Astronaut Kate Rubbins Takes Molecular Biology To Space | Sequences DNA For The First Time In Space
DNA sequencing in microgravity. It just happened.
Astronaut Kate Rubins, who also has a background in molecular biology, conducted the test using a miniaturized device that was delivered to the International Space Station just last month aboard the International Space Station.
You might be wondering why we need to test the DNA of astronauts while on missions, beyond that it just sounds cool. Well, according to NASA, it’s to help astronauts diagnose an illness, or potentially identify microbes that might identify a health threat.
The portable sequencer – called MinION – was developed by UK-based Oxford Nanopore Technologies, and allows researchers to identify an organism’s DNA sequence using a technique called nanopore sequencing.
In nanopore sequencing, an electric current is sent through tiny pores in cell membranes to pick up changes in ion flow as DNA molecules pass through the nanopores. These changes can then be used to decode the sample’s DNA sequence.
Rubins used the MiniON sequencer to analyze prepared DNA samples from a mouse, bacteria and a virus. The same analysis was done with equipment down on the ground, with theaim of reading out and matching up the chemical letters of genetic code – that is, adenine, guanine, cytosine and thymine.
“Welcome to systems biology in space,” said Rubins in a statement, after the first few DNA molecules had been successfully sequenced.
“This is a wondrous technical achievement by Oxford Nanopore and NASA. I am proud of UCSC’s key role in helping build the foundation that made it possible,” said Mark Akeson, professor of biomolecular engineering at UC Santa Cruz.
Charles Chiu, MD, PhD, director of the UCSF-Abbott Viral Diagnostics and Discovery Center, who led the team at UCSF said “Up until recently technology for sequencing in space hasn’t been available because sequencers are generally large bulky instruments.”
Chiu said a big unknown was whether the microgravity in space would affect the microfluidics of the sequencing device.
“It didn’t turn out to be a huge problem,” Chiu said. His team’s analysis of the space and Earth data found comparable results. “We essentially got equivalent data, and it’s of very high quality, probably within the top 20 percent of nanopore runs that we do routinely here on Earth,” Chiu said.
In this initial proof-of-principle experiment, the samples were prepared on Earth and researchers selected organisms whose DNA has already been completely sequenced so that they knew what results to expect.
Using the device in the microgravity environment introduces several potential challenges, including the formation of air bubbles in the fluid, according to Aaron Burton, NASA planetary scientist and principal investigator.
On Earth, bubbles rise to the top of a liquid solution and can be removed by centrifuge, but in space, bubbles are less predictable.
“In space, if an air bubble is introduced, we don’t know how it will behave. Our biggest concern is that it could block the nanopores,” said Burton.
As the researchers compare results from the sequences collected in microgravity and on Earth, so far everything seems to match up, according to a NASA press release. “A next step is to test the entire process in space, including sample preparation as well as performing the sequencing,” said project manager and NASA microbiologist Sarah Castro-Wallace. Then astronauts can move beyond creating a known DNA sequence and actually extract, prepare and sequence DNA to identify unknown microbes on orbit.
“Onboard sequencing makes it possible for the crew to know what is in their environment at any time,” Castro-Wallace said. “That allows us on the ground to take appropriate action – do we need to clean this up right away, or will taking antibiotics help or not? We can resupply the station with disinfectants and antibiotics now, but once crews move beyond the station’s low Earth orbit, we need to know when to save those precious resources and when to use them.”
In addition, the sequencer can become a tool for other science investigations aboard the station. For example, researchers could use it to examine changes in genetic material or gene expression in orbit rather than waiting for the samples to return to Earth for testing.
The MinION, made by Oxford Nanopore Technologies, has been employed at field laboratories in some of the remotest areas on Earth – and may someday take a trip to Mars.