Recent research reveals the critical function of extracellular vesicles in facilitating gene transfer among sea microorganisms, offering a fresh perspective on gene exchange in marine ecosystems. This discovery introduces the concept of ‘protected extracellular DNA’ (peDNA) as a broader term for genetic carriers, expanding the focus beyond just viruses and suggesting new avenues for ecological studies.
It’s now understood that extracellular vesicles play a more significant role in horizontal gene transfer in marine environments than previously believed.
Microorganisms in the ocean are constantly involved in the exchange of genetic information. This process, known as horizontal gene transfer (HGT), is crucial for the evolution of various species and contributes to the spread of antibiotic resistance among bacteria. Earlier theories suggested that this gene exchange primarily occurred through direct cell contact, free-floating DNA, or through viruses.
A team led by Susanne Erdmann at the Max Planck Institute for Marine Microbiology in Bremen has demonstrated the importance of extracellular vesicles in the genetic information transfer process in marine life.
Tiny yet numerous: Viruses, GTAs, EVs
Viruses, although small, are abundant in seawater, with up to 10 million present in every drop. They can carry not only their DNA but also parts of the DNA from their host organism to other cells.
The study of viruses involves filtering seawater samples through very fine filters to isolate viruses, GTAs (gene transfer agents), and extracellular vesicles (EVs).
For this particular study, researchers collected water samples from the North Sea Island of Helgoland. The research was facilitated by Silvia Vidal from the Max Planck Institute for Marine Microbiology.
GTAs are virus-like entities that carry only host DNA, while EVs are membrane-bound vesicles that detach from the host cell’s surface. EVs can transport a variety of molecules, including enzymes, nutrients, RNA, and often DNA fragments.
The significant role of EVs in transporting genetic material
Contrary to previous assumptions, Erdmann’s team found a substantial amount of host DNA in the seawater samples that was not carried by viruses. Identifying the transport mechanism for this DNA was complex. Erdmann, who heads the Max Planck Research Group Archaea Virology at the institute in Bremen, described the method used to associate DNA sequences with specific transport mechanisms, such as viruses, GTAs, or EVs.
The findings indicated that a large portion of the DNA was transported via extracellular vesicles, not through the traditionally recognized pathways.
Extracellular vesicles: More than cellular debris
Previously considered cellular waste, extracellular vesicles have been recognized in the past fifteen years for their diverse cellular functions. Dominik Lücking, a Ph.D. student in Erdmann’s group and the study’s primary author, emphasized the fundamental role of EVs in genetic material exchange between cells. The research has been published in the journal ISME Communications.
The authors recommend a shift in terminology, moving from ‘virome’ to ‘protected extracellular DNA’ or peDNA, to more accurately describe the variety of genetic carriers in marine samples.
This study lays the groundwork for future peDNA research in various ecosystems, including oceans and beyond. It opens the door for exploring the role of extracellular vesicles in other environments like soil, freshwater systems, or even the human gut. Erdmann anticipates further discoveries in the realm of horizontal gene transfer in various ecosystems.
Reference: The study “Extracellular vesicles are the main contributor to the non-viral protected extracellular sequence space” by Dominik Lücking, Coraline Mercier, Tomas Alarcón-Schumacher, and Susanne Erdmann was published on 17 October 2023 in ISME Communications.
Frequently Asked Questions (FAQs) about Extracellular Vesicles Ocean
What is the new discovery about gene transfer in ocean microorganisms?
Recent research has found that extracellular vesicles play a crucial role in horizontal gene transfer among ocean microorganisms. This challenges previous beliefs that gene exchange primarily occurred through direct cell contact, free-floating DNA, or viruses.
What are extracellular vesicles and why are they significant?
Extracellular vesicles (EVs) are membrane-bound vesicles that detach from a cell’s surface. They are significant because they can transport a variety of molecules including DNA, and play a major role in the transfer of genetic material between cells in marine environments.
How do extracellular vesicles contribute to horizontal gene transfer in oceans?
Extracellular vesicles contribute to horizontal gene transfer by carrying DNA fragments between microorganisms in the ocean. This process is a key factor in the evolution of marine species and the spread of antibiotic resistance among bacteria.
What was the methodology used in this study on extracellular vesicles?
The study involved filtering seawater samples to isolate viruses, gene transfer agents (GTAs), and extracellular vesicles (EVs). DNA sequences were then analyzed to determine their specific transport mechanisms, revealing the significant role of EVs.
What impact does this study have on future research?
This study suggests a shift in focus from the traditional ‘virome’ concept to ‘protected extracellular DNA’ or peDNA. It lays the foundation for future research in various ecosystems, not just marine, but also soil, freshwater, and the human gut.
More about Extracellular Vesicles Ocean
- Max Planck Institute for Marine Microbiology
- ISME Communications Journal
- Horizontal Gene Transfer Overview
- Extracellular Vesicles Research