How does the human genome respond when the familiar pull of gravity is temporarily removed? A research team at New York University has explored this question by exposing living human cells to 24 hours of simulated microgravity.
The experiment found that cell nuclei became noticeably larger, increasing around 14% in area and 18% in volume. The nucleolus, a structure linked to ribosome production, also developed a smoother form. Yet the DNA inside the nucleus remained strikingly steady.
A resilient genetic architecture
Human DNA is tightly folded into chromatin, an intricate structure that helps regulate gene activity. Despite the physical changes in the nuclei, researchers observed less than 5% variation in chromatin density. Its movement and coordinated dynamics within cells also showed no meaningful shift.
To simulate microgravity, the team used a random positioning machine, which continuously rotates cell samples along two axes. This method averages the direction of gravity over time while allowing scientists to monitor cellular behavior in real time.
The study also separated microgravity effects from fluid movement caused by the rotating system. While simulated microgravity itself did not produce a significant rise in markers of DNA double-strand breaks, stronger fluid flows increased these markers by nearly 30%. The distinction highlights the importance of controlling mechanical conditions in space-biology experiments.
New perspective for space biology
The research used HeLa cells and examined a short, 24-hour period, so it does not fully represent how healthy tissues may respond during long-duration space missions. It also focused on genome structure rather than measuring every possible change in gene activity.
Still, the findings indicate that the genome's three-dimensional organization can remain highly robust when gravitational cues are reduced. Published in Science Advances, the work offers a clearer way to distinguish the effects of microgravity from other physical stresses.
As human activity in space expands, this approach could help shape more precise studies of cellular health and support the design of future long-duration exploration missions.
