Biological Research in Canisters-17-2: Understanding Anoxic Response in Arabidopsis (BRIC-17-2) - 07.28.16
The Biological Research in Canisters (BRIC) hardware supports a variety of plant growth investigations. The Biological Research in Canisters-17-2: Understanding Anoxic Response in Arabidopsis investigation focuses on the growth and development of Arabidopsis seeds in microgravity. Specimens are preserved with a chemical fixative and returned to the ground for post-flight evaluation. Science Results for Everyone
Information Pending Experiment Details
Simon Gilroy, Dr., University of Wisconsin, Madison, WI, United States
NASA Kennedy Space Center, Cape Canaveral, FL, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
September 2012 - March 2013
- Biological Research in Canisters-17-2: Understanding Anoxic Response in Arabidopsis provides a better understanding of how space flight affects gene expression related to oxygen limiting conditions in Arabidopsis seedlings.
- BRIC-17-2 seeks to determine how many responses observed on orbit can be explained by oxygen limiting conditions and/or disruption of gravity sensing mechanisms or a combination of both.
- This investigation advances understanding of the development of anoxic response in space and earth, and to possibly develop potential genetic engineering countermeasures to this stress.
The major goal of this project is to define the responses of plants to the stresses inherent in space flight. The lack of buoyancy-driven convection (air flow) in microgravity can lead to depletion of oxygen in unstirred regions, such as around plant roots. This observation leads to the hypothesis that some of the alterations in plant growth observed in space relate to anoxic stress, i.e. the stress induced by limited oxygen availability. Preliminary results from a project funded by the National Science Foundation strongly suggest a role for Calcium ion (Ca2+ ) signaling in the anoxic response of the Arabidopsis plant. Two cellular Ca2+ transporters have also been identified, named ACA1 and CAX2 that when mutated lead to plants showing enhanced resistance to low oxygen stress on Earth. These mutants also provide a tantalizing hint of cross-talk between the gravity and anoxia sensing systems through this Ca2+ signaling network as they also show reduced gravity-directed directional growth (gravitropic response). This Biological Research in Canisters-17-2: Understanding Anoxic Response in Arabidopsis experiment tests the central hypothesis that anoxic response induced in the space flight environment operates through Ca2+-dependent signaling that involves the action of the Ca2+ transporters ACA1 and CAX2. It is also predicted that if anoxic challenge is a significant element influencing plant growth in space, mutants in these two genes survive better than the wild-type plants.
These ideas are tested by germinating and growing wild type and the ACA1 and CAX2 mutants on the International Space Station (ISS) in the BRIC hardware and then using DNA microarray technology to compare gene expression profiles in these plants. This approach defines the pattern of molecular responses to the space flight environment. These gene expression fingerprints are compared with ground-based controls grown at a range of known reduced oxygen levels to ask to what extent the patterns seen in space can be explained by response to a defined anoxic stress. In addition, it is speculated that the anoxia and gravity sensing systems of the plant interact through shared Ca2+ response elements and so anoxic response systems may themselves be altered through disruptions of the plant gravity sensing machinery in microgravity. By comparison of the gene expression profiles from the space flown material to a second set of ground-based controls where gravity response is disrupted by, slowly rotating the plant on a fixed surface, so as to approximate a microgravity environment (clinorotation), the extent to which response to anoxic challenge may be modified by altered gravity sensing events in the plant are also assessed.
Together these results should allow the cataloging of gene expression changes elicited by the stresses of space flight and assessment of the degree to which anoxic stress represents a significant component of this stress environment. This research also tests whether genetic engineering of the Ca2+ response pathway through ACA1 and CAX2 represents a valid strategy towards developing plants resistant to the stressful environment of space flight.
The BRIC-PDFU hardware provides the capability to grow seedlings and cell cultures, deliver water and RNAlater in one piece of hardware without the need for a glovebox. This approach minimizes resources such as volume, mass and crew time.
As with all basic research, an improved understanding of basic growth phenomena has important implications for improving growth and biomass production on Earth and thus will benefit the average citizen.
Operational Requirements and Protocols
Must be imbibed within seven days of docking to the ISS (first actuation). Fixation with RNAlater must occur eight days after first actuation (second actuation). After fixation, the two BRIC canisters must be transferred to the MELFI for freezing of the samples at-20 °C or less. The samples are good for months if kept at -20 Degree Celsius. Frozen samples are planned for return on the same SpaceX mission as launched. No downlink of data is required.
At an experiment-specific time point, the BRIC-17-2 payload hardware (BRIC canisters, Actuator Tool and Rod Kit) is accessed for actuation per operational requirements specified above. A rod is removed from the Rod Kit and inserted into the BRIC-PDFU Actuator Tool. The BRIC-PDFU Actuator Tool is attached to the selected BRIC-PDFU canister lid first position and is used to mechanically force either water or RNAlater into the Petri dish volume. Twenty-four hours after fixation, the BRIC canisters must be transferred to the MELFI for freezing of the samples at -20 deg. C or less.
Decadal Survey Recommendations
Plant and Microbial Biology P2
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Ground Based Results Publications
Choi W, Toyota M, Kim S, Hilleary R, Gilroy S. Salt stress-induced Ca2+ waves are associated with rapid, long-distance root-to-shoot signaling in plants. Proceedings of the National Academy of Sciences of the United States of America. 2014 April 29; 111(17): 6497-6502. DOI: 10.1073/pnas.1319955111. PMID: 24706854.