How are fruit flies like astronauts? For one thing, both will fly on the next space shuttle mission. For another, both have immune systems to keep them healthy.
Image to right: The fruit fly's short lifespan makes it ideal for this experiment. Credit: NASA
Here's another question: How are middle school students like astronauts? Thanks to NASA, they can both use fruit flies to learn more about the immune system.
On the next space shuttle flight, NASA will be including a Drosophila melanogaster (fruit fly) research payload. The experiment will use flies to study how the conditions in orbit affect their immune systems. Scientists hope that observing the changes in the flies' immune systems will help NASA better understand how spaceflight affects humans, as well.
But scientists aren’t the only ones who can use flies to learn about the immune system. NASA's "Flies in Space" Web site lets students learn more about fruit flies, the fly immune system and its similarity to the human system, space biology at NASA and the scientific method. The site also features a section for educators, with hands-on activities related to the fruit fly experiment. In addition, the educator section includes information about how the activities on the site are aligned with national standards and a worksheet that students can complete as they explore the site.
Image to left: Fruit flies have been studied during previous space shuttle missions. Credit: NASA
When human beings spend time in space, their bodies go through changes. For example, two of the many changes that occur in microgravity are a decrease in the mass of the astronauts' muscles and bones, and a decrease in immune system function. These changes in the astronauts' physiology have been seen for short flights on the space shuttle. However, the changes are particularly important factors for the crews who live up to six months on the International Space Station or for long-duration travel to Mars or the moon. When astronauts go on missions to Mars, they will have to spend even longer periods of time in space to go there and return.
The effects of microgravity and other spaceflight factors can put the health of the astronauts at risk. As a result, it is vital that NASA continue to learn more about how and why these changes happen in order to figure out how to counteract them to keep the astronauts healthy. That's where the fruit flies come in.
Despite the obvious differences, fruit flies actually do have many things in common with humans at the genetic, cellular and biochemical levels. These similarities mean that the scientific knowledge gained in these areas may be applied to understanding human biology as well. For research here on Earth, the fruit fly is considered a model system to study because of its biological similarities to humans. Furthermore, due in part to this similarity, the fruit fly is an ideal subject for study in space. Their small size means that large numbers of them can be included in an experiment, giving scientists the ability to confirm that the data from the experiment is statistically significant. The flies also reproduce quickly, meaning that a generation of fly progeny that has only experienced microgravity and the space flight environment can be studied during a single shuttle flight.
Scientists have observed that astronauts' immune systems in space do not function as well as they do on Earth. As a result, an astronaut may grow more susceptible to becoming sick and having the illness last longer because his immune system cannot effectively destroy the invading germs. This problem with the immune system is compounded, because the astronaut's own body already carries bacteria and fungi that are normally kept under control by the immune system when on Earth. Furthermore, scientists have observed that the virulence of microorganisms, such as bacteria and fungi, increases in the spaceflight environment. All together, these biological factors could create problems for astronauts on long-duration missions, where the return to Earth and medical treatment may take a very long time. As briefly discussed above, some of the molecular and biochemical processes that control the activity of the immune system are the same in flies and humans. Also, some of the cells that kill virulent microorganisms are similar between humans and flies.
Image to left: The fruit fly experiment will be carried on the upcoming STS-121 space shuttle mission. Credit: NASA
The fruit fly experiment will investigate how these immune systems function and processes are affected by spaceflight and also how the virulence of a fly fungal pathogen changes. When the flight specimens are returned, the scientists will conduct molecular biological tests, examine immune system cells and organs, and infect the flies and larvae with bacteria or fungi to assess immune system function or fungal virulence. With this information, the scientists will begin to answer the how and why questions concerning immune system function in space and may use the data to develop countermeasures to help astronauts.
Students learn more about this research on flies in space from the "Flies in Space" Web site. They can interact with some of the scientists working on the project. Recent online chats in English and Spanish allowed students to discuss the experiment with Dr. Kevin Sato, a payload scientist who works at NASA Ames Research Center for Lockheed Martin Space Operations. The site also features an "Ask an Expert" page where students can submit questions about the flies and the experiment. The Web site is available in English and in Spanish.
Image to right: Payload scientist Kevin Sato recently participated in an online chat with students about the experiment. Credit: NASA
Your students may not realize how much they have in common with astronauts or flies, but they can find out more with these resources.
David Hitt/NASA Educational Technology Services