When the Artemis 1 mission blasts off Monday from the Kennedy Space Center in Florida on its 42-day mission to circumnavigate the Moon, its Orion spacecraft will be uncrewed.
But that doesn’t mean there won’t be passengers aboard.
One University of British Columbia scientist will be watching anxiously as his payload — an experiment containing 6,000 yeast strains — heads out into the black.
When it returns, he’ll perhaps have some clues on how to protect astronauts in the heavens, and how to improve life for cancer patients on Earth.
That’s heady stuff, the sort of which legacies are fashioned. So it’s no small wonder that UBC translational genomics professor Corey Nislow is excited.
In the 20 years that he has been nurturing his yeast strains, through tens of thousands of experiments, they will never have been this far from home.
Eleven years ago, in 2011, when his yeast hitched a ride on the last space-shuttle mission, Nislow had a front-row seat for the launch. He’s not afraid to admit that when the engines roared — when his yeast began its journey to the International Space Station — he cried.
This time, mimicking the 1968 Apollo 8 mission, the spacecraft carrying his yeast will orbit the Moon several times before returning to Earth. It will spend 42 days in space, far from the protection offered by the Earth’s atmosphere and magnetosphere — our planet’s magnetic bubble.
And upon the yeast’s return, it might yield the keys to improving cancer treatments here and protecting astronauts on their way to Mars.
“I watched the Apollo landings and I never in a gazillion years imagined that I would have any connection to it. It’s cool stuff,” Nislow says.
Of important note is that we humans share 50 per cent of our DNA with yeast cells. So information gleaned from Nislow’s yeast is applicable to us, he says.
But the yeast in question — his experimental tool — is extraordinary stuff. It’s mutant yeast.
To create his 6,000 mutant strains, Nislow and his team have snipped out one — and only one — gene sequence from the original strain and replaced it with a unique identifying sequence. Somewhat like a bar code. Six thousand times.
Now, when he introduces an irritant — say a radical change in temperature, or a particular drug — he can see which genes are affected. Using those “bar codes,” he can count the numbers of each strain are left in his experimental sample, and thereby determine which strains might have died, or which showed a slowdown in reproduction.
If one strain of the 6,000 dies off, while the rest survive, he can reasonably determine that the part of the gene sequence that he replaced with the “bar code” is important in dealing with that irritant.
More practically, what he gets from his gene sequencer after such experiments is a profile for that irritant. So, for example, if he treats his yeast specimen with aspirin, he’ll get a particular profile from the sequence — like a spectrograph — and if he later tests an unknown drug, and comes up with the same profile, he can reasonably determine that the drug is aspirin.
Knowing the profiles for the tens of thousands of drugs tested on his yeast, and knowing the functions of its various gene sequences, he can use the information he’s collected over the past two decades to indicate what might be the best drugs to begin trials on for treatment of, for example, COVID or monkeypox.
And that’s all related to why Nislow is sending yeast to the Moon. He wants to learn something about which genes are involved in DNA repair.
Outside of the Earth’s protective cocoon, all things are bombarded with high-energy radiation from the sun, and that can break down and change DNA. So far, we don’t have any kind of practical shielding that can efficiently protect astronauts from this radiation.
“We” — tellingly, Nislow often refers to his yeast in the first person plural — “are going to be exposed to radiation 10 to 20 times the allowable amounts for any terrestrial exposure,” he says.
On Earth, we’re protected by the Van Allen belt, a zone of energetic charged particles held in place by the planet’s magnetic field. (The International Space Centre is in a low enough orbit that it, too, is protected by the Van Allen belt.)
The short duration of their missions — about a week — meant the Apollo astronauts of the 1960s and ’70s weren’t much affected by that radiation, but those who will eventually be going to Mars will be out of the Earth’s magnetic protection for about a year.
“We have a very clear hypothesis to test or negate, and that is that the genes involved in DNA repair will be sensitive (to cosmic radiation),” says Nislow.
He suspects this because experiments he’s done with a particle accelerator bombarding his yeast with high-energy radiation have shown that several gene sequences are sensitive.
“Our bodies and yeast have over 50 genes involved in DNA repair. Our experiments so far have only given us a hint of which ones are important.
“The enumeration that we do after the Artemis samples come back will give us a much clearer picture of the relative roles of all of those DNA repair genes.”
The experiment he’s sent aboard the Artemis mission is, of necessity, a small, entirely self-contained DIY-looking payload. It’s about the size of a shoebox and it’s powered by nine 9-volt batteries.
Inside, over the course of the mission, that yeast will reproduce. A lot.
“I’m excited about sending these particular yeast, because they’re going to go through seven generations,” he says. “In essence, we’re getting a snapshot of what would happen to a human genome over the course of 150 years.”
When Nislow’s payload returns from the moon, with seven new generations of yeast and nine completely dead batteries, the work will be just beginning.
To get data that he can extrapolate to model the exposure of humans to 150 years — seven generations — of cosmic radiation exposure, the prodigal yeast cells will have to be broken down, their DNA retrieved and fed into a gene sequencer.
If Nislow finds a particular gene sequence that seems to be sensitive to radiation, he can pass that on to researchers whose work specializes in that particular gene, in the hopes that they may find ways to treat that gene to be less sensitive to cosmic radiation.
While the applications to space exploration are obvious, there’s a terrestrial benefit too.
In radiation therapy for cancer, the goal is to damage the DNA of cancer cells, without harming that of healthy cells. But though those therapies have gotten better and more specific over the years, cancer patients still suffer a lot of collateral damage.
If researchers could find a way to treat the gene sequences responsible for DNA repair in such a way that they suffer less from the radiation therapy, patients would suffer far fewer side effects.
And that, said Nislow, is still just the tip of the iceberg.
“When these samples come back, they’re going to be a resource, (and) not just for our lab. We’re going to be banking these cells, sharing these cells with the community and sharing all the sequencing data with the community, because we can only analyze a little bit of it.
“There’s a real legacy element to this.
“You know, my parents are still alive, and this is what they get excited about. They always say, ‘Are you still working on yeast?’
“And now I get to say, ‘Yeah, and we sent them to the moon.’”
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