Scientists from Stanford University have made a groundbreaking discovery in the human digestive tract, identifying a new class of life called “obelisks.” This significant finding, which is currently undergoing the review process, was published on the biorxiv platform.
Under the guidance of biologist Ivan Zheludev, the research team examined 5.4 million genetic sequence datasets and successfully pinpointed nearly 30,000 distinct “obelisks.” These novel entities were found in approximately 10% of human microbiomes. Remarkably, analysis of one dataset revealed that “obelisks” were present in 50% of samples extracted from patients’ oral cavities, suggesting the possibility of different types of “obelisks” residing in various parts of the human body.
Distinguishing themselves through their unique characteristics, “obelisks” are a category of diverse RNAs with a size of approximately 1000 nucleotides. Scientists believe that their relatively small size contributed to their long-lasting elusion. These genetic elements exhibit a remarkable symmetrical structure, composed of intertwined RNA strands.
What makes “obelisks” particularly intriguing is their lack of discernible sequences or structural similarities to any known biological agents. As a result, researchers hypothesize that they may represent an entirely new cohort of entities, bridging the gap between simpler genetic molecules and more complex viruses.
Among the myriad of microorganisms residing in our microbiome, the scientists managed to single out one specific type of microbial cell – Streptococcus sanguinis bacteria, commonly found in the human mouth. This particular microbe contained an “obeslik” with a 1137-nucleotide loop.
Furthermore, the “obelisks” possess genetic codes for a novel class of proteins, named “clades” by the researchers. These proteins constitute at least half of the “obeslik’s” genetic material, and their striking similarity across all “obelisks” suggests their potential involvement in the replication process of these entities.
What sets “obelisks” apart from other well-known RNA elements, such as viroids, is their ability to encode proteins. In contrast, they do not appear to possess genes for constructing the protein shells that RNA viruses, including Covid-19, utilize when outside of cells. Additionally, “obelisks” are considerably larger than genetic molecules commonly found within cells, such as plasmids in plants and bacteria, which are primarily composed of DNA.
Despite their remarkable discovery, scientists have yet to determine the effects of “obelisks” on their bacterial hosts or the mechanisms through which they propagate between cells. Consequently, the current hypothesis is that these