NanoRacks-University of Florida-Squids-1 (NanoRacks-UF-Squids-1) examines the effect of the space environment on the normal developmental time line of the cooperative relationship between the Hawaiian Bobtail Squid Euprymna scolopes and the luminescent bacterium Vibrio fischeri. The goal of this project is to determine whether beneficial microbes that typically associate with animal tissues are negatively impacted by microgravity.Principal Investigator(s)
National Aeronautics and Space Administration (NASA)Sponsoring Organization
National Laboratory (NL)ISS Expedition Duration
March 2011 - September 2011
27/28Previous ISS Missions
Microbes play a significant role in the normal development of animal tissues. NanoRacks-University of Florida-Squids-1 (NanoRacks-UF-Squids-1) examines the effects of microgravity on the normal developmental interactions between an animal host and a bacterial symbiont (the smaller member of the cooperative relationship). The model system between the squid Euprymna scolopes and the luminescent (light emitting) bacterium Vibrio fischeri is used to examine the effects of the space environment on animal-microbe symbioses. NanoRacks-UF-Squids-1 is supported by an instrument grant from Promega Corporation and a research grant from the Florida Space Grant Consortium.
A two-pronged approach is used to examine the impact of microgravity on this symbiosis. First the symbiosis is examined under simulate microgravity using rotating bioreactors called high-aspect-ratio rotating wall vessel bioreactors (HARVs). The HARVs provide a low-shear environment for both the host and symbiont, thereby simulating the space environment. Second, a small pilot experiment is flown on the STS-134 shuttle mission to examine the symbiosis under natural microgravity conditions.
When squid hatch from their eggs they are born without bacteria (aposymbiotic) and must acquire those bacteria from the surrounding seawater. To acquire those bacteria the squid uses specialized ciliated cells on the surface of the light organ. However, only a specific strain of the bacterium, Vibrio fischeri, is capable of colonizing the squid light organ. Once the bacteria move inside the light organ the squid is considered symbiotic and the V. fischeri induces a developmental remodeling of the host light organ. The ciliated cells used to initiate the symbiosis die through apoptosis (cell death) and begin to regress. This developmental restructuring of the light organ is essential for the normal development of the host squid.
The research complements those studies underway in pathogenic organisms (Wilson et al., 2007), as several gene pathways (e.g., hfq) are common to both mutualistic and pathogenic organisms. By understanding what commensal/mutualistic bacteria are experiencing in microgravity, we can deepen our understanding of human health in the space environment.Earth Applications
For the approximately 3.8 billion years that life has existed on Earth gravity has been one of the few constants throughout the evolution process. By experimenting in microgravity conditions we can potentially assess the impact gravity has had on life’s evolution as well as delineate developmental triggers or cues that may otherwise be obscured by gravity. This may expand our basic understanding of how gravity has influenced the evolution of life on Earth.
Oneconstraint of this experiment is having enough replicate animals to complete a robust scientific experiment. Another constraint is the need for crewmember participation and so replicate experiments might not always follow the same time line. Full automation may eventually be required.Operational Protocols
Approximately 14 hours post launch a crewmember activates the experiment by pushing to the first plunger stop to add symbiotic bacteria to host squid.
Experiment is allowed to incubate for 28 hours and then the crewmember terminates the experiment by pushing the plunger to the last stop, thus preserving the animal in preservative.