Octopuses redesign their brains when it gets cold

Octopuses are one of the smartest animals on the planet, and also the strangest. They have about the same number of neurons as dogs, but more than half of those cells are distributed throughout the slippery cephalopod’s eight arms rather than being contained in the central brain.

As researchers reported on June 8, cell, From there the neurological anomalies only get more bizarre. They found that octopuses have the following abilities: recode the neuron In response to temperature changes, those cells produce different proteins. Just as people adjust their clothes to the weather outside, octopus RNA is the genetic molecule that carries the instructions of DNA to make the proteins that are the workhorse of the cell. The researchers suspect that these “brain edits” help octopuses adapt to the heat and cold of the changing seasons. They do this to an “extraordinary degree,” says co-senior author Joshua Rosenthal, a biologist at the Marine Biology Institute in Woods Hole, Massachusetts.

RNA editing occurs when an external force activates certain enzymes in the body’s cells that cause chemical changes in the cells. RNA. Depending on the changes, cells produce proteins in different forms, or isoforms. Because RNA is a temporary molecule, changes made to the genetic information it carries are not permanent. In theory, this feature makes RNA a powerful tool for adapting to changing environmental conditions on the go.

In humans, RNA editing affects protein production in less than 3 percent of genes, whereas Rosenthal and his colleagues previously All sophisticated species of cephalopodsIn other words, all cephalopods other than nautilus recodes most of the neuronal proteins.

The researchers wanted to follow up on that earlier work to see what factors drive RNA editing in cephalopods. They started with temperature change because temperature change is a simple environmental condition that changes from season to season and even from day to day.

Scientists first collected a dozen wild animals California two-spotted octopus (Octopus Vimacroides), a species whose genome has already been decoded. They habituated the animals to aquariums containing either hot or cold water. A few weeks later, the researchers looked at some 60,000 sites in animal genomes that had already been identified as sites where enzymes edit RNA. They found that about a third of those sites had changed, and these changes happened rapidly, on a scale of hours to days. “We expected to find altered sites here and there, but we didn’t. This was very global,” said co-senior author, physicist at Tel Aviv University, RNA Eli Eisenberg, whose research has focused on

The researchers found that almost all the changes were caused by the cold. And among those changes are the functions of cell membranes, synapses (which transmit nerve signals), autophagy (programmed cell death) and calcium binding (plays a variety of roles within neurons). The researchers confirmed that isoforms made by the edited RNA had altered function, but “we still don’t know how these thousands of changes, or some of them, drive adaptation.” No,” Eisenberg says. “Understanding the global impact of all the changes happening in unison is left for future research.”

Finally, the research team also collected wild octopuses. Among them is another related species, the beryl two-spot octopus (octopus)—summer and winter. The researchers found that these individuals displayed the same temperature-tracking RNA-associated changes as the California bispeckled octopus studied in the lab.

Unlike humans and other mammals, octopuses cannot regulate their own body temperature. Researchers therefore suspect that RNA editing may play a role in protecting invertebrate neurons from temperature fluctuations. “Organisms are choosing to express different isoforms, each better in its own right,” Eisenberg says. “There’s never been a single instance of that happening in a mammal.”

Indiana University Bloomington biologist Heather Handley, who was not involved in the study, called the new paper a “true masterpiece.”

“This study adds to the data showing that RNA editing can be dynamically controlled,” she says. “Previous studies have focused primarily on regulation during development and disease, but this study shows that RNA editing is a molecular means of adapting protein function in response to environmental changes such as temperature. It shows that it works.”

Rosenthal, Eisenberg and colleagues plan to continue this line of work by investigating additional factors that may cause changes in protein production, such as pH, oxygen levels and social environment. “How far-reaching is the ability to adapt through RNA editing?” says Rosenthal. “I have a lot of interesting work to do.”