MicroRNAs play a key role in the development of complex brains

MicroRNAs play a key role in the development of complex brains

Cephalopods like octopuses, squids and cuttlefish are extremely smart animals with advanced nervous programs. In “Science Advances”, a staff led by Nikolaus Rajewsky of the Max Delbrück Heart has now proven that their evolution is linked to a dramatic growth of their microRNA repertoire.

If we go far sufficient again in evolutionary historical past, we encounter the final recognized widespread ancestor of people and cephalopods: a primitive wormlike animal with minimal intelligence and easy eyespots. Later, the animal kingdom could be divided into two teams of organisms – these with backbones and people with out. Whereas vertebrates, notably primates and different mammals, went on to develop massive and sophisticated brains with various cognitive talents, invertebrates didn’t. With one exception: the cephalopods.

Scientists have lengthy questioned why such a posh nervous system was solely in a position to develop in these mollusks. Now, a world staff led by researchers from the Max Delbrück Heart and Dartmouth School in america has put forth a doable motive. In a paper printed in “Science Advances”, they clarify that octopuses possess a massively expanded repertoire of microRNAs (miRNAs) of their neural tissue – reflecting comparable developments that occurred in vertebrates.

“So, that is what connects us to the octopus!” says Professor Nikolaus Rajewsky, Scientific Director of the Berlin Institute for Medical Techniques Biology of the Max Delbrück Heart (MDC-BIMSB), head of the Techniques Biology of Gene Regulatory Components Lab, and the paper’s final writer.

He explains that this discovering in all probability means miRNAs play a basic function within the improvement of advanced brains.

In 2019, Rajewsky learn a publication about genetic analyses performed on octopuses. Scientists had found that lots of RNA enhancing happens in these cephalopods – that means they make intensive use of sure enzymes that may recode their RNA. “This obtained me pondering that octopuses might not solely be good at enhancing, however may produce other RNA tips up their sleeve too,” recollects Rajewsky. And so he started a collaboration with the Stazione Zoologica Anton Dohrn marine analysis station in Naples, which despatched him samples of 18 totally different tissue varieties from lifeless octopuses.

The outcomes of this analyses have been shocking: “There was certainly lots of RNA enhancing happening, however not in areas that we consider to be of curiosity,” says Rajewsky. Essentially the most fascinating discovery was in truth the dramatic growth of a well known group of RNA genes, microRNAs. A complete of 42 novel miRNA households have been discovered – particularly in neural tissue and largely within the mind. On condition that these genes have been conserved throughout cephalopod evolution, the staff concludes they have been clearly useful to the animals and are due to this fact functionally necessary.

Rajewsky has been researching miRNAs for greater than 20 years. As a substitute of being translated into messenger RNAs, which ship the directions for protein manufacturing within the cell, these genes encode small items of RNA that bind to messenger RNA and thus affect protein manufacturing. These binding websites have been additionally conserved all through cephalopod evolution – one other indication that these novel miRNAs are of purposeful significance.

New microRNA households

“That is the third-largest growth of microRNA households within the animal world, and the biggest exterior of vertebrates,” says lead writer Grygoriy Zolotarov, MD, a Ukrainian scientist who interned in Rajewsky’s lab at MDC-BIMSB whereas ending medical faculty in Prague, and later. “To offer you an thought of the size, oysters, that are additionally mollusks, have acquired simply 5 new microRNA households because the final ancestors they shared with octopuses – whereas the octopuses have acquired 90!” Oysters, provides Zolotarov, aren’t precisely recognized for his or her intelligence.

Rajewsky’s fascination with octopuses started years in the past, throughout a night go to to the Monterey Bay Aquarium in California. “I noticed this creature sitting on the underside of the tank and we spent a number of minutes – so I assumed – one another.” He says that an octopus may be very totally different to a fish: “It isn’t very scientific, however their eyes do exude a way of intelligence.” Octopuses have equally advanced “digicam” eyes to people.

From an evolutionary perspective, octopuses are distinctive amongst invertebrates. They’ve each a central mind and a peripheral nervous system – one that’s able to performing independently. If an octopus loses a tentacle, the tentacle stays delicate to the touch and might nonetheless transfer. The explanation why octopuses are alone in having developed such advanced mind features may lie in the truth that they use their arms very purposefully – as instruments to open shells, as an illustration. Octopuses additionally present different indicators of intelligence: They’re very curious and might bear in mind issues. They will additionally acknowledge folks and truly like some greater than others. Researchers now consider that they even dream, since they alter their shade and pores and skin constructions whereas sleeping.

Alien-like creatures

“They are saying if you wish to meet an alien, go diving and make pals with an octopus,” says Rajewsky. He is now planning to hitch forces with different octopus researchers to type a European community that may enable higher alternate between the scientists. Though the neighborhood is at the moment small, Rajewsky says that curiosity in octopuses is rising worldwide, together with amongst behavioral researchers. He says it is fascinating to research a type of intelligence that developed solely independently of our personal. But it surely’s not straightforward: “If you happen to do checks with them utilizing small snacks as rewards, they quickly lose curiosity. Not less than, that is what my colleagues inform me,” says Rajewsky.

“Since octopuses aren’t typical mannequin organisms, our molecular-biological instruments have been very restricted,” says Zolotarov. “So we do not but know precisely which varieties of cell specific the brand new microRNAs.” Rajewsky’s staff are actually planning to use a way, developed in Rajewsky’s lab, which is able to make the cells in octopus tissue seen at a molecular stage.


Max Delbrück Heart for Molecular Drugs within the Helmholtz Affiliation

Journal reference:

Zolotarov, G., et al. (2022) MicroRNAs are deeply linked to the emergence of the advanced octopus mind. Science Advances. doi.org/10.1126/sciadv.add9938.

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