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Octopus brains evolved to share surprising properties with ours: ScienceAlerts

EMBARGO Friday November 25 1900 GMT | Saturday, November 26, 6am AEST

Our cute blue marble from a planet teeming with an incredible variety of life forms, but some are far more exotic than others.

This is especially true of the octopus, an animal so strange that it regularly invites comparisons to aliens.

Indeed, if ever there was a creature on Earth strange enough to have evolved elsewhere, According to British neurologist Anil SethIt’s octopus. Even some fringe theory We think octopuses might be aliens.

Still, there’s ample evidence strongly linking octopus evolution to Earth, and a new team led by systems biologist Nicholas Ragowski of the Max Delbrück Center for Molecular Medicine has just discovered that.

It’s very interesting.

It’s a feature that octopus brains share with humans and other vertebrates: huge deposits of microRNAs in their neural networks.

“this,” Kata Rajewsky”,“ What connects us with octopuses!

Octopuses are curious in many ways. They are smartas well as other cephalopods, like squid. Squid brain has been found Almost as complex as a dog’s brain. There’s even evidence to suggest it Octopuses can dream This has rarely been confirmed in invertebrates.

Unlike other intelligent animals, its nervous system is widely distributed, with most of its 500 million-odd neurons scattered across its arms. Every arm is capable Make decisions independently May continue to respond to stimulation after cutting it.

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The complex nervous system and intelligence of cephalopods is a puzzle. These features are relatively common in vertebrates, but are particularly important among invertebrates.

There is something else very strange about octopuses and other cephalopods. Their bodies can quickly modify their RNA order Quickly to adapt to their environment. This is not how adaptation normally works; Usually, it starts with DNA and these changes carry over to RNA.

This prompted Ragowski to wonder what other RNA secrets the octopus might hold.

Analyzing 18 samples obtained from dead octopuses – provided by the Anton Dohrn Marine Research Institute Zoological Station in Italy – Rajewsky and his team sequenced the RNA mainly from common octopusgurita vulgaris This study also included the two-spotted polyp throughout California (bimaculoid octopus) and Hawaiian bobtail squid (Scolop Euprymna).

Sequencing provides a profile of the mRNA and small RNAs within. The results are amazing.

common octopus (common octopus). (Bernat Espegoli / iNaturalist, CC BY-NC 4.0)

“There’s a lot of editing in RNA, but not in areas that we think are important,” she said. Rajewski explained.

What the team found was that the octopuses contained many microRNAs or miRNAs. They found 164 miRNA genes clustered into 138 miRNA families in the common octopus and 162 miRNA genes clustered into the same 138 families in the California two-spotted octopus. And 42 new families, mostly in the brain and neural networks.

miRNAs are non-coding RNA molecules that are heavily involved in regulating gene expression and bind to larger RNA molecules to help cells adapt the proteins they produce.

The fact that these miRNA families are conserved in octopuses, such as RNA binding sites, suggests that they still play a role in octopus biology, although scientists don’t yet know what that role is or which cells participate in the RNA. . with.

“This is the third largest expansion of the microRNA family in the animal world and the largest outside vertebrates,” said the biologist. Grigory Zolotarovnow at the Genome Organization Center in Spain, formerly at Rajewsky’s lab.

“To give you an idea of ​​size, clams, which are also molluscs, have gained just five new microRNA families since they last shared a common ancestor with octopuses — while octopuses have gained 90!”

two-fingered octopus (bimaculoid octopus). (wademcmillan/iNaturalist, CC BY-NC 4.0)

The only similar magnification occurs in vertebrates, albeit on a slightly different scale. The human genome encodes, by context, everything around it Matags of 2,600 miRNAs. But there are as many miRNAs in the octopus family as there are in animals like chickens and frogs.

The researchers say these findings suggest that complex intelligence, including in cephalopods, could be related to RNA expansion.

Interestingly, this is not the only similarity between octopus brains and those of vertebrates. Scientist found before Human and octopus brains contain a large number of cell types called transposons. There seems to be a lot more going on inside an octopus’ head (and arms) than we realize.

The next step for Rajewsky’s team is to try to understand exactly what these microscopic particles are doing.

“The observed explosion of the miRNA gene repertoire in coliform cephalopods may indicate,” the researchers wrote“that miRNAs and perhaps their specialized neuronal functions are closely related and may be required for the emergence of complex brains in animals.”

Research published in Scientific progress.

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