genes
Astronaut twins Scott (at right) and Mark Kelly participated in NASA's Twins Study while (and after) Scott spent close to a year in space [NASA]

New Delhi: Scott Kelly and Mark Kelly, the twin astronaut brothers, have been in the news. They have been part of an experiment reminiscent of the infamous Mengele experiments with twins in the Nazi era. Like Mengele, the experimenters sought to exploit the nearly identical genes to study genetic changes, and unlike Mengele, the experiments conducted were far from gruesome, in fact, exciting to be precise.

The experiment, dubbed “Twin Study” by NASA, involved studying the effect of space travel on the genetic makeup. For this, Scott Kelly made his trip to the international space station where he stayed for 340 days while his brother remained on earth as a control subject. Scott returned to earth about two years ago and has been studied ever since.

Space travel and its effect on the human body have been studied in the past. Among various effects space travel has on human beings, elongation of the telomeres is widely popular (telomeres are the “capping regions” of chromosomes and their shortening is directly related to ageing). Other known effects can be described as deleterious at best, which include muscle atrophy, deterioration of the skeleton, a weakened immune system and so on. The Kelly brothers have, for the first time, provided an opportunity for the effect of space travel to be studied just like in laboratories with a control and a test subject, thanks to their near-identical genetic makeup.

Scott Kelly’s re-entry into earth received immense attention from the scientific community as well as the media. The observations from the studies found great attention from the general public too. So, on the one hand, NASA declared in one of its press releases that “93% of Scott’s genes returned to normal after landing. However, the remaining 7% point to possible long-term changes in genes related to his immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.” On the other, the media speculated changes in the genetic makeup of Scott Kelly, some even claiming that Scott was no longer genetically identical to Mark!

What the press release actually intended to say was that Scott’s gene expression had changed. In simple terms, the genes were the same, but what they produced and the amount of the production had changed. This, to be fair is not an uncommon phenomenon. Mountaineers, deep-sea divers, all experience changes in their gene expression, which returns to normal levels after the stress-inducing factor is withdrawn. What is surprising in this case is that the changes observed have persisted even after two years; the gene expression of 7% of Scott Kelly remains altered compared to his brother.

This essentially means that although the genetic makeup of the brothers hasn’t changed, the way the genes behave has. The genes which were found altered in their expression have been termed “space genes”, which include genes “related to [Scott Kelly’s] immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia [excess carbon dioxide in the bloodstream.”

What this means in the long term will have to be evaluated and studied. As for now, NASA is continuing with its studies and definitive answers can be hoped to be achieved when the research findings are formally published.