For the first time ever, DNA sequencing was made possible under conditions of microgravity aboard the International Space Station using the palm-sized MinION device, last weekend. Headed by astrobiologist Aaron Burton, this is the successful culmination of four years of joint effort between talented people working in the Biomolecule Sequencer Project under NASA and Oxford University.
Sequencing is the molecular equivalent of getting a unique thumbprint for any organism. This can be done by the process of identifying the order of nucleotides within any DNA molecule. Until today, while on the International Space Station, it was difficult to conclusively diagnose any illness among astronauts or identify microbes in their surroundings.
Prior to this project, all samples would have had to be flown down to Earth to be sequenced and identified. This is because, almost all current sequencing techniques are reliant on the effect of gravity.
Nucleotides carry proteins of varying weight. The order of nucleotides is figured out by measuring the different rates of movement of nucleotides through a medium. This is impossible under conditions of microgravity. The MinION DNA sequencing device changed all of this.
The MinION was developed by Oxford Nanopore Technologies in 2014. Weighing only 120 grams, it works by utilising electrolysis to force the DNA strand through the nanopores in the device. By analysing the current changes, the pores which are blocked by the DNA can be identified and the specific DNA sequence can be obtained.
Potential problems included the formation of air bubbles in fluid. With gravity, bubbles rise to the surface and can be removed by centrifugation, but under microgravity conditions, bubbles behave unpredictably. The concern was that these bubbles might block nanopores in place of the DNA strands, giving a false positive.
To prevent other variables, entire sequencing process was tested on a NASA Extreme Environment Mission Operation or NEEMO, in an Aquarium Base research facility located 60 feet underwater off the coast near Florida. Everything went smoothly and only then was the investigation allowed to proceed to testing under space conditions.
Aboard the International Space Station, the experiments were conducted by Astronaut Kathleen Rubins, who has a BSc in molecular biology and a PhD in cancer biology. She sequenced mouse, virus and bacteria DNA on the MinION while researchers sequenced identical samples on Earth. After comparison of results between the sequences in space and on Earth, it was proven that the Biomolecule Sequencer experiment performing under microgravity conditions was a resounding success.
With a way to sequence DNA in space, time will be cut down in examining changes in genetic material or gene expression in orbit or identifying new samples in real-time and calculating its similarity to the human genome. Together, this will help in understanding the physiology of that organism – what would help it grow better, limit its growth or if it is harmful, how it will negatively affect the health of the astronauts. Rather than guesswork, such useful information would allow astronauts to make better decisions in their investigations.
Ultimately, it is hoped that this novel technique would move us closer to understanding the age-old question of understanding the origin of life.
NASA prepares for first-ever in-space DNA sequencing experiment. (2016, July 22). Retrieved from https://www.nasaspaceflight.com/2016/07/nasa-prepares-first-space-dna-sequencing-experiment/
First DNA Sequencing in Space a Game Changer. (2016, August 30). Retrieved from https://www.nasa.gov/mission_pages/station/research/news/dna_sequencing