Worms in space
Creepy crawlers help scientists understand how space radiation affects DNA.
Thu, May 14, 2009 at 03:40 PM
On board the shuttle Atlantis, which touched down last Monday at Edwards Air Force Base in California, about 100,000 C. elegans worms wriggled in a container after spending six months at the International Space Station. Even though they are only about the size of the tail on a comma, the worms are part of ongoing experiments to test the effects of space radiation on DNA. The study could eventually help astronauts survive long trips to the space station, the moon, or even Mars.
“We know that these animals respond very much like humans when they get hit with ionizing radiation (the type is that is common in space),” says David Baillie, the primary investigator of the study. “Using live animals, we think that we have a better chance of determining the type of damage that occurs.”
Researchers know that radiation in space can turn certain genes on that aren’t expressed on earth. It can also turn others off and cause them to change or mutate. Scientists often use tests on earth to determine how radiation can alter DNA, but by monitoring organisms and astronauts that travel into space, researchers can evaluate what happens when crew members are bombarded with different types of radiation in the cosmos.
“We know about the radiation environment, but we don’t know about the long-term effects of radiation from space completely yet,” says Jeffrey Jones, a medical officer at the Johnson Space Center in Texas. “There are a lot of areas of uncertainty or unknowns about what will happen if people are in space for a long time and get exposed to large amounts of radiation.”
C. elegans worms are particularly well-suited to helping scientists figure out the answers to some of these questions. The species shares one third of its DNA with humans, it was the first animal to have its genome sequenced, and it’s one of the simplest multi-cellular organisms, explains Nathaniel Szewczyk, a researcher on the project from the University of Pittsburgh. During the last experiment, worms gave birth almost every week, resulting in 28 generations of C. elegans in just six months.
“Until now, no one has really grown an animal for more than two or three generations in space,” says Szewczyk.
While the worms were on the shuttle, school children observed their progress through a project called Orions Quest, which helped to fund the study as well as get kids interested in science and space. They reported their findings back to the researchers and now that the animals are back, researchers can see how the worms developed in that environment and determine if radiation had any harmful or beneficial consequences.
Since much of the radiation on the space station is similar to the radiation on earth, “We do not expect to see much increase in the mutation rate compared to the animals here on earth,” says Baillie. But they do expect some damage, and “results so far are in line with what we were expecting,” says Cassie Conley, a NASA researcher who is consulting on the project. The scientists will study the DNA from the worms over the next several months to a year, comparing the DNA from the space travelers to the DNA from their earthling cousins that were grown in the lab as control subjects.
The study could help researchers determine how radiation affects organisms over time before NASA sends astronauts on future missions, some of which could last longer than a year. This information could, in turn, make prolonged stays in space safer for humans; in the future, researchers may focus on developing technology to protect humans from harmful radiation as they are exploring the solar system.
“Eventually we are hoping to use the worm as a tool for improving human health during space flight,” says Conley.
Story by Susan Cosier. This article originally appeared in Plenty in June 2007.
Copyright Environ Press 2007