Tag Archives: fungus

Mushroom.

Researchers identify gene that makes plants and fungi play nice — we’ll use it to make better crops

Researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) are hacking the plant-fungi relationship to help us grow better, more productive, more resilient crops.

Mushroom.

Image credits Gustavo Torres.

The team has identified a specific gene that controls the symbiotic relationship between plants and fungi in the soil and used it to facilitate symbiosis in a plant species that typically resists such fungi. The research paves the way towards the development of food and bioenergy crops that can withstand harsh growing conditions, resist pathogens and pests, require less chemical fertilizer, and produce more plentiful per acre.

Magic ‘shrooms

“If we can understand the molecular mechanism that controls the relationship between plants and beneficial fungi, then we can start using this symbiosis to acquire specific conditions in plants such as resistance to drought, pathogens, improving nitrogen and nutrition uptake and more,” said ORNL molecular geneticist Jessy Labbe, the paper’s first author.

“The resulting plants would grow larger and need less water and fertilizer, for instance.”

The fungi Labbe refers to are known as mycorrhizal fungi (a mycorrhiza is a symbiotic association between a fungus and a plant), and they form a sheath around plant roots that benefits both participants. An estimated 80% of plant species have mycorrhizal fungi associated with their roots.

The plant receives water and raw minerals, particularly phosphorus, and ‘trades’ carbon-rich compounds in return. The fungal structure extends much farther than the plant host’s roots, allowing it to tap into a larger volume of soils. There is also some evidence suggesting these fungi also communicate with neighboring plants to limit the spread of pathogens and pests.Their relationship is so close that these fungal helpers may have been what allowed the ancient colonization of land by plants.

Given the importance of this partnership, biologists have been really eager to find the genetic mechanisms which underpin it. The current discovery is the culmination of 10 years of research at the ORNL and partner institutions that focused on producing better bioenergy feedstock crops such as the poplar tree (Populus).

Together with improvements in genomic sequencing, quantitative genetics, and high-performance computing over the last decades, the team drew on the ORNL data to narrow down the search to a particular receptor protein, PtLecRLK1. Once they had identified the likely candidate gene, the researchers took to the lab to validate their findings. Lab testing later confirmed that they were onto the right gene.

The researchers chose Arabidopsis, a plant known to treat the mycorrhizal fungus L. bicolor as a threat for the experiments. They engineered a version of this plant to expresses the PtLecRLK1 protein and then inoculated the plants with L. bicolor. The fungus completely enveloped the plant’s root tips, they report, forming a fungal sheath indicative of symbiote formation.

“We showed that we can convert a non-host into a host of this symbiont,” said ORNL quantitative geneticist Wellington Muchero, a co-author of the paper. “If we can make Arabidopsis interact with this fungus, then we believe we can make other biofuel crops like switchgrass, or food crops like corn also interact and confer the exact same benefits. It opens up all sorts of opportunities in diverse plant systems. Surprisingly, one gene is all you need.”

Jerry Tuskan, the director of the DOE’s Center for Bioenergy Innovation (CBI), which supported this research, calls the results “remarkable”, saying it paves the way towards new bioenergy crops that can thrive “on marginal, non-agricultural lands.”

“We could target as much as 20-40 million acres of marginal land with hardy bioenergy crops that need less water, boosting the prospects for successful rural, biobased economies supplying sustainable alternatives for gasoline and industrial feedstocks,” he concludes.

The paper “Mediation of plant–mycorrhizal interaction by a lectin receptor-like kinase” has been published in the journal Nature Plants.

Cordyceps sinensis on caterpillars from collection of Womens collective, Munsiyari. Credit: Wikimedia Commons.

A parasite worth three times its weight in gold is disappearing — and with it hundreds of thousands of jobs

Cordyceps sinensis on caterpillars from collection of Womens collective, Munsiyari. Credit: Wikimedia Commons.

Cordyceps sinensis on caterpillars from collection of Womens collective, Munsiyari. Credit: Wikimedia Commons.

During the summer days, thousands gather on the Tibetan plateau on the lookout for that year’s most prized commodity — buried orange sticks that look like withered carrots with a dark-brown rod at the top. The orange lump is, in fact, a dead caterpillar while the stick is a parasitic fungus that has devoured the unfortunate insect. If you’re not impressed yet, understand that the caterpillar fungus can sell for three times more than gold, kilogram for kilogram.

But a new study is confirming what many who harvest the highly prized fungus have known deep down for quite some time: the world’s most valuable parasite is disappearing. The culprit is overharvesting with a sprinkle of — what’s by now a usual suspect — climate change.

The fungal ‘gold mine’ is running out

Ophiocordyceps sinensis, known as Yarsa-gumba (यार्सागुम्बा, which is Nepali for “winter worm, summer grass”) is an entomopathogenic fungus that grows on insects, particularly the larvae of moths within the family Hepialidae.

Thousands of people living in Tibet and neighboring Bhutan depend on the caterpillar fungus for their livelihoods. They harvest the fungus and then sell it to dealers that bring it to markets in China. The caterpillar fungus is highly regarded in traditional Chinese and Tibetan medicine, where it’s used as an immune system booster and to treat all sorts of conditions, including cancer.

The caterpillar fungus’ anti-cancer properties have never been proven in a clinical trial. However, there are studies that suggest the fruiting body has some pharmaceutical effects that can be used to treat conditions such as hyposexuality, night sweats, hyperglycemia, hyperlipidemia, asthenia, arrhythmias, and other heart, respiratory, renal and liver diseases. It, at least, does not seem worthless in medicine like rhino horn (Chinese market demand is threatening the iconic animals with extinction). But is it worth its hefty price?

Weighing the precious Caterpillar fungus in Gyegu-Yushu, Southern Qinghai, China. Credit: Wikimedia Commons.

Weighing the precious Caterpillar fungus in Gyegu-Yushu, Southern Qinghai, China. Credit: Wikimedia Commons.

In 2008 the price of C. sinensis was around USD $13,000 per kg, earning it the name “soft gold” in China. As of August 2012, the price rose to USD $111,560 per kg and, according to The Atlantic’s Ed Young, some of the biggest and most attractive pieces can fetch $140,000 per kilogram — more than three times the price of gold.

The global market for “soft gold” is estimated to be worth $5 billion to $11 billion, contributing a hefty chunk of Tibet’s and Bhutan’s GDP. It’s estimated that 40% of the rural cash income in the Tibet Autonomous Region comes from the dark-brown fruiting body, supporting hundreds of thousands of people. But their luck seems to be running out.

Kelly Hopping, an ecologist at Boise State University, interviewed hundreds of collectors and went to the field to gather samples and analyze the chilly Himalayan climate. Reporting in the Proceedings of the National Academy of SciencesHopping and colleagues found that “harvesters increasingly attribute declining production to overexploitation, while models indicate that climate warming is also contributing to this decline.”

“We find that, according to collectors across four countries, caterpillar fungus production has decreased due to habitat degradation, climate change, and especially overexploitation. Our statistical models corroborate that climate change is contributing to this decline,” the authors of the new study wrote.

According to the researchers, the caterpillar fungus grows best at 3,000 to 5,000 meters above sea level, being most comfortable at temperatures of 5 to 20 degrees Fahrenheit (-15 to -5 Celsius). The problem is that the Himalayan winters have been warming up considerably due to climate change, affecting the harvest of the fungus. Although, it has to be said that the fungus is the least of our worries in the case of a warming Himalayas, whose glaciers are often referred to as the ‘third pole’. These glaciers feed the giant rivers of Asia and meet water demand for over three billion people.

Local authorities are aware of the caterpillar fungus’ decline and, in countries such as Bhutan, there are quotas for how much people are allowed to harvest. The hefty price, however, attracts poachers who — just like in the tragedy of the commons — are quick to seize their chance before someone else beats them to it.

If the caterpillar fungus disappears or dwindles to a shadow of its former self, hundreds of thousands of people will be out of work. This will be a huge challenge for Tibet and Bhutan, whose governments will have to find a way to offer new opportunities for many of its poor and untrained citizens.

This fungus senses gravity using a gene it borrowed from bacteria

If you zoom in on it, the pin mold fungus Phycomyces blakesleeanus looks like a ghastly pine forest with its thin, elongated bodies reaching upwards. But how does the fungus know which way is up? According to a new study, it does so via a bacteria gene that it acquired and tweaked in order to create gravity-sensing crystals. 

Phycomyces fruiting bodies. Each stalk is a single cell that elongates to form a structure 1-3 cm tall, with a spore-containing sphere at its tip. The spores accumulate melanin as they mature, explaining the black color. Inset: An OCTIN crystal from Phycomyces blakesleeanus; the crystal is about 5 microns across, dwarfing typical bacteria (1-2 microns in length) from which the OCTIN gene is likely to have been acquired.

Most people would consider fungi pretty dull — after all, all they do is grow, spread their spores and then grow some more. However, fungi have much more going for them than it initially appears.

How do you know which way is up (bonus points if you’ve read or seen Ender’s Game)? For us, as humans, the question almost doesn’t make any sense. Without going too much into the biomechanics of how we sense which way is up and which way is down, suffice to say that all animals have at least some idea of up and down. But plants and fungi grow upwards, so they, too, have developed mechanisms that aid them.

Researchers have known for quite a while that the pin mold fungus has octahedral protein crystals that, when placed in fluid-filled chambers (vacuoles), detect gravity. However, it was unclear exactly when and how they developed this ability. In order to clear this up, biologists purified the crystals and identified a protein which they named OCTIN. They found clear evidence of something called horizontal gene transfer, meaning that the fungus borrowed the ability from bacteria.

Basically, genetic information can be transmitted either vertically (from parents to offspring) or horizontally. Horizontal gene transfer (HGT) occurs when DNA is transferred between unrelated individuals. It typically happens to acquire useful functions, such as resistance to environmental extremes and expanded metabolic capacity. However, in most cases, HGT tends to happen through enzymes that confer these traits, and the original and acquired functions tend to remain closely related to each other.

This time, that’s wasn’t the case.

“We were surprised that OCTIN-related genes are found in bacteria and that all the evidence pointed to horizontal gene transfer from bacteria into the ancestor of Phycomyces,” said the authors. “This was intriguing because estimates of sedimentation show that bacteria are too small to employ gravity sensing structures. This made it clear that we were looking at the emergence of an evolutionary novelty based on how the proteins assembled.”

It’s also remarkable that the fungal OCTIN crystals can dramatically swell and dissolve based on the biochemical environment, which forms or breaks bonds between proteins. This also happens in bacteria, but on a much smaller scale. The overall crystal size was also much larger in the fungus than in the bacteria.

The presence of the OCTIN protein is not the end of the story. Researchers took things one step further and tried to “convince” mammalian cells to make fungal OCTIN, but these cells did not form crystals. Dr. Gregory Jedd, who led the group at the Temasek Life Sciences Laboratory from the National University of Singapore, concluded:

“We are currently searching for these factors with the aim of reconstituting OCTIN crystal formation in the test tube. This will allow us to better understand and manipulate the assembly process and its products. High-order assemblies like those formed by OCTIN are not uncommon in nature. Identifying and studying these types of proteins will not only reveal mechanisms of adaptation and evolution, but can also lead to engineered smart protein assemblies with applications in areas such as drug delivery and immune system modulation.”

Journal Reference: Nguyen TA, Greig J, Khan A, Goh C, Jedd G (2018) Evolutionary novelty in gravity sensing through horizontal gene transfer and high-order protein assembly. PLoS Biol 16(4): e2004920. https://doi.org/10.1371/journal.pbio.2004920

Hospital.

Drug-resistant candida outbreaks in the UK despite hospital efforts to control it

Over 200 UK patients in more than 55 hospitals have been infected or colonized by a highly drug resistant strain of fungus, Candida auris.

Hospital.

Image via Pixabay.

Three of these hospitals have seen large outbreaks of C. aureus, all of which were since officially declared over by health authorities. Luckily, nobody lost their lives. In fact, no deaths have been attributed to the fungus since it was first found in the UK back in 2013. However, during these latest outbreaks, some 50 patients developed clinical infections and 27 developed blood infections, which can be life-threatening. Most of the UK cases had been detected by screening, rather than investigations for patients with symptoms.

The scary thing about the C. aureus is how fast it’s emerging, and the sheer anti-fungal resistance this thing seems to possess. It was first identified in Japan in 2009 and has spread to more than a dozen countries since. The CDC lists around 100 known instances of the fungus in nine US states so far, and a further 100 where it didn’t cause an infection.

Most people who contract the fungus don’t develop an infection or only develop a mild one. Which is very bad news for those patients because if you do, things take a sharp turn south. The fungus can be deadly if contracted by patients with weakened or compromised immune systems, but the real risk is developing an invasive infection. Over a third of those who develop an invasive infection with C. auris die, though there were no reported deaths in the UK outbreak.

Such an infection can become almost impossible to beat back with drugs because C. auris is highly resistant to a broad spectrum of anti-fungal compounds. Every case in the UK so far has shown reduced responsiveness to fluconazole, the bread-and-butter of antifungal defense. Most of them were resistant to multiple other drugs, and some are resistant to all three main classes of antifungal drugs used to treat Candida and other fungal infections.

This resistance also allows C. auris to spread through the environment and between patients with surprising ease. One in three of the UK hospitals hit by the recent outbreak reported difficulty in eliminating the fungus from their premises for more than a year. The fungus was found on “the floor around bed sites, trollies, radiators, windowsills, equipment monitors and key pads, and also one air sample.” In light of these findings, healthcare officials have implemented new protocols, such as having healthcare workers wear better protective equipment and isolating all patients colonized or infected by the fungus.

Despite the risk, officials want to assure the UK public that their hospitals are safe.

“Our enhanced surveillance shows a low risk to patients in healthcare settings. Most cases detected have not shown symptoms or developed an infection as a result of the fungus,” Dr Colin Brown of Public Health England’s national infection service told the BBC.

But the rapid emergence of the fungus, combined with its high drug resistance, has public health officials worried. A CDC report this July highlighted the yeast as a “serious global health threat.”

Fungus-derived molecule enables axon regrowth — potentially treating brain and spinal chord injuries

One family of proteins that plants use to combat fungal infections could have an unexpected use: repairing axons — the long thread-like parts of a nerve cell.

Fluorescent bundles of axons.
Image credits Minyoung Choi / Wikipedia.

Axons are the large projections that neurons use to ferry signals to other parts of the body. They’re the main component of white matter, and without them, the nervous communication in the body would grind to a halt. Axonal damage can also lead to a host of disabilities associated with conditions such as spinal cord injury or stroke.

Andrew Kaplan, a PhD candidate at the Montreal Neurological Institute and Hospital of McGill University, was trying to find a substance that could help undo the damage for people suffering these conditions as part of Dr. Alyson Fournier’s team, professor of neurology and neurosurgery and senior author on the study. During his research, he found one family of proteins with neuroprotective functions known as 14-3-3 which could hold the key to creating axon-repairing drugs.

This family of proteins takes on a surprising role in plants which are fighting off a certain fungal strain. The fungus releases a marker molecule called fusicoccin-A. When exposed to this molecule, the plants’ leaves will wilt but their roots grow longer. This happens because fusicoccin-A affects 14-3-3’s normal interaction with other proteins, promoting growth.

“While 14-3-3 is the common denominator in this phenomenon, the identity of the other proteins involved and the resulting biological activities differ between plants and animals,” says Kaplan.

Kaplan’s theory was that fusicoccin-A could be used to harness 14-3-3 for use in repairing axons. He and his team placed mechanically damaged neurons in a culture with the substance and waited to see what happened.

“When I looked under the microscope the following day the axons were growing like weeds, an exciting result that led us to determine that fusicoccin-A can stimulate axon repair in the injured nervous system,” says Kaplan.

Beyond brain or spinal chord injuries, axonal damage also plays a central role in other disorders and diseases, such as multiple sclerosis or neurodegenerative conditions. Fusicoccin-A and similar molecules could become the starting point for a new class of drugs to treat and repair this damage. Kaplan says future research should aim to better understand the underlying mechanism by which fusicoccin-a improves axonal repair, which can be used to develop even more powerful medication.

One protein called GCN1 holds particular promise. The team found that GCN1 and 14-3-3 bonding can be an important factor in the fusicoccin-A-induced growth.

“We have identified a novel strategy to promote axon regeneration with a family of small molecules that may be excellent candidates for future drug development,” says Fournier.

“This is an exciting advance because the field has struggled to find treatments and identify targets for drugs that stimulate axon repair.”

The full paper “Small-Molecule Stabilization of 14-3-3 Protein-Protein Interactions Stimulates Axon Regeneration” has been published in the journal Neuron.

 

 

Farmer ants still struggle with undomesticated crops, study finds

A new Panama Smithsonian Tropical Research Institute (STRI) finds that modern relatives of the first fungus-farming ants still haven’t domesticated their crops. The study draws a strong parallel between the difficulties these ants faced and early human farmers faced.

Image via pixadus.

Some time after the dinosaurs went extinct 60 million years ago, the ancestors of leaf-cutter ants decided it was time to settle down. Just like us, they traded hunting and gathering for a more secure source of food — agriculture. You can still see their legacy snaking in busy lines through the rainforest carrying bits and pieces of plants over their heads. All this material underpins a huge, almost industrial agricultural complex. But for all their hard work, the ants’ harvest is limited by a farmer’s worst nightmare — a wild crop.

A new study at the Smithsonian Tropical Research Institute (STRI) in Panama revealed that living relatives of the earliest fungus-farming ants still have not domesticated their crop, a challenge also faced by early human farmers.

Modern leaf-cutter ants and the fungus they grow can’t survive without each other. The fungus is so important to the ants that young queens take a bit of it from the home nest and the colony they establish revolves around the farms they set up from this tiny bit. The fungus, in turn, doesn’t have to waste energy producing spores to reproduce itself. But what if the fungus…wants to make spores?

“For this sort of tight mutual relationship to develop, the interests of the ants and the fungi have to be completely aligned, like when business partners agree on all the terms in a contract,” said Bill Wcislo, deputy director at the STRI and co-author of the new publication in the Proceedings of the National Academy of Sciences.

“We found that the selfish interests of more primitive ancestors of leaf-cutting ants are still not in line with the selfish interests of their fungal partner, so complete domestication hasn’t really happened yet.”

Humans harvest vegetables before they go to seed — at this stage, the plants start diverting most of their energy and nutrients towards producing seeds, thus limiting their value as foodstuffs. And just like us, ants want to make sure that the fungus puts as little energy as possible into growing spores so it will grow bigger and fatter. What ants want is for the fungus to grow hyphae, the thread-like protrusions which they can eat. But the crop has its own plan so the ants carefully starve it into doing what they want.

Marie Curie Post-Doctoral Fellow of Jacobus Boomsma’s lab at the University of Copenhagen Jonathan Shik and his team found in an STRI study of Mycocepurus smithii — an ancestor of the leaf cutters that has not yet domesticated its fungal crop — that the ants alter what they feed the fungus to limit its spore production. The ants carefully manage the protein and carbohydrate content of the fertilizer they use to control how many mushrooms their cultivars produce. When they fed it mulches rich in carbohydrates, the fungus can produce both hyphae and mushrooms. But carefully rationing the amount of protein it receives can prevent the fungi from making mushrooms.

The downside of this is that by starving their crops, the ants severely limit the output of their fungal cultivars.

“The parallels between ant fungus farming and human agriculture are uncanny,” Shik said. “Human agriculture evolved in the past 10,000 years.”

“It took 30 million years of natural selection until the higher attine ants fully domesticated one of their fungal symbiont lineages. We think that finally resolved this farmer-crop conflict and removed constraints on increased productivity, producing the modern leaf-cutter ants 15 million years ago,” Boomsma said.

“In contrast, it took human farmers relatively little time to domesticate fruit crops and to select for seedless grapes, bananas and oranges.”

The full paper titled “Nutrition mediates the expression of cultivar–farmer conflict in a fungus-growing ant” has been published in the journal PNAS.

Lichens actually comprise a threesome, not a partnership

When the nature of lichens was discovered 140 years ago, they became the most prominent example of symbiosis, a term that defines a mutually beneficial relationship between two dissimilar organisms.

Image credit Pixabay

Image credit Pixabay

In the case of lichen, the filaments of a single fungus create protection for photosynthetic algae or cyanobacteria, which provide food for the fungus in return. However, a new study reveals that there is actually a third organism involved in this relationship – a yeast that likely provides the structure for “leafy” or “branching lichens.”

“These yeast are sort of hidden just below the surface,” said John McCutcheon, a genome biologist at the University of Montana, and senior author of the study. “People had probably seen these cells before and thought they were seeing something else. But the molecular techniques we used happened to be especially good for spotting the signal of a separate organism, and after years of looking at the data it finally occurred to us what we were seeing.”

McCutcheon’s team made the discovery after studying two lichen species obtained from Missoula, Montana mountains – Bryoria fremontii and B. tortuosa. Despite B. tortuosa possessing a yellow color due to the presence of vulpinic acid, genetic tests revealed identical fungus and alga in both species. However, they also discovered the genetic signature of a third species – a basidiomycete yeast – in both species, although it was more abundant in B. tortuosa.

Additional testing of 56 different lichens from around the world revealed that each one has its own variety of basidiomycete yeast, suggesting that lichens actually comprise a threesome, not a couple, essentially rewriting 150 years of biology.

The team believes that this newly discovered yeast could play a role in creating the large structures seen in macrolichens, which would explain why these particular lichens are hard to grow in the lab when using just a fungus and alga.

“This doesn’t prove that they’re necessary to create the structure of the macrolichens, or that they do anything else for that matter,” McCutcheon said. “But its early days. It took a lot of work just to discover that they were there. We’re interested if the yeast is making these important compounds, or possibly enabling the other fungus to make them. We don’t know, but it’s the obvious next question.”

Journal Reference: Basidiomycete yeasts in the cortex of ascomycete macrolichens. 21 July 2016. 10.1126/science.aaf8287

White Nose Bat Syndrome spreads deeper into the U.S. — first case confirmed west of the Rockies

The first case of white nose syndrome, a disease that has wreaked havoc on bat populations in the eastern U.S. has been identified west of the Rockies. The disease’s spread threatens to drastically impact bat populations there, altering ecosystems throughout the country.

Hikers discovered a little brown bat with white nose syndrome on a trail east of Seattle last in mid-March this year, the Department of Fish and Wildlife and the U.S. Geological Survey announced on Tuesday. This marks the first incidence of the deadly fungus west of the Rockies. The ailing bat was taken to an animal shelter, where it died two days later.

Picture of a little brown bat with white nose syndrome, taken in New York state, Oct 2008.
Image credits to U.S. Fish and Wildlife Service Headquarters.

USGS National Wildlife Health Center’s Wildlife Disease Diagnostic Laboratories branch chief David Blehert thinks it’s “surprising and unusual” to find the fungus spread this far west — the closest the syndrome has been identified before was Nebraska, some 1,300 miles from the site.

 “We’ve been dreading this,” said senior scientist at the Center for Biological Diversity Mollie Matteson in an interview for The Huffington Post. “This is a drastic jump.”

“This is the first time, to our knowledge, that there has been a long-range jump of the fungus,” Blehert said.

Caused by the fungus Pseudogymnoascus destructan, white nose syndrome can wipe out entire bat colonies. It gets its name from the white fuzzy fungal growths on the noses, wings and ears of affected bats. The devastating disease spreads throughout bodily tissue, disrupting physiological processes and interrupting essential hibernation periods, causing bats to waste away.

It has already caused the deaths of more than 6 million bats in the eastern U.S, in what some describe as the steepest decline or North American wildlife of the past century.

Seven different species of cave hibernating bats in 28 U.S. states and five Canadian provinces have been affected by white nose syndrome since 2006, when the first case was recorded in upstate New York. Two of these species are native to Washington state.

“I wish I could be optimistic, but given what we have seen on the East Coast, it’s hard to,” said Sharlene E. Santana, assistant professor of biology at the University of Washington.

“We knew it was coming [to the West], but we didn’t know it would be so soon,” Matteson said.

Range of white nose syndrome.
Image credits Washington Department of FIsh and Wildlife.

Blehert’s analysis of the Washington bat revealed that the disease was at an advanced stage, suggesting it had been present in the area for quite some time. Genetic sequencing indicates that the animal is a native to the area.

“We don’t know how the fungus got there,” Blehert said.

The fungus could have been transported bat-to-bat — which would have taken an extraordinarily long time. Or, as Blehert suspects, through human travel and trade, one of the largest spreader of infectious diseases. Humans aren’t affected by the fungus but act as carriers and are believed to (unknowingly) play a central part in transporting the disease across the country. Hikers’ and spelunkers’ clothes and gear can transport the fungus, according to the researchers.

Little brown bat with white-nose syndrome in Greeley Mine, Vermont, March 26, 2009.
Image credits Marvin Moriarty/USFWS, via flirk.

Unfortunately there is no proven method to cure the disease or at least halt its spread.

“We had hope that by the time [white nose syndrome] started to spread to the West, that there were more effective treatments in place,” Matteson said.

Scientists are now looking into the genetic code of the fungus to determine its point of origin and try to set up precautions to halt its spread around the world — the fungus most likely arrived in the U.S. on a human carrier from Asia or Europe where it’s endemic. They’re also looking into creating a vaccine that could give the bats a fighting chance against white nose syndrome.

“For years, we have been saying there needs to be stricter protocol put in place to minimize the chance of a jump like this via human transmission,” Matterson added.

Authorities are now putting abandoned mines and caves under lock-down to protect resident bat colonies. Federal agencies encourage visitors to decontaminate themselves and gear before entering an area with bats, but Matteson argued decontamination should be mandatory.

“We have species that are at risk of going extinct; it’s the least that could be done.”

Bats are an integral part of an ecosystem, and scientists are concerned about the chain reaction their loss might have on plant and animal life, including humans. If the bat population declines, insects would thrive and devastate agricultural areas. Populations of disease-carrying insects would also be left unchecked.

However, there might still be hope. Because bats in the western U.S. tend not to hibernate in large groups, the disease might not spread as widely or quickly from bat to bat. But far less is known in general about how bats hibernate on the West Coast, Matterson said, which means the bats could already be dying.

“As the case in Washington indicates, the disease has already been there for a couple years, and it just got discovered this past month,” she added.

“One of the huge problems with white nose syndrome has been that the [government] response was slow to get off the ground, it was disorganized, a lack of leadership, there wasn’t any decontamination requirement for western public lands, no cave closures.”

“There will be more in the future,” she concluded. “We need to learn our lesson.”

Wildlife officials encourage people who encounter sick or dead bats to report it via an online reporting tool or telephone hotline, 1-800-606-8768.

fungus

Fungi eat yummy minerals from rocks using acid and mechanical force

Fungi were thought to have a minimal impact on minerals’ bioweathering but recent study suggests that fungi are a lot more aggressive than they were given credit. They use acid to access precious nutrients like iron and burrow deep into rocks using mechanical force to further their reach.

fungus

MIcroscope view of the Talaromyces flavus fungus collected from a mine in China. Credit: Henry Teng

Researchers at George Washington University collected a fungus called Talaromyces flavus from a mine in Donghai, China. They then brought the fungus home and let it munch on a mineral called lizardite in a controlled lab setting. Previously, researchers who studied mineral degradation at the hand of fungal or microbial activity would mix the organisms with crushed minerals. In our case,   T. flavus was allowed to eat the mineral whole for four days, mimicking a fungus-mineral interface interaction found in the real world.

After those four days, the team led by  Henry Teng, a geochemist at George Washington University, washed the lizardite mineral and inspected the marks left by T. flavus. The results were pretty astonishing: many long, thin channels and small, round pits — the marking of a fungus feast — littered the mineral’s surface.

fungus eating mineral

A tiny, 125-micrometer-long channel carved out of rock by the fungus. Credit: Henry Teng

The methods of attack were also explained. First, the fungus releases spores that drop the pH by a factor of ten. This highly acidic environment dissolves the mineral, forming a soup which the fungus can easily ingest, but not before releasing a chemical called siderophore which facilitates iron intake. Once the iron at the surface of the mineral is depleted, T. flavus extends fillaments called  hyphae which burrow inside,  leaving behind channels stretching 200–2000 nanometers.

Intriguingly, the mineral had become amorphous in some parts where it should have had an orderly crystalline structure. This observation suggests the fungus used mechanical force to destroy the mineral, in addition to chemical forces.

Another experiment was set up, this time the lizardite was crushed in mixed in a solution with the fungus. Far less of the mineral was degraded in this suspended setting, suggesting interface interaction is a lot more powerful. Teng and colleagues claim that the fungus is responsible for forty to fifty percent of the total bioweathering of the mineral, compared to only one percent previously thought.

“Compared to bacteria, fungi are overlooked, understudied, and very few studies [looked] at these interfaces between fungi and mineral,” said Steeve Bonneville , a biogeochemist at the Free University of Brussels in Belgium who was not involved in the paper, which he called “a very solid study.” The new research provides evidence that “fungi can be a major player in mineral alteration and more generally in biogeochemical cycles,” Bonneville said.

The researchers only studied one species of fungus though, and some traits may be unique to T. flavus. The study‘s results might motivate others to investigate this interaction using other species.

Why is all this important? Apart from understanding how fungi and minerals interact, the findings will help build better models of plant growth. Trees and vegetables rely on mineral nutrients to grow. “Most of the nutrients in rock and soil are in geological form,” Teng said. “Roots cannot directly use that. Plants depend on the fungi to colonize their roots.”

Oldest fungus fossil set the stage for life on land 440 million years ago

For millions of years life was almost exclusively confined to the oceans, while on land primitive plant species dotted the landscape. The transition from marine to land life is poorly understood, given fossil records hundreds of million years old are rare. The striking finding of what looks like the oldest fungus is helping researchers piece together the grand picture. The fungus called  Tortotubus helped plant life by holding the soil together and recycling nutrients. An early land lover, the Tortobu might have been a key part of the land ecosystem that eventually grew to foster complex land life.

Tortotubus fungus filaments at various stages of development .Credit Martin R. Smith

Tortotubus fungus filaments at various stages of development .Credit Martin R. Smith

Tortotubus was  smaller than a human hair, and one of the first organisms to thrive on land. Judging from the hundreds of tiny fossils 440 to 450 million years old, this ancient fungus was widespread. Samples were found in Libya and Chad, but also New York State, Sweden and Scotland.

During these times, the oceans were teeming with complex life like jawless fish, arthropods, squid relatives and more. The land was a different matter entirely. Bacteria,  simple mossy and lichen-like plants were all that could be found. That’s because organisms had a lot of challenges to face. The UV exposure was a lot more threatening seeing there wasn’t much ozone to block the rays, temperature varied wildly — too fast for creatures to have time to adapt — and organic matter was scarce.

Creatures like Tortotubus probably weren’t the first land organisms, but no older such fossil was found. There’s a lot subsequent terrestrials have to thank Tortobus, too.

“By the time Tortotubus went extinct, the first trees and forests had come into existence,” said Martin Smith of Britain’s Durham University, who conducted the research while at the University of Cambridge.. “This humble subterranean fungus steadfastly performed its rotting and recycling service for some 70 million years, as life on land transformed from simple crusty green films to a rich ecosystem that wouldn’t look out of place in a tropical greenhouse today.”

It’s been a good week for science, it seems. Another study out of the Massachusetts Institute of Technology found an ancient sea sponge was likely the first animals on Earth, having been around for at least 640 million years. As researchers find more such striking fossils, humanity might one day understand how it all started.

Fungus turns frogs into sex zombies, but then kills off whole species

A new study of Batrachochytrium dendrobatidis (Bd), a deadly fungus that affects amphibians worldwide, found that it spreads by making males’ mating calls more attractive to females. The pathogen alters the reproductive habits of different species of amphibians, explaining why frogs and related species continue to disappear across the globe.

“If true—that the fungus is manipulating individuals’ behaviors to facilitate its spread—then this is extraordinary,” says Michael Ryan, a herpetologist at the University of Texas, Austin, who was not involved in the study.

The Japanese frog is one of the few species resistant to Bd. But individuals are still becoming infected.
Image credits to wikimedia user Alpsdake

Bd causes a condition named chytridiomycosis or chytrid fungus disease, which destroys amphibians‘ skins, disrupts their immune systems and ultimately causes heart failure and death. It was first discovered in the 1990s when several species of frogs in Australia and Central and South America went through massive die-offs.

The extinction of hundreds of amphibian species in recent years has been attributed to Bd, and it could potentially affect one third of the amphibian species currently on the planet. While there is no known cure for the fungus, a few species of frogs are known to survive several years after infection — indicating a certain level of adaptation towards fighting it.

But as Bd has been relatively contained up to now and species are being exposed to it for the first time, usually there is little natural defense against the fungus.

“Some people think that amphibian populations are declining primarily due to catastrophic die-offs caused by Bd,” says Bruce Waldman.

“But the story is much more complicated than that.”

Southern mountain yellow-legged frogs (Rana muscosa) killed by the chytrid fungus.
Image via sciencedaily

Waldman and his student Deuknam An studied Japanese tree frogs (Hyla japonica) in the wild to find out how Bd affects species seemingly resistant to it. This amphibian, which inhabits area in central Asia, Korea and Japan, hasn’t been experiencing the massive die-offs associated with the pathogen even though individuals are getting infected.

The team studied and recorded the mating calls of 42 male Japanese tree frogs from June to mid-August 2011 (during the mating season) in the rice paddies of South Korea. Here’s a recording of a normal call:

They looked for things such as the number of pulses per note, repetition rate of pulses, number of notes or total duration of the call. Out of this sample, nine frogs tested positive for Bd. These were slightly larger than their uninfected counterparts (40.17mm on average compared to 39.24mm.)

The team also reported that these males became lethargic, but put more effort into their calls compared to the others– for example, they produced longer songs, a trait which females are known to prefer. Here’s a recording of a Bd-infected male:

If you were a female Japanese frog, your lady-frog-parts would be on fire right now.

“Therefore one would expect the amount of calling to be lower in infected males,” Ryan notes.

“But this is not what the study found—and that’s very surprising.”

This suggests, he adds, that Bd can act like a parasite and turn its host into a zombie. These zombie males then go on to spread Bd further in the population by using their fungus-fueled sex appeal: the females they mate with become infected too, and their offspring inherit the fathers’ susceptibility to chytrid fungus disease.

The team hasn’t been able to figure out how Bd changes the host’s behavior, but they to have a theory. They point out that the force of natural selection may be looming over these males, which put an extra effort into their calls in order to reproduce faster as a way to compensate for their shorter lifespans.

But the end result is that while the infected males certainly get more action, the population as a whole is severely harmed.

“Bd has an impact on frog populations even when we don’t see outbreaks of chytridiomycosis,” says Cori Richards-Zawacki, a behavioral ecologist at the University of Pittsburgh in Pennsylvania.

Richards-Zawacki recently found that the disease causes male leopard frogs in the lab to up their reproductive efforts. Although it might seem that a species has adapted to Bd and shows no clinical signs of the disease, she says, “in reality it’s still stressed by the infection, which is likely to take a less dramatic but still important toll on the population over time.”

Waldman says that these “sublethal” effects can kill off a species even if it survives the initial die-off from the pathogen.

“Some of these populations that were hard hit are coming back, but slowly. Their populations are small, and that leaves them vulnerable to other random catastrophic events that might lead to extinction.”

The scientists looked at only one frog species—and only one of its life history stages, Waldman also notes.

“It shows that Bd continues to be an enigma.”

Agricultural behaviors recorded in bees for the first time

Cristiano Menezes of the Brazilian Agricultural Research Corporation has discovered farming behaviors in bees, adding them to the list of social insects that practice agriculture.

Up to now, these black-and-gold balls of fluff were believed to rely solely on pollen and nectar for sustenance. However, a particular species, Scaptotrigona depilis — the Brazilian stingless bee — has been observed growing fungus to be fed to their larvae. Menezes says that if other species that rely on fungi for survival are found, there will be some serious concerns about using fungicides in agriculture.

He was studying the bees in the lab, when he found what the believed to be fungus contamination in their hives. But, looking at all 30 hives he had collected as specimens, he found it in each and every one. Even more suspiciously, it was growing inside brood cells — the structures that house a hive’s developing larvae. Hmm.

Stingless bee brood chambers.
Image via newsweek

Taking a closer look at the presumed contaminant, Menezes began intuiting that maybe it wasn’t the fungi living off the bees, but the other way around. And indeed, it’s a keystone element of the hive — it permeates the cerumen, the waxy material bees build their stuff out off. After the bees lay an egg in each cell, and regurgitate food for the larva, the fungus starts growing from the cerumen into the cell. When the egg hatches, the larva feeds on the fungus, and it can’t feed on anything else. When the team tried to grow bees on a fungus-free diet, the survival rate of larvae dropped immensely, from 72 to only 8 percent.

“The survival difference may be either due to some nutrients provided by the fungus, or due to the fungus protecting the regurgitated food from spoiling,” the team reports.

When the bees leave their hive to start a new colony, they take some cerumen with them, so “seed” their new brood cells, proving that the bees understand and utilize the fungal agent.

“It is clear that the fungus profits from dispersal with the bees, both to new colonies and within the nest, and is offered a protected environment,” says Duur Aanen of Wageningen University in the Netherlands.

Menezes calls it “proto-farming” — the bees show some agricultural behaviours, such as “planting” the fungus, and providing stable conditions and nutrients for it to grow, then harvest it, but don’t actively tend to it. These behaviors are seen in other social insects as well, such as ants or termites — one species of ants was reported to even farm animals for meat.

“It is an exciting example of the complex connections between insects and microscopic life,” says Cameron Currie of the University of Wisconsin. “And it illustrates the important roles for beneficial symbionts in insects.”

Both Menezes and Currie think there are more farming bees to be found.

“Given the substantial diversity of bees, many of which are poorly studied, it is likely that other bees engage in similar associations,” Currie says.

This raises concern about the use of fungicides, which while not directly harmful to bees, may be affecting them by killing off their symbiotic fungi, Menezes’s team concludes.

Crops farmed by leafcutter ants show signs of domestication: Leafcutter ants became farmers 50 million years before humans

Leafcutter ants in South America grow fungus as crops, this has been known for quite a while. But their crops show clear signs of domestication, which means that when it comes to farming, the ants might have beaten us by some 50 million years.

Ant farmers

Atta cephalotes tending to their garden. Image credits: Alexander Wild.

When people started growing crops, they unwittingly made changes to the plants’ genome. For example, wheat, bananas, tobacco and strawberries are all polyploid – more than two paired (homologous) sets of chromosomes.  Now, Danish researchers from Copenhagen have found that leafcutter ants crops exhibit similar traits. While natural fungus and the one grown by less specialized ants consistently has two copies of each set of chromosomes, leafcutter crops are ployploid, having between five and seven copies. This is a major indication that a plant (or in this case, a fungus) is becoming domesticated.

“Polyploidisation is the fastest way to make a domesticated crop,” says Rachel Meyer from New York University. It makes it larger and more robust because it increases the number of copies of each gene, producing more gene products like growth hormones and immune proteins.

Early humans favored polyploid plants for their productivity and increased yield, and the same is probably happening with the ants.

“About 50 million years ago, fungus-growing ants gave up their lives as hunter-gatherers to become fungal farmers,” says Kooij. He thinks the leafcutters took it further by selecting the more productive, polyploid fungi and encouraging their growth.

 

There was another similarity between the ants and early human farmers: as agriculture developed, populations grew by several orders of magnitude. Unspecialized ants can have colonies of thousands or tens of thousands of workers, while leafcutter ant colonies number in the millions. These extremely successful insects basically dominate the rainforest, with a single colony having yields of up to 500 kilograms from their fungal crops.

“The results of our study provide yet another piece of the puzzle to explain how these ants have been so extremely successful,” says Kooij.

Image via Bilfinger.

Ants, fungus and bananas

Previously, the ant-fungus relationship was considered a type of symbiosis, but more and more research has hinted to the idea that the ants are actually growing the fungus, and this is not simply a biological relationship. Fungus-growing ants actively propagate, nurture and defend the fungus. When a queen starts a new colony, she actually takes a pellet of the fungus with her, starting a new garden at the new colony site. The relationship is so specialized that in most cases, the fungus doesn’t even grow outside the ant colonies, and there are no ant colonies without the fungus – it’s strikingly similar to human agriculture.

But there’s another side to it: polyploid species are often unable to reproduce sexually, which means that there is less risk for breeding with external species. This means that the crop is limited to asexual reproduction: this also means that plants like bananas for example have no seeds, which makes them tastier for us. It seems logical that the same is happening for ants.

“Humans have made edible bananas, bigger sugarcane and strawberries,” says Meyer. “And we’re currently making new polyploids for bigger kiwi fruit and seedless watermelon.”

So, as I was discussing with some friends, does this mean that ants are intelligent? This seems to suggest so.

Journal reference: Journal of Evolutionary Biology, DOI: 10.1111/jeb.12718

home-dust

How many germs you can find in your home: about 9,000 different species

After they analyzed dust samples collected from 1,200 US households, researchers at University of Colorado at Boulder identified over 9,000 different species of microbes, bacteria and fungus. The exact makeup depends on where the home is located, the gender of the people living inside and whether or not pets are present.

home-dust

Image: Red Beacon

What if I told you there were germs cramming every inch of your home? Most people are already aware of this, thankfully. Others freak out, partly because they might not understand that’s it perfectly natural this way. You weren’t affected by the germs until your heard the news, and you shouldn’t be after you find out. Nevertheless, there have been countless studies that document the germs living inside your home. This is, however, the most extensive by far revealing the extent of the biological makeup that comprises a typical American home.

The research is also another success story of citizen science coming to the rescue, as all the samples were collected by regular folks who then mailed them to the university. About 1,200 households responded to the call and sent dust collected from obscure locations people never usually bother cleaning, like the ledges above the door. The participants also filled out a questionnaire which asked what were their living and household habits, whether or not they were vegetarian, had pets and so on.

Some of the key findings:

  • The average American household has more than 2,000 different species of fungus and 7,000 species of bacteria.
  • Some of the fungus species include common strains like Aspergillus, Penicillium, Alternaria and Fusarium. 
  • Most of the fungus comes from outside the home so the fungus makeup of a home depends on where this is located.
  • Distinct bacteria were found in homes where only women or men lived. That’s because some types of bacteria are more common in women than men, and vice-versa. For instance, in male-dominant homes scientists found two types of skin-dwelling bacteria belonging to the genuses Corynebacterium and Dermabacter, as well as the fecal-associated genus Roseburia, in greater abundance than in female-dominant homes. The researchers attribute the difference in hygiene habits.
  • Having a dog or cat for a pet significantly altered the bacteria makeup of a home. In fact, having pets was the most influential factor that determine the biological ecosystem of your home. The researchers could determine whether or not dogs or cats lived in a home with an accuracy of 92% and 83%, respectively.

The researchers say that most of these microorganisms and fungi they identified are harmless.

“People do not need to worry about microbes in their home. They are all around us, they are on our skin, they’re all around our home – and most of these are completely harmless.

“It is just a fact of life that we are surrounded by these microbes,” concludes Dr Noah Fierer, associate professor of ecology and evolutionary biology at University of Colorado at Boulder.

 

hair-ice

Nature’s toupee: fungus weaves astonishing hair-ice

For over a century since it was described, a peculiar type of ice known as hair-ice or ice wool has been puzzling scientists. Now, the mystery seems to have been solved. The uncanny fine hairs of ice, which are only 0.02 mm thick and can grow to 20 cm in length, are actually caused by a fungus.

hair-ice

Image: Christian Mätzler

If this is the first time you’ve heard of hair-ice, you’re not alone. It’s quite a rare event. It only grows in latitudes between 45 and 55 degrees N in the forests where there are particular conditions for humidity. Typically, you’ll find these growing during the chilly mornings right before the sun rises and melts them, and only on  the surface of the unfrozen wood body of certain moist and rotten branches of broad-leaf trees.

 

In 1918, a German scientists called Alfred Wegener  first proposed that these amazing hair-ice crystals which follow a surprisingly orderly structure are caused by a fungus. Wegener and his assistants noticed a whitish cobwebby coating on the surface of the hair-ice bearing rotten wood. Upon closer examination, the coating was found to be a mycelium  – a mass from which fungus grows.

Many years later, retired Swiss professor Gerhart Wagner proved there’s a relation between the fungus and the beautiful cotton-ice that grows trees. Him and colleagues treated samples of hair-ice bearing wood with fungicides or dunked them in hot water and found the ice crystal formation in thin hairs was suppressed. After carefully analyzing the wood samples with microscopic techniques, Wagner and colleagues discovered eleven different species of fungus. Only one fungus was found present in all samples, a species called  Exidiopsis effusa

hair-ice fungus

Image: Gisela Preuß

Christian Mätzler from the Institute of Applied Physics at the University of Bern in Switzerland, a close collaborator of Wagner, found the ice is formed by a process known as ice segregation.

“Liquid water near the branch surface freezes in contact with the cold air, creating an ice front and sandwiching a thin water film between this ice and the wood pores. Suction resulting from repelling intermolecular forces acting at this wood–water–ice sandwich then gets the water inside the wood pores to move towards the ice front, where it freezes and adds to the existing ice,” Mätzler explains.

So, basically the shape of the ice is determined by the tiny pores found in the rotten wood. It’s like the ice gets extruded, much like a 3D-printer jets plastic through its nozzle. But where does the fungus come in all this? Chemical analysis suggests the samples contain  lignin and tannin, which are metabolic products of fungal activity. It may be very well that these components prevent large ice crystals from forming, retaining the clear and beautiful hair-like appearance. The findings appeared in the journal Biogeosciences.

Fungal Disease Kills 5 million North American bats in only Seven Years

In just 7 years, a disease called white-nose syndrome has killed more than 5 million North American bats, almost wiping out entire colonies. The disease has been reported in caves and mines of 25 states throughout the Northeastern U.S. and no treatment or practical way of halting the disease has been proposed.

The disease is caused by a fungus, Pseudogymnoascus destructans, which colonizes the bat’s skin. The disease is responsible for killing somewhere between 5 and 7 million bats. Even though several compounds (antifungals, fungicides, and biocides) where shown to effectively inhibit the growth of the fungus, there is no plan to actually fight the disease. The fungus was first described in 2006.

Bat suffereing from white nose syndrome. Image via Caving News.

A new study has quantified the damage done to bat colonies by the fungus, and their findings are extremely worrying. Before the emergence of the disease, colonies in the US were approximately 10 times more numerous than their European counterparts – but now, it’s almost the other way around, with population decline ranging between 60 and 98 percent.

To make this even more disturbing, bats also provide valuable environmental services; as nighttime insect predators, they are considered some of the most valuable non-domestic creatures from an economic point of view. A drop in the number of bats will lead to a rise in the number of mosquito and pests, ultimately leading to financial damage and human diseases. There is also a risk of the spores contaminating humans as well.

The US Fish & Wildlife Service (USFWS) has called for a moratorium on caving activities in affected areas and strongly recommends to decontaminate clothing or equipment in such areas after each use. Cave management and preservation organizations have been requesting that cave visitors limit their activities and disinfect clothing and equipment that has been used in possibly infected caves.

If you are visiting a cave with a bat colony, please pay extra attention to decontaminating your clothes, or, if not possible, don’t visit it at all.

Source: Science Mag

Zombie ant fungi ‘know’ brains of their hosts

A while ago, we were telling you about the infamous “zombie ant fungus” – a parasitic fungus that reproduces by manipulating the behavior of ants. It’s one of the most gruesome acts in nature – the parasite fungi infect tropical ants, literally taking control of their actions, ultimately leading the infected ant to march to its death at a mass grave near the ant colony, where the fungus spores erupt out of the ant’s head so it can spread even further, infecting more ants. Now, a new study has shown that the fungus knows how to differentiate between ant species, emitting mind controlling chemicals only when it infects its natural target host.

Zombified ant – image via Wired.

The finding suggests that the fungus “knows” its target, offering more light into this rather poorly understood phenomenon.

“Fungi are well known for their ability to secrete chemicals that affect their environment,” noted lead author Charissa de Bekker, a Marie Curie Fellow in Penn State’s College of Agricultural Sciences, and Ludwig Maximilian of the University of Munich. “So we wanted to know what chemicals are employed to control so precisely the behavior of ants.”

The Ophiocordyceps fungus infects many species of fungus, so it’s quite curious that it only exerts its mind controlling abilities on one of them; even though it infects and kills other species as well, it can’t influence their behavior.

“The brain of the target species was the key to understanding manipulation,” de Bekker said.

In order to figure out how this works, they removed ant brains and artificially kept them alive in the lab, exposing them to the fungus.

“This was ‘brain-in-a-jar’ science at its best,” said co-author David Hughes, assistant professor of entomology and biology, Penn State. “It was necessary to reduce the complexity associated with the whole, living ant, and just ask what chemicals the fungus produces when it encounters the ant brain.

“You don’t get to see a lot of behavior with fungi,” he said. “You have to infer what they are doing by examining how they grow, where they grow and most important, what chemicals they secrete.”

While analyzing this interaction, the team found thousands of unique chemicals, most of them completely unknown to science.

“There is no single compound that is produced that results in the exquisite control of ant behavior we observe,” de Bekker said. “Rather, it is a mixture of different chemicals that we assume act in synergy.

“But whatever the precise blend and tempo of chemical secretion,” she said, “it is impressive that these fungi seem to ‘know’ when they are beside the brain of their regular host and behave accordingly.”

Though remarkable, the finding isn’t surprising – such a complex, behavior altering mechanism was bound to have a complicated underlying mechanism. Hughes notes:

 “This is one of the most complex examples of parasites controlling animal behavior because it is a microbe controlling an animal — the one without the brain controls the one with the brain. By employing metabolomics and controlled laboratory infections, we can now begin to understand how the fungi pull off this impressive trick.”

Furthermore, they also found that this phenomenon isn’t restricted to the tropical areas, as initially proposed – it also happens in North America.

Journal Reference: Charissa de Bekker, Lauren Quevillon, Philip B Smith, Kim Fleming, Debashis Ghosh, Andrew D Patterson and David P Hughes. Species-specific ant brain manipulation by a specialized fungal parasite. BMC Evolutionary Biology 2014, 14:166  doi:10.1186/s12862-014-0166-3

Cuban treefrogs. Photo: oseph Gamble

Hundreds of amphibian species all over the world killed by fungus infection, but there may yet be hope

Since the 1990s, biologists have witnessed a sudden demise of amphibian species. So far, hundreds of species have become extinct after becoming plagued by a wretched fungus. From mountain lakes to meadow puddles, no matter the continent, frogs are dying everywhere – a demise that might spell an ecological meltdown. There may still be hope yet, according to a recent study which found frogs can learn to fight and adapt to the killer fungus under certain conditions. If needed, the findings provide a solid basis for potential future efforts to interfere in the pandemic and save the world’s amphibians.

A killer fungus

Chytrid fungus, Batrachochytrium dendrobatidis.

Chytrid fungus, Batrachochytrium dendrobatidis.

Batrachochytrium dendrobatidis, Bd for short, is the fungus in question. Its spores land on the skin of amphibians, burrowing down deeper under the skin where it releases a poisonous toxin that slowly kills the host by paralyzing the immune cells. Since the fungus and its killing behaviour were first observed, scientists hypothesize the infections may have driven hundreds of species extinct. The death toll could increase by a couple of orders of magnitude if the phenomenon is left unchecked and a critical point is reached.

Amphibians are a vital part of the ecological food chain. They feed on mosquitoes and all sorts of insects, and their own turn make up an important food source for birds and other small animals. For instance, in the forests of the northeastern United States, the biomass of amphibians outweighs birds, mammals and all other vertebrates. If Bd is left unchecked, however, the world’s ecosystems, especially the fragile ones, could become seriously threatened.

The past two decades has seen a lot of studies on Bd published, which have significantly helped solve the problem by broadening our understanding of the fungus – how it infects its host, how it kills it, how it multiplies, genetics and so on. We’ve also learned that some amphibian populations have learned to fight Bd and even resurface after being nearly wiped out.

Will those who survive be the key?

Cuban treefrogs. Photo: oseph Gamble

Cuban treefrogs. Photo: oseph Gamble

Jason R. Rohr, an expert on the fungus at the University of South Florida, and colleagues believe these recovering amphibians produce a much stronger immune system in response to the Bd infection. To test this theory, several Cuban tree frogs were infected with Bd spores then inserted  in a heated chamber where they stayed at 86 degrees for 10 days. Heat kills the fungus, and the researchers repeated the procedure three times.

Exposing the frogs to Bd this many times significantly improved their immune response. They produced more immune cells, and the fungus produced fewer spores. Thus, exposed frogs had a much better chance of surviving an infection than a novice. Moreover, the immune response became stronger after each exposure.

Dr. Rohr and team also found that the frogs could avoid infections altogether by staying away from the fungus. In the experiment that proved this fact, oak toads were inserted in a double sided chamber; one side was contaminated with fungal spores, while the other was fungus-free. They found that toads that had never been exposed to the fungus would explore both sides of the chamber, becoming infected along the way. The toads that were previously exposed to the infection (then treated with heat as in the first experiment) tended to avoid the infected side of the chamber.

These experiments show that it is possible for amphibian populations to beat the fungus. It’s highly plausible that some infected specimens in the wild had managed to beat the infection by taking refuge in a warm spot. After that, these survivors stayed away from future infections and passed this information to offspring.

Resurfaced frog populations gives credence to this idea, but let’s not get ahead of ourselves too much. The odds are still in the favor of the Bd fungus, but is there anything we can do? Dr. Rohr says spraying populations with dead Bd spores might improve their chances of survival when hit by Bd infections. Karen R. Lips of the University of Maryland is skeptical of this particular solution, citing the fact that wild amphibians are already exposed to both live and dead spores. “We live in a Bd world,” she said. Even so, “any evidence that some amphibians are surviving with disease is good news,” she said.

The findings appeared in the journal Nature.

The huge bread nuking microwave machine. (c) BBC

Microwave technique makes bread last for 120 days, without chemical or other preservatives

Fresh sliced bread

About one in three breads is thrown away because it gets too tough and infected, and thus inedible, because of mold. Scientists at an American company have found a way to keep bread fresh for up to two months after they zapped it in a sophisticated microwave array. This killed the bacteria and fungi that lead to mold formation.

Typically, if not frozen, a loaf of bread may last for up to seven days. In a world where 15 million children die each year from hunger, the develop world throws away some 40% of its food. In money that’s $165bn in the US alone.

When bread is concerned, its biggest threat is mold, which is caused by a fungus called Rhizopus stolonifer. This fungus thrives off the moisture garnered from evaporated water from the bread, which is usually wrapped in plastic bags, ironically creating ideal conditions. Manufactures try to keep the bread unspoiled from as long as possible by adding preservatives, then add extra chemicals to compensate for the lack of taste.

The huge bread nuking microwave machine. (c) BBC

The huge bread nuking microwave machine. (c) BBC

An US based company called Microzap used a giant metallic microwave device that resembles an industrial production line to zap a slice of bread and kill the mold spores in around 10 seconds. The device is typically used to kill bacteria such as MRSA and salmonella, but the researchers discovered it works just as well for bread munching bacteria as well.

“We treated a slice of bread in the device, we then checked the mould that was in that bread over time against a control, ” Microzap chief executive Don Stull explained.

“And at 60 days it had the same mould content as it had when it came out of the oven.”

It won’t work at home

The machine isn’t quite like your home microwave oven, though, so you won’t be able to make this work for you.

“We introduce the microwave frequencies in different ways, through a slotted radiator. We get a basically homogeneous signal density in our chamber – in other words, we don’t get the hot and cold spots you get in your home microwave.”

The device seems like a godsend for bread manufactures around the world, since it would allow bread to last for a longer time, while also cutting back chemical use. Some are worried, however, that this might up the cost of bread in an already tight margin industry. In the end, it’s all up to the consumer. Hopefully nuked bread won’t stir them away from the shelf.

“We’ll have to get some consumer acceptance of that,” Stull said. “Most people do it by feel and if you still have that quality feel they probably will accept it. “

via BBC

 

Zombie-ant fungus infection

Hyper-parasite defends ant colonies from zombie-ant fungus

Last year, we reported on one of the most gruesome and horrific acts that goes on in nature; it seems so unreal, like if some sort of SciFi monstrous scenario transcended into the realm of reality, that one has a hard time wrapping his head around it. Yes, as some of you might have read previously, I’m talking about the zombie-ant fungus or Ophio­cordy­ceps. These parasite fungi infect tropical ants, literary taking control of their actions, ultimately leading the infected ant to march to its death at a mass grave near the ant colony, where the fungus spores erupt out of the ant’s head so it can spread even further.

Zombie-ant fungus infection Now, scientists at Penn State University who have been studying interactions between the zombie-fungus and their host ants have found that there’s a third player at work. Coming to the rescue of the tropical ants, it seems, is another fungi – a parasite of parasite, typically referred to as an hyper-parasite. So, the counter-par­a­sites keep the first one in check and help pre­vent it from over­run­ning en­tire ant col­o­nies.

“In a case where biology is stranger than fiction, the parasite of the zombie-ant fungus is itself a fungus — a hyperparasitic fungus that specializes in attacking the parasite that turns the ants into zombies,” Hughes said. The research will be published in the journal PLoS ONE.

“The hyperparasitic fungus effectively castrates the zombie-ant fungus so it cannot spread its spores,” said Hughes, who is an assistant professor of entomology and biology, and a member of the Center for Infectious Disease Dynamics at Penn State. “Because the hyperparasitic fungi prevents the infected zombie-ant fungus from spreading spores, fewer of the ants will become zombies.”

The team of biologists, lead by Hughes, created a detailed model which offered extra insights regarding the fungus-infected ants and the parasite-infected zombie-ant fungus interaction. Previously, scientists had known that ants ward off infections by carefully grooming each other, now the model reveals the effect of ant behavior on limiting infection. Nature often sends in unexpected allies to aid those threatened by atypical enemies.

“Interest­ingly, be­yond the well-known ef­fect of de­fen­sive ant be­hav­ior, our new re­search re­veals the added ef­fect of the cas­trat­ing ac­tions of the hyperpar­a­site fun­gi, which may re­sult in sig­nif­i­cantly lim­it­ing the spread of the zom­bie-ant fun­gus,” Hughes said.

The sci­en­tists re­port that only about 6.5 per­cent of the spore-producing or­gans of the zom­bie-ant fun­gus were vi­a­ble.

“Even though there are a lot of dead and in­fected zom­bie ants in the neigh­bor­hood, only a few of the spores of the zom­bie-ant fun­gus will be­come ma­ture and able to in­fect healthy ants,” Hughes said. “Our re­search in­di­cates that the dan­ger to the ant col­o­ny is much smaller than the high dens­ity of zom­bie-ant ca­dav­ers in the gra­veyard might sug­gest. This com­plex in­ter­ac­tion be­tween ant col­o­nies, their brain-mani­pu­lat­ing par­a­sites, and oth­er fun­gi capa­ble of lend­ing as­sis­tance to the col­o­ny un­der­scores the need to study so­cial in­sects un­der nat­u­ral con­di­tions.”

The findings were reported in the journal PLoS ONE.

source: Penn State University