Octopuses, Squids Trade Genomic Evolution for RNA Editing to Adapt to Their Environment

A new study has revealed that cephalopods, such as octopuses and squids, have the ability to change and edit their RNA to adapt to different conditions without changing their basic DNA sequence.

Scientists from the Marine Biological Laboratory (MBL) in Woods Hole and Tel Aviv University discovered that 60 percent of RNA transcripts in a squid's brain is recoded by editing. According to Scientific American, squids contain 20,000 genes, and 11,000 of which undergo RNA editing.

However, squids are not the only cephalopod that can massively edit its RNA. The researchers noted that two species of octopus and the common cuttlefish are also capable of RNA editing.

RNA editing happens when enzymes swap out one RNA base for another in order for an organism to adapt to its environment and survive. A news release from GEN reveals that only one percent of the RNAs of humans and fruit flies are recoded -- a stark contrast to the cephalopod's 60 percent.

Joshua Rosenthal, Ph.D., senior scientist at MBL and co-senior study investigator, said the new discovery proves that RNA editing did not start in molluscs but are in fact "an invention of the coleoid cephalopods."

“In mammals, very few RNA editing sites are conserved; they are not thought to be under natural selection. There is something fundamentally different going on in these cephalopods where many of the editing events are highly conserved and show clear signs of selection," Rosenthal added.

The study said that because of the high percentage of RNA editing in cephalopods, these creatures have suppressed their ability for genomic evolution just to maintain their flexibility in RNA editing. This means that cephalopods, despite their lack of evolution, may be older than previously thought.

The new study, entitled "Trade-off between Transcriptome Plasticity and Genome Evolution in Cephalopods," was published in the journal Cell.