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.
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:
- Ultra Portable Nanopore Sequencing (<200 grams).
- Simulation of Mars using Thermal Vacuum Chamber & Sequencing under Mars-like Conditions.
- Use of space radiation analogs to demonstrate robustness of biological reagents and sequencing chips.
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:
- Brookhaven National Lab RadWorker I Training Guide
- MIT OCW 22.01 Introduction to Ionizing Radiation
- MIT OCW 22.101 Applied Nuclear Physics
- MIT OCW 22.106 Neutron Interactions and Applications
(MIT OCW courses developed by others at MIT)
National Academies Press Reports:
- Radiation Hazards to Crews of Interplanetary Missions: Biological Issues and Research Strategies (1996)
- Managing Space Radiation Risk in the New Era of Space Exploration (2008)
- Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation (2012)
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