Cephalopods (squid, octopus, cuttlefish, or nautilus) are emerging animal models and include iconic species for studying the link between genomic innovations and physiological and behavioral complexities. Coleoid cephalopods (cuttlefish, squid, and octopus) possess the largest nervous system among invertebrates. The common octopus (Octopus vulgaris) has been at the center of a long-standing tradition of research into diverse aspects of cephalopod biology, including behavioral and neural plasticity, learning and memory recall, regeneration, and sophisticated cognition. However, no chromosome-scale genome assembly was available for the common octopus to aid in functional studies. To fill this gap, researchers sequenced and assembled a chromosome-scale genome of this species.
The common octopus (Octopus vulgaris). Image credit: Albert Kok / CC BY-SA 3.0.
“Octopus vulgaris has long been used as a model for the study of learning and cognitive capabilities in invertebrates, and is also used as a comparative system in the study of neural organization and evolution,” said University of Vienna researcher Dalila Destanović and colleagues.
“Furthermore, recent advances in the culture of this species’ early life stages have increased its suitability for molecular approaches and have provided important developmental staging information.”
“One bottleneck to studying Octopus vulgaris is the lack of a chromosome-scale genome assembly.”
In their research, the authors sequenced the genome of an adult male Octopus vulgaris collected in the Gulf of Naples, Italy by fishermen in May 2021.
This reference genome, which is highly resolved at the chromosome level, will allow the scientific community to better understand the characteristics and biology of these fascinating animals on the one hand, and also to trace the evolutionary history of Octopus vulgaris on the other.
“With our current technologies used in genomics research, we were able to create a kind of ‘genome map’ for the octopus, showing how genetic information is arranged at the chromosome level,” Dr. Destanović said.
The researchers were able to identify 30 chromosomes in the Octopus vulgaris genome, in which 99.34% of 2.8 billion base pairs are arranged.
B comparing the species’ genome with the genomes of four other octopus species, they were able to show that all chromosomes exhibit numerous structural changes that have occurred during evolution by breaking off pieces of chromosomes, rearranging them and reconnecting them at the same chromosome.
“Even among closely related species, we observed numerous structural changes of the chromosomes,” Dr. Destanović said.
“This finding poses questions on genome dynamics throughout their evolutionary history and opens the door to investigate how this relates to their unique traits.”
“The dynamic evolutionary history of the octopus genome spans a period of 44 million years — and many exciting research questions are still open.”
The results were published in the journal G3: Genes, Genomes, Genetics.
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Dalila Destanović et al. A chromosome-level reference genome for the common octopus, Octopus vulgaris (Cuvier, 1797). G3: Genes, Genomes, Genetics, published online October 18, 2023; doi: 10.1093/g3journal/jkad220
