Recently I learned something about DNA that blew my mind, and in this thread, I'll attempt to blow your mind as well. Behold: Chargaff's 2nd Parity Rule for DNA N-Grams.
If you are into cryptography or reverse engineering, you should love this.
Thread:

DNA consists of four different 'bases', A, C, G and T. These bases have specific meaning within our biology. Specifically, within the 'coding part' of a gene, a triplet of bases encodes for an amino acid
Most DNA is stored redundantly, in two connected strands. Wherever there is an A on one strand, you'll find a T on the other one. And similarly for C and G:

T G T C A G T
A C A G T C A

(note how the other strand is upside down - this matters!)
If you take all the DNA of an organism (both strands), you will find equal numbers of A's and T's, as well as equal numbers of C's and G's. This is true by definition.
This is called Chargaff's 1st parity rule.
https://t.co/jD4cMt0PJ0
Strangely enough, this rule also holds per strand! So even if you take away the redundancy, there are 99% equal numbers of A/T and C/G * on each strand *. And we don't really know why.
This is called Chargaff's 2nd parity rule.
Lots of people have advanced theories for why the number of C's and G's should match up, but as yet no slam dunk explanation has been reported. But, hold on, things are about to get even weirder! https://t.co/hO3ybOdPrR
It turns out the rule also holds for N-grams of bases! That is, as long as you both 'complement' and 'reverse' them. So for N=1, %C and %G are equal.

For N=2, this says that percentage of CC (%CC) and %GG are also equal, as are %AG and %CT (complemented AND reversed) etc.
You can compare this to turning a book upside down and reading it back to front, and finding that all three-letter words occur with equal frequency before and after turning over the book.
For DNA triplets like 'AAA', this looks like this. Left in blue is frequency of 'AAA', the right orange bar shows the reverse complement 'TTT'. And so on for all other 31 triplets. The correspondence is stunning:
And here are the tiny tiny differences for each triplet, all smaller than 0.2%. Note that this plot shows data for _all_ known bacterial chromosomes:
So why is this the case? There are lots and lots of theories, but there is no consensus yet. And that is what makes it so super interesting!
At the very core of life hides a mystery, a mystery that is easy to research from a computer. And I hope that one day soon we'll know for sure what is going on!
/ends

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JUST ONE PERSON—UK 🇬🇧 scientists think one immunocompromised person who cleared virus slowly & only partially wiped out an infection, leaving behind genetically-hardier viruses that rebound & learn how to survive better. That’s likely how #B117 started. 🧵 https://t.co/bMMjM8Hiuz


2) The leading hypothesis is that the new variant evolved within just one person, chronically infected with the virus for so long it was able to evolve into a new, more infectious form.

same thing happened in Boston in another immunocompromised person that was sick for 155 days.

3) What happened in Boston with one 45 year old man who was highly infectious for 155 days straight before he died... is exactly what scientists think happened in Kent, England that gave rise to #B117.


4) Doctors were shocked to find virus has evolved many different forms inside of this one immunocompromised man. 20 new mutations in one virus, akin to the #B117. This is possibly how #B1351 in South Africa 🇿🇦 and #P1 in Brazil 🇧🇷 also evolved.


5) “On its own, the appearance of a new variant in genomic databases doesn’t tell us much. “That’s just one genome amongst thousands every week. It wouldn’t necessarily stick out,” says Oliver Pybus, a professor of evolution and infectious disease at Oxford.
So it turns out that an organization I thought was doing good work, the False Memory Syndrome Foundation (associated with Center for Inquiry, James Randi, and Martin Gardner) was actually caping for pedophiles. Uhhhh oops?


Since this, bizarrely, turned out to be one of my longest videos ever (??) here's a quick thread to sum it up for those of you like myself with short attention spans. 1/10

In the '90s the False Memory Syndrome Foundation was founded to call attention to the problem of adults suddenly "remembering" child abuse that never actually happened, often under hypnosis. Skeptics like James Randi & Martin Gardner joined their board. 2/10

A new article reveals that the FMSF was founded by parents who had been credibly and PRIVATELY accused of molestation by their now-adult daughter. They publicized the accusation, destroyed the daughter's reputation, and started the foundation. 3/10

The FMSF assumed any accused pedo who joined was innocent, saying "We are a good-looking bunch of people, graying hair, well dressed, healthy, smiling; just about every person who has attended is someone you would surely find interesting and want to count as a friend" 😬 4/10
https://t.co/a6yrWK5dqg


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https://t.co/e3RBxj0ly3


https://t.co/cJlCMqyP2v


https://t.co/5n5TK67iKB

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