Coleoid cephalopods, including squids, octopuses, and cuttlefish, possess an RNA-editing capability that allows them to alter protein functions without changing their DNA, according to research published in the journal Cell. A team led by bioscientists from the University of California, San Francisco (UCSF) found that this process, mediated by adenosine deaminase acting on RNA (ADAR), creates a level of genetic flexibility far exceeding that of other animals, ScienceAlert reported.
Squid RNA editing alters protein stability and organelle health
The UCSF study focused on the longfin inshore squid (Doryteuthis pealeii) to determine the actual effects of these transcriptomic changes. Researchers analyzed the proteome—the full complement of approximately 24,000 proteins—and discovered that RNA editing affects protein activity, stability, localization, and how proteins interact with one another.
Jack Moen, a cellular and molecular scientist at UCSF and the study’s first author, stated that these edits can regulate organelle health. Because the process modifies the RNA instructions rather than the DNA master blueprint, the animals can generate proteins with different properties without risking permanent, harmful mutations.
Did you know? Cephalopods possess the most complex nervous systems seen in invertebrates, a trait researchers suggest emerged alongside their robust ADAR-editing abilities.
Optic lobe activity exceeds gill protein editing
To measure the scale of these edits, the research team examined nearly 8,000 editing sites across more than 2,000 different proteins. They compared the squid’s optic lobe, which manages visual responses, against the gills, which handle respiration.
The data showed that the optic lobe exhibits more frequent and complex editing activity than the gills. This suggests that the sophisticated central nervous system relies more heavily on RNA malleability to function. The study noted that these edits often occur in protein-coding sequences rather than “junk” DNA.
RNA editing creates new proteins and human-like mitochondria
The research identified 5,000 short proteins that do not appear in the reference squid proteome or the Swiss-Prot database of 14,000 organisms. This indicates that RNA editing can create entirely new protein sequences.
This recoding also modifies the behavior of mitochondria. The researchers found that edited squid mitochondria become more environmentally stable and better at recycling themselves, making them more similar to human mitochondria. Recoding affects creatine systems, which provide the energy bursts required for complex brain processes and evasive movements.
| Feature | Standard DNA Process | Cephalopod RNA Editing |
|---|---|---|
| Blueprint | Fixed DNA sequence | Malleable RNA “remix” |
| Mutation Risk | Permanent if DNA changes | Reversible and ephemeral |
Theoretical protein diversity outweighs atoms in the universe
While the actual number of proteins these animals produce is unknown, the theoretical potential is vast.
The researchers noted that the specific structures of ADAR enzymes contribute to this capacity, though further research is required to understand why this extreme flexibility is unique to cephalopods compared to other animals.
Common questions about cephalopod RNA editing
Does RNA editing change the squid’s DNA?
No. The process modifies the RNA instructions used to build proteins, meaning the DNA master blueprint remains unchanged and no mutations are passed down.
Which organs show the most editing?
The optic lobe shows significantly more complex and frequent editing activity than the gills, linking the process to the squid’s advanced nervous system.
How does this affect squid energy?
Recoding affects the creatine systems, which allows the squid to produce the bursts of energy needed for rapid evasive maneuvers.
The research was detailed in the study published in Cell.
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