from the don't-mind-dividing-down-the-line dept.
When cells divide, they usually generate two identical daughter cells. However, there are some important exceptions to this rule: When stem cells divide, they often produce one differentiated cell along with another stem cell, to maintain the pool of stem cells.
Yukiko Yamashita has spent much of her career exploring how these “asymmetrical” cell divisions occur. These processes are critically important not only for cells to develop into different types of tissue, but also for germline cells such as eggs and sperm to maintain their viability from generation to generation.
She spent her Ph.D. studying how cells make exact copies of themselves, but as a postdoc she turned her attention to exceptions to that process, which is very important because that is how one original cell can turn into so many different kinds of tissues. She focused on so-called junk DNA. These sequences make up most of the genome, but were thought to be useless because they don’t code for proteins. However, her work showed that stretches of junk DNA act like barcodes that label each chromosome to keep them bound together. Without the codes, the chromosomes scatter and leak out of the cell nucleus. Her lab also showed that these barcodes are unique to each species, and that the junk DNA of one species cannot necessarily code the chromosomes of another.
“[...] We think that might be one of the big reasons why different species become incompatible, because they don’t have the right information to bundle all of their chromosomes together into one place,” Yamashita says.
Yamashita also studied germline cells, which are the cells that give rise to eggs and sperm cells. When typical cells divide many times, small errors eventually creep in and genetic sequences start to get lost, but a cell may have hundreds of copies of these critical genes so this isn't fatal. However, germline cells are so basic that they cannot afford to lose genetic sequences because the daughter cells wouldn't be viable.
Yamashita and her colleagues found that germline cells overcome this by tearing sections of DNA out of one daughter cell during cell division and transferring them to the other daughter cell. That way, one daughter cell has the full complement of those genes restored, while the other cell is sacrificed.
[...] “If skin cells did that kind of thing, where every time you make one cell, you are essentially trashing the other one, you couldn’t afford it. You would be wasting too many resources,” she says. “Germ cells are not critical for viability of an organism. You have the luxury to put many resources into them but then let only half of the cells recover.”
(Score: 2, Insightful) by Anonymous Coward on Wednesday April 20 2022, @02:50AM (3 children)
Somehow, I never believed the idea that massive parts of our DNA were "junk". Some bits, sure, perhaps evolution isn't a great garbage collector. Over time more and more gets decoded and the amount of "junk" is reduced.
(Score: -1, Offtopic) by Anonymous Coward on Wednesday April 20 2022, @03:11AM
Also the supposed junk status of the Y chromosome. Another misandrist talking point fails to pan out.
(Score: 3, Insightful) by anubi on Wednesday April 20 2022, @03:30AM (1 child)
Ever seen the output of a disassembler?
WDASM, IDA, Sourcer 7, etc?
Anyone care to try to convince me that all that stuff that is not a valid instruction is just junk code, and can nipped out?
I used to fish through this stuff all the time to keep old abandonware running. Usually old DOS stuff.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by hopdevil on Thursday April 21 2022, @02:59AM
Many times. Usually you just set the processor wrong. It'll execute. Either that or it's obfuscated
(Score: -1, Troll) by Anonymous Coward on Wednesday April 20 2022, @06:00AM
This is why Brits cannot cross breed with anyone, because they are too racist to admit that it is possible and that the Hairy Prince could have procreated with an American, that may have some Colin Hapernicht blood. Oh, the hugh manatees, or the racial purity swine. I wish that it was true, but turns out, we are all human, and I can fuck you and produce a baby, as fully human as either of us. Thank you, genetics!
(Score: 1, Interesting) by Anonymous Coward on Wednesday April 20 2022, @12:56PM (2 children)
Per the saying "God don't make no junk" (introns) - not even "JUNK DNA" or otherwise known as Introns!
Though while NOT used for protein synthesis, they DO alter expression preferences (possible defense vs. disease for example OR possibly, evolution) of what DOES get transribed into DNA during reverse transcription of RNA into DNA.
* Over time, I've also "heard tell" that the non-coding sequence introns are also "store" immunity signatures (how to make cures OR resistance) vs. diseases like viruses etc. (like a mugshot wall of "most wanted criminals" in federal offices you may have seen).
HOWEVER/DISCLAIMER - I haven't been able to DIRECTLY verify that last part on "cure storage" though, admittedly really... well, other than if you *THINK* about it? Perhaps that is what is done by alteration of what gets expressed via EXONS (what does get expressed).
Thus, the next generation of a species, for example, that if the species is being killed off by say, predator venom OR even diseases, expresses resistance or even IMMUNITY via this mechanism of genetic expression shuffling that introns/junk DNA allegedly do.
APK
P.S.=> I'm not a professional geneticist OR virologist etc. BUT I am SO glad I took this as my science during CS degree work vs. say, the typical PHYSICS done by most computer science grads - it's coming in more handy than I ever thought it would in the intervening years since those "halcyon days of yore" (especially nowadays with MORONS "playing with fire" they still do NOT really fully understand DNA & all its constituent parts' interactions + using it in a HUGE "genetic experimental trial" that is harming folks left & RIGHT (ala mRNA & the bogus vax that does NOT work - like me saying I've read/heard tell of cure storage by introns/junk DNA? The "experts" are learning MORE & MORE about it, as do I when I find time OR am interested in seeing what's changed in that field - & it HAS but still imo, NOT enough to go playing around with it "pell mell"/"willy nilly" etc. - et al))... apk
(Score: 0) by Anonymous Coward on Monday April 25 2022, @04:14PM (1 child)
Maybe LINE-1 might have something to do with this.
https://en.wikipedia.org/wiki/LINE1 [wikipedia.org]
It supposedly has viral DNA sequences in it from past viruses cells have been exposed to? The covid vaccine may modify this area (not sure?) with the help of associated human reverse transcriptase associated with these genes?
https://www.youtube.com/watch?v=TTmYlA9CPn0 [youtube.com] (OK, I don't know how accurate these Youtube videos are, take them with a grain of salt).
https://www.frontiersin.org/articles/10.3389/fcell.2020.00657/full [frontiersin.org]
(Score: 0) by Anonymous Coward on Monday April 25 2022, @04:17PM
Another article
Reverse-transcribed SARS-CoV-2 RNA can integrate into the genome of cultured human cells and can be expressed in patient-derived tissues
https://www.pnas.org/doi/10.1073/pnas.2105968118 [pnas.org]
(though other articles claim that this hasn't been proven?)
(Score: 0) by Anonymous Coward on Wednesday April 20 2022, @04:14PM
"Junk" only applies to the thinking of those naming the unknown, junk.
One aspect of non-coding DNA I think of, are the approximately 20,000 "switches" that turn expressions on or off.
That implies there will never be enough time for evolution or human-kind to evaluate the effects of those 2^20000 bit combinations.