Octopuses have earned a reputation as clever aquatic escape artists. But in addition to being underwater Houdinis, these creatures (and other coleiod cephalopods like cuttlefish and squid) were recently discovered to have another mind-blowing trick: they can rewire their own genetic material to adapt more quickly to their environment.
Researchers found that octopuses and their relatives can edit and recode the RNA component of genes, which allows them to reprogram cells (often in their nervous systems) and adapt to external stimuli in the environment, such as a change in water temperature. Changes at the RNA level manifest in the formation of different versions of proteins from the same gene. The result is that these cephalopods can make transient changes that don’t have an effect long-term on their overall evolution and that could even be turned on or off by the cephalopod herself.
Researchers believe the reason for the cephalopod’s overall slow rate of evolution is due to the extreme possibility of change and editing in their RNA. As per the study’s lead author Joshua Rosenthal: “If a squid and octopus want to edit a base, they must preserve the underlying RNA structure. This means that the RNA structure can’t evolve. If it collects mutations as a result of DNA mutations, it would no longer be recognized by the editing enzymes. We normally think of mutations as the currency of evolution. But in this case their accumulation is suppressed.” The slow rate of change in cephalopod DNA also may indicate that these sea creatures have been around longer than previously believed.
Beyond the fact that this recoding provides yet another example for why these sea creatures are fascinating, researchers continue to be interested in and slightly mystified by the reasons behind this action, although some believe their extreme use of RNA editing is linked to their intelligence and their behavioral complexities. Further fueling this idea were the findings by researchers that less intelligent and less cephalopod species such as the nautilus had far lower levels of RNA editing.
However, the intelligence/RNA editing connection is not as clear as the water cephalopods love to swim around in. “It’s a really interesting phenomenon, but it’s unclear why they need so much RNA editing,” says Jianzhi Zhang from the University of Michigan. “It’s not absolutely clear if it has to do with behavior; humans have very complex brains and behaviors and in us, RNA editing is very rare.” Indeed, RNA editing is found in mere dozen of sites out of the 20,000 genes in the human body, while the cephalopods studied ranged from 80,000-130,000 editing sites. The study’s authors, however, also consider the possibility that “protein recoding may not be the primary function of editing in cephalopods” and that perhaps another purpose, such as immunity, might be the goal.
The study was published in Cell.
Lead image via Wikimedia Commons