Astronaut’s DNA No Longer Matches His Identical Twin’s After Year Spent in Space
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Epigenetics are not that foreign a concept that people should assume the average reader won't understand them or will find it any less amazing.
I have never heard the word epigenetics until now and am still confused about what exactly happened to this guy.
It is how you can have the same genetic code in your brain as you skin, but the cells the genes are part of are completely different.
It's how you can have a hard drive with a ton of information on it, but choose to read only small portions at a time
Epigenetics. It's the make-file for your genetic source code. Certain conditions can cause certain parts of your genetic code to be uncommented or commented-out within any given cell or set of cells. There are actually a number of different kinds of 'comments' (histone modifications [1]) - each set of marks are particular to a different compiler, in different contexts. And these comments/marks are copied with some fidelity to daughter-cells/children along with a high-fidelty copy of the underlying genetic code itself.
So the genes (DNA) themselves are not being heritably altered, rather the recipe for which gene is produced, when, and where can be subtly changed. But again, the same mechanisms that permit the change in expression of those genes during a lifetime (of an organism, or a cell) can be subsequently changed in the next just as easily.
In this way you can store the code for some trait or capability over many generations without having it always be running. It can manifest itself in individual organisms or cells as having very different phenotypes even while possessing the same underlying genetic code.
Picture a Glucose detector wrapped around a DNA segment that encodes something to break down Glucose. If you zero Glucose inside the nucleus you stop producing stuff to deal with it.
The difference for this analogy is cells never stop compiling. On the other hand if you think of cell division as a reboot it's a better fit.
The similarities to Von Neumann architecture are .. unsettling.
Also, it's well established that there are plenty of feedback loops here. An active gene can code for the production of a protein that activates or inactivates other genes. There are numerous pathways by which external stimuli can amplify or inhibit all of these feedback loops, so external conditions often result in changes to which genes are tagged.
As you can imagine, the state-space of all of this is immense; far larger than just the number and type of genes that you have. Mapping it all is a vast project that might easily take thousands of years.
This barely scratches the surface. This process, along with others that modify how DNA is folded, brings certain genes closer together (while moving others farther apart), increasing (or decreasing) the likelihood of all sorts of first, second, and third order (...) interactions between them and their products.
And we've only just begun...
> This barely scratches the surface. This process, along with others that modify how DNA is folded, brings certain genes closer together (while moving others farther apart), increasing (or decreasing) the likelihood of all sorts of first, second, and third order (...) interactions between them and their products.
> And we've only just begun...
Horribly vague, care to elaborate mathematically or at least provide some study links? The 'DNA folding' you propose begs resolution from some study using quaternions or attractors, or ... ?
Perhaps the science has advanced since this video was created, but I think it is a fine primer on the subject.
spoiler: they won't all undergo the same epigenetic changes either.
According to the article: Preliminary results from NASA's Twins Study reveal that 7% of astronaut Scott Kelly's genes did not return to normal after his return to Earth two years ago.
According to my memory, and now looked it up: Chimps and bonobos in particular take pride of place as our nearest living relatives, sharing approximately 99 percent of our DNA, with gorillas trailing at 98 percent.
Good thing they put a picture in the article of the guy, haha.
I thought of that as well while reading about the 7% they mention, but then I assumed they were talking about 7% of the genes that are specific to human kind.
He's a great speaker, and a cool guy and tackles some of the most interesting (at least to hear about) science in genomics
[1] https://www.dropbox.com/s/sfg6rdmgxjwdpil/Mason_NEB_talk_AGB... [2] https://twitter.com/mason_lab/status/964151387687972864
The article avoids all the interesting technical details. In case you are wondering if this is possible and how much of this is an exaggeration, the title of the research article is "The Landscape of DNA and RNA Methylation Before, During, and After Human Space Travel (Twins Study - Mason) - 09.27.17" https://www.nasa.gov/mission_pages/station/research/experime...
Methylation is an usual process that the cells use for enabling and disabling genes expression. It's reversible, somewhat permanent and somewhat inheritable. If you like a bad analogy, it's like making a change in the bios setup of your computer or updating the configuration of the wifi-router. It's not a firmware upgrade or a hardware modification. More info: https://en.wikipedia.org/wiki/DNA_methylation
Maybe, but what is really causing the DNA methylation? The article pins it mostly on epigenetics or environment, the 'stress of space travel', including dietary constraints and oxygen levels all of which are valid.
- https://theconversation.com/epigenetics-can-stress-really-ch...
- http://sitn.hms.harvard.edu/flash/2017/stress-induced-dna-mo...
- https://www.scientificamerican.com/page/sponsored/nestle/how... ooh, sponsored article, didn't catch that the first time.
However, the CNN article only briefly mentions 'radiation' as a factor and likely is lumping that into the 'stressful environment' case repeated several times.
Realistically, cosmic rays or radiation are far more likely to the be prevailing indicator for DNA disruption but are not plainly disclosed here. Despite much research having been done on this specific topic.
Wikipedia states: https://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays "The potential acute and chronic health effects of space radiation, as with other ionizing radiation exposures, involve both direct damage to DNA, indirect effects due to generation of reactive oxygen species, and changes to the biochemistry of cells and tissues, which can alter gene transcription and the tissue microenvironment along with producing DNA mutations."
From this paper: https://arxiv.org/abs/1406.6641 "In the present paper, we suggest the BNR as a cause of genetic “fails” in living cells, that is one of the possible origins of the so called spontaneous mutations. Cells exposed to the shower of electrons and ions, caused by the collision of a neutron and a proton of water, could be annihilated or experience a permanent damage, in particular, a damage in the DNA."
Cosmic radiation detrimental effects to DNA confirmed by NASA in this study: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/200800...
And more poignantly, from https://www.vencoreweather.com/blog/2017/6/26/1200-pm-cosmic... ( do not read full link if you are easily panicked ): "... there are other consequences of increasing cosmic rays according to “Spaceweather.com” including the penetration of commercial airlines, dosing passengers and flight crews enough that pilots are classified as occupational radiation workers. [Dose rates are expressed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x]"
Sorry for the data dump, I just happened to be researching cosmic ray effects the past few evenings and have collected many interesting facts on the topic. The most I have concluded at this point is that humans, as currently derived, are not made for space travel.
Radiation and cosmic rays produce random mutations, where one of the bases of the DNA is changed by another base. (IIRC the radiation breaks the old base, and when the copy or correction enzymes see the mess, they may make a mistake and use the wrong base.)
Methylation is on purpose. Some part of the cell "decides" to enable or disable a gen, and send the correct enzymes to add or remove the methyles in the bases of the specific part of the gene.
(There are also some arm races between bacteria and virus that attack bacteria. The bacteria has an enzyme that split the DNA at points with some specific patterns, to try to kill the virus that enter the cell. The parts of the DNA of the bacteria with this pattern are methylated, so the enzyme doesn't attack the DNA of the owner. https://en.wikipedia.org/wiki/Restriction_modification_syste... )
Search for "93%" in https://www.nasa.gov/feature/nasa-twins-study-investigators-...
Couldn't an astronaut's DNA be sampled before and after a mission and compared?
It is always better to have more data points to rule out several variables, especially considering that it is rare to have an astronaut with a twin sibling.
> As a result, the more relevant comparison (and one NASA did) is Scott's DNA before and after his time in space. That can tell us how many changes were picked up while in space. But as noted above, he would have probably picked up some mutations even if he sat here on Earth. And that's where his twin Mark, who did sit here on Earth, comes in. Mark's before and after gives us a sense of the normal background rate of mutation on Earth. Comparing that rate to Scott's tells us the important number: the degree to which this rate is elevated in the environment of low-Earth orbit.
Then why is it significant that time in space changed it?
> To better understand the genetic dynamics of each twin, Mason and his team focused on chemical changes in RNA and DNA. Whole-genome sequencing revealed that each twin has more than expected unique mutations in his genome -- in fact, hundreds.
So both experienced hundreds more unique mutations? But OK, let's say that it was Scott Kelly who experienced more mutations. But which tissues did they sample? Sperm?
> Preliminary results from NASA's Twins Study reveal that 7% of astronaut Scott Kelly's genes did not return to normal after his return to Earth two years ago.
This is about gene expression, not necessarily mutations. And it's the key take home. Given that we've known for some decades that radiation causes mutations.
How much was abnormal during the trip?
I run into this on news sites several times a week. I assume these are ads which are sneaking by the ad networks filter and running scripts on the page, just not sure how they are so damn pervasive?
If these ads aren’t being paid for with stolen credit cards, then why aren’t they people buying them getting slammed with CFAA charges? Is it that hard to track these clowns down?