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

Frog-killing fungus paralyzes amphibian immune response

2013-10-18
(Press-News.org) A fungus that is killing frogs and other amphibians around the world releases a toxic factor that disables the amphibian immune response, Vanderbilt University investigators report Oct. 18 in the journal Science.

The findings represent "a step forward in understanding a long-standing puzzle – why the amphibian immune system seems to be so inept at clearing the fungus," said Louise Rollins-Smith, Ph.D., associate professor of Pathology, Microbiology and Immunology. Although the identity of the toxic fungal factor (or factors) remains a mystery, its ability to inhibit a wide range of cell types – including cancerous cells – suggests that it may offer new directions for the development of immunosuppressive or anti-cancer agents.

The populations of amphibian species have been declining worldwide for more than 40 years. In the late 1990s, researchers discovered that an ancient fungus, Batrachochytrium dendrobatidis, was causing skin infections, and the fungus is now recognized as a leading contributor to global amphibian decline.

Rollins-Smith, an immunologist, and her colleagues have been studying the immune response to the fungus for more than 10 years.

"Amphibians have excellent and complex immune systems – nearly as complex as humans – and they should be able to recognize and clear the fungus," she said.

In early studies, the investigators demonstrated that some frogs produce anti-microbial peptides in the skin that offer a first layer of defense against the fungus. But when the fungus gets into the layers of the skin, Rollins-Smith said, the conventional lymphocyte (immune cell)-mediated immune response should be activated to clear it.

They found in the current studies that recognition of the fungus by macrophage and neutrophil cells was not impaired.

"We think it's not a block at the initial recognition stage," Rollins-Smith said. "The macrophages and neutrophils can see it as a pathogen, they can eat it up, they can do their thing."

But during the next stage of the immune response, when lymphocytes should be activated, the fungus exerts its toxic effects. The investigators demonstrated that B. dendrobatidis cells and supernatants (the incubation liquid separated from the cells) impaired lymphocyte proliferation and induced cell death of lymphocytes from frogs, mice and humans. The toxic fungal factor also inhibited the growth of cancerous mammalian cell lines.

The toxic factor was resistant to heat and proteases (enzymes that cut proteins into pieces), suggesting that it is not a protein. It appears to be a component of the cell wall, because drugs that interfere with cell wall synthesis reduce its inhibitory activity and because the zoospore – an immature form of the fungus that lacks a cell wall – does not produce the factor.

The new findings suggest the possibility that toxic factors – in addition to acting locally to inhibit the immune response – might also get into the circulation and have neurotoxic effects, Rollins-Smith said.

"Fungal infection causes rapid behavioral changes – frogs become lethargic and start to crawl out of the water – suggesting that even though the fungus stays in the skin, the toxic material is having effects elsewhere."

The studies, led by graduate students J. Scott Fites and Jeremy Ramsey, could also suggest new conservation measures for species that may be medically important.

"Amphibian skin has long been favored in folklore for its medicinal properties," Rollins-Smith said. "Frogs are a rich source of potentially useful molecules that might work against human pathogens."



INFORMATION:

The research was supported by grants from the National Science Foundation. Other authors of the Science paper include Whitney Holden, Sarah Collier, Danica Sutherland, Laura Reinert, Sophia Gayek, Terence Dermody, M.D., Thomas Aune, Ph.D., and Kyra Oswald-Richter, Ph.D.



ELSE PRESS RELEASES FROM THIS DATE:

Costly cigarettes and smoke-free homes

2013-10-18
Researchers at the University of California, San Diego School of Medicine say high-priced cigarettes and smoke-free homes effectively reduce smoking behaviors among low-income individuals – a demographic in which tobacco use has remained comparatively high. Writing in the October 17, 2013 issue of the American Journal of Public Health, principal investigator John P. Pierce, PhD, professor and director of population sciences at UC San Diego School of Medicine, and colleagues found that expensive cigarettes – $4.50 or more per pack – were associated with lower consumption ...

Mysterious ancient human crossed Wallace's Line

2013-10-18
Scientists have proposed that the most recently discovered ancient human relatives -- the Denisovans -- somehow managed to cross one of the world's most prominent marine barriers in Indonesia, and later interbred with modern humans moving through the area on the way to Australia and New Guinea. Three years ago the genetic analysis of a little finger bone from Denisova cave in the Altai Mountains in northern Asia led to a complete genome sequence of a new line of the human family tree -- the Denisovans. Since then, genetic evidence pointing to their hybridisation with ...

Scientists discover genetic disease which causes recurrent respiratory infections

2013-10-18
Cambridge scientists have discovered a rare genetic disease which predisposes patients to severe respiratory infections and lung damage. Because the scientists also identified how the genetic mutation affects the immune system, they are hopeful that new drugs that are currently undergoing clinical trials to treat leukaemia may also be effective in helping individuals with this debilitating disease. For the study, led by the University of Cambridge in collaboration with the Babraham Institute and the MRC Laboratory for Molecular Biology, the researchers first examined ...

Bladder bacteria vary in women with common forms of incontinence

2013-10-18
MAYWOOD -- Women with common forms of urinary incontinence have various bacteria in their bladder, according to data presented today by researchers from Loyola University Chicago Stritch School of Medicine. Researchers also found that some of these bacteria may differ based on their incontinence type. These findings were presented at the 34th Annual Scientific Meeting of the American Urogynecologic Society in Las Vegas. They stem from Loyola's Urinary Research and Educational Collaboration, an institutional effort to identify and characterize urinary bacteria and how ...

Adaptability to local climate helps invasive species thrive

2013-10-18
The ability of invasive plants to rapidly adapt to local climates -- and potentially to climate change -- may be a key factor in how quickly they spread. According to new research published in Science by UBC evolutionary ecologist Rob Colautti, it is rapid evolution -- as much as resistance to local pests -- that has helped purple loosestrife to invade, and thrive in, northern Ontario. "The ability of invasive species to rapidly adapt to local climate has not generally been considered to be an important factor affecting spread," says Colautti, an NSERC Banting Postdoctoral ...

Researchers advance toward engineering 'wildly new genome'

2013-10-18
In two parallel projects, researchers have created new genomes inside the bacterium E. coli in ways that test the limits of genetic reprogramming and open new possibilities for increasing flexibility, productivity and safety in biotechnology. In one project, researchers created a novel genome—the first-ever entirely genomically recoded organism—by replacing all 321 instances of a specific "genetic three-letter word," called a codon, throughout the organism's entire genome with a word of supposedly identical meaning. The researchers then reintroduced a reprogramed version ...

Death from drugs like oxycodone linked to disadvantaged neighborhoods, fragmented families

2013-10-18
Death from analgesic overdose, including the painkillers oxycodone and codeine, is more concentrated in economically disadvantaged neighborhoods with a prevalence of high divorce, single-parent homes than deaths from unintentional causes, according to research conducted at Columbia University's Mailman School of Public Health. Yet, compared to heroin overdose deaths, analgesic overdoses were found to occur in higher-income neighborhoods. This study is among the first to provide a framework that helps explain the geographical distribution of analgesic overdose in urban areas. ...

FDA must find regulatory balance for probiotics says Univ. of Md. law prof

2013-10-18
The U.S. Food and Drug Administration (FDA) should consider the unique features of probiotics — bacteria that help maintain the natural balance of organisms in the intestines — in regulating their use and marketing, says Diane Hoffmann, JD, director of the Law and Health Care Program at the University of Maryland Francis King Carey School of Law and lead author of the a newly released Science article, "Probiotics: Finding the Right Regulatory Balance." "The U.S. Food and Drug Administration (FDA) has no definition of probiotics and regulates them based on whether they ...

Gene regulation differences between humans and chimpanzees more complex than thought

2013-10-18
Changes in gene regulation have been used to study the evolutionary chasm that exists between humans and chimpanzees despite their largely identical DNA. However, scientists from the University of Chicago have discovered that mRNA expression levels, long considered a barometer for differences in gene regulation, often do not reflect differences in protein expression—and, therefore, biological function—between humans and chimpanzees. The work was published Oct. 17 in Science. "We thought that we knew how to identify patterns of mRNA expression level differences between ...

UCLA psychologists report new insights on human brain, consciousness

2013-10-18
UCLA psychologists report new insights on human brain, consciousness UCLA psychologists have used brain-imaging techniques to study what happens to the human brain when it slips into unconsciousness. Their research, published Oct. 17 in ...

LAST 30 PRESS RELEASES:

New study shows biochar’s electrical properties can influence rice field methane emissions

Guangdong faces largest chikungunya outbreak on record

Tirzepatide improves blood sugar control in children aged 10-17 years with type 2 diabetes inadequately controlled on existing therapies (SURPASS-PEDS trial)

An old drug, in a low dose, shown to be safe and effective in preventing progression of type 1 diabetes in children and young people (MELD-ATG trial)

Study reports potential effects of verapamil in slowing progression of type 1 diabetes

Fresh hope for type 1 diabetes as daily pill that slows onset confirms promise at 2-year follow-up

New estimates predict over 4 million missing people who would be alive in 2025 if not for inadequate type 1 diabetes care

So what should we call this – a grue jay?

Chicago Quantum Exchange-led coalition advances to final round in NSF Engine competition

Study identifies candidates for therapeutic targets in pediatric germ cell tumors

Media alert: The global burden of CVD

Study illuminates contributing factors to blood vessel leakage

What nations around the world can learn from Ukraine

Mixing tree species does not always make forests more drought-resilient

Public confidence in U.S. health agencies slides, fueled by declines among Democrats

“Quantum squeezing” a nanoscale particle for the first time

El Niño spurs extreme daily rain events despite drier monsoons in India

Two studies explore the genomic diversity of deadly mosquito vectors

Zebra finches categorize their vocal calls by meaning

Analysis challenges conventional wisdom about partisan support for US science funding

New model can accurately predict a forest’s future

‘Like talking on the telephone’: Quantum computing engineers get atoms chatting long distance

Genomic evolution of major malaria-transmitting mosquito species uncovered

Overcoming the barriers of hydrogen storage with a low-temperature hydrogen battery

Tuberculosis vulnerability of people with HIV: a viral protein implicated

Partnership with Kenya's Turkana community helps scientists discover genes involved in adaptation to desert living

Decoding the selfish gene, from evolutionary cheaters to disease control

Major review highlights latest evidence on real-time test for blood – clotting in childbirth emergencies

Inspired by bacteria’s defense strategies

Research spotlight: Combination therapy shows promise for overcoming treatment resistance in glioblastoma

[Press-News.org] Frog-killing fungus paralyzes amphibian immune response