Related Experiment Video
Updated: Jul 4, 2025
07:20
Human Colonoid Monolayers to Study Interactions Between Pathogens, Commensals, and Host Intestinal Epithelium
Published on: April 9, 2019
9.1K
Viroid-like colonists of human microbiomes
Ivan N Zheludev1, Robert C Edgar2, Maria Jose Lopez-Galiano3
1Stanford University, Department of Biochemistry, Stanford, CA, USA.
Biorxiv : the Preprint Server for Biology
|January 31, 2024
Summary
Scientists discovered "Obelisks," a new class of RNA elements in the human microbiome. These viroid-like entities possess unique genetic features and are widespread globally, potentially impacting microbial communities.
Area of Science:
- Microbiology
- Virology
- Genomics
Background:
- Viroid-like elements, termed "Obelisks," were identified in human gut metatranscriptomic data.
- Obelisks exhibit distinct characteristics including circular RNA genomes, predicted secondary structures, and novel protein-coding regions.
Approach:
- Analysis of human gut metatranscriptomic data revealed a novel class of RNA elements.
- Phylogenetic analysis confirmed Obelisks form a distinct group unrelated to known biological agents.
- Large-scale genomic searches identified numerous Obelisk instances across diverse environments and continents.
Key Points:
- Obelisks are prevalent in human gut and oral microbiomes, with varying compositions across anatomical sites.
- Some Obelisks encode hammerhead ribozymes, suggesting potential catalytic activity.
- Obelisks were found within the bacterial species *Streptococcus sanguinis*, indicating potential host interactions.
Conclusions:
- Obelisks represent a previously unrecognized, diverse class of RNA elements colonizing global microbiomes.
- Their widespread presence and unique features suggest a significant, yet understudied, role in microbial ecosystems.
Related Concept Videos
01:29Bacterial Flora of the Large Intestine
451
The gut microbiome is formed by a vast and diverse community of bacteria that colonizes our large intestine. These bacteria start residing in the gut from birth and continue diversifying throughout life, influenced by factors such as diet, lifestyle, and stress. The gut bacterial community also includes bacteria from food and those that enter the colon through the anus.
The normal gut flora of the colon plays a critical role in generating essential vitamins such as vitamins K, B5, and B7.
The normal gut flora of the colon plays a critical role in generating essential vitamins such as vitamins K, B5, and B7.
451
01:51Prokaryotic Cells
122.5K
Prokaryotes are small unicellular organisms that include the domains—Archaea and Bacteria. Bacteria include many common organisms, such as Salmonella and E. coli, while the Archaea include extremophiles that live in harsh environments, such as volcanic springs.
Like eukaryotic cells, all prokaryotic cells are surrounded by a plasma membrane, have genetic material in the form of single, circular DNA, a cytoplasm that fills the interior of the cell, and ribosomes that synthesize proteins....
Like eukaryotic cells, all prokaryotic cells are surrounded by a plasma membrane, have genetic material in the form of single, circular DNA, a cytoplasm that fills the interior of the cell, and ribosomes that synthesize proteins....
122.5K
01:10Intracellular Movement of Viruses and Bacteria
2.8K
Intracellular bacteria and viruses often comprise a group of highly infectious pathogens that can cause several diseases. Bacterial pathogens include those belonging to the genus Rickettsia responsible for conditions such as rocky mountain spotted fever and the Mediterranean spotted fever; Chlamydia, a genus responsible for a sexually transmitted disease; Coxiella burnetii, an agent responsible for Q fever. Viral pathogens include vaccinia—a poxvirus, and herpes simplex virus—a...
2.8K
02:33Retroviruses
12.3K
Retroviruses and retrotransposons both insert copies of their genetic elements into the genome of the host cell. Thus, the viral genes are passed on when the host genome is replicated or translated. A typical retroviral DNA sequence contains 3-4 genes that encode the different proteins required for its structural assembly and function as a molecular parasite. This DNA is transcribed into a single mRNA, which is very similar in structure to conventional mRNAs, i.e., it is capped at the 5’...
12.3K
00:46Genomic DNA in Prokaryotes
43.9K
The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the nucleoid. The chromosome is tightly wound, or supercoiled, for efficient storage. Prokaryotes also contain other circular pieces of DNA called plasmids. These plasmids are smaller than the chromosome and often carry genes that confer adaptive functions, such as antibiotic resistance.
Genomic Diversity in Bacteria
Although bacterial genomes are much...
Genomic Diversity in Bacteria
Although bacterial genomes are much...
43.9K
01:10Retrovirus Life Cycles
46.0K
Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the...
46.0K