Octopus and Human Brains Share the Same 'Jumping Genes'

An anonymous reader quotes a report from SciTechDaily: An exceptional organism with an extremely complex brain and cognitive abilities makes the octopus very unique among invertebrates. So much so that it resembles vertebrates more than invertebrates in several aspects. The neural and cognitive complexity of these animals could originate from a molecular analogy with the human brain, as discovered by a research paper that was recently published in BMC Biology and coordinated by Remo Sanges from Scuola Internazionale Superiore di Studi Avanzati (SISSA) of Trieste and by Graziano Fiorito from Stazione Zoologica Anton Dohrn of Naples. This research shows that the same 'jumping genes' are active both in the human brain and in the brain of two species, Octopus vulgaris, the common octopus, and Octopus bimaculoides, the Californian octopus. A discovery that could help us understand the secret of the intelligence of these remarkable organisms.

Sequencing the human genome revealed as early as 2001 that over 45% of it is composed of sequences called transposons, so-called 'jumping genes' that, through molecular copy-and-paste or cut-and-paste mechanisms, can 'move' from one point to another of an individual's genome, shuffling or duplicating. In most cases, these mobile elements remain silent: they have no visible effects and have lost their ability to move. Some are inactive because they have, over generations, accumulated mutations; others are intact, but blocked by cellular defense mechanisms. From an evolutionary point of view even these fragments and broken copies of transposons can still be useful, as 'raw matter' that evolution can sculpt.

Among these mobile elements, the most relevant are those belonging to the so-called LINE (Long Interspersed Nuclear Elements) family, found in a hundred copies in the human genome and still potentially active. It has been traditionally though that LINEs' activity was just a vestige of the past, a remnant of the evolutionary processes that involved these mobile elements, but in recent years new evidence emerged showing that their activity is finely regulated in the brain. There are many scientists who believe that LINE transposons are associated with cognitive abilities such as learning and memory: they are particularly active in the hippocampus, the most important structure of our brain for the neural control of learning processes. The octopus' genome, like ours, is rich in 'jumping genes', most of which are inactive. Focusing on the transposons still capable of copy-and-paste, the researchers identified an element of the LINE family in parts of the brain crucial for the cognitive abilities of these animals. The discovery, the result of the collaboration between Scuola Internazionale Superiore di Studi Avanzati, Stazione Zoologica Anton Dohrn and Istituto Italiano di Tecnologia, was made possible thanks to next-generation sequencing techniques, which were used to analyze the molecular composition of the genes active in the nervous system of the octopus.

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