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This 200-Acre, ‘Humungous Fungus’ May Help Unravel Why Cancer Genes Are Unstable

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the individual mushrooms of  Armillaria

The individual mushrooms on this 200-acre fungus only live a few weeks, but the organism itself has been around for some 2,500 years, scientists think. (Credit: Johann Bruhn)

In the mid-’80s, scientists discovered a giant fungus growing in Michigan’s Upper Peninsula. Now, researchers have found the organism is at least 2,500 years old. And the secret to the mushroom’s longevity might be a genome that’s highly resistant to mutation, the team reports today in the journal Proceedings of the Royal Society B. The discovery could help researchers figure out why cancer genomes are so unstable.

Forest Recycler

In 1983, Johann Bruhn planted red pines in the forest. Within the next few years, the trees began to die. The trend continued for about 15 years. Bruhn, a forest health specialist at the University of Missouri in Columbia, traced the trees’ deaths to a species of honey mushroom dubbed Armillaria gallica, a parasitic fungus that preys on trees weakened by drought, insects and other fungal infections. Bruhn examined the fungus, taking it out of the forest to find out whether a unique clone was responsible for the deaths. That’s when he stumbled on something unexpected.

“It looked like one of these clones … extended off into the forest,” Bruhn said. “We didn’t know how far.”

So he and a team of researchers collected more fungus samples further and further afield. By 1992, the researchers knew the fungus was big. They estimated its mass (about 11 tons) and age (at least 1,500 years-old) and reported their findings in a scientific journal.

But the team hadn’t reached the edge of what became known as the “humongous fungus.” That only happened in the last few years. Now, Bruhn and colleagues estimate the fungus is about 1,000 years older and four times bigger than they previously thought.

mushroom clone sample

An isolated sample of the “humungous fungus” clone. (Credit: Johann Bruhn)

Cancer Contrast

The discovery begged the question: How did it survive for so long and get so big? The researchers suspected that the fungus must be incredibly stable genetically. So the team sequenced the organism’s genome from collected samples.

“It turned out that this fungus, this clone of Armillaria gallica, has an extremely low rate of mutation,” Bruhn said. The find is especially surprising given the fungus is so large. Bruhn and colleagues estimate it spreads through nearly 190 acres of the forest floor.

The individual mushrooms themselves last just a few weeks, but the clone itself, as identified by its genetic code, persists. Bruhn compares it to a redwood tree, where the most ancient wood cells are long-dead. “The defining feature of an individual is its unique genetic code that defines the rule set for its continued existence,” he said. “In this sense, the cell lineage of the humungous fungus dates back to a single sexual mating event roughly 2,500 years ago that defines its way of life.”

And, perhaps most intriguingly, the stability of the mushroom’s genome stands in stark to contrast to cancers, which have radically unstable genetic material.

“Our A. gallica must be at the opposite extreme as cancer,” Bruhn said. The fungus’ mutation rate is “a counterpoint to cancer mutation.”

“It could be an interesting point of comparison,” James Anderson, a population geneticist who co-led the new work with Bruhn, said in a statement. “Cancer is so unstable, mutates at a high rate and is prone to genomic changes, while A. gallica is a very persistent organism with few mutations.”

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Ecology

Today’s letters: ‘Visionary’ plans don’t always work in Ottawa

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The opinion piece written by Tobi Nussbaum, CEO of the NCC, declares that a “bold, visionary transit plan” would showcase the capital.

As a long-term resident of Ottawa, I’ve had it with visionary plans. In the 1950s, the streetcars serving Ottawa so well were sent to the scrapyards. In the early ’60s, Queensway construction bulldozed established neighbourhoods and ripped the city apart. Later in the decade, the downtown railway station, which could have formed the hub of a commuter network, was relocated to the suburbs. These actions, in the name of “progress,” were undertaken with the “vision” to make Ottawa a car-reliant city.

Now we have an LRT, built just in time for most people to realize that they do not have to go downtown as they can work from home.

Current thinking is pushing a new “link” between Ottawa and Gatineau, with yet more expensive and disruptive infrastructure projects being touted, including a tramway or another tunnel under the downtown core.

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Ecology

That was then: Biggest earthquake since 1653 rocked Ottawa in 1925

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A regular weekly look-back at some offbeat or interesting stories that have appeared in the Ottawa Citizen over its 175-year history. Today: The big one hits.

The Ottawa Senators were playing a Saturday night game against the Montreal Canadiens at the Auditorium, the score tied 0-0 halfway through the second period. Sens’ rookie Ed Gorman and the Habs’ Billy Boucher had just served penalties for a dustup when the building began to make “ominous creaking sounds.” A window crashed to the ground.

Nearby, at Lisgar Collegiate, all eyes were on teenager Roxie Carrier, in the role of Donna Cyrilla in the musical comedy El Bandido. She had the stage to herself and was singing “Sometime” when the building rocked, the spotlight went out, and someone in the audience yelled “Fire!”

At a home on Carey Avenue, one woman’s normally relaxed cat suddenly arched its back, rushed around the room two or three times, spitting angrily, and climbed up the front-window curtains.

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Ecology

Ottawa delays small nuclear reactor plan as critics decry push for new reactors

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TORONTO — Canadians will have to wait a little while longer to see the federal government’s plan for the development of small nuclear reactors, seen by proponents as critical to the country’s fight against global warming.

Speaking at the opening of a two-day virtual international conference on Wednesday, the parliamentary secretary to the minister of natural resources said the plan will lay out key actions regarding the reactors. Its launch, Paul Lefebvre said, would come in the next few weeks.

“We’re still putting the finishing touches on it,” Lefebvre said. “The action plan is too important to be rushed.”

Small modular reactors — SMRs — are smaller in size and energy output than traditional nuclear power units, and more flexible in their deployment. While conventional reactors produce around 800 megawatts of power, SMRs can deliver up to 300 megawatts.

Proponents consider them ideal as both part of the regular electricity grid as well as for use in remote locations, including industrial sites and isolated northern communities. They could also play a role in the production of hydrogen and local heating.

“SMRs will allow us to take a bold step of meeting our goal of net-zero (emissions) by 2050 while creating good, middle class jobs and strengthening our competitive advantage,” said Lefebvre.

Natural Resources Minister Seamus O’Regan had been scheduled to speak at the conference but did not due to a family emergency.

Industry critics were quick to pounce on the government’s expected SMR announcement. They called on Ottawa to halt its plans to fund the experimental technology.

While nuclear power generation produces no greenhouse gas emissions, a major problem facing the industry is its growing mound of radioactive waste. This week, the government embarked on a round of consultations about what do with the dangerous material.

Dozens of groups, including the NDP, Bloc Quebecois, Green Party and some Indigenous organizations, oppose the plan for developing small modular reactors. They want the government to fight climate change by investing more in renewable energy and energy efficiency.

“We have options that are cheaper and safer and will be available quicker,” Richard Cannings, the NDP natural resources critic, said in a statement.

Lefebvre, however, said the global market for SMRs is expected to be worth between $150 billion and $300 billion a year by 2040. As one of the world’s largest producers of uranium, Canada has to be part of the wave both for economic and environmental reasons, he said.

“There’s a growing demand for smaller, simpler and affordable nuclear technology energy,” Lefebvre said.

Joe McBrearty, head of Canadian Nuclear Laboratories, told the conference the company had signed a host agreement this week with Ottawa-based Global First Power for a demonstration SMR at its Chalk River campus in eastern Ontario. A demonstration reactor will allow for the assessment of the technology’s overall viability, he said.

“When talking about deploying a new technology like an SMR, building a demonstration unit is vital to the success of that process,” McBrearty said. “Most importantly, it allows the public to see the reactor, to kick the tires so to speak, and to have confidence in the safety of its operation.”

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