The discovery of viruses that secretly rule the oceans of the world. Know the details

Scientists report that thousands of mysterious viruses recently discovered in the world’s oceans are having a major impact on ecosystems, in part by “reprogramming” the hosts they infect, and the new research, published in the journal Science, focuses on viruses containing RNA. It is a molecular cousin of DNA.

According to the “RT” website, examples of RNA viruses are abundant in human diseases, for example corona and influenza viruses are dependent on RNA, but when it comes to RNA viruses in the sea, scientists only learn about the diversity that can be found and the range of hosts that can infect it.

Based on the new study, co-lead author Guillermo Dominguez Huerta, who was a postdoctoral researcher in viral ecology at Ohio State University (OSU), said at the time of the study: “We are sure that most RNA viruses microbial eukaryotes infected in the sea. ” Fungi, protists and, to a lesser extent, invertebrates and eukaryotes are organisms with complex cells that carry their genetic material within the nucleus.

These viral hosts – fungi and protists, which include algae and amoebas – draw carbon dioxide from the atmosphere and thus affect the amount of carbon stored in the ocean. By infecting these organisms, the RNA viruses may be affecting how carbon in general flows through the ocean, said Stephen Wilhelm, lead researcher in the research group for aquatic microbial ecology at the University of Tennessee Knoxville, who was not involved in the new study. not.

“Given the abundance of RNA virus particles, knowing that they can do so continues to build the story of how important viruses are to the world in terms of how energy and carbon flow,” Wilhelm said.

Dominguez Huerta and colleagues reported earlier this year that they had found more than 5,500 previously unrecognized RNA viruses in the world’s oceans.

For that study, published April 7 in Science, the team analyzed 35,000 water samples collected from 121 sites in the five oceans by the Tara Oceans Consortium, an ongoing global study examining the impact of climate change in the oceans.

These water samples are full of plankton – microorganisms that float in the stream and often act as hosts for RNA viruses.

To discover the viruses within this plankton, the researchers scanned all the RNA in the plankton cells to find a specific fragment of the genetic code called the RdRp gene.

“This is the only coding sequence commonly found in all RNA viruses,” says Dominguez Huerta, who is currently a scientific consultant at Virosphaera. However, the RdRp gene is absent in cells and other virus types.

In the end, the team found so many RNA viruses hidden in plankton that they proposed to multiply the number of phyla of RNA viruses – the broad taxonomic group under the “kingdom” – from five to 10 to to classify all.

From there, the researchers wanted to better understand how these viruses spread around the world.

Scientists have determined that viral communities can be categorized into four main regions: Arctic, Antarctic, temperate and tropical, epipelagic, meaning near sea level, and temperate and tropical Mesopelagic, which are approximately 656 to 3,280 feet (200 to 1,000 meters). ) means under water. Interestingly, it appears that the diversity of viruses was greater in the polar regions, although there are a variety of hosts infected in warm waters.

To identify viral hosts, the team used several strategies; For example, one method involves comparing the genomes of RNA viruses from known hosts with those of newly discovered viruses, and another method involves searching for rare sections of viral RNA in the genomes of host cells, where pieces of DNA are sometimes found in the could be left eye. It.

This analysis revealed that many RNA viruses in the sea infect fungi and protists, some invertebrates infect and a small proportion infect bacteria.

Huerta said the team also unexpectedly discovered that 95 of the viruses carry genes that they “stole” from their host cells, and in the host, these genes help metabolic processes within the cell, and the researchers concluded that this discovery indicates that viruses have tampered with the metabolism process in some way, in order to maximize the production of new viral particles.

After identifying hosts that are likely to infect marine viruses, the team determined that about 1,200 viruses could be involved in carbon exports – the process by which carbon is extracted from the atmosphere, incorporated into marine organisms and then “exported” to the deep sea. where those organisms sink.On the bottom of the sea after death.

The deeper this carbon stock is, the more likely it is to be stored in the ocean before being recycled into the atmosphere, according to the Monterey Bay Aquarium Research Institute. models.

The new study suggests that infection of marine organisms with RNA viruses may be another previously unrecognized factor that drives the flow of carbon into the oceans, as viruses alter the cellular activity of the host they infect.

RNA viruses can also cause carbon flux by separating their hosts and wasting trapped carbon in the ocean, Wilhelm said, as viruses often explode from their host after rapidly replicating inside.

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