The investigation was designed to analyze how DNA breaks are repaired in the space environment. The student team developed their approach after recognizing that astronauts face an increased risk of cancer when they return to Earth after long-term spaceflight. This increased risk stems from DNA damage that isn’t repaired correctly, previous research has suggested.
“We decided we wanted to really understand what happens to DNA repair pathways in space,” said Vijayakumar, now a junior at Yale University studying molecular biophysics and biochemistry. A separate device called MinION was able to sequence the repaired DNA in the copies. By sequencing the DNA, the astronauts were able to determine that it was correctly repaired — all in the absence of gravity.
The experiment involved using CRISPR/Cas9 in yeast cells to create double-strand breaks at a particular place in the yeast genome. The astronauts waited to allow the cells to repair the damage they caused. Then, the team produced copies of this repaired section of the DNA using a technique known as polymerase chain reaction, or PCR, in an onboard tool called miniPCR. The entire experiment took place in space, without the requirement of returning any cells to Earth for further analysis. The Genes in Space-6 team waited for a visual marker as confirmation that CRISPR successfully edited the cells. When the astronauts picked up the plate, they observed a single red colony, the signal the team was hoping to see.
“The double strand breaks that this experiment simulated by using CRISPR is something that occurs with astronauts because of the galactic cosmic ray radiation component,” Koch said. “And that’s something that’s very difficult to shield against when you’re out in space.” When we’re on Earth, DNA is protected from damage by the planet’s atmosphere and magnetic field. When astronauts leave Earth, their DNA is at risk from sustaining damage. If the DNA repairs itself incorrectly, mutations can occur.
“We were able to verify for the first time that CRISPR/Cas9 does successfully cut in space and establish this amazing gene editing tool in space for the first time,” Vijayakumar said. “It helps set up this whole molecular biology toolbox and workflow that can later be used to hopefully answer our original questions and so many other questions.” The student team was able to watch the astronauts conduct the experiment in space in real time. The four students also had the opportunity to work with scientists on their experiment as well as pulling together the results for publication.
“We set limits on the radiation exposure that a given astronaut is allowed to experience during their spaceflight career based on the science of what the implications of that radiation is, so it’s a big component of deep spaceflight missions and understanding how long we can take those missions.” The results of the experiment were published in a study in the journal PLOS ONE in June. These findings can provide a model for future DNA research studying cell repair, as well as help facilitate countermeasures or potential pharmaceutical treatments. It also sets up the potential for enabling further genome editing in space. “It’s something that we are very cognizant of as astronauts for both long-duration, low-Earth-orbit spaceflights but also deeper space flights going to the moon and Mars,” Koch said.
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