 7 per cent of animal protein in North America, in Asia they represent about 23 per cent of consumption.

Humans consume low levels of methylmercury by eating fish and seafood. Methylmercury compounds specifically target the central nervous system, and among the many effects of their exposure are visual disturbances, which were previously thought to be solely due to methylmercury-induced damage to the brain visual cortex. However, after combining powerful synchrotron X-rays and methylmercury-poisoned zebrafish larvae, scientists have found that methylmercury may also directly affect vision by accumulating in the retinal photoreceptors, i.e. the cells that respond to light in our eyes.

Dr. Gosia Korbas, BioXAS staff scientist at the Canadian Light Source (CLS), says the results of this experiment show quite clearly that methylmercury localizes in the part of the photoreceptor cell called the outer segment, where the visual pigments that absorb light reside.

"There are many reports of people affected by methylmercury claiming a constricted field of vision or abnormal colour vision," said Korbas. "Now we know that one of the reasons for their symptoms may be that methylmercury directly targets photoreceptors in the retina."

Korbas and the team of researchers from the University of Saskatchewan including Profs. Graham George, Patrick Krone and Ingrid Pickering conducted their experiments using three X-ray fluorescence imaging beamlines (2-ID-D, 2-ID-E and 20-ID-B) at the Advanced Photon Source, Argonne National Laboratory near Chicago, US, as well as the scanning X-ray transmission beamline (STXM) at the Canadian Light Source in Saskatoon, Canada.

After exposing zebrafish larvae to methylmercury chloride in water, the team was able to obtain high-resolution maps of elemental distributions, and pinpoint the localization of mercury in the outer segments of photoreceptor cells in both the retina and pineal gland of zebrafish specimens. The results of the research were published in ACS Chemical Biology under the title "Methylmercury Targets Photoreceptor Outer Segments".

Korbas said zebrafish are an excellent model for investigating the mechanisms of heavy metal toxicity in developing vertebrates. One of the reasons for that is their high degree of correlation with mammals. Recent studies have demonstrated that about 70 per cent of protein-coding human genes have their counterparts in zebrafish, and 84 per cent of genes linked to human diseases can be found in zebrafish.

"Researchers are studying the potential effects of low level chronic exposure to methylmercury, which is of global concern due to methylmercury presence in fish, but the message that I want to get across is that such exposures may negatively affect vision. Our study clearly shows that we need more research into the direct effects of methylmercury on the eye," Korbas concluded.

INFORMATION:

Acknowledgments: This work was supported by the Canadian Institutes of Health Research, the Saskatchewan Health Research Foundation and the Natural Sciences and Engineering Research Council of Canada.

ELSE PRESS RELEASES FROM THIS DATE:

Study provides insights on protecting world's poor from climate change

2013-09-12

The worst impacts of climate change on the world's poorest fishing communities can likely be avoided by careful management of the local environment and investing in the diversification of options for local people, according to the Wildlife Conservation Society and James Cook University. Climate change is already putting pressure on fishers who depend on nature for their livelihoods. In a new study, scientists found large differences in the potential to adapt based on the local mixture of social and environmental characteristics, requiring a variety of management approaches ...

Health care safety net catches suburban poor

2013-09-12

CHICAGO --- A new study shows significant health benefits for uninsured people living under the federal poverty level in the suburbs when they receive access to primary care. Uninsured residents in a suburban collar county of Chicago reported a big improvement in their health status and increased their preventive care and screenings after one year of access to primary care, reports Northwestern Medicine research. The study illustrates the potential benefits of the Affordable Care Act (ACA) implementation and a promising solution to accessible health care for what are ...

Researchers identify ancient ancestor of tulip tree line

2013-09-12

BLOOMINGTON, Ind. -- The modern-day tulip tree, state tree of Indiana as well as Kentucky and Tennessee, can trace its lineage back to the time of the dinosaurs, according to newly published research by an Indiana University paleobotanist and a Russian botanist. The tulip tree, Liriodendron tulipfera, has been considered part of the magnolia family. But David Dilcher of Indiana University Bloomington and Mikhail S. Romanov of the N.V. Tsitsin Main Botanical Garden in Moscow show that it is closely related to fossil plant specimens from the Lower Cretaceous period. Their ...

Everyday sadists take pleasure in others' pain

2013-09-12

Most of the time, we try to avoid inflicting pain on others — when we do hurt someone, we typically experience guilt, remorse, or other feelings of distress. But for some, cruelty can be pleasurable, even exciting. New research suggests that this kind of everyday sadism is real and more common than we might think. Two studies led by psychological scientist Erin Buckels of the University of British Columbia revealed that people who score high on a measure of sadism seem to derive pleasure from behaviors that hurt others, and are even willing to expend extra effort to make ...

Central mechanism underlying electroacupuncture effects visceral hypersensitivity

2013-09-11

Irritable bowel syndrome patients extensively suffer from chronic visceral hypersensitivity, with involvement of all levels of the brain-gut axis, as well as various neurotransmitters. Chronic visceral hypersensitivity can occur in the periphery, spinal cord and central nervous system, which has been shown to be the main pathophysiological mechanism underlying abdominal pain in patients with irritable bowel syndrome. Acupuncture at Tianshu (ST25) and Shangjuxu (ST37) has been reported to relieve visceral hypersensitivity for irritable bowel syndrome. Xinxin Guo and colleagues ...

Anti-inflammatory and anti-thrombogenic effects of atorvastatin in acute ischemic stroke

2013-09-11

The population of northeastern China has a high incidence of ischemic stroke. Previous studies have shown that intracranial large-artery atherosclerosis is one of the main causes of ischemic stroke, and that the mechanisms are related to inflammation and thrombosis of the affected arteries. A recent study by Lianqiu Min and colleagues from Liaoning Medical University observed the effects of atorvastatin treatment in 89 patients from northeastern China with acute ischemic stroke caused by intracranial large-artery atherosclerosis by measuring changes in the levels of markers ...

The mechanism of astragaloside IV promoting sciatic nerve regeneration

2013-09-11

Astragaloside IV, the main component of the traditional Chinese medicine astragalus membra-naceus, has been shown to inhibit inflammation, oxidation, and apoptosis, and exerts immu-noregulatory effects. Xiaohong Zhang and colleagues from School of Pharmacutical Sciences, Jilin University investigated whether astragaloside IV could promote the repair of injured sciatic nerve. Denervated sciatic nerve of mice was subjected to anastomosis. The mice were intraperitoneally injected with 10, 5, 2.5 mg/kg astragaloside IV per day for 8 consecutive days. The researchers found that ...

Tiny diamonds to boost treatment of chemoresistant leukemia

2013-09-11

Singapore, 11 September 2013 – By binding multiple molecules of a common leukemia drug with nanodiamonds, scientists from the National University of Singapore (NUS) and University of California, Los Angeles (UCLA) managed to boost the delivery of the drug to leukemic cells and retain the drug within the cells to combat the cancer. This novel discovery, reported for the first time, addresses one of the major challenges in the treatment of leukemia where the cancer cells develop ways to pump drugs out of the body before they can do their job, particularly after they are ...

Map of galactic clouds where stars are born takes shape

2013-09-11

SYDNEY: A UNSW-led team of astronomers has begun to map the location of the most massive and mysterious objects in our galaxy – the giant gas clouds where new stars are born. Using a telescope at Coonabarabran that narrowly escaped devastation in a recent bushfire, the team identifies the galactic clouds of molecular gas - which can be up to 100 light years across - from the carbon monoxide they contain. "On Earth, carbon monoxide is poisonous – a silent killer. But in space, it is the second most abundant molecule and the easiest to see," says Professor Michael Burton, ...

Obesity combined with exposure to cigarette smoke may pose new health concerns

2013-09-11

Contact: Michael Bernstein m_bernstein@acs.org 317-262-5907 (Indianapolis Press Center, Sept. 6-11) 202-872-6042 Michael Woods m_woods@acs.org 317-262-5907 (Indianapolis Press Center, Sept. 6-11) 202-872-6293 American Chemical Society Obesity combined with exposure to cigarette smoke may pose new health concerns INDIANAPOLIS -- Millions of people who are obese and smoke tobacco may face additional health problems -- including their responses to common prescription medicines -- that extend beyond the well-known links with cancer, heart attacks and stroke, ...

Why Some Bacteria Survive Antibiotics and How to Stop Them - New study reveals that bacteria can survive antibiotic treatment through two fundamentally different “shutdown modes”

The eyes have it

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: