“Obelisk”, a new human biological creature whose function is unknown.

An international team involving the Institute of Molecular and Cellular Plant Biology (CSIC-UPV) has discovered a new biological entity in bacteria living in the human mouth and intestines, which they call “Obelisk”, which they do not know about. its functions and consequences, but it has the potential to revolutionize the understanding of the boundaries of life.

The discovery, published this Wednesday in the journal Cell and led by Nobel laureate Andrew Fire, was made through bioinformatics studies of genetic sequences obtained from 440 human fecal samples, of which seven percent represented this biological entity. Likewise, massive bioinformatics analyzes have discovered some 30,000 species of “obelisks” in biological samples collected across the planet, both in natural ecosystems (soils, rivers, oceans…) and in wastewater or animal microbiomes.

Obelisks are infectious agents with tiny circular RNA genomes of just 1,000 nucleotides, much smaller than the RNA genomes that some viruses use to reproduce. “These RNA rings are highly complementary, allowing them to adopt a stable rod-like structure reminiscent of the Egyptian monuments that give them their name,” explained CSIC researcher Marcos de la Peña.

“They lack the protein coat that viruses have, but like viruses, they are able to encode proteins,” de la Peña said.

As a plant scientist, de la Peña noted that the obelisks resemble viroids, a family of subviral agents that infect plants and with which they share a circular RNA genome and the common presence of intrinsic ribozymes. -cut.

“However, plant viroids are even smaller, approximately 300 or 400 nucleotides, and do not encode proteins. However, obelisks occupy an intermediate position between viruses and viroids, which calls into question their origin and classification,” the researcher said.

Although their functions are unknown, researchers have pointed to a possible role in regulating cellular activity, with significant health implications, as the microbiomes in which these bacteria live influence numerous physiological aspects, from digestion to the immune system.

De la Peña stressed that this discovery “could revolutionize” what is known so far about virology and biology, as well as the very origin of life on Earth.