Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 21/05/2017 09:52:01
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An absolutely fascinating question was sent in to the Ask the Naked Scientists podcast (https://www.thenakedscientists.com/podcasts/ask-naked-scientists)this week in South Africa.
It was so interesting that I thought I'd pitch it here for us to discuss. The caller asked "what would be the effect on the erosion/shrinkage of your telomeres when travelling in space compared with staying on Earth?"
In other words, relative to a person - or even yourself - staying on Earth, do your cells age faster when you travel at high speeds in space?
I suppose there will be two considerations here: the effects of special relativity, because you will be travelling faster than someone on the planet's surface, but also general relativity, because the effects due to gravity will be lessened in deep space.
What does everyone think?
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In general the affect will be well more than overshadowed by the massively increased amount of radiation they will be exposed to, which on Earth, at the bottom of 100km of reasonably absorbent nitrogen, water vapour and some nice green ionising oxygen, get very much attenuated to a low level. Add to that the magnetic field, which tends to turn high energy particles away from the more habitible regions, and tends to cause them to lose energy in spiralling around field lines from magnetic pole to magnetic pole, thus losing even more energetic particles ( charged particles all lumped together as ions, even if half are single electrons, and most are high energy protons moving at a pretty good chunk of C as they arrive, in all cases not a good thing to have hit your fleshy bits and make a bad impression on the DNA you kind of need to keep things ticking correctly) as light shows.
All in all the guy on the ground probably will live longer, so long as he avoids the major things that stop you in most places, and while he might have shorter telomeres by a few molecules after a decade or three over the flying twin, the twin likely will have a lot more metastising cells in there, causing all sorts of problems. Might not kill quickly, as in the case of many cancers, but will definitely have a big reduction in prospects of an enjoyable life.
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For most healthy cell types, the telomeres shrink every time the cell divides.
Healthy cells will only divide when nearby cells die, and more cells are needed to replace them and support healthy tissue functions.
As noted by SeanB, the increased radiation in space is likely to kill more cells, and so the remaining healthy cells will need to divide more often to compensate. This suggests that astronauts traveling at non-relativistic velocities will have shorter telomeres than their stay-at home twin at the bottom of Earth's atmosphere.
Once teleomeres get too short, the cells enters sensescence, and just sits there.
Cells that have active telomerase are able to maintain their telomeres, but this is mostly reserved for stem cells.
Cancerous cells sometimes turn on telomerase (or alternate mechanisms for telomere lengthening), and this allows them to grow into dangerous tumors, bypassing the senescence safety-net.
See: https://en.wikipedia.org/wiki/Telomere
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NASA is interested in the work of Dr Lindsay Wu for this very reason. He and his team have discovered that Nicotinamide Mononucleotide (NMN) can repair damaged DNA. It took only one week for the DNA of old mice to be indistinguishable from that of young mice.
https://www.sciencedaily.com/releases/2017/03/170323141340.htm
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Wonder how this would work on HELA cells, as they are almost immortal, even if they are no longer really human. Then wonder if any of them have tried it on larger mammals.
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They intend to start a limited clinical trial on a small number of individuals in Boston. The anomalous cells are a different matter I think. They do activate the repair functions then become dormant.
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https://www.nasa.gov/mission_pages/station/research/news/flatworm_regeneration
This investigation is a first step toward understanding how gravity affects an organism’s mechanisms for repair and renewal. Researchers hope to map the cell signaling processes that help the worms’ bodies locate cellular damage and instruct an area or appendage to regrow. They are observing the worms in space to find out how these processes may be disrupted by the lack of gravity.
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There is a good book about flatworms and how you can decapitate them and regrow a head with all the functions and memories ! you can even cut one up into many pieces and all the bits will regrow !!! yes into fully functioning Planarian worm.
Look up a book called "The First Brain"
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There is a good book about flatworms and how you can decapitate them and regrow a head with all the functions and memories ! you can even cut one up into many pieces and all the bits will regrow !!! yes into fully functioning Planarian worm.
Look up a book called "The First Brain"
Or look at this interview we did with Carrie Adler on flatworm regeneration (https://www.thenakedscientists.com/articles/interviews/worms-regenerate-themselves).