They detect a new biological entity that lives in the human body

Madrid. An international team, with the participation of the Institute of Molecular and Cellular Biology of Plants (CSIC-UPV), discovered in the bacteria that live in the mouth and intestines of humans a new biological entity that they called obelisk, whose effects and function are unknown, but it could revolutionize the understanding of the limits of life.

This discovery, which was published in Cell and has been led by Nobel Prize winner Andrew Fire, was carried out through bioinformatic studies of genetic sequences obtained from 440 human fecal samples, of which 7 percent presented this biological entity.

Likewise, massive bioinformatics analyzes found nearly 30 thousand species of obelisks in biological samples collected throughout the planet, both in natural ecosystems (soils, rivers, oceans) and in wastewater or in animal microbiomes.

Obelisks are infectious agents with a tiny circular ribonucleic acid (RNA) genome of only a thousand nucleotides, far below the RNA genomes that some viruses use to reproduce.

These RNA circles are highly self-complementary, allowing them to adopt a stable rod-shaped structure reminiscent of the Egyptian monuments that give them their name.explained CSIC researcher Marcos De la Peña.

They lack the protein coat that characterizes viruses, but like viruses, they are capable of encoding proteins.pointed out de la Peña.

As a scientist who works at a plant research center, de la Peña indicated that the obelisks are reminiscent of viroids, a family of subviral agents that infect plants and with which they share the circular RNA genome and the usual presence of self-cutting ribozymes. .

“However, plant viroids are even smaller, with about 300 or 400 nucleotides, and do not encode proteins. For all this, obelisks are halfway between viruses and viroids, which poses a challenge to their origin and classification ”said the scientist.

Although their functions are unknown, researchers pointed out a possible role in the regulation of cellular activity with significant implications for health, since the microbiomes where these bacteria live influence numerous physiological aspects, from digestion to the immune system.

De la Peña has stressed that this discovery can revolutionize what is known so far about virology and biology, as well as the origin of life on Earth itself.