Detecting DNA in space

[dropcap]I[/dropcap]f there is Christopher Carr, a research scientist in General Hospital (MGH) and Maria Zuber, the E.A. Griswold Professor of Geophysics and MIT, Harvard University and MGH have exposed the heart of their tool—a DNA-sequencing microchip—to radiation doses similar to those that might be expected during a robotic expedition to Mars. After exposure to such radiation—including protons and heavy ions of oxygen and iron—the microchip analyzed a test strain of E. coli, successfully identifying its genetic sequence.

Carr says the group’s results show the microchip can survive up to two years of a Mars mission, it still will be able to sequence.”

The life on Mars, past or present, would have to be extremely resilient: The planet’s atmosphere, made mostly of carbon dioxide, is 100 times thinner than Earth’s, providing very little warmth. Temperatures can plummet to minus 195 degrees Fahrenheit.

On the other hand, the deep subsurface of Mars is not much different from that of Earth, which is known to harbor microbes. Results from the life.

To detect such subterranean life, a DNA-sequencing instrument on the surface of Mars would have to withstand temperature swings and steady exposure to DNA sequences.

Carr and his colleagues tested the effects of Mars-like radiation on a commercially available sequencing chip. The tested chip contains 1.3 million microwells, each of which can hold a single bead containing an amplified fragment of DNA that can be used to generate a DNA sequence.

To test the chip’s resilience to radiation, the team traveled to DNA fragments from E. coli. Despite their exposure to radiation, the chips were able to analyze DNA and correctly identified the bacterial sequences.

“These chips are great candidates to do sequencing on Mars without any modifications that we know of right now,” Carr says. “We essentially see no impact from radiation. That was a critical thing for us to show.”

Chris McKay, a planetary scientist with the Space Science Division of DNA-sequencing chip, such as the one used in this experiment, is a promising candidate for future life-detecting missions to Mars and other planets.

The paper by Carr and colleagues “reports on an important step forward on the development of DNA sequencers for planetary missions,” says McKay, who did not contribute to the research. “In addition to being part of the search for life on other worlds, the DNA searcher would be relevant to assessing sites for DNA sequencing can also withstand similar radiation levels. Taken together, Carr says, the results suggest genetic sequencing may be a viable process in space.

Beyond Mars, Carr says, DNA sequencing may be of interest in places such as Jupiter’s moon Europa, where liquid oceans may harbor signs of life. More promising, Carr says, are places like Enceladus, a moon of Saturn that is thought to be in a potential habitable zone, and that has much less intense radiation.

“I do think we’ll see DNA sequencing in space at some point,” Carr says. “Hopefully we’ll get a chance to be a part of that.”

The paper is titled “Life Detection.”

Jennifer Chu - Phys.org