The Search for Extra-Terrestrial Genomes

Life beyond Earth could be similar to all known life, e.g. using similar building blocks such as amino acids, proteins, lipids, and informational polymers similar to nucleic acids (DNA, RNA). If it exists, life on Mars could be related to life on Earth due to meteoritic exchange. We are building the Search for Extra-Terrestrial Genomes (SETG), to test this hypothesis during a future life detection (e.g., rover) mission to Mars.

For a technical overview, see these slides, this video, or this paper.

From Synthetic Mars Analog Samples to Point of Care Diagnostics

We have developed Mars analog sediments representing different regions on Mars. We spike in microbes, typically Bacillus subtilis spores, to simulate a life-bearing sample. Using these analogs, we validated manual and automated extraction methods, working with our industrial partner Claremont Biosolutions LLC. These automated methods have great relevance for point of care diagnostics.

For more details: Mojarro A, Ruvkun G, Zuber MT, Carr CE. Nucleic acid extraction from synthetic Mars analog soils for in situ life detection. Astrobiology 2017 Jul 13. doi: 10.1089/ast.2016.1535 PMID 28704064 OpenAccess

Low Input Nanopore Sequencing

To accurately quantify performance, we have tested multiple spore counting methods and developed a method to count single genomes using digital droplet PCR. We recently used this method to demonstrate extraction and sequencing down to the equivalent of 10,000 spores without amplification.

For more details: Mojarro A, Hachey J, Ruvkun G, Zuber MT, Carr CE. CarrierSeq: a sequence analysis workflow for low-input nanopore sequencing. bioRxiv https://doi.org/10.1101/175281

See also: A. Mojarro, J. Hachey, R. Bailey, M. Brown, R. Doebler, G. Ruvkun, M. T. Zuber, C. E. Carr. Nucleic Acid Extraction and Sequencing from Low-Biomass Synthetic Mars Analog Soils. Lunar & Planetary Sci XLVIII, The Woodlands, Texas, March 21-25, 2017. Abstract # 1585 (poster) https://goo.gl/6xeAJJ

Exploring Mars on Earth

To study the limits of life and to test instrumentation we carry out fieldwork at terrestrial analogs of Mars (photos). Examples include:

  • Volcán Copahue, Argentina, an active volcano with acidic iron-rich hydrothermal streams.
  • Haughton Impact Structure, Devon Island, Nunavut, Canada, a 20+ million year old impact crater in a polar desert with low mean annual temperatures.
  • Spotted Lake, Canada, a hypersaline magnesium sulfate rich analog for paleolakes on ancient Mars

Recent work: Pontefract A, Zhu TF, Walker VK, Rowedder H, Lui C, Zuber MT, Ruvkun G, Carr CE. Microbial Diversity in a Hypersaline Sulfate Lake: An Analog of Ancient Mars. Frontiers in Microbiology, 26 Sept 2017 doi: 10.3389/fmicb.2017.01819 PMID 29018418 OpenAccess

See also: A. Pontefract, J. Hachey, A. Mojarro, V. K. Walker, H. Rowedder, T. F. Zhu, C. Lui, M. T. Zuber, G. Ruvkun, C. E. Carr. Understanding Habitability and Biosignature Preservation in a Hypersaline Mars Analog Environment: Lessons from Spotted Lake. Lunar & Planetary Sci XLVIII, The Woodlands, Texzas, March 21-25, 2017. Abstract # 1124 https://goo.gl/YBBRg6

Other significant contributions to date include:

Space Radiation and Biology

The use of biological components in a space instrument is antithetical to prior instrumentation. Biological reagents must survive space radiation, among other challenges. We use several facilities to simulate space radiation and test both biological reagents and hardware. These include:

Educational materials:

(MIT OCW courses developed by others at MIT)

National Academies Press Reports:

A Biological Future

Enabling automation of sample-to-sequence on Earth and in space will have profound impacts from clinical medicine to synthetic biology.

Support: NASA NNX15AF85G