Tag Archives: RNA

Biology for Worldbuilding: Immutably Mutable Genetics of Octopuses

[Above: Drawing of Octopus vulgaris by  Comingio Merculiano (1845-1915) circa 1896, published in Jatta Giuseppe (1860-1903). Public Domain via Wikimedia Commons.] 

This post is the first in the series aimed at people who write speculative fiction–sci-fi, fantasy, horror, etc–and are looking for worldbuilding inspiration. In each post, we’ll take a look at a biological trait and explore how that trait might shape a species and the cultures/societies said species might form. Since these posts are mostly about hypothetical alien or fantasy worlds, I want to stress that these posts are thought experiments and highly spectulative.

Humans cultures are obsessed with the idea of inheriting fixed traits–such as nobility, honesty, and magical abilities–from ancestors.  It’s the basis of feudalism and hereditary rule. It’s at the root of the Nature vs. Nurture debate. And today, it’s one of the main reasons why people get their genomes sequenced.  The concepts of DNA and bloodlines will probably be used to justify racism, power grabs, and high fantasy plot twists for decades to come.

Thanks to DNA sequencing studies, the evidence is pretty clear: many traits and predispositions to certain traits can be passed down from parent to parent. People still tend to assume that traits–especially physical ones and “innate” abilities–are more or less determined by DNA and that the environment’s role, if it has one, is secondary.  After all, you can’t just rewrite your own genetic code, right?

Well…if you’re an octopus, squid, or cuttlefish, you kind of can…at the RNA level, anyway.

That, imho, would be an interesting trait for a sci-fi alien or fantasy beastie to have, and in sentient, society-forming life forms, it could have a profound impact on how they behave and see themselves.

[Flamboyant cuttlefish doesn’t care who Jon Snow’s parents are.] via GIPHY

First, some science explanation:

Octopuses, squid, and cutteflish–collectively known as the “coleoid cephalopods“–transcribe the sequences in their DNA into RNA pretty much the way everyone else does, but then, they add an extra step that allows them to make proteins that aren’t encoded in their genomes: They have enzymes that pull As, Gs, Cs, and Ts off of the RNA backbone and replace them with new base pairs in a process called RNA editing.

Mammals and other animals can edit our RNAs and do have the RNA-editing enzymes floating around in our cells, but we don’t use the ability very often. RNA-editor enzymes are very picky and can only edit base pairs that are flanked by specific sequences. (If you want to get especially specific about it, an RNA-editing target has to be surrounded by base pairs that allow the RNA to tie itself up in a knot with the target sticking out.)  For our purposes, the thing you need to remember is that: octopuses and company can alter the proteins their cells are making very rapidly by rewriting their RNA, and they do it all the time.  

That ability can be useful for quickly adjusting to cold water or in neurons that need to be able to respond to cues quickly in general. But it comes with a catch.

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Why You Can Blame Your Metabolism on Liver Proteomics Instead of Your Genes

Blaming things on genetics–everything from lateness to diet quirks–is wildly popular these days. However, DNA’s role in your body’s overall destiny has been greatly exaggerated. Sure, DNA is the “master blueprint”, but any one gene from that blueprint can contain instructions for making hundreds or thousands of tiny cell parts. And even so, there are plenty of cell parts that defy the master template.

Proteins–tiny biological machines made from proteins that you eat– are key players in pretty much every biological process that happens. Yet, their behavior remains almost impossible to decipher. Scientists have gotten pretty good at decoding genes and RNA snippets, and tracking a single type of protein is pretty doable. Also, since RNA snippets are templates for building proteins, scientists often use RNA diet to estimate the total number of proteins. But there are thousands of different protein forms in every cell; tracking all of them at once remains basically impossible.

However, variations in those proteins can make an enormous difference in processes like weight gain. And according to a new study, our most-used method for estimating protein numbers–counting the RNAs–only works about 30% of the time. 

As in, according to science’s latest numbers, at least 2/3rds of all “genetic bad luck” happens outside of genes. 

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