As extraordinary creatures with extremely complex brains and cognitive abilities, octopuses are unique among invertebrates. So much so that it is more like a vertebrate than an invertebrate in some ways. As Remo Sanges from Scuola Internazionale Superiore di Studi Avanzati (SISSA), Port of Trieste, and Graziano Fiorito from Stazione Zoologica Anton Dohrn, Naples, recently published a study in BMC Biology The paper found that the neural and cognitive complexity of these animals may stem from molecules similar to those in the human brain. The study shows that the same “jumping gene” is active in the human brain and in two species of octopus — the common octopus and the California double-spotted octopus. The discovery could help understand the secrets to the intelligence of these extraordinary creatures.
As early as 2001, sequencing of the human genome found that more than 45% of them consisted of transposon sequences, so-called “jumping genes”, which can be copied from one place in a human genome through a molecular copy-paste or cut-and-paste mechanism. Move a place to another place, achieve rearrangement or duplication. For the most part, these moving elements are silent: they have no visible effect and lose the ability to move. Some jumping genes are inactive because they have accumulated generations of mutations; other intact jumping genes are blocked by cellular defense mechanisms. From an evolutionary perspective, even broken copies of these fragments and transposons can still be the “raw material” for evolutionary sculpting.
The most important of these mobile elements are those belonging to the long interspersed repeats (LINE) family, which are found in one hundred human genome copies and may still be active. Traditionally, the activity of these LINEs was thought to be a vestige of the past, a remnant of the evolutionary process of these mobile elements, but new evidence has emerged in recent years that their activity is finely regulated in the brain. Scientists believe that LINE transposons are involved in cognitive abilities such as learning and memory: they are particularly active in the hippocampus, the most important structure in our brain for the neural control of learning processes. Like ours, the octopus genome is rich in “jumping genes,” most of which are inactive. Focusing on transposons that are still capable of copy-pasting, the researchers found an element of the LINE family in a brain region critical to cognition in these animals.
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