Yeast colony survival in microgravity depends on ammonia mediated metabolic adaptation and cell differentiation (Micro-9) - 11.15.17

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Science Objectives for Everyone
Yeast cells are used as models for studying human health and illnesses, including cancer, so scientists need to understand normal and abnormal behavior among individual cells and in colonies. Yeast colony survival in microgravity depends on ammonia mediated metabolic adaptation and cell differentiation (Micro-9) studies how microgravity affects yeast cell biology, providing new targets for research or possible methods for treating microgravity’s ill effects.
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Information Pending

The following content was provided by Fathi Karouia, and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Micro-9

Principal Investigator(s)
Timothy G. Hammond, M.B.B.S., Durham Veterans' Affairs Medical Center, Durham, NC, United States

Holly H. Birdsall, M.D., Ph.D., Department of Veterans Affairs Office of Research and Development, Washington, DC, United States
Corey Nislow, seqWell Inc., Beverly, MA, United States
Guri Giaever, Ph.D, University of British Columbia, Canada
Patricia Allen, M.S., US Department of Veterans Affairs, Durham, NC, United States

NASA Ames Research Center, Moffett Field, CA, United States
BioServe Space Technologies, University of Colorado, Boulder, CO, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
NASA Research Office - Space Life and Physical Sciences (NASA Research-SLPS)

Research Benefits
Earth Benefits, Scientific Discovery

ISS Expedition Duration
March 2016 - September 2016

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview
The research to be conducted by Yeast colony survival in microgravity depends on ammonia mediated metabolic adaptation and cell differentiation (Micro-9) examines how spaceflight and microgravity affects yeast cell biology. An understanding of the biological characteristics and functions of yeast cells as both an individual element, and as a component of colonies, is critical for defining diseases and abnormal behavior of organs and tissues. There are similarities between multicellular yeast colonies and tumors of clusters of mammalian cells in tissue culture. Thus insights into the effect of microgravity on cell to cell signaling may have far-reaching applications. It is anticipated that the data from this study can provide further insight into identifying cellular factors that may contribute to crew health risks. The identification of specific cellular factors may provide targets for further research or therapeutic intervention. Microgravity provides a unique cell culture environment, which allows studies of drug metabolism at electrical (redox) states not achievable on the ground. Space based redox states mirror tumor metabolism, giving the studies direct relevance for cancer drug therapy at the clinical bedside.


The Yeast colony survival in microgravity depends on ammonia mediated metabolic adaptation and cell differentiation (Micro-9) objectives are:
  • Specific Aim 1: To evaluate the role of ammonia-based signaling in the cellular and genetic differentiation of giant yeast colonies under simulated microgravity conditions (ground experiments).
  • Specific Aim 2: To determine the role of Msn4 and Sfp1 in the cellular and genetic differentiation of giant yeast colonies with changes in ammonia production under simulated microgravity conditions (ground experiments).
  • Specific Aim 3: To confirm and extend the results obtained in the ground-based studies on the changes in ammonia dependent Msn4 and Sfp1 mediated genetic and cellular differentiation of giant yeast colonies in the true microgravity environment (flight experiment).
The proposed flight experiment tests whether changes in ammonia convection in real, and simulated microgravity, mediate Msn4- and Sfp1-dependent genetic and cellular differentiation of giant yeast colonies. Yeast strains are spotted on Omnitrays, and following temperature activation grow to the size of a quarter over a four week period. Aliquots of up to seven Omnitrays can be placed in each PHAB. A PHAB is a temperature conducting containment device for plates. The Commercial Generic Bioprocessing Apparatus (CGBA) can support up to six plate habitats (PHABs). The clones are strains with normal (wildtype or Sod1Δ), partial (Ctt1Δ), or no (Sok2Δ) ammonia production. With eGFP gene expression reporters for metabolic switch (CIT3, ATO1, ATO3, and JEN1) and Msn4 (SSA4) and Sfp1 (YIL052C) dependence. The first part of Micro-9 looks at GFP expression, with and without ammonia production and removal. Additionally, genome wide analysis are performed using the yeast deletion series of strains on wild type background, SOK-2 deletion (ammonia pathway), and TRR-1 deletion (redox pathway) as a biologically relevant cloning control in order to define the metabolic pathways mediating responses to microgravity. The number of days to incubate the yeast samples in space is determined from the data collected in Specific Aims I, II and the SVT.
  • A cold stowage double transport bag held at 4°C is used to transport samples. The CGBA on board the International Space Station (ISS) is used to incubate the cells at 30°C for the duration of the experiment while on orbit.
  • 5 PHABs with 7 Omnitrays spotted with the heterozygous yeast deletion series on wildtype, TRR1 background, and Sok-2 deletion backgrounds.
  • 1 PHAB composed of 2 Omnitrays, each poured with agar for cell growth and a dye for measuring ammonia with 24 wells for GFP expression, and 5 Omnitrays spotted with the heterozygous yeast deletion series as previously described.

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Space Applications
This investigation studies how yeast cells respond to microgravity by measuring changes in the way they communicate and carry out normal functions. Yeast are model organisms for a variety of biological processes, so understanding how they change during spaceflight provides new information on the potential health risks of long-term space exploration.

Earth Applications
Multicellular colonies of yeast share similarities with large cell clusters used to study cancer. New insights into how microgravity affects cell-to-cell communication in yeast could have implications for a wide range of cancer biology research. In addition, microgravity provides a unique cell culture environment that allows cells to metabolize drugs at rates they could not achieve on the ground. Space-based responses to oxidative stress mirrors the metabolism of tumors, so experiments in this investigation are directly relevant for cancer therapy.

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Operational Requirements and Protocols

The protocol follows steps based on previous successful flight studies. The experiment can be entirely performed merely by modulating the temperature of the cultures within the PHABs. Yeast cells are viable for many weeks quiescent at 4°C. Different strains are spotted on solid agar which has been loaded in a commercial off-the-shelf (COTS) Omnitray. Samples are stored at 4°C during transport, and “activated” and grown at 30°C once on board station. A time course for each yeast strain is completed. There is one time point of 26 days (or as long as vehicle docking will allow). All samples are “terminated” by cooling to 4°C, once time point is reached. Samples are transported back to Earth at 4°C, and returned to PI’s lab as soon as possible.

Once launch vehicle is docked with the ISS, within approximately two days the samples are transferred to ISS and placed into CGBA from the cold stowage transport bag. A CGBA, present on board the ISS, is used to incubate the samples at 30°C. The incubation CGBA is pre-set to activation temperature prior to sample transfer from the docked vehicle.
Pre-Warm CGBA:
The CGBA is commanded to raise temperature to 30°C approximately 24 hours prior to the transfer of the PHABs to CGBA.
All PHABs are inserted into the 30°C CGBA in order to be activated. The end time point occurs on the same day, and the temperature of the entire unit is dropped to 4°C. Subsequently, all PHABs are transferred back to the initial 4°C transport bags, approximately 24 hours before hatch close for return transport back to Earth.
Sample transfer of time course 1 (~28+ days):
S/N:01-06 PHABs transferred from 4°C to 30°C @ approximately dock plus 2-4 days.
All PHABs are transferred from the 4°C CGBA to the cold stowage transport bag for transport back to Earth approximately 2-6 days before undock, and transport bag stored in return vehicle at least 24 hours before hatch close.

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Decadal Survey Recommendations

Plant and Microbial Biology P2

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Results/More Information

Information Pending

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Related Websites

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