Aboard the SpaceX Dragon’s next resupply mission to the International Space Station (ISS) will be 20 “unique” passengers — laboratory mice — poised to play a vital role in preparing humans to go to Mars. They’ll do so by being part of a study to help determine how space affects circadian rhythms and the microbiome.
“This rodent research mission — just NASA’s seventh since completion of the ISS and the rejuvenation of America’s space biology program — is analogous to the Year in Spacehuman twin’s study, but we will in effect be working with 10 identical siblings from two different families,” says Fred Turek, director of Northwestern’s Center for Sleep and Circadian Biology (CSCB). “Because a trip to Mars and back is expected to take several years, we need to determine how the gut’s microbiota might be altered in zero gravity over long timescales.”
Turek and Martha Vitaterna, CSCB deputy director, are principal investigators of the study that seeks to identify genetic and environmental factors influencing mammalian adaptation to space. The 20 mice aboard the ISS, half of which will spend a record 90 days in orbit, will be complemented by Earth-bound controls living in a highly specialized NASA simulator that replicates the exact minute-by-minute conditions — but with gravity — inside the Space Station.
The study will highlight the space environment’s effects on circadian rhythms and the microbiome, as well as on related physiological systems. The microbiome consists of the trillions of microorganisms, mostly bacteria, which live on and in humans.
“Imbalances in the microbiome have been associated with a number of diseases and conditions, from obesity and diabetes to dementia,” says Turek, the Charles E. and Emma H. Morrison Professor of Biology. In 2014, these CSCB researchers became the first to show that disruption of circadian rhythms could disrupt the microbiome.
Circadian rhythms — innate 24-hour cycles in living things — influence most biological functions. Molecular, metabolic, cellular, endocrine, stress, and immune responses are all regulated by our internal “clock.”
“It’s important to understand how space travel may impact the circadian system, since it coordinates so many biological processes” says Vitaterna. “The exertion of liftoff, absence of gravity, and confined living arrangement all add to the stress of life in space, and the key to adapting may be in the body’s ability to maintain harmony across systems.”
The study will mark several “firsts” for science aboard the ISS. It will be the first project to include a side-by-side comparison of two different strains of mice, an experimental design that will allow researchers to understand the role of genetic differences in shaping the body’s responses to zero gravity. NASA’s small mass measurement device — used to quantify the mass of objects in the microgravity environment — will be used for the first time to measure mice “weight.” The research team will also conduct three 48-hour video sleep-monitoring sessions.
Turek and Vitaterna are among the dozens of investigators who continue to study data from astronaut Scott Kelly, and his identical twin brother, Mark, during Scott’s historic one-year mission aboard the ISS.
“We are working closely with the other Twins Study teams to piece together a more complete picture of the effects of long space missions on the human body,” says Turek, who has worked with NASA on various projects since 1987. “What we learn will help us safeguard the health of astronauts, and it will also help us improve human health on Earth.”
Results of this twins study are scheduled for publication later this year.
“With the twins we only had two subjects and we could not prescribe that they eat the same, or live similar lifestyles while Scott was in space,” says Vitaterna. “With this new project, we will be able to control for diet and also further examine the liver, spleen, and fat to learn the ways in which individual components affect one another.”
The new NASA-sponsored rodent study will be conducted with collaborators Peng Jiang, CSCB; Stefan Green, University of Illinois at Chicago; and Ali Keshavarzian head of gastroenterology at Rush University Medical Center, all of whom assisted in the twins study.
Three Decades of NASA Collaboration
Fred Turek’s relationship with NASA stretches back nearly 30 years to 1987, when he was appointed to the National Academies of Sciences, Engineering, and Medicine Committee of Space Biology and Medicine. As an oversight committee, the CSBM was responsible for making recommendations to NASA regarding all life sciences issues. Turek remained a CSBM committee member for eight years, serving as chair for the second half of his tenure. Ahead of John Glenn’s historic return to space in 1998, Turek was part of a small working group made up of circadian, sleep, bone, and muscle experts who gave recommendations to NASA on the benefits and risks of putting an older astronaut into orbit. From 2001 to 2007, Turek sat on the board of trustees of the Universities Space Research Association, a nonprofit nongovernment entity that did contract work for NASA. He has also carried out NASA-supported experiments in microgravity during parabolic flights on the KC-135 aircraft. In 2013, NASA asked Turek and other investigators to explore the possibilities of conducting research during the Year in Space mission.