by Abigail Mullen
On March 27, 2015, NASA astronaut Scott Kelly left Earth for the International Space Station (ISS), where he would complete a yearlong mission. According to Space, one of the most interesting aspects of this mission was that Scott Kelly’s twin stayed on Earth in order study how being in space affects people’s bodies and genes. Since twins share the same genes, Kelly’s twin, Mark acted as a control by remaining on Earth. The primary results of this “Twin Study” now have been released. One of the major findings was gene expression, which is where scientists were able to identify which genes turn on or off. The results are significant in understanding the risks of going into space. Scientists know this happened to space travelers, but did not know the extent or specifics of the effects.
The other objectives of this study were to analyze bone and muscle health, microbiome of the G.I. tract, and genome sequencing on DNA and RNA. The telomeres, the end of chromosomes, were lengthened in Scott’s white blood cells. According to NASA, this could be due to increased exercise and decrease in caloric intake.The stress hormone, cortisol, was slightly decreased during the one year mission, but IGF-1, a hormone that has a similar structure to insulin, increased. This increase in IGF-1 is linked to the determination of bone and muscle health. There were expected differences in the twins’ microbiome since they lived in different environments and had different diets. However, there was a change in the ratio of two dominant bacterial groups, Firmicutes and Bacteroidetes, in Scott’s G.I. tract while he was in space. Scientists noticed an increase in methylation, using this study involves putting methyl groups onto different areas of DNA. Methylation usually prevents the gene with methyl groups from being expressed. An increase in methylation would mean less genes are expressed while in space.
These studies show the impacts that space has on humans which will be incredibly important if we plan to travel in space or even move there. Twin studies are an excellent way to show differences in humans and this study may reveal much about the effects of space on the human body.