Scientists have discovered a new type of virus-like entity that lives in the human mouth and gut. They have named them obelisks, after their rod-shaped appearance and their uncertain nature. Obelisks are circular bits of RNA that can self-replicate and encode one or two proteins. They are neither viruses nor viroids, but something in between. The discovery of obelisks raises many questions about their origin, function, and impact on human health.

Obelisks: How Were They Discovered and What Do They Look Like?

Obelisks were discovered by a team of researchers from Stanford University, who were studying the human microbiome, the collection of microbes that inhabit our body. The researchers used a technique called RNA sequencing to analyze the RNA molecules present in the saliva and stool samples of healthy volunteers. They expected to find RNA from bacteria, viruses, and human cells, but they also found something unexpected: thousands of circular RNA molecules that did not match any known organism.

The researchers named these molecules obelisks, after the ancient Egyptian monuments that have a similar shape. Obelisks are about 300 to 400 nucleotides long, which is much smaller than most viruses. They have a single-stranded RNA genome that can fold into a rod-like structure. Obelisks can also self-cleave and re-ligate their genome, which is a way of replicating themselves. Obelisks have one or two genes that encode proteins called obulins, which have no similarity to any other known proteins.

Obelisks: Where Do They Come From and What Do They Do?

The origin and function of obelisks are still unknown. The researchers speculate that obelisks may have evolved from RNA plasmids, which are circular DNA molecules that can replicate independently of the host cell. RNA plasmids are common in bacteria, but they have never been found in humans before. Obelisks may have acquired the ability to encode proteins and to escape from the host cell, becoming more like viruses.

The researchers also wonder what obelisks do in the human body. They suggest that obelisks may have a symbiotic relationship with the human microbiome, helping the bacteria to survive or to communicate with each other. Obelisks may also have an effect on the human immune system, either by stimulating or suppressing it. Obelisks may also have a role in human diseases, such as cancer, autoimmune disorders, or infections. However, these hypotheses need to be tested with further experiments.

Obelisks: How Common and Diverse Are They?

The researchers estimate that obelisks are very common and diverse in the human body. They found more than 2,000 different types of obelisks in the saliva and stool samples of 37 healthy volunteers. They also found that obelisks are more abundant in the mouth than in the gut, and that they vary from person to person. The researchers believe that obelisks may be present in other body sites as well, such as the skin, the lungs, or the blood.

The researchers also compared the obelisks with those found in other animals, such as mice, dogs, cats, cows, and pigs. They found that obelisks are unique to humans, and that they have no close relatives in other species. This suggests that obelisks may have co-evolved with humans, and that they may have a specific role in human biology.

Obelisks: A New Frontier for Microbiology and Medicine

The discovery of obelisks opens a new frontier for microbiology and medicine. Obelisks are a new type of virus-like entity that challenges the existing classification and definition of life. Obelisks are also a new component of the human microbiome that may have important implications for human health and disease. Obelisks may also offer new opportunities for biotechnology and drug development, as they may have novel functions and properties.

The researchers hope that their study will inspire more research on obelisks and their role in human biology. They also hope that their study will raise awareness and curiosity about the diversity and complexity of life on Earth, and the potential for discovering new forms of life in unexpected places.