Meet the octopus! Complete genome sequence mapped

Meet the octopus!  Complete genome sequence mapped

Scientists have just produced the first ever genome sequence for an octopus.

A collaboration of scientists from three countries have produced the first complete genome sequence for an octopus, mapping the genes for the species Octopus bimaculoides.

The announcement was published in Nature on Wednesday, and culminated several years of work and a lot of phone calls to colleagues around the world in Japan, Germany and the United States, according to the scientists.

The researchers selected the small California Two-Spot octopus because it was relatively easy to raise under lab conditions, and it’s offspring immediately act like the adults.

The research group was surprised to find the species, which had a massive genome, with 2.7 billion base-pairs, as compared to humans with about 3 billion, did not reach that level through duplication of genes as had been previously thought.  For some reason the octopus species had grown a much larger set of genes than most marine animals.

The sequencing revealed the octopus had about 10 times the number of a gene called protocadherins than what you would expect to find in an invertebrate.  The total of 168 protocadherins was even twice as many as found in most mammals.  Those genes have been found to regulate the interaction and development of neurons in other animals, and may help explain why the octopus is so intelligent.

The researchers also found a high number of genes that are able to rearrange their position in the genome.  These genes called transposons are referred to as “jumping genes” by scientists, because they relocate themselves to places in the genome where you would not expect them to be.

Octopuses separated themselves from other mollusks, which have been better understood, some half a billion years ago, and until now, have been difficult to study at the molecular level.  Even a close kin, the squid, moved away from the octopus on the family tree about 270 million years ago.

The scientists are hoping to understand how the animals develop from a single cell into hatchlings, and how the brain of the octopus controls its behavior, especially with regard to mating and reproduction.



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