But that doesn’t mean there won’t be passengers on board. A University of British Columbia scientist will watch anxiously as his payload — an experiment containing 6,000 yeast strains — heads for the black. When he returns, he may have some clues about how to protect astronauts in the skies and how to improve the lives of cancer patients on Earth. This is intoxicating, the kind that legacies are made of. So it’s no wonder UBC translational genomics professor Corey Nislow is excited. In the 20 years he has been cultivating his yeast strains, through tens of thousands of experiments, he would never be this far from home. Eleven years ago, in 2011, when his mother embarked on a ride on the final space shuttle mission, Nislow had a front-row seat to 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 its yeast will orbit the Moon several times before returning to Earth. It will spend 42 days in space, far from the protection offered by Earth’s atmosphere and magnetosphere – our planet’s magnetic bubble. And after the yeast’s return, it may hold 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 million years imagined I’d have anything to do with it. It’s cool stuff,” says Nislow. Importantly, we humans share 50 percent of our DNA with yeast cells. So the information gleaned from Nislow’s yeast is applicable to us, he says. But the yeast in question—his experimental tool—is something extraordinary. It’s a mutated yeast. To create his 6,000 mutant strains, Nislow and his team cut out one – and only one – gene sequence from the original strain and replaced it with a unique identification sequence. Sort of like a barcode. Six thousand times. Now, when he introduces a stimulus—say a radical change in temperature, or a particular drug—he can see which genes are affected. Using these “barcodes,” he can count the numbers of each strain left in his experimental sample and thus determine which strains may have died or which have slowed down in reproduction. If one strain out of 6,000 dies, while the rest survive, it can reasonably determine that the part of the gene sequence it replaced with the “barcode” is important for dealing with that irritant. More practically, what one gets from one’s gene analyzer after such experiments is a profile for that irritant. So, for example, if he treats his yeast sample with aspirin, he will get a specific profile from the sequence – like a spectrograph – and if he later tests an unknown drug and finds the same profile, he can reasonably determine that the drug is aspirin . By knowing the profiles of the tens of thousands of drugs tested in his yeast and knowing the functions of its various gene sequences, he can use the information he has collected over the past two decades to suggest what might be the best drugs to start testing. treatment of, for example, COVID or monkey pox. And all of this is related to why Nislow is sending yeast to the Moon. He wants to know something about which genes are involved in DNA repair. Outside of Earth’s protective cocoon, all things are bombarded with high-energy radiation from the sun, and this can break down and change DNA. So far, we don’t have any kind of practical shielding that can effectively protect astronauts from this radiation. “We” — revealingly, Nislow often refers to his yeast in the first person plural — “will be exposed to radiation 10 to 20 times the amounts allowed for any terrestrial exposure,” he says. On Earth, we are protected by the Van Allen belt, a band of energetic charged particles held in place by the planet’s magnetic field. (The International Space Center is in low enough orbit to be protected by the Van Allen belt as well.) The short duration of their missions – about a week – meant that the Apollo astronauts of the 1960s and 70s were not affected much by this radiation, but those who eventually go to Mars will be outside of Earth’s magnetic shielding for about a year. “We have a very clear hypothesis to test or disprove, and that is that genes involved in DNA repair will be sensitive (to cosmic radiation),” says Nislow. He suspects this because experiments he has done with a particle accelerator that bombards his yeast with high-energy radiation have shown that several gene sequences are sensitive. “Our body and yeast have over 50 genes involved in DNA repair. Our experiments so far have given us only a hint of which ones are important. “The enumeration we do after the Artemis samples return will give us a much clearer picture of the relative roles of all these DNA repair genes.” The experiment sent on the Artemis mission is, by necessity, a small, completely self-contained, DIY-like payload. It is about the size of a shoebox and is powered by nine 9 volt batteries. Inside, during the mission, this yeast will reproduce. Very. “I’m excited to send this particular yeast, because it will go through seven generations,” he says. “Essentially, we’re taking 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 have just begun. To get data he can extend to model people’s exposure to 150 years – seven generations – of cosmic radiation exposure, the yeast cells will have to be broken up, their DNA recovered and fed to a gene sequencer . If Nislow finds a particular gene sequence that appears to be sensitive to radiation, he can pass it on to researchers whose work specializes in that particular gene, in the hope that they might find ways to make that gene less sensitive to cosmic radiation. While the applications in space exploration are obvious, there is also a terrestrial benefit. In radiation therapy for cancer, the goal is to damage the DNA of cancer cells without damaging that of healthy cells. But although these treatments 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 would suffer less from radiation therapy, patients would suffer far fewer side effects. And that, Nislow said, is still only the tip of the iceberg. “When these samples come back, they will be a resource, (and) not just for our lab. We’re going to commit those cells, we’re going to share those cells with the community, and we’re going to share all the sequencing data with the community, because we can only analyze a small piece of it. “There is a real heritage element to it. “You know, my parents are still alive, and that’s what excites them. They always say, “Are you still working with yeast?” “And now I can say, ‘Yeah, and we sent them to the moon.’ SHARE:
