We’re beginning to understand our bodies with more and more complexity every day through new research and studies. Of course we know that internal factors “change” our DNA. For example, eating a bowl of ice cream increases the amount of sugar in our blood. The body needs to be able to control and keep the blood sugar at a consistent level by creating and secreting insulin throughout the body to decrease the blood sugar. It would be an awful waste of energy and resources if our body constantly made insulin at a high level during times when we don’t need it. Therefore, there are specialized cells in the pancreas that can turn the insulin genes “on” or “off” when needed through gene expression. For the curious, type 1 diabetes is caused by the destruction of the cells in the pancreas that secrete insulin.
Recently, scientists have realized that our environment may be changing gene expression in our bodies without actually changing the sequence of the DNA which occurs through mutations (think cigarettes or UV radiation). This relatively new field of genetics is called epigenetics. Epigenetics studies cellular and physiological phenotypic trait variations that result from external or environmental factors that switch genes on and off and affect how cells express genes. Through DNA methylation (think of this as an “on” and “off” button for genes), histone modifications (think of this as the glue that keeps the genome together), and a few other complicated processes, epigenetics plays a vital role in the expression of our genome. Epigenetics explains why brain cells and skin cells develop; even though they both originated from stem cells that contained the exact same genetic information. Different genes were expressed through epigenetics which gave rise to different cells–we wouldn’t want brain cells on our hands, and we definitely wouldn’t want skin cells in our brains!
But as explained earlier, epigenetics studies physiological variations that result from external or environmental factors too! One study done by scientists at the Karolinska Institute in Stockholm made their volunteers exercise only one leg on the bike. The results? The researchers found that more than 5,000 sites on the genome of muscle cells from the exercised leg now featured new methylation patterns. Most of the genes with the new methylation patterns are known to play a role in energy metabolism, insulin response and inflammation within muscles. Diet is also another external factor that controls epigenetic changes. Does resveratrol sound familiar? If not, if you had a glass of wine recently, you’ve consumed resveratrol! Resveratrol is a compound found in the skin of grapes, and therefore, in wines. The BRCA-1 protein is a tumor suppressor involved in repair of DNA damage. Epigenetic mechanisms contribute to its reduced expression in breast tumors. Resveratrol was shown to prevent this epigenetic silencing, effectively inhibiting tumor development in laboratory studies.
Clearly, our environment has an impact on our genome, whether we realize it or not. And since research in epigenetics is still so new, we are constantly learning about new interactions between our environment and our body. Pollution, for example, has been shown to have a negative impact on elderly men. One study showed that chronic exposure to traffic-related pollutants was associated with significantly reduced lung function in elderly men through epigenetics.
Sure, we’re learning about how our environment on Earth is affecting our genomes, but NASA is also doing a study on how, you guessed it, space affects our genomes.
We know that pollutants and other environmental factors affect our genomes, but what about the void of space? Using the word “void” to describe space is a little inaccurate. In space, there is a significant danger to an astronaut’s health caused by the galactic cosmic rays and solar energetic particles. In addition, there is the weightlessness that may or may not be taking a toll on the astronaut’s health–their blood flows weightlessly in their bodies, so who knows what kind of impact this can have on their health over a long period of time?
That’s why identical twin astronauts Scott and Mark Kelly decided to be the first to experiment. Since they are identical twins, their genomes are exactly the same–that is, except for any differences that may result because of epigenetic changes in space. In fact, many studies in epigenetics involve identical twins; it allows for scientists to have a “control” in their research.
In March 2015, veteran astronaut Scott Kelly began a one-year stint living aboard the International Space Station. It was the longest amount of consecutive time that any American astronaut has spent in space. His brother Mark Kelly stayed on Earth and served as a control in the study. Scott intermittently sent blood samples during his time on the ISS, which allowed the research team at NASA to monitor changes in his blood levels throughout his time in space. Using genomic sequencing, the research team will determine any differences between Scott and Mark’s genomes.
Stay tuned to find out what the results were in this sci-fi-like experiment!