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| Analysis of a Novel Sensory Mechanism
in Root Phototropism (Tropi) |
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Experiment/Payload
Overview |
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Brief Summary
Arabidopsis thaliana (thale cress) plants sprouted from seeds will
be video taped and mature plants will be harvested. Later, the mature
plants will be analyzed at the molecular level to determine what genes
are responsible for successful plant growth in microgravity. Insights
gained from Tropi can lead to sustainable agriculture for future long
duration space missions.
Principal Investigator
• John Kiss, Ph.D., Miami University, Oxford, OH
Co-Investigator(s)/Collaborator(s)
• Richard Edelmann, Ph.D., Miami University, Oxford, OH
• Roger Hangarter, Ph.D., Indiana University, Bloomington,
IN
• Melanie Correll, Ph.D., University of Florida, Gainesville,
FL
Payload Developer
Ames Research Center, Moffett Field, CA
Sponsoring Agency
National Aeronautics and Space Administration (NASA)
Expeditions Assigned
14
Previous ISS Missions
While Tropi is a new experiment, other studies of plant growth
and development have been conducted on ISS.
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Experiment/Payload Description |
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Research Summary
• Tropi is a plant growth experiment that will investigate
how plant roots from Arabidopsis thaliana (thale cress) respond
to varying levels of light and gravity.
• Plant growth under various gravity conditions (0g to 1.0g) is
achieved using a rotating centrifuge.
• Plants grown will be analyzed to determine which genes are responsible
for successful plant growth in microgravity.
• This experiment will help gain insight into how plants grow
in space to help create sustainable life support systems for long
term space travel.
Description
Tropi consists of dry Arabidopsis thaliana (thale cress) seeds
stored in small seed cassettes. Arabidopsis thaliana is a rapidly
growing, flowering plant in the mustard family. The seed cassettes
will be flown inside the European
Modular Cultivation System (EMCS).
The seeds will remain dry and at ambient temperature until hydrated
by an automated system of the EMCS. At specified times during the
experiment, the plants will be stimulated by different light spectrums
and by different gravity gradients. The only work required by the
crew is to replace video tapes and harvest the plants when they
are grown. Once the plants are harvested they will be stored in
the Minus Eighty Degree Laboratory Freezer for ISS Minus
Eighty Degree Laboratory Freezer for ISS (MELFI) until their return to
Earth. Part of the experiment relies on a biochemical analysis of
the returned plants, but the investigators will gather a large amount
of data from video taped images of the plants, watching their roots
as they develop in the EMCS.
The EMCS is an experiment facility for biological investigations
under microgravity. It shall allow for cultivation, stimulation
and crew assisted operation of biological experiments under well
controlled conditions. Depending on the experiment specific hardware,
it can be adapted to different applications e.g. to (larger) plants,
invertebrates and in potential future configurations also for confocal
microscopic observations or for aquatic species. EMCS is designed
as a payload for the EXPRESS rack. It will be launched inside an
EXPRESS transportation rack on a utilization flight. The EMCS facility
will be transported to the dedicated EXPRESS rack in the US Lab
on ISS. The resupply modules for gas and water will be exchanged
in intervals of three months to one year. The EMCS experiments are
composed Experiment Containers (EC) and Experiment Unique Equipment
(EUE) which are inside the EC. The EC's are loaded manually by crew
in the facility. Once the loading by the crew is completed, the
experiments will be performed automatically inside the EMCS.
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Applications |
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Space Applications
During long-term space exploration it will be necessary to provide
astronauts with regenerative sources of food as well as supplemental
methods to recycle carbon dioxide into breathable oxygen. As new
information about how plants grow in microgravity emerges, sustainable
plant-based life support systems may be developed.
Earth Applications
Further understanding of how plants grow and develop at a molecular
level can lead to significant advancements in agricultural production
on Earth.
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Operations |
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Operational Requirements
During its ascent, Tropi requires no resources. The dry seeds are
contained in five seed cassettes located in the EMCS. Once in orbit,
the seeds will be hydrated automatically. Through the experiment,
video will be taken allowing the ground team to evaluate and study
the progress of development of the plants. Ninety percent of the
science return is base on video analysis. The crew will harvest
the plants and store the specimens in MELFI. They are also required
to change out the video tapes.
Operational Protocols
Seed cassettes containing dried Arabidopsis thaliana seeds will
be initiated in the EMCS automatically. The EMCS will introduce
water to the seeds to activate growth. Video cameras will record
the growth and development of the plants. Once the plants are grown,
the crewmembers will harvest the plants and place them in the cold
storage in MELFI. The plants will be returned to the ground team
for further study.
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Related Web Sites |
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• The
Arabidopsis Information Resource
• University
of Miami, Department of Botany
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Images |
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EMCS sample cartridge that will be
spun in the EMCS centrifuge. Inset image is of Arabidopsis thaliana
(thale cress) seedlings like the ones that will be used for Tropi.
Tropi will compare the growth of root tips toward light in the absence
of gravity, and allow the distinction between two redundant internal
plant growth systems that respond to different colors of light.
Image courtesy of NASA, Johnson Space Center.
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Screenshot of Tropi during Expedition
14 shows several cassettes in an Experiment Containers (EC) and
the growth of young Arabidopsis thaliana seedlings during the "growth
phase". Image courtesy of NASA, Johnson Space Center.
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Screenshot of Tropi at the beginning
of "stimulation phase". This image will be used in analysis
of tropisms. Image courtesy of NASA, Johnson Space Center.
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Principle Investigator John Kiss,
Ph.D., from Miami University, Oxford, OH, and Ann-Iren Kittang from
the Norwegian University of Science and Technology, Trondheim Norway,
sit at the control console at N-USOC (Norwegian User Support and
Operations Centre) in Trondheim, Norway during the second run of
the Tropi investigation.
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NASA Image: ISS014E10652 - View of
the TROPI seedling cassette for the European Modular Cultivation
System (EMCS) - Experiment Container (EC) in the Destiny laboratory
module during Expedition 14.
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RNA gels of frozen plant samples
from the Tropi investigation. Gel A shows samples returned in Decmeber
2006 did not yield any RNA. Gel B shows RNA in the samples returned
in June 2007 following the establishment of cold transfer procedures.
Image courtesy of Dr. John Kiss.
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Close-up of Arabidopsis seedlings
with seed cassette cover removed. Image courtesy of Ames Research
Center, Moffett Field, CA.
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Dwarf Arabidopsis plant (left). Dwarf
Arabidopsis plant (right). Image courtesy of Ames Research Center,
Moffett Field, CA.
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European Modular Cultivation System
(EMCS) Tropi experiment unique equipment (EUE) shown stimulating
Arabidopsis seedlings with blue light (left). ENCS Tropi EUE shown
stimulating Arabidopsis seedlings with red light (right). Image
courtesy of Ames Research Center, Moffett Field, CA.
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