International Caenorhabditis elegans Experiment First Flight-Radiobiology (ICE-First-Radiobiology) studies the effects of radiation on living organisms by comparing space-flown normal and genetically modified strains of worms with comparable worms grown on Earth for differences in the presence and expression of glutamine rich proteins. 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)
Canadian Space Agency (CSA), Ottawa, Ontario, Canada
Canadian Space Agency (CSA)Sponsoring Organization
Information PendingISS Expedition Duration
October 2003 - April 2004
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-Radiobiology is one of several experiments that investigated 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. It is known that radiation exposure is increased during space flight and that this can damage or mutate cells in organisms. In fact, radiation is seen as one of the greatest obstacles to human spaceflight. Investigators took advantage of the array of genetic tools available for C. elegans to look at this problem by analyzing the distribution of a specific protein, the antigen mdf-2, which is essential for normal cell division. Alterations in the production of this antigen lead to a great number of defects including chromosome abnormalities, X-chromosome non-disjunction or loss, problems in gonad development, and embryonic lethality (the quality of being deadly). Another way to evaluate the biological effect of space radiation is to study the G-tracks which are present in the C. elegans genome. There are approximately 395 strings of DNA coding for 18 or more repeating units of the amino acid Glutamine, called glutamine series (G-tracks). One third of these G-tracks occur adjacent to known coding regions. The probability of one stretch of 18 Gs occurring by chance is 1 in 64 billion; thus, it seems unlikely that the presence and location of these strings is random. Scientists have shown previously that the protein Dog-1 coded for by the gene Dog-1 (standing for deletion of G) is required for the maintenance of G-tracks and that in the absence of Dog-1 function deletions occur spontaneously in genes containing G-Tracks. Dog-1 mutants show multiple genetic deletions as well as chromosomal abnormalities. Scientists compared space-flown normal and Dog-1 mutant strains of worms with comparable worms grown on Earth for alterations in the G-tracks. The hypothesis was that G-tracks play a key role in maintaining genome stability and that the Dog-1 mutant could be used as a sensitive assay of genomic damage in response to radiation.
Results from the ICE-First-Radiobiology experiment may help scientists more clearly understand how different organisms are affected by radiation exposure while in the microgravity environment.Earth Applications
By understanding fundamental processes in C. elegans, scientists can achieve a better understanding of such processes in humans. The breakdown of these essential functions often results in disease and medical pathologies, thus allowing scientists to use C. elegans to study development, nerve function, behavior and aging. This study can lead to a further understanding of how radiation may affect human function on Earth as well as in space.
ICE-First-Radiobiology 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.
Rose A, Zhao Y, Hohnsen R, Baillie D. Worms in Space? A Model Biological Dosimeter. Gravitational & Space Biology; 2005.