International Caenorhabditis elegans Experiment First Flight-Development (ICE-First-Development) studies the morphometry (measurements) of larval (immature) C. elegans development during space flight. C. elegans (nematode worms) are relatively simple organisms that are used as a model for a wide variety of biological processes. The ICE-First investigation is a collaborative effort conducted by scientists from several countries which have the opportunity to work as a team to design related experiments that would produce valuable results for scientists across multiple disciplines.Principal Investigator(s)
NASA Ames Research Center, Moffett Field, CA, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration
October 2003 - April 2004Expeditions Assigned
8Previous ISS Missions
The precursor to ICE-First (flown during Expedition 8), BRIC-60/C. elegans, flew on STS-107 (Columbia). Following the break-up of Columbia upon re-entry into the Earth's atmosphere, the samples were located among debris in East Texas and returned to NASA.
ICE-First-Development is one of several experiments that investigate the effects of spaceflight on a model organism of the nematode worm family (Caenorhabditis elegans) and aims to develop links to human physiology in space. The organism chosen for this study is known to be able to mate, reproduce and develop apparently normally during space flight.
C. elegans is a round worm or nematode (Phylum Nematoda) measuring around 1mm and is found naturally in soil. Its body is composed of 959 cells and includes complete reproductive, nervous, muscular, and digestive systems. C. elegans are hermaphrodites (displaying two genders and possessing the ability of self fertilization). Its life span is about 2-3 weeks; although, concerning the liquid medium used for this study at 25°, the life cycle is around 5 days. The entire genome has been sequenced and consists of 97 million base pairs (compared to the 3,000 million found in the human genome) and around 20,000 genes (compared to the 30,000 that humans have) and an entire library of well characterized mutants are available. C. elegans has been used as a model system for various medical pathologies and was the subject of the 2002 Nobel Prize in Medicine or Physiology because the process of programmed cell death or apoptosis was first discovered while studying C. elegans development.
Spaceflight is thought to affect mammalian development at specific ?critical periods? during infancy. Although worm cultures have grown successfully during several previous spaceflights, it is not yet known whether spaceflight exerts non-lethal effects on worm development. In liquid CeMM (C. elegans Maintenance Medium), larvae shed cuticles as they molt and progress to the next developmental stage. The length of the shed cuticles is indicative of the length of the larvae at the time when they molt, and thus can be used as a measure for larval development. For this experiment, scientists measure the range of lengths exhibited by shed cuticles in media from cultures that have been returned alive. The distribution of length data ndicates the number and progression of larval moults during development in space. The researchers have pre-determined the normal progression of development in CeMM on Earth, which is the first analysis of C. elegans development in space.
Traditionally, C. elegans is almost exclusively grown on Nematode Growth Medium (NGM) with the uracil auxotrophic bacterium Escherichia coli (E. coli) as a food source. This standardization of culturing has proved essential in understanding the biology of C. elegans on Earth. In parallel to these efforts, a minority of researchers pursued developing a chemically defined medium for C. elegans growth (CeMM). After many years of effort, this medium was completed and published. This alternative culturing medium was selected by NASA as ideal for growing C. elegans in space for a number of reasons. First, unlike traditional culturing, which requires astronauts to frequently transfer worms to new plates, CeMM allows worms to be cultivated without transfer for at least four times as long. Second, the new medium, in a liquid form, can be used for automated culturing and experimentation; thereby removing the need for astronaut intervention (e.g. the medium would also be useful for unmanned satellite and/or interplanetary missions). Third, the chemically defined nature of the medium removes the theoretical health concerns to astronauts surrounding the use of a bacterial food for C. elegans in flight. Fourth, the chemically defined nature of the medium removes the concerns of altered E. coli metabolism in flight being a confounding variable in determining the effects of spaceflight on C. elegans. Lastly, the new medium, in a liquid form, removes the potential masking of microgravity effects due to the surface tension forces (10,000-100,000G) that hold worms to plates.
ICE-First-Development presents opportunities for further studies including the possibility of automated experiments in flight, which is critical for experiments on deep space flights to other planetary bodies.Earth Applications
By understanding growth and development processes in C. elegans, scientists can gain insight that could ultimately lead to the development of effective medical regimens that could contribute to the well being of humans.
ICE-First-Development samples are placed in either the Kubik Topaz or Kubik Amber incubator before and after the launch. Filming is required immediately upon the arrival on Earth for later evaluation. The samples are required to stay either frozen or refrigerated until their return to scientists in Toulouse, France two days prior to landing.Operational Protocols
The C. elegans samples are transported to the launch pad in Baikonur, transferred into the Kubik Topaz (incubator with microgravity plate) and kept at 18 degrees C. Three days after the launch, 3 samples are transferred into the Kubik Amber (incubator with centrifuge), while the other five samples remain in Kubik Topaz. On the last flight day, four of the C. elegans samples are injected with a fixative by the crew and all of the samples are placed in Kubik Topaz on the Soyuz and returned to Earth. Upon return to Earth, the containers are filmed to evaluate the behavior of the C. elegans following space flight. The small bags containing the culture of the worms are either frozen or refrigerated until they are returned to their respective principal investigators for detailed analysis.
ICE-First-Development shows that the growth and development of space flown C. elegans, using either liquid or solid CeMM, was essentially the same as C. elegans grown under similar conditions in the laboratory. These results are as anticipated based upon previous demonstrations of normal growth and development in flight for animals grown on the traditional NGM (Nematode Growth Medium), and from the extrapolation of normal growth and development in flight for animals grown on both NGM and solid CeMM; the later data were generated by extrapolation due to the delayed recovery of samples following the tragic breakup of the Space Shuttle Columbia. The demonstration of grossly normal growth and development suggests that CeMM presents opportunities for further studies including the possibility of automated experiments in flight, which is absolutely critical for experiments on deep space flights to other planetary bodies.
Zhao Y, Johnsen RC, Baillie D, Rose A. Worms in Space? A Model Biological Dosimeter. Gravitational and Space Biology. 2005; 18(2): 11-16.