"So far, the octopus has revealed three big clues as to how it generates brain complexity: it has multiplied its set of circuit-building protocadherin genes and its network-regulating zinc fingers. It has also unleashed RNA editing to generate more complexity on the fly."
Could someone elaborate on the last sentence please?
RNA editing involves modifying transcripts such that one gene can encode for many separate proteins. The different proteins may only differ at few amino acids but these modifications typically occur in functional domains eg ligand binding sites, pore domains etc. This allows an increase in functional diversity without an increase in genomic complexity.
I don't know why this was down voted so far it was killed so I vouched for it.
It is however a bit obscure. Perhaps this could be rephrased in more common HN terms as "the octopus's genetic mechanism quite aggressively uses epigenetic mechanisms" or "calls genetic 'subroutines' in ways unfamiliar in chordates (like us).
I found it weird that the article called the octopus' brain morphology "weird" given that we really only have one other model (again, that of vertebrates) to follow. Though there are more vertebrates by far, perhaps the octopus makes more sense and we are the centralised weirdos?
"Weird" does not mean "bad" — just different [from what we commonly expect]. Anyway, there are also some aspects to the physiology that you might not expect, such as the esophagus running through the center of the executive brain. A bit of crab shell might pierce it, for example.
I tend to agree, but it's interesting that depending on how much the norms of one's prevailing culture emphasize conformity, as they have in the recent past, "weird" can be interpreted as a pejorative.
meta: dead comments / shadow bans can be for other reasons than down votes. some new accounts get shadow banned immediately; I assume there's some anti spam stuff working on the backend. This was @jaspwn's first comment, so that's probably what happened.
It's like compression - the unpacker plus compressed data takes less space than directly writing all modified copies.
It is actually higher complexity but shorter code. More vulnerable to mutations in one sense (damaging codon hits multiple genes), but less in another (shorter length means lower likelihood of damaging a codon).
The 'normal' process is that a cell starts with it's permanent DNA in the nucleus. Part of the DNA [1] is transcribed to a string of RNA, this RNA is translated to a protein. There is an encoding where the sequence of base pairs along the DNA strand unambiguously specifies the sequence of amino acids that form the protein. The proteins then do the work in the cell (eg. the protocadherins and zinc fingers article mentions).
Cephalopods edit their RNA before translation to a protein on a huge scale. Apparently 60% of the RNA sequences in a squid brain study were modified (presumably before translation to a protein) https://phys.org/news/2015-03-squid-enrich-dna-blueprint-pro... So most of the proteins in that squid brain are not in it's genome (although similar ones are).
Could someone elaborate on the last sentence please?