Octopus brain and human brain share the same 'jumping genes'

The octopus is an unique creature with incredible brain complexity and cognitive abilities that are unmatched by other invertebrates. So much so that it resembles vertebrates in certain ways more than it does invertebrates. According to a study recently published in BMC Biology and organized by Remo Sanges from SISSA in Trieste and Graziano Fiorito from Stazione Zoologica Anton Dohrn in Naples, the neurological and cognitive complexity of these creatures may have its roots in a molecular parallel with the human brain.

The study demonstrates that the same "jumping genes" are active in the brains of two different species, the common octopus Octopus vulgaris and the Californian octopus Octopus bimaculoides. We might be able to unravel the mystery of these amazing critters' intellect thanks to this discovery.

Molecular copy-and-paste or cut-and-paste mechanisms allow transposons, sometimes known as "jumping genes," to "jump" from one location in an individual's genome to another, shuffling or duplicating, as early as 2001's sequencing of the human genome revealed. Most of the time, these moving parts are silent since they no longer move and have no observable impact. Some have become dormant as a result of generations' worth of mutations, while others are unaltered but obstructed by cellular defensive mechanisms. Even these broken copies of transposons and their fragments can still serve as "raw matter" for evolution to mold, which is important from an evolutionary perspective.

The most significant of these mobile elements are those from the so-called LINE (Long Interspersed Nuclear Elements) family, which is present in the human genome in 100 copies and is still possibly active. Although it was previously believed that the activity of LINEs was only a relic of the past, a byproduct of the evolutionary processes involving these mobile elements, current research has revealed that LINE activity is tightly controlled in the brain. Many scientists think that LINE transposons are connected to cognitive functions like learning and memory because they are particularly active in the hippocampus, which is crucial for the neuronal control of learning processes in human brains.

Similar to our genome, that of the octopus is full of "jumping genes," the majority of which are dormant. The researchers found a member of the LINE family in regions of the brain essential for these animals' cognitive capacities by concentrating on the transposons still capable of copy-and-paste. The discovery was made possible by next-generation sequencing techniques, which were used to examine the molecular makeup of the genes active in the octopus nervous system. It was the result of a collaboration between Scuola Internazionale Superiore di Studi Avanzati, Stazione Zoologica Anton Dohrn, and Istituto Italiano di Tecnologia.

According to Remo Sanges, director of the Computational Genomics laboratory at SISSA, who began working on this project while a researcher at Stazione Zoologica Anton Dohrn of Naples, "the discovery of an element of the LINE family, active in the brain of the two octopus species, is very significant because it adds support to the idea that these elements have a specific function that goes beyond copy-and-paste." An multinational team of more than twenty researchers from different countries worked on the study, which was published in BMC Biology.

According to Giovanna Ponte from Stazione Zoologica Anton Dohrn, "I literally jumped on the chair when I saw a very strong signal of activity of this element in the vertical lobe, the structure of the brain that in the octopus is the seat of learning and cognitive abilities, just like the hippocampus in humans."

The similarity between humans and octopuses that demonstrates the activity of a LINE element in the seat of cognitive abilities, according to Giuseppe Petrosino from Stazione Zoologica Anton Dohrn and Stefano Gustincich from Istituto Italiano di Tecnologia, "could be explained as a fascinating example of convergent evolution, a phenomenon for which the same molecular process develops independently, in response to similar needs, in

According to Graziano Fiorito, head of the Department of Biology and Evolution of Marine Organisms at the Stazione Zoologica Anton Dohrn, "the octopus brain is functionally analogous in many of its traits to that of mammals." In order to further our understanding of the evolution of intelligence, the identified LINE element also represents a very fascinating possibility for investigation.

DOI 10.1186/s12915-022-01303-5

Method of Research - Experimental study

Article Title:

Identification of LINE retrotransposons and long non-coding RNAs expressed in the octopus brain

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