Octopuses Can Rewire Their Brains to Brave Chilly Waters

Octopuses can edit their brains at the cellular level in response to changes in temperature, researchers reported in the journal Cell last week.

Unlike mammals, the eight-limbed animals don’t thermoregulate, meaning they can't maintain a consistent body temperature on their own. In the new study, after researchers placed octopuses in warmer and colder conditions, the creatures edited their RNA, a molecule that carries the instructions for making proteins from DNA. The researchers theorize that, since octopuses can’t thermoregulate, this process could guard against brain damage from changes in temperature, according to Scientific American’s Rachel Nuwer.

Researchers don’t know yet how this RNA editing affects how octopuses function. “What would be nice to see in future is what types of behaviors are affected by these different types of changes—their reaction speeds, their ability to camouflage,” Robyn Crook, a neurobiologist at San Francisco State University who didn’t work on the study, tells NPR’s Ari Daniel.

“This paper is just an extremely important first step to really understand more how [cephalopods] deal with the environment,” Michael Kuba, an ecologist at the University of Naples in Italy who wasn’t involved in the research, tells Live Science’s Kiley Price.

Octopuses, which are considered to be very intelligent, have abilities humans can only dream of, including changing their color and texture to hide in their surroundings, regenerating lost limbs, and releasing black ink as a defense mechanism.

By editing RNA, they can also change what proteins they make. Less than 3 percent of human genes are affected by RNA editing sites, writes Popular Science’s Laura Baisas. In a 2017 study, some of the same researchers found that cephalopods extensively edit their RNA. Over 60 percent of the RNA inside cephalopod brains gets edited, per NPR.

“The beauty of RNA editing is that, on one hand, you change the genetic information and it’s quite fluid, and on the other hand, you will keep the DNA intact,” Eli Eisenberg, a co-author of the study and geneticist at Tel Aviv University in Israel, tells Live Science.

In the new study, the researchers looked at adult California two-spot octopuses in laboratory conditions. After allowing the octopuses to acclimate to the lab conditions for a few weeks, they gradually shifted the temperature of the water to about 55 degrees Fahrenheit for some of the octopuses and to about 72 degrees Celsius for others. The octopuses were then kept at the new temperatures for 10-12 days.

When they studied the octopuses’ RNA afterwards, the researchers found “astounding high levels” of editing, most of which was in the nervous system, Joshua Rosenthal, a co-author of the study and neurobiologist at the Marine Biology Laboratory, tells Science News’ Freda Kreier.

Extensive edits had taken place, and they started within a matter of hours of the temperature changes. The researchers looked at around 60,000 places in the octopuses’ genomes where RNA is edited, and a third had changed, writes Scientific American. Most of the edited sites were more heavily edited for octopuses in the colder environment, Eisenberg tells Popular Science.

“We expected to see here and there a few sites that had changed, but no, this was something very global,” Eisenberg tells Scientific American.

The researchers got similar results when they studied members of the same species in the wild. They also studied how the editing might affect the functioning of two particular proteins. They found that the edits changed the proteins’ structures in a way that would affect their functioning, per Popular Science.

Heather Hundley, a biologist at Indiana University Bloomington who was not involved in the research, tells Scientific American that the new paper is “a true tour de force.”

“In the context outside of cephalopods, the main way to change the [protein] sequence and get a new kind of protein is through mutation and evolution,” Matthew Birk, a co-author of the study and biologist at St. Francis University, tells Popular Science. “That takes generations and hundreds and thousands of years, while this is days. That was very exciting.”

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.