A virus frozen in the Siberian permafrost since the Ice Age has been revived.
P sibericum infects amoeba, not humans, and is huge by viral standards. It has 500 genes, while the influenza virus has just eight – proving that when it comes to making you sick, size doesn’t matter. At 1.5μm wide it can be seen with an optical microscope, and is the size of small bacteria. The results were reported in PNAS. P sibericum’s large genome makes it a Megaviridae, but it differs substantially from previously known species. The paper’s authors, led by husband and wife team Jean-Michel Claverie and Chantal Abergel of Aix-Marseille Université, speculate that the discovery could represent a link between previously known Megaviridae and Iridoviruses, a family of viruses that infect invertebrates and occasionally fish and reptiles. Claverie and Abergel discovered the first supersized virus in 2003 and several others since. Pithos is the Greek word for containers used to store food and wine, whose shape the virus resembles. “We’re French, so we had to put wine in the story,” Claverie told Nature.
The virus itself is harmless, but the researchers responsible warn that Global Warming could release more malign lifeforms from the frozen ground. The French National Centre for Scientific Research (CNRS) warned, that the discovery, “Has important implications for public-health risks in connection with exploiting mineral or energy resources in Arctic Circle regions that are becoming more and more accessible through global warming.” The virus was found at the bottom of a 30m sample collected in Chukotka, East Siberia, and named Pithovirus sibericum. It follows from the discovery that the seeds of plants buried at the same time could be brought to flower.Even aside from its great age, the Pithovirus has enough unusual features to attract attention. At one end it has a honeycomb structure capping its opening. Where most viruses take over the nucleus of their host’s cells to reproduce, this one uses the cytoplasm. While having a large genome by the standards of most viruses, the Pithovirus has a third as much material as some Megaviridae, despite being even larger spatially. “That huge particle is basically empty,” says Claverie. “We thought it was a property of viruses that they pack DNA extremely tightly into the smallest particle possible, but this guy is 150 times less compacted than any bacteriophage [viruses that infect bacteria]. We don’t understand anything anymore!” “The revival of viruses that are considered to have been eradicated, such as the smallpox virus, whose replication process is similar to that of Pithovirus, is no longer limited to science fiction,” the CNRS statement continued. “The risk that this scenario could happen in real life has to be viewed realistically.”
An expedition to the depths of the New Hebrides trench has found it inhabited by different life forms from other deep ocean trenches. Shockingly, the researchers think even in these locations, the most remote on the planet from human influence, climate change may be a threat. Deep sea-trenches occur when an oceanic plate is pushed under another plate. Although trenches can be thousands of kilometers long, they’re so narrow they take up only a small portion of the globe. “These new finds are a stark reminder that even the deepest parts of the world are intrinsically linked to the productivity of the surface waters,” said Jaimieson. “Should the current system change, it is highly likely to have significant cascading effects on the deep sea community. The deep sea is potentially a kind of silent victim in the era of a changing climate.” The phenomenal water pressures within the trenches make them a challenge to explore, leading to the observation that we know less about the bottom of the ocean than we do about the surface of the Moon.
The New Hebrides trench, 7km deep and 1500km north of New Zealand has been particularly neglected in the past, and when a mission visited it using an underwater robot late last year they were surprised with the images returned.
“What we found was an entirely different deepwater fish community. Fish were surprisingly few in number and low in diversity and not at all what we expected. The fish we would always expect to see, the grenadiers, were completely absent. The fish that dominated the area were a group called cusk eels which are far less conspicuous elsewhere,” said Alan Jamieson of the Oceanlab at the University of Aberdeen, UK. “As well as the difference in biodiversity we also stumbled across another surprise – the area in and around the New Hebrides Trench was swarming with large bright red prawns which are typically seen in very low numbers in other areas.” While the depths of the trenches might be expected to resemble each other more than the waters above, Jamieson believes differences in the surface waters may be responsible. “If you look at the New Hebrides trench, and where it is geographically, it lies under very unproductive waters – there is not a lot happening at the surface of the tropical waters. It seems the cusk eels are specialists in very low food environments, whereas the grenadiers require a greater source of food.” Film director James Cameron famously became the first person to travel to the bottom of the deepest trench of all, the Mariana, for 50 years in 2012. Cameron described the depths as almost devoid of life. While this might have been a result of the 1000 atmospheres of pressure crushing all but the hardiest creatures, it is also possible that the distance from the continental shelf is more significant, with nutrients less likely to be washed down in such locations.
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