|Hawaiian bobtail squid, Euprymna scolopes|
image credit: news.wisc.edu
The space shuttle, Atlantis, landed on July 21, 2011, marking the end of NASA’s final shuttle mission, STS-135. For obvious reasons, a lot of attention was given to the event and the crew aboard the final flight. However, there were some passengers that did not receive the recognition they deserved. Some baby squid, no bigger than a fruit fly, accompanied the human astronauts on Atlantis' last voyage.
But these Hawaiian bobtail squids were not just stowaways on NASA's last two shuttle missions, they also played an important role in a study, led by Jamie Foster, conducted on the shuttles. The squid naturally live with special bacteria, Vibrio fischeri, inside of their light organ. These bacteria are able to emit light and allow the squid to luminesce, which helps them evade predators at night. The most interesting part of the relationship is that the bacteria are able to change the development of the squid’s light organ. The presence of Vibrio actually physically changes the inside of the squid. Before the squid are able to gather the bacteria, their light organ is shaped to promote entry and growth of Vibrio. After the bacteria are settled in special pockets of the organ, called crypts, the light organ physically changes to promote light emission. This squid-Vibrio mutualistic relationship or symbiosis is a far simpler version of other more complex symbioses. One example is the relationship between humans and the many different bacteria that live in our gut.
Sending the squid into space allow researchers to observe any changes microgravity could have on Vibrio’s ability to cause these physical changes in the squid. Before they sent the squid into space, they wanted to be sure that microgravity would be a valid variable to investigate. First, they let some squid interact with Vibrio in a rotating bioreactor to simulate the gravity conditions in space. Other squid were kept at normal gravity conditions as a control. The effects of simulated microgravity were measured by how many squid survived the three day test and how well they could luminesce over the course of the study . There was a slight decrease in squid survival rate for those exposed to microgravity conditions. More importantly, there was a significant decrease in the ability of the squid to luminesce after 48 hours in microgravity conditions. This could be because of Vibrio’s decreased growth rate in these conditions.
This pilot study's results suggested that the maintenance of the squid-Vibrio symbiosis may be negatively influenced by microgravity conditions. So, the next step was to test the squid during natural microgravity conditions by sending them into space. The results of these small space studies may help us understand how other symbioses are affected by microgravity. All humans have important microorganisms in or on their bodies. Human astronauts and their beneficial bacteria or yeast may experience similar changes seen in the squid-Vibrio system during space travel. Though squid in space may seem strange, these types of studies could become an important in ensuring the health of future astronauts.