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Earthworm Jim. Credit: Sega

Worms in space are proof of how microgravity warps your DNA

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Nov 30, 2020, 1:45 PM EST

Caenorhabditis elegans is brainless and almost everything else-less, but what this nematode does have are cells and genetic mechanisms remarkably like those in humans.

NASA’s Genelab and the University of Exeter collaborated on a study of how these worms’ genes reacted to the zero-G environment on the ISS, and what they found could mean danger for future astronauts, especially since we won’t have any artificial gravity like the Starship Enterprise anytime soon. After worms were exposed to both hypergravity (which astronauts experience during takeoff) and microgravity (the absence of gravity in space), changes were observed in around a thousand genes.

The thousand changes in throughout the C. elegans transcriptome, or all the messenger RNA expressed by particular genes, were what ended up warping many of the worms’ functions. Most surprising was that many of the same changes, happened in both hypergravity and microgravity. This concordance in reactions, meaning the way they mirrored each other, goes against previous assumptions that the changes which occurred with the addition of gravity would be the inverse of the changes occurring when the environment was void of gravity.

Even the most hardcore sci-fi geek probably wouldn’t want to turn into a space mutant.

“The fact that concordance is dominant seems to suggest that any change from [Earth] gravity takes C. elegans out of their native environment and disrupts their homeostasis, triggering a similar systemic response independently of the direction in which gravity is altered,” said Timothy Etheridge of the University of Exeter, who co-authored a study recently published in iScience.

When DNA cannot be transcribed properly, yoru funcitons are going to go off. Homeostasis is the maintenance of whatever processes an organism needs to keep itself stable, and Earth organisms are clearly not made to hang out in microgravity for too long because their homeostasis gets thrown off. Reactions to both increased and decreased gravity in the worms showed that the inner workings of their bodies became unstable when they were exposed to levels of gravity that were too high or too low. The worms were exposed to high gravity in a centrifuge and to low gravity on the ISS.

Possibly the scariest result the worms showed were genetic changes that altered the function of neurons, which are the same cells in the nervous system that zap information to other nerve cells as well as muscle and gland cells. Even worms without a brain have neurons. Something else affected by the genetic changes that came with both rocketing and plummeting gravity was cellular metabolism, or the biochemical reactions within the worms’ cells that kept them alive. Some of the adverse effects from these changes included lower insulin production and sluggishness.

There has already been proof of altered DNA from extended exposure to microgravity, but the study on C. elegans has provided some unprecedented information, even though the researchers were not able to distinguish responses that came from specific tissues. This means that changes in neurons and changes in metabolism may or may not be related. If they did occur separately, then metabolic alterations would occur throughout the organism in the face of altered gravity, regardless of what types of tissue they affected.

Neurons, however, are extremely metabolic. Disturbing an organism’s metabolism will probably affect neuronal tissue regardless of whether neuronal and metabolic responses are related.

“Defining precise molecular adaptations to altered gravity in C. elegans should ultimately provide the foundations for progressing understanding on the mechanisms of spaceflight-induced health decline in mammals and, eventually, humans,” Etheridge said.

Genetic changes in the worms could reveal the molecular functions that are affected in humans. Profiles of genes that weren’t exactly transcribed the right way, because the alien environments they were exposed to screwed them up, may eventually help scientists figure out preventative measures for astronauts headed to the Moon and back (and beyond).

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