| Oh heck, me too - since I was responding to your only comment just minutes ago, here is again :) 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... )