Part 4 of 5 Parts (Please read Parts 1, 2 and 3 first)
#8 – Living in space changes how genes are expressed
Andy Feinberg at Johns Hopkins University conducted a study that followed how each of the Kelly twins’ epigenetics differed based on their environment. Epigenetics is the study of how genes express themselves. In two separate populations of white blood cells, Feinberg found multiple regions of the genome where DNA methylation had occurred. Methylation is the process responsible for turning genes on and off. The chemical modifications found by the researchers to Scott’s genome were located near two interesting regions. One was close to a gene known to help regulate the growth of telomeres and another was found close to a gene related to collagen production. Although Scott did experience epigenetic changes while he was on the ISS, the researchers discovered that the majority of the changes were found within the expected range of variability for his twin on Earth. The results related to telomere growth and collagen production are consistent with the findings of other Twins Study projects.
#9 – Artery walls thicken while in space
Stuart Lee at KBRWyle in the NASA Johnson Space Center’s Cardiovascular and Vision Lab performed a study about inflammation and oxidative stress which is damage caused by free radicals in the air. It can impact the structure and effectiveness of arteries. In order to accomplish this, the researchers examined the twins’ arteries using ultrasound as well as collected blood and urine samples throughout the mission. During and immediately after the mission, the researchers found that Scott’s inflammation biomarkers were elevated and that the wall of his carotid artery was thicker than it was preflight. Neither of these changes were found in Mark during his stay on Earth. The researchers do not know whether the thickening of Scott’s carotid artery is a temporary and reversible adaptation to living in space or if it is evidence of permanent and premature arterial aging.
#10 – Proteins that regulate fluids increase while in space
Brinda Rana of the University of California conducted a study to collect urine samples from Scott and Mark before, during and after the mission. This allow Rana to identify certain biomarker proteins that are connected with space-related bodily changes, such as muscle and bone loss, metabolic and cardiovascular changes and the altered regulation of fluids within the body. The researchers discovered that while Scott was in space, he excreted proteins at different concentration than his brother Mark on Earth. Specifically, Scott had elevated levels of a protein called Aquaporin 2. This protein helps form the pathways used to carry water through cell membranes in the kidneys. Because aquaporin 2 assists in the regulation of how water is transported within the body, it also serves as an important indicator of a body’s overall hydration status. Significantly, the researchers found that Scott’s increase in aquaporin 2 during spaceflight was correlated with higher levels of plasma sodium. This is an indicator of dehydration. Though further study is needed, the researchers believe that the increase in aquaporin 2 and plasma sodium may be connected to fluids shifting throughout Scott’s body while he was in a microgravity environment. This is important because fluids tend to migrate to the head which causes visual impairment and intracranial pressure. These changes have been documented in studies of other astronauts.
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