Yeast and humans have a lot in common. That’s why these Canadian scientists are sending some into space | TSWT News


When NASA’s Artemis 1 lifts off from a Florida launch pad as soon as Monday, it won’t take a human crew on a 42-day mission to orbit the moon and return to Earth. But experiments aboard the rocket could lead to solving an annoying problem that stands in the way of long-term human spaceflight: cosmic rays.

University of British Columbia pharmaceutical scientist Corey Nislow was just a toddler when Apollo 11 landed on the moon in 1969. the Van Allen belts around the planet.

Apollo 17, the last human journey to the moon completed 50 years ago in December, took just 12 days.

“Once you exit the safety of the Van Allen belts,” Nislow said, “there is currently no shielding available that can protect biological material, including crew members, from the effects of cosmic rays.”

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Those effects can include everything from an increased chance of developing cataracts to cancer. The International Space Station (ISS) is in low Earth orbit (LEO) and astronauts aboard the ISS are in Earth’s protective magnetosphere.

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NASA says the goal of the Artemis program is to land on Mars one day. But first, the space agency needs Artemis missions to land on the moon again.

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But extended missions to the moon and what NASA expects could be a nearly two-year return trip to Mars pose serious risks.

“Frankly, if we go to Mars, a return trip will expose a crew member to 10 to 100 times the allowable radiation limit,” Nislow said.

1st biological material out of Earth’s orbit in 50 years

The work Nislow and his collaborators are doing with NASA to mitigate the effects of cosmic rays will send the first biological material out of Earth’s orbit in 50 years. And the substitute for flesh-and-blood astronauts is something most people have in their pantry: yeast.

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“Although yeast and humans are separated by a million years of evolutionary time, half of all yeast genes function almost identically to human genes,” Nislow said.

Yeast, a single-celled microorganism, has about 6,000 genes. Nislow, who holds the Tier 1 Canada Research Chair in translational genomics, says the yeast cells in the experiment aboard the Orion spacecraft atop Artemis 1 were individually altered to produce 6,000 genetically unique versions. Each version has a different gene deleted and replaced with a short splice of unique TSWT known as a barcode, making it easy for researchers to identify and track the variant.

UBC pharmaceutical scientist Corey Nislow says that once the spacecraft leaves the Van Allen belts around Earth, the crew members on board will no longer have protection from cosmic rays. (Corey Nislow)

Once the spacecraft is out of protection from Earth’s magnetic field, the dried yeast will be rehydrated remotely, allowing it to grow and divide while being bombarded with cosmic rays. Five or six weeks later, when the spacecraft crashes into the Pacific Ocean, the shoebox-sized container that contains the experiment will be recovered and returned to Nislow’s lab at UBC. The hope is to find individual genes in the cells that have withstood the radiation or been able to repair any damage.

“And then we can ask what drugs or chemicals at our disposal can help reduce the sensitivity of a particular gene and that’s where we can look at countermeasures,” Nislow said.

Yeast cells are the perfect astronauts

It’s a fascinating opportunity, according to Prof. Doug Boreham, a radiation biologist at the Northern Ontario School of Medicine in Sudbury.

“They’re going to look at survival when they get these things back, which is very cool,” Boreham said, noting that yeast cells make the perfect astronauts. “They don’t have to breathe. They don’t need water. They don’t eat. They don’t care what temperature it is. But still they live.’

The interior of the shoebox-sized yeast experiment aboard Artemis 1 is on display prior to final assembly at Kennedy Space Center in Florida. (Corey Nislow)

In fact, yeast cells are such ideal surrogates for humans that they are at the heart of another experiment aboard Artemis that Boreham and his colleagues are helping to support. BioSentinel is a small satellite the size of a cinder block that will be deployed in deep space. It contains yeast samples that are rehydrated in stages over a period of weeks using a blue nutrient solution.

The solution will turn pink as the yeast is metabolized and an onboard optical sensor will measure the color changes. Cells that cannot repair the damage of cosmic rays will be less pink and more blue. But the monsters will not return to Earth for study. BioSentinel transmits the data as it orbits the sun until it runs out of power.

Douglas Boreham, a radiation biologist and chief of medical sciences at the Northern Ontario School of Medicine in Sudbury Ontario, said yeast cells make the perfect astronauts. (NOSM 2018)

Boreham is involved in the project science, saying it involves comparing data from BioSentinel with samples grown simultaneously at his university and two kilometers underground at Canada’s deep underground research facility, SNOLAB.

“We’re looking at the fundamental mechanisms involved in cells that manage and repair the effects of cosmic rays,” Boreham said, recognizing that there are limitations to the experiments.

Single-celled organisms like yeast just want to grow and divide, he says. However, human cells can ‘communicate’ with each other. Human cells exposed to stress and damage such as radiation create free radicals, which boost our immune system. Humans also have tumor suppressor genes, which can cause the self-destruction of cells that can no longer be repaired.

“You don’t get that in a yeast model,” Boreham said.

‘Very important experiments’

But it’s all critical work, according to Canadian astronaut Dr. Roberta Bondar.

“Those are very, very important experiments and those are things we need to do very quickly,” Bondar said.

Bondar, a neurologist, flew aboard NASA’s space shuttle Discovery 30 years ago and then analyzed the health data of astronauts from 20 missions. She says the effects of radiation on a prolonged spaceflight could harm the mission.

“So that includes things like altered cognitive functions or maybe even impaired motor functions and behavioral changes,” Bondar says. “These are things that would be scary in a closed environment in some kind of spacecraft.”

Nislow believes it would be unethical to send humans on a space journey of more than a year until a way to reduce those radiation risks is found.

And he hopes that experiments with one of the oldest life forms on Earth will make it possible for humans to travel safely to other worlds.

“Without being hyperbolic, it’s a very, very important step.”


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