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Message: <blockquote data-quote="imhotep" data-source="post: 28982577" data-attributes="member: 562115">We all know that the instructions to build an organism is contained in DNA. Cells copy those instructions into messenger RNAs, (mRNA) Then, cellular machinery called ribosomes read the mRNAs to build proteins by stringing amino acids together. Most of the time, the protein’s composition conforms to the DNA template for the protein’s sequence of amino acids.Even a small change can prevent a protein from doing its job properly, with possibly deadly consequences. Only occasionally is a change beneficial. It seems wisest to preserve genetic instructions as they are written. Unless you’re an Octopus or a Squid.Soft-bodied cephalopod species including octopuses, squid and cuttlefish recode RNA in their nervous systems at tens of thousands of sites, compared with about a thousand or fewer sites in humans, mice, fruit flies and other animal species. Though scientists have been documenting the number of editing sites, they will need new tools to directly test how recoding influences cephalopod biology.Cephalopods can edit & modify RNA, the molecule used to translate information from the genetic blueprint stored in DNA, while leaving the DNA unaltered. This RNA editing can cause divergences from the DNA instructions, creating some proteins that have different amino acids than specified by the DNA. Editing chemically modifies one of RNA’s four building blocks, or bases. Those bases are often referred to by the first letters of their names: A, C, G and U, for adenine, cytosine, guanine and uracil (RNA’s version of the DNA base thymine). In an RNA molecule, the bases are linked to sugars; the adenine-sugar unit, for instance, is referred to as adenosine.Cephalopods excel at a type of editing known as adenosine to inosine, or A-to-I, editing. This happens when an enzyme called ADAR2 strips a nitrogen and two hydrogen atoms off adenosine (the A). That chemical peel turns adenosine into inosine (I)In most of a cephalopod’s body, RNA editing doesn’t often affect the makeup of proteins. But in the nervous system, it’s a different story. In longfin squids’ nervous systems, 70 percent of edits in protein-producing RNAs recode proteins. And RNAs in the nervous system of the California two-spot octopus (Octopus bimaculoides) are recoded three to six times as often as in other organs or tissues.Having a wide selection of proteins may give cephalopods more flexibility in responding to the environment, or give it a variety of solutions to the problem in front. In the nervous system, RNA editing might contribute to flexibility in thinking, which could help explain why octopuses can unlock cages or use tools. Even though not clearly understood, perhaps RNA editing provides some evolutionary advantage.  If it’s not all that helpful, why have cephalopods persisted with RNA recoding for hundreds of millions of years? <img src="/styles/default/xenforo/smilies/default/oo.gif"  class="smilie" loading="lazy" alt=":oo:" title="Oo    :oo:" data-shortname=":oo:" /></blockquote>

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