Octopuses have developed a remarkable defense mechanism to safeguard their delicate nervous system against extreme temperature variations. They possess the extraordinary ability to rapidly recode key proteins in their nerve cells, ensuring the uninterrupted functioning of critical neurological activities even during drastic temperature drops. This exceptional adaptation is made possible by their capacity to edit RNA on the fly, a superpower observed in select species of octopuses, squids, and cuttlefish.
Researchers at the University of Chicago’s Marine Biological Laboratory, led by marine biologist Joshua Rosenthal, have shed light on this unusual strategy through their recent study published in Cell. They highlight that while genetic information is typically considered fixed, environmental factors can influence the encoding of proteins. In cephalopods, this phenomenon occurs on a significant scale. Rosenthal explains, “RNA recoding gives organisms the option to express a diverse quiver of proteins when and where they choose. In cephalopods, most of the recoding is for proteins that are really important for nervous system function, so the natural question is, are they using this to acclimate to changes in their physical environment?”
Unlike organisms where genetic instructions for survival change gradually through generational DNA tweaks, cephalopods exhibit a different mechanism. In 2015, scientists discovered that squids, cuttlefish, and octopuses possess the ability to modify RNA even after it has left the nucleus, enabling rapid physiological responses. The precise reason for this unique RNA editing capability has remained elusive, although adapting to temporary environmental changes seems plausible. Marine organisms, including octopuses, experience a wide range of temperatures, and RNA editing offers a flexible and agile response without the long-term permanence associated with DNA editing.
To investigate further, a team of researchers led by marine biologist Matthew Birk from the Marine Biological Laboratory and Saint Francis University conducted a study using California two-spot octopuses (Octopus bimaculoides). By acclimating these octopuses to warm or cold water and comparing their genetic information against a database genome, they made astonishing findings. Over 20,000 individual sites out of the 60,000 known editing sites showed temperature-sensitive editing, revealing the global nature of this phenomenon. Interestingly, the editing primarily occurred in response to acclimating to cold water, affecting neural proteins sensitive to cold temperatures. Tests on structural proteins critical for octopus nervous system function further confirmed the impact of these changes.
The researchers also assessed the speed at which these changes occur. By gradually adjusting the temperature in the octopuses’ tanks, they observed significant alterations in RNA editing within a day, with the new steady-state levels reached within four days. These rapid responses indicate that cephalopod RNA editing serves as a defense mechanism against potentially dangerous conditions. It is speculated that RNA editing is a widespread strategy employed by octopuses and squids to adapt to changing environments, including factors such as low oxygen levels, pollution, and shifting social conditions.
This groundbreaking research opens up avenues for further exploration into the utilization of RNA editing in cephalopods and offers valuable insights into their remarkable ability to adapt and survive in diverse environmental conditions.
By Impact Lab