Oxford Nanopore’s GIF of a nanopore reading a DNA strand. Credit: Oxford Nanopore Technologies
As space exploration moves to venture further into the solar system, new technologies are being created. One of these is the ability to analyze genetic material, such as DNA, in space. Typically this requires extensive preparation, complex machinery, and is costly. However, an innovative new device has made its way to the International Space Station.
Able to fit in the palm of a hand, Oxford Nanopore Technology’s minION device is able to sequence DNA. Sequencing is the method of determining the exact order of nucleotides in a DNA and/or RNA molecule.
Deoxyribonucleic acid (DNA) is the molecule responsible for the development and function of an organism. Composed of two paired strands, each individual strand is comprised of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C). Adenosine will always be paired with thymine and guanine with cytosine in what is called a base pair. It is the order of these bases that determines the expression of a gene. Ribonucleic acid (RNA) is similar to DNA but has uracil (U) instead of thymine and is the genetic material found in some viruses such as HIV.
Each organism has a unique number and arrangement of nucleotide bases. Based on this, DNA sequencing can be used to identify an organism. At 3 billion base pairs, sequencing the entire human genome remains expensive and tedious compared to other organsims. Most genetic testing focuses on specific parts of the genome.
MinION uses a hollow tube called a nanopore that is a few nanometers in diameter and made of protein. Nanopores are typically found in the membranes of cells. In the minION device, these nanopores are inserted in a membrane created of a synthetic polymer and is bathed in an electrochemical solution. A potential is applied across this membrane creating an ionic current. As a single strand of DNA is passed through the nanopore, the current changes as each nucleotide passes through. This technology can be used to identify DNA, RNA, and even proteins.
Astronaut and molecular biologist Kate Rubins successfully sampled DNA from a mouse, virus, and bacteria. The genome from these samples has previously been completely sequenced so the researchers would know what a successful DNA sequence reading would look like. All samples were prepared on Earth and sent to the International Space Station. Experiments were conducted both in space and on Earth, validating that the device could survive a trip to space and still work.
The successful demonstration of DNA sequencing in orbit has many applications. This capability allows for the identification of microbes in orbit. Sequencing can be used in the diagnosis of disease to select the proper medication. Researchers are looking into integrating this technology into robotics for future Mars missions to detect life based on DNA and DNA-like molecules.
Now that it has been validated that the device can survive and function in space, the next step will be to do the entire process in space-from sample preparation to sampling. Once this is accomplished researchers will be able to begin to study DNA in the space environment.