For the first time in history, scientists were finally able of sequencing the entire genome of an octopus. More than that, this is actually the first time for all cephalopods – including the nautilus, octopus, and cuttlefish – to have their genome mapped out.
Graduate student Caroline Albertin, the leader of the research team, supervised the use of “genome shotgun sequencing,” a method that allows scientists to split the DNA into small fragments, which in turn are assembled in light of the observed sequencing overlays. The California Two Spot Octopus – scientifically named Octopus bimaculoides – was the subject of the study.
According to the findings, more than 33,000 genes make up the entire genome of an octopus, and about 2.7 billion base pairs make up its DNA. Compared with the number of genes found in humans, which counts up to 25,000 at most, the octopus has substantially more.
Out of this number, researchers discovered some genes that only the octopus possesses among vertebrates, genes that are mostly responsible for their advanced brains, and for their special tissues found around the suction valves on their eight legs.
Due to its highly advanced neurological system, the octopus is one of the most intelligent among invertebrates; its brain contains roughly half a billion neurons – a significantly higher amount than any other organism similar in size.
Scientists have thus discovered that the intelligence of an octopus is mostly caused by the 168 cadherin genes that contain a protein that aids in the development of neurons.
In the case of the great majority of invertebrates, these cadherin genes are scarce. But when it comes to the octopus, it turns out it has approximately the same levels of this gene as mammals and other vertebrates, including humans.
The octopus’ complex neural network is also responsible for its ability to change color in order to camouflage during hunting. Even though the source of this amazing skill is still unknown, scientists are more positive about finding an answer now that they have the entire genome at hand.
Other discoveries involved the finding of a unique arrangement of Hox genes, the ones responsible for how the animal’s body plan forms during the embryonic stage. Usually, the Hox genes in the DNA sequence come in order, from the front of the animal to the back. But with octopuses, these genes are displayed all over the genome, which researchers think is due to a special chromosomal fragmentation.
Researchers say this is just the beginning of studying the fascinating way the octopus’ genome differs from what is seen in the invertebrates’ world, and the mechanisms it uses in order to survive.
Image Source: SB Seasons