After a world voyage that sampled the ocean from pole to pole, scientists have discovered nearly 200,000 inhabitants of marine viruses.
In the marine ecosystem, tiny creatures called microbes account for most of the ocean's biodiversity and over half of its biomass. However, much less is known about the viruses – packets of genetic information replicating in other living things – in the oceans. The scientists studied the viral community of marine viruses, their diversity and their function, in particular the effects on microbes. On Thursday, they announced the creation of a huge, global catalog of marine viruses, an important step in answering many of these questions.
"He expands our knowledge of the biological entities on our planet," Ann Gregory, opposite Gizmodo.
The data are from 146 samples taken on board the schooner Tara on several expeditions, including 41 samples from a voyage to the Arctic Ocean in 2013. The researchers first had to find out if the genetic material in the sample was viral or not, comparing different bioinformatic tools with known viruses, said study author Ahmed Zayed, a graduate student at Ohio State University. Then they compare the DNA strands with each other to divide them into virus populations.
The analysis revealed 195,728 virus populations, 12 times more than the previous analysis of a smaller tare dataset. A closer look revealed that these populations appear to be organized into five meta-communities, which researchers call ecological zones: Arctic; Antarctic; deeper than 2,000 meters; 150 to 1,000 meters; and temperate / tropical waters with depths of 0 to 150 meters. It is perhaps surprising that latitude did not predict viral diversity.
It's an exciting work. Microbes are perhaps the main driver of the biochemical processes of the ocean, and microbes are infected by viruses. "I think people are aware that viral diversity far exceeds that of large-scale microbial diversity," said Alison Buchan, a professor at the University of Tennessee, Knoxville, to Gizmodo. "However, there have not been many studies that have attempted to quantify the extent of this diversity."
What do you do with such a big record? They mainly research to better understand the roles of all these viruses. Just as the rabies virus can increase the aggression of an infected animal to facilitate transmission, some of these viruses may be important for the ocean's chemical processes. Many of them also lead to the death of the microbes. And maybe this huge new supply of genetic information contains something useful to humans.
"Maybe you can win it for new genes," Gregory said. With this genetic information, researchers may discover novel antibiotics in May.
This record is certainly not comprehensive, warned Gregory and Zayed. It only includes viruses that contain DNA, not those that contain RNA (DNA is simply a pair of complementary strands of genetic material, while RNA is a single strand). Buchan also noted that this is more of a snapshot. Six months later, they may have had different results, she said.
This research is a great reminder that the oceans, as we know life on Earth, are full of unknowns.