Worms in Space! The ELERAD Experiment
C. elegans worms (Credit: Simon Fraser University/Genome Canada/Genome BC/Canadian Space Agency)
The scientific community's most popular worm is helping Canadian researchers document the radiation risks that astronauts will face on a trip to Mars.
Scientists at Simon Fraser University (SFU) are studying genetic damage in worms that spent about seven months on the International Space Station (ISS) in 2006 and 2007, producing between five and 10 generations of animals. The primary goal of this study was to validate new advanced technologies needed to do the complex analysis of how space radiation changes genes.
In this "proof of principle" experiment, "a genome returned from space has been shown to have damage that we could define very precisely," said principle investigator David Baillie, Canadian Research Chair in genomics at SFU. One worm came back from space "with an extra piece of DNA inserted into the genetic material, carrying extra copies of eight different genes."
The worms, known as C. elegans, were chosen because they're used extensively in medical research on Earth and the entire sequence of their genes is well known. About half their genome is similar to human genes, so the scientists believe the results of their study will be applicable to humans.
The fact that the worms reproduce rapidly is significant because one goal of this research is to identify radiation damage to reproductive organs that can be passed on to offspring. Since genetic damage often kills organisms, the SFU scientists developed a new strain of the worms that allows them to keep damaged organisms alive so they can be studied.
The SFU team is also testing a device called a DNA-array chip that enables them to identify genetic mutations quickly. For the first time, it was successfully used to detect DNA damage in a worm from space.
"The chips have turned out to be more useful-and have worked better-than we thought," said Baillie. "We didn't know we could do this before we used the chips, but now we know they do work."
Baillie also hopes to "resequence" the genes in the space worms-basically counting and studying every single one. Comparing this sequence with that of normal worms on Earth might uncover even more subtle changes.
"We could look at genomes that didn't show obvious signs of genetic damage. A lot of the damage is actually silent -- you only see it when you sequence."
The Canadian Space Agency funded this study because space radiation is a major obstacle to human spaceflight, said Luchino Cohen, a program scientist with CSA's space life sciences group. "It allows us to determine the effect of space radiation on a complete genome, which we really don't know yet. Once we know the impact of radiation on the whole genome, we can be better armed to develop countermeasures."
However, to better understand the risks of a trip to Mars, Baillie has to send his worms farther out than the Space Station, which is protected from the worst space radiation by the Earth's magnetic field. A high-flying satellite or an unmanned probe to the moon might provide suitable platforms.
"The goal is to get outside the magnetosphere because that's where we expect the real damage to occur."