Pioneering discovery: Scientists identify giant viruses in the Greenland ice sheet
Scientists at Aarhus University in Denmark announced the discovery in an article published in the journal "Microbiome". This discovery could have significant implications for the study of melting ice in the Arctic.
The bag in the image, which apparently is just dirty water, contains several microorganisms, including darkening ice algae - Photo Reproduction/Laura Perini
Researchers at Aarhus University in Denmark announced the discovery of giant viruses in the Greenland ice sheet that infect algae and can influence their growth. This discovery not only offers new insights into microbial life in extreme environments, but also has important implications for the study of Arctic ice melt. The announcement was made through an article published in the magazine "Microbiome".
What are Giant Viruses?
Giant viruses, also known as megaviruses", due to their gigantic size compared to common viruses, are a special type of large nucleocytoplasmic DNA viruses, which have much larger genomes and more complex structures than typical viruses. While most viruses have just a few dozen genes, giant viruses can have hundreds or even thousands of genes.. That is, they contain many unique genes not found in other life forms. They were first identified in seawater and soil samples, but this is the first time they have been discovered in an ice sheet.
Discovery
The samples with the collections removed from the ice. A small pipette contains many microorganisms. - Photo Reproduction/Laura Perini
The team of researchers, when analyzing ice samples, found several giant viruses, some of which have an average size of around 2.5 micrometers. To make a comparison, common viruses are between 20 and 200 nanometers (where 1 nanometer is equivalent to 0.001 micrometers), while bacteria usually have an average size between 2 and 3 micrometers. These similarly sized microorganisms were first discovered in 1981, when scientists found them in the ocean.
These viruses specialized in infecting marine green algae have also been found in terrestrial soil and even in humans. However, this is the first time that giant viruses have been found inhabiting the microalgae-dominated ice and snow surface of Greenland.
During sampling campaigns in Greenland, researchers found these unusual viruses in places including the south side of the ice sheet and three glaciers on the east side. The samples were collected from cryoconite sediments, ice cores and layers of green and red snow, which are colored due to the growth of algae. Researchers found these unusual viruses during sampling campaigns in Greenland, in locations including the south side of the ice sheet and three glaciers on the east side.
Samples were collected from cryoconite sediments, ice cores and layers of green and red snow, which are colored due to algae growth. The main hypothesis is that these viruses feed on algae found in snow and can act as a natural mechanism for regulating their populations.
Meaning of Discovery
Laura Perini, postdoctoral fellow in the Department of Environmental Science at Aarhus University, highlights the importance of controlling algal growth on polar ice to prevent the surface from darkening and losing its ability to reflect sunlight. According to her, viruses associated with these algae could play an important role in reducing ice melt. Despite limited knowledge about these viruses, the researcher believes that studying them further can provide answers about their specificity and efficiency.
Research methodology
Despite their size, these viruses are not visible to the naked eye, and scientists have not yet been able to observe them even using an optical microscope. The discovery was made only through DNA analysis in the samples collected. By examining this broad set of information for specific genes, the researchers found sequences similar to those of already known giant viruses.
Furthermore, to confirm that the viral DNA did not come from long-dead microorganisms, they also extracted all the mRNA from the samples, which are molecules responsible for providing the instructions for producing the proteins that the virus needs. If these molecules are present, it means the virus is active. Perini stated that, by finding the same markers present in the total DNA in the sequenced mRNA samples, we can conclude that the viruses are alive and active.
Next steps
Scientists are hoping that through further studies they can gain a deeper understanding of the giant viruses and their role in the Arctic ecosystem. This is particularly important due to the high temperatures being recorded globally, which are leading to a significant decrease in the extent of sea ice in the region. Perini also highlighted that a new scientific study will be launched later this year with additional information about the giant viruses that infect microalgae cultivated on the surface of the Greenland ice.
