Using C. elegans to understand the adaptation to spaceflight

Colonization of other planetary bodies is ultimately required for our survival. This poses problems similar to but more challenging than any terrestrial life form successfully entering a new ecologic niche. There are many biological alterations that are known to occur during spaceflight and these can be studied in people or animals models. We have been using the genetic laboratory model C. elegans to understand the molecular basis of these changes.

Past work developed a chemically defined medium for growth of this worm in space and revealed a life history alteration in response to diet. Validation of this diet for use in space occurred on the ill-fated final mission of the Space Shuttle Columbia. We were able to recover live animals following Columbia’s break up on re-entry, which has implications both for the inter-planetary transfer of life by natural means and for return of biological materials from space. Further work revealed that C. elegans can be successfully grown in this medium in space for > 12 generations without any overt long term detrimental consequences which is both longer than has been demonstrated for any animal to date and is long enough for a mission to Mars. Accordingly, we are currently exploring the possibility of sending this worm on an interplanetary return mission to Phobos. In parallel, we have demonstrated reproducible gene expression changes in response to spaceflight which are attenuated by on-board centrifugation.

In general terms, these genes are “cytoskeletal” or “metabolic”. We are now preparing to fly genetic mutants to determine if specific molecular pathways are responsible for causing these changes in gene expression in space. Also in parallel, we have demonstrated that some of the “cytoskeletal” gene expression changes are associated with altered expression of muscle attachment complexes that are required for normal force generation and metabolic capacity. We are now examining the physiologic role of this presumptive muscle intrinsic repair pathway in man and also examining if the gene expression changes we observe in spaceflown C. elegans are also observed in humans subject to bed rest. In sum, in our preparations to send and grow a small animal on another planetary body, we have learned more about the normal mechanisms this animal uses to sense and response to the terrestrial environment and are exploring how we can apply this knowledge to improve both Astronaut and general human health, with a particular focus on muscle and metabolism.