Takuro Nakayama/Universidade de Tsukuba
Sukunaarchaeum amazing
Tiny, cell phone and very peculiar. A strange body, recently discovered, challenges the whole understanding of life.
The mysterious Sukunaarchaeum amazing was found inside the plankton Citharist Royalduring a genomic study to map its DNA and that of associated symbiotic bacteria.
The researchers led by the University of Daladasie geneticist Ryo Harada were perplexed with what they identified: a small circle of DNA that did not correspond to any of the known life forms.
With just 238,000 pairs of bases – much less than many viruses, which can reach between 735,000 and 2.5 million – the parasite cell shows a degree of specialization and dependence on the host never seen before.
And despite being a cell, delegates virtually all metabolic functions to its host, such as viruses. Almost all of your genes serve only to ensure the replication of your own DNA.
“Sukunaarchaeum can represent the nearest cellular entity discovered until the moment it approaches a viral strategy of existence“The researchers write in the article, cited by.“ This extreme specialization challenges our fundamental understanding of the minimum requirements for cell life. ”
Its genome is described as “deeply simplified” in the study – in May in Biorxiv and waiting for pairs review – no recognizable metabolic pathways and with an extreme dependence on the body that welcomes it.
However, unlike viruses, he keeps genes to produce his own replication machinery such as ribosomes, messenger and transfer arn.
Japanese researchers believe that the Sukunaarchaeum belongs to the domain of archery – group from which eukaryotes evolved, where humans include. Its circular genetic structure also brings it closer to the known bacteria and arms.
In addition, the body is likely to produce proteins capable of forming a membrane around its small genome, facilitating interaction with the host plankton.
It should be noted that the Sukunaarchaeum It offers no benefit visible to the host: it is just a parasite, in practice.
After all, where is the border between what is alive or dead? If viruses are not considered alive because they are unable to replicate themselves autonomously, then where is an organism that replicates, but completely depends on another to survive?
